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In this paper, first of all improved techniques are described to measure packaged MEMS or MOEMS surfaces through- transmissive-media (TTM) at higher magnifications. Secondly, a universal housing is presented for TTM-objective line and for different material and thickness of glass. Finally, the measurement results for low and high magnifications will be given for dispersion-compensated objectives, as well as some MEMS application examples.
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We present measurements and numerical findings of resonance effects in aluminum metal gratings on fused silica substrates. The spectral characterization measurements of the gratings are done with white light in the wavelength range of 600nm up to 1600nm. Nonlinear effects have been studied with a fs-laser system at the resonance wavelength of the gratings. The metal layers of the gratings are 20nm to 40nm thick, the gratings period is 500nm or 1000nm and the narrow gaps between the metal stripes consist of about 8nm thick aluminum oxide stripes. These structures were produced with a special micro structuring process and coating technique. Numerical modeling shows that light can pass through these gratings for a characteristic resonance wavelength. For fs-pulses we found the transmission to decrease for increasing pulse energy.
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This paper summarizes some of latest developments by QED Technologies (QED) in the field of high-precision polishing and metrology. Magneto-Rheological Finishing (MRF) is a deterministic sub-aperture polishing process that overcomes many of the fundamental limitations of traditional finishing. The MR fluid forms a polishing tool that is perfectly conformal and therefore can polish a variety of shapes, including flats, spheres, aspheres, prisms, and cylinders, with round or non-round apertures. Over the past several years, QED's Q22 family of polishing platforms, based on the MRF process, have demonstrated the ability to produce optical surfaces with accuracies better than 30 nm peak-to-valley (PV) and surface micro-roughness less than 0.5 nm rms on an ever-widening variety of optical glass, single crystal, and glass-ceramic materials. The MRF process facilitates the correction of the transmitted wavefront of single elements and/or entire systems, as well as enabling the inducement of specific desired wavefront characteristics (i.e., other than making surfaces perfectly flat or spherical), which is beneficial for applications such as phase correction or other freeform applications. QED's Sub-aperture Stitching Interferometer (SSI) complements MRF by extending the effective aperture, accuracy, resolution, and dynamic range of a phase-shifting interferometer. This workstation performs automated sub-aperture stitching measurements of spheres, flats, and mild aspheres. It combines a six-axis precision stage system, a commercial
Fizeau interferometer, and specially developed software that automates measurement design, data acquisition, and the reconstruction of the full-aperture map of figure error. Aside from the correction of sub-aperture placement errors (such as tilts, optical power, and registration effects), the SSI software also accounts for reference-wave error, distortion, and other aberrations in the interferometer's imaging optics. By addressing these matters upfront, we avoid limitations encountered in earlier stitching work and significantly boost reproducibility beyond that of the integrated interferometer on its own.
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Because of the demand for better performance in optical systems, there's a continuing effort to find more efficient ways of producing large optics. FOERC's involvement in developing new techniques for the fabrication of large optical components has resulted in the AOMTIL (Advanced Optical Manufacturing Technology Integrated Line). The purpose of the AOMTIL is to demonstrate the novel manufacturing process and technology for large optics in modern optical system. The progress of AOMTIL is presented in the paper. There are mainly four parts in AOMTIL as follows, the ultra-precision grinding, deterministic figuring or polishing, perfect surface conditioning and precision optical metrology. The preliminary results of the AOMTIL show the possibility to yield more than 20 pieces large optical components per month and the advantages in achieving high accuracy. Optical flats larger than 500mm in diameter have been produced with flatness better than λ/10 peak to valley.
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Non-equilibrium ionization plays a critical role in Z-pinch gas discharge produced plasma (GDPP) EUV source. However, the physics of the processes, plasma and surface discharges produced, magneto-hydrodynamic, photon radiation transport, and plasma-electrode interactions, which lead to EUV emission, is intrinsically complex. Many simplifying assumption are inevitable with numerical simulations, resulting in low-credibility outcomes. With the learning and generalization abilities, artificial neural networks (ANN) have been applied to model and optimize a Z-pinch plasma source, which is characterized with a experimental design at varied operational parameters including electric power input, applied voltage/current, pulse repetition, MPC parameters, electrode geometry, xenon flow rate as well as convention efficiency, EUV source size, radiation power etc.
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A hydrofluoric acid (HF) bonding method has been applied for the thin film filters integration. The quality of bonding was examined by the evaluation of bonding strength and the observation of bonding interface. The bonding strength depends on the applied pressure and temperature during bonding. The maximum bonding strength was more than 10 MPa. High quality bonding interface was observed by scanning electron microscope and transmission electron microscope. A color filer array of red, green and blue (RGB) was designed to separate the white light. The filters were integrated into a glass body successfully by HF bonding. Its transmittance spectra were unchanged after heating at 450oC for 20 hours. In addition, integration of filters was carried out to fabricate an optical demutiplexer for coarse wavelength division multiplexing system. It was confirmed that the integrated filter array acted as a demutiplexer.
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Zinc sulphide (ZnS), a significant Infrared (IR) optical material, is applied to window, lens and dome in many optoelectronic systems where a suitable antireflection (AR) and protective coating is required to enhance the transmission. In this paper, the transmittance characteristics and deposition process considerations of AR coatings on ZnS substrate are investigated in detail. Through the theoretical analyses and real process experience of common materials such as magnesium fluoride (MgF2), silicon dioxide (SiO2) and silicon monoxide (SiO), and the deposition and environmental test of yttria (Y2O3) coating, an optimum 5-layer structure is finally employed, which consists of a bonding layer with ZnS substrate, thin Y2O3 film, and a 4-layer stack of germanium (Ge) and SiO as high and low refractive index coating materials, respectively. Then, experimental implementation of the AR design is presented, especially the deposition of Y2O3, Ge and SiO materials. The fabricated coating conforms to the tests of humidity, temperature shock, abrasion and adhesion given in the MIL-C-48497 environmental stability standards and shows an average transmittance of 96% for a given application in 3-5μm wavelength region with a peak beyond 98% at 4.2μm on 3mm thick ZnS substrate. Moreover, due to stable deposition process of Ge and SiO, better AR coating with higher spectral transmission can be easily designed and fabricated through more layers of Ge and SiO.
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Firstly, a reverse synthesis method is outlined for the determination of the optical constants of infrared coatings from transmittance spectrum data by optimizing the physical thickness, refractive index and extinction coefficient, which can apply to all kinds of transmission spectra and do not rely on the existence of interference fringe patterns and the absorption of substrates. A lot of deposition experiments with the ion-assisted deposition (IAD) technique have firstly done about infrared optical materials ZnS, YF3, Ge and DLC (diamond-like-carbon), in order to obtain high dense and low absorbance layers in the 3-5μm and 8-12μm spectral windows. Using the reverse synthesis method, the refractive index and extinction coefficient of these materials have been obtained accurately. The appropriate deposition parameters and the problems from the deposition process are in detail discussed in this paper. YF3 has been then associated with ZnS and Ge layers so as to obtain antireflection coatings with high performance on Ge and Si substrates in 3-5μm and/or 8-12μm range. In addition, a novel multi-layer infrared AR coating utilizing DLC film as one of the low index films has also been developed for Si and Ge substrates. The optical performance is satisfied (average transmittance is no less than 97%, maximum transmittance is more than 98%, from 8μm to 11.5μm), which is better than that of a single film of one quarterwave DLC coating with interior surface multi-layer AR coated on Ge substrates. However, the adhesion between multi-layer AR coatings and DLC coating is not well, leading to coatings falling off from substrates after humidity test and moderate abrasion test, according to MIL-F-48497. Through a lot of experiments, a non-absorbing coating material has been found as bonding layer to solve this problem. The optical properties of three kinds of infrared coatings and the environmental and physical durability test results including high/low temperature test, abrasion test, salt solubility test, etc, are also in detail presented in this paper.
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The low temperature control system of single photon detection device avalanche photodiode (APD) is researched. Avalanche photodiode is used for photon detector with high sensitivity. In order to reduce dark current, its operating environmental temperature needs to be lowered by a semiconductor thermoelectricity cooling apparatus. In accordance with the peculiarity of single photon detection system and the technology of semiconductor thermoelectric Peltier cooling, an APD cooling control system is designed and produced by properly selecting components and using some necessary control circuits. The accuracy and the lowest temperature of this control system can amount to 0.1oC and -50oC, respectively. Above all, the low temperature can be adjusted successively.
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Recently, RB SiC as a two-phase mirror material has taken particularly attraction because of its readily formable to near-net-shape. But it is difficult to obtain high quality optical surface due to the polish rate differences between SiC and Si components. Typical defects, such as polishing scratches, pores and surface irregularities which are mostly caused by the inhomogeneity of SiC and Si phase distributions are easily detected. The solution is the addition of a thick coating to cover these surface defects which may be polished to improve the quality of optical surface. Two thick coatings, PVD Si and PVD SiC, were applied by RF magnetron sputtering in this paper. After a series of sputtering parameters optimization, both the coatings' surfaces show fewer defects than that of RB SiC after polished. Results from this PVD progress, the surface morphologies' changes in optimization and the surface defects after polished are presented.
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V2O5 and Ta2O5 mixed powders were pressed as sputtering target. Ta-doped vanadium oxide thin films were deposited on SiO2 substrates by modified Ion Beam Enhanced Deposition (IBED) method. The VO2 film with a preferential orientation (002) was formed after post-annealing in nitrogen or argon atmosphere. The measurement results of resistance dependence on temperature indicated that the vanadium dioxide films showed a typical characteristic of phase transition. The phase transition temperature of the IBED VO2 film doped with 3 atm.% Ta decreased from 68oC to about 48oC. The reasons why the Ta-doping decrease the phase transition temperature were as followed: the atom radius of Ta larger than that of V atom, which introduce strain in the grain; the replacement of When V4+ replaced by Ta5+ the ionic bond could elongate and introduce superfluous electrons in the d valence shell, then make the gap of d energy band to decrease.
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Aspheric surface can be thought as being enveloped by a series of spherical surfaces with their centre on the same axis but having different positions. These spherical surfaces are tangent with the aspheric surface. A Φ600 CNC aspheric grinding machine with this novel operating principleis manufactured. The machine was reported in August 2005. We choose δp, ε and αp as the key parameters of our grinding machine. δp is the distance between the cup shaped tool's bottom and the vertex of the aspheric surface. αp is the rotational angle of the cup shaped tool. ε is the space angle of the cup shaped tool during the fabrication process of convex aspheric surface. This grinding machine can be used to fabricate a conic concave aspheric surface continuously about three hours. But we need change the cup shaped tool one time when we fabricate a conic convex aspheric surface in also about three hours. The grinding machine can also be used to fabricate high-order aspheric surface. In the last report we intoroduced that we used this machined fabricating a RC telescope system's primary and the secondary mirror. The PV-value is less than 5μm for the primary Φ350 concave hyperbolic aspheric surface which departure is about 55μm. The residual errors can be removed easily. This machine have been improved both the cup shaped tool and filter system. Using this grinding machine we have fabricated another Φ460 concave aspheric surface during the last month. The PV-values of these two mirrors are both less than 7μm. The aspheric grinding machine can be fitted for fabricating concave conicoids.
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We present our experimental results on fabricating optical waveguides by laser micromachining, structure-light illuminating, and optical spatial dark solitons in iron doped lithium niobate (LiNbO3:Fe) crystals. After that we propose a novel approach to fabricate three-dimensional (3-D) optical circuits in LiNbO3 crystals by combining the three light-induction techniques listed above. By employing laser micromachining, a curved and a Y-branches waveguides are successfully fabricated. With binary and SLM-prepared optical masks, Y-branches and gradient planar waveguides are experimentally demonstrated. By utilizing one-dimensional (1-D) optical spatial dark solitons, planar, Y-branches, and square channel waveguides are formed. The results show that each of the three methods can be employed to write optical waveguides in LiNbO3 crystals. By combing the three methods, 3-D light circuits can be created in 45o-cut bulk crystals by several procedures. Initially, a quasi-planar optical circuit is created in a thin layer of the crystal by structure-light illuminating with an optical mask. Then, a planar circuit is generated by utilizing a 1-D dark soltion. And then, form multi-layer planar circuits are formed by altering the positions of the crystal or writing beam. Finally, laser micromachining is used to link the different layers to form a 3-D light circuit. Furthermore, functional 3-D integrated optical system may be implemented by using the proposed approach.
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Using pyromellitic dianhydride (PMDA) and bis(4-aminophenyl) ether (ODA) as monomer materials, the polyamic acid (PAA), a precursor of polyimide (PI), was synthesized. PAn was doped and modified with the polyamic acid by solution mixing method, and the modified PAn/PAA blend with good solubility and forming-film was obtained. Then uniform PAn/PI complex thin film with good forming-film and thermo-stability can be prepared by solvent casting and followed by thermal imidization process at the temperature of 150oC-250oC for 60 min. Conductance experiments showed the surface conductivity of PAn/PI thin films can raise to 10-5S from 10-10S and change with the increase of the content of PAA. IR and UV-vis spectra showed that it has a chemical doping reaction between PAn and PAA during mixing, and the absorption of PAn/PI complex films in UV-vis region appears red shift and the peak shape becomes broad. The degenerate four-wave mixing experimental results showed that the third-order optical nonlinear susceptibility χ(3) of PAn/PI thin films can be markedly enhanced and the maximum χ(3) can reach 8.85×10-10esu, which presents good third-order nonlinear property.
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The Mirror-Confinement-type Electron Cyclotron Resonance (MCECR) plasma source has high plasma density and high electron temperature, and it is quite useful for plasma processing, and has been used for etching and thin-film deposition. Carbon films have received much attention recently due to their interesting properties such as extreme hardness, high electrical resistivity, low coefficient of friction, superior mechanical properties, chemical inertness, biocompatibility, high transparency and chemical inertness, which are close to those of diamond. In this paper, the carbon films about 50nm thickness were deposited on Si (100) by MCECR plasma sputtering the sintered carbon target with the argon plasma, and its properties were studied. The bonding structure of the film was analyzed by using the x-ray photoelectron spectropscopy (XPS) and the nanostructure was evaluated with the high-resolution transmission electron microscopy (HRTEM). The tribological properties (friction coefficient, wear rate, and wear life) of the film are investigated by using the Pin-on-Disk tribometer under the conditions that the normal load is 1N and the sliding velocity is 0.05m/s. The nanohardness of the films was measured by using the nanoindenter under conditions that the maximum displacement is 30nm and the maximum load is 500μN. The surface morphology was studied by using the atomic force microscope (AFM).
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Aspherical optics are more and more exploited in optical set-up since they reduce the number of components and therefore the overall size and weight of the system. Their manufacturing has been made easier by ion beam etching for many years. Nevertheless, the ablation rate has to be known accurately for each material and the degradation of the surface roughness has to be taken under control. Some examples of achievements will be shown. The main key feature is the knowledge of the original absolute shape of the surface to be figured. In some cases, interferometric measurement is not well suited and heavy to set up for high aspherical surfaces with deep sag. To avoid the drawbacks of interferometry measurements, a low cost scanning measurement device has been designed and built whose performance allows defining the topology of any surface up to 150 * 90 mm2 area with an accuracy better than 80 nm. Perspective of extension to larger surface will be presented.
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Machining of aspheres represents an extra field in the manufacturing of optical components. The deviation from the sphere has a big impact on machining and testing equipment, tools and technologies, achievable specifications and costs. The production of aspheres deals with special problems such as mid-spatial frequency errors, centering tolerances and slopes, not known in that degree from manufacturing of spheres. Over the past 20 years JENOPTIK Laser, Optik, Systeme GmbH has gained a wide experience of this application area. Recent results give a review on what is required to execute the transition from standard quality to high-precision aspheres, off-axis parts and free forms.
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A new photoelectric model of silicon based position sensitive detector (PSD) is built and the formulas of the photocurrent and spectral response are got with it. The effect of every layer thickness and SiO2 thickness to the spectral response is analysis and calculation. The spectral response of PSD is affected by the thickness of p layer mainly at short wavelength and by the thickness of the depletion layer mainly at long wavelength. With the results, a new silicon based near infrared two dimensional pincushion PSD is designed and fabricated. Some necessary tests show that the peak spectral sensitivity of our device is 0.626A/W at 920nm wavelength.
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A novel polishing and shaping process called fluid jet polishing (FJP) is introduced in this paper. Different from classical polishing methods, the material is removed by collision and shearing actions between the abrasive particles and the work piece in FJP, and the classical Preston Equation does not represent the polishing process correctly. It is necessary to establish a new mathematical model to do this. By using monofactorial experimental method, the important process parameters of FJP including working pressure, processing time and the rotational speed of the work piece were investigated in experiments. Based on the experimental results, the expressions between the important process parameters and the amount of removed material were constructed through data fitting. And then we put forward a new mathematical model to describe the polishing process of FJP, and control the amount of removed material quantitatively. The construction of this equation is a theoretical basis to realize numerical controlled fluid jet polishing, and foundation of applying this technology to modern optical fabrication
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Magnetorheological finishing (MRF) is a technique in which a magnetic-field stiffened ribbon of MR fluid is used to polish a workpiece. MR fluids are essentially suspensions of magnetizable particles immersed in a nonmagnetic fluid. These complex fluids show a unique ability to undergo rapid, nearly completely reversible, significant changes in their mechanical and optical properties upon application of an external magnetic field. The aim of this work is essentially to investigate the effect of microstructure and viscosity behavior of magnetorheological suspensions under the external electro-magnetic field. A viscometer equipped with a circular shape electro-magnetic coil around the testing tube is used. The viscosity of the MR fluids is experimentally studied with the change of the magnetic density. The microstructure and behavior of bending chains in MR fluids are observed by applying an electro-magnetic field.
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This research investigates the diamond grinding mechanism of optical glass and the resulted surface and sub-surface by a novel ultra-stiff machine tool, Tetraform 'C'. During the grinding process, an acoustic emission (AE) sensor and a piezoelectric dynamometer were used to monitor the grinding process and the grinding force components correlating to different characteristics of the material removal transition. SEM and AFM microscopes were used to evaluate the ground workpiece surface topography and sub-surface integrity. The nano-indentation technique was applied to evaluating the ground glass surface properties in terms of nano-hardness and elastic modulus. The Experimental results show that for BK7, nanometric quality surfaces (Ra < 5 nm) with minimal subsurface damage depth (< 1μm) could be achieved with a relatively large diamond grit size (6-12μm) metal bonded grinding wheel at a high material removal rate, due to the ultra high closed loop stiffness of Tetraform 'C'.
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Sphere lenses have been used for long time. But it is well known that sphere lenses theoretically have spherical aberration, coma and so on. And, aspheric lenses attract attention recently. Plastic lenses are molded easily with injection machines, and are relatively low cost. They are suitable for mass production. On the other hand, glass lenses have several excellent features such as high refractive index, heat resistance and so on. Many aspheric glass lenses came to be used for the latest digital camera and mobile phone camera module. It is very difficult to produce aspheric glass lenses by conventional process of curve generating and polishing. For the solution of this problem, Glass Molding Machine was developed and is spreading through the market. High precision mold is necessary to mold glass lenses with Glass Molding Machine. The mold core is ground or turned by high precision NC aspheric generator. To obtain higher transferability of the mold core, the function of the molding machine and the conditions of molding are very important. But because of high molding temperature, there are factors of thermal expansion and contraction of the mold and glass material. And it is hard to avoid the factors.
In this session, I introduce following items. [1] Technology of glass molding and the machine is introduced. [2] The transferability of glass molding is analyzed with some data of glass lenses molded.
[3] Compensation of molding shape error is discussed with examples.
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SiO2/ZrO2 gel films were derived from Zr-butoxide modified chemically with β-diketones and then mixed with Tetraethyl orthosilicate via Sol-Gel process. The obtained gel films showed an absorption band, in characteristic of the π-&pi* transition of chelate ring at around 334 nm, and its refractive index was changed from 1.463~1.647. The Si-O-Zr, Zr-O bands were detected by FTIR. The result indicated that SiO2 and ZrO2 integrated uniformly in the films on micro molecule magnitude. The negative tone gel films were irradiated with high pressure mercury lamp through mask and then leached in ethyl alcohol. The above process gave uniform surface-relief gratings of periods at 2.0μm. The present study had proved that the photosensitive gel films were versatile for the fabrication of micro optical devices
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In general, the high resolution of a microscopy could be acquired by increasing the NA (numerical aperture) of lens, and simultaneously increasing the luminous flux. But many experiments shows: in turbid media, the NA of the lens we use is larger, the radius of focal spot is larger and the resolution decreases on the contrary. Because of highly scattering, there are different characters of focusing and propagation in turbid media .We simulate the process of photons motion in turbid media by means of Monte Carlo method according to a known model with representative parameter: changing the NA of lens in the program, the gray-scale images of the light spot in various layer are obtained. We also plot two figures; (1) distribution of the normalized light intensity versus the transverse axis; (2) the radius of light spots as a function of depth. In the figures: the trends of distribution of the normalized light intensity are coincident and centralized; when lens with larger NA is used, the normalized light intensity curve is further from the axis; it is also found the size of the focal spot is bigger and light beams focus in turbid media deeper. All above expound: the NA of the lens is larger; the radius of focal spot is larger in turbid media. In addition, it also suggests various factors including scattering, absorption and scalar diffraction etc must be taken into account when we choose the lens to focus in turbid media.
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Computer-Aided Alignment (CAA) is an effective method for improving image quality of an optical system. This paper studies some key techniques of CAA for space telescope, including the mathematical model of CAA, the acquirement and processing of aberration data, the establishment of sensitivity matrix and the solution of misalignment. A numerical simulation of a space telescope has been performed to verify the ability and accuracy of the method.
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The optimal exposure distances for 3-D optical waveguides induced by laser micromachining in LiNbO3 crystals are theoretically and experimentally investigated. By solving the photorefractive dynamic equations, the optimal distances for waveguide fabrications are numerically specified when the focused laser beams scans along the different directions. The simulations show that the optimal exposure distance is not dependent on the scanning directions of the writing beam, but the index distributions of the fabricated waveguides are seriously dependent on them. When the writing beam scans the crystal along the axis c, optical waveguides cannot be fabricated efficiently. However, in this case, symmetric refractive index changes can be obtained, so called as sandwich illumination method. By scanning LiNbO3: Fe crystal with a focused green laser beam, experimental demonstrations are performed. The light-induced index changes are measured by employing digital holography. The experimental results coincide with the theoretical analyses. Additionally, a curved waveguide is experimentally formed. The near field pattern and the results of the guiding tests show that the waveguide are successfully written in the LiNbO3:Fe crystal.
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Durham University's Centre for Advanced Instrumentation (CfAI) have developed a technique for fabricating monolithic multi-faceted mirror arrays using freeform diamond machining. Using this technique, the inherent accuracy of the diamond machining equipment is exploited to achieve the required relative alignment accuracy of the facets, as well as an excellent optical surface quality for each individual facet. Monolithic arrays manufactured using this technique, have been successfully applied in the Integral Field Unit for the GEMINI Near-InfraRed Spectrograph (GNIRS IFU), which was recently commissioned at GEMINI South. In this paper, we present details of the fabrication process and optical performance of these components. We will also briefly discuss how their implementation has facilitated the GNIRS IFU's opto-mechanical system design and subsequent integration and test, and highlight the resulting improvement in
system performance.
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A Microlens array is a critical component for optimizing display functions. With the increasing usage of display systems in photonic products nowadays, more attention is being paid to the research and development of fabrication technology for microlens arrays. Ultra-precision machining with a fast tool servo (FTS) is one of the leading methodologies for fabrication of high-quality optical microstructural surfaces. FTS is an independently operated positioning device, which provides an indispensable solution for machining optical microstructures with sub-micrometer form accuracy and nanometric surface finish, without the need for any subsequent post processing. The surface quality of an FTS machined surface depends largely on the selection of cutting conditions. However, the achievement of ultra-precision surface finishing depends greatly on the experience and skill of the machine operators. Determination of optimal cutting conditions can stabilize the quality of the fabricated microlens array. In this paper, the effect of cutting conditions such as depth of cut, feed rate, spindle speed and surface speed are investigated; and optimal surface roughness and surface profiles in ultra-precision machining with FTS can be observed.
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One of the main factors driving ICs in complexity is the improvement in photolithography to print small features. The use of immersion imaging and resolution enhancement technology (RET) will extend the ArF lithography to produce small features. With the patterns size decreasing, the absolute CD variation has a bigger relative importance on small features. The process windows are used to see if a certain process is compatible with the dose and focus budget. We discuss the impact of illumination, numeric aperture, phase-shifting mask and polarized light on process windows using ArF immersion lithography to print line pattern exposed features in photo resist on 45nm node. The interaction between the process windows and illumination, numeric aperture, phase-shifting mask and polarized light are calculated using a full photo resist model. The analysis gives fundamental insight into the optimum conditions necessary for printing these patterns both individually and simultaneously. The results show that illumination, numeric aperture, phase-shifting mask and polarized light can contribute to the process capability. The dipole illumination system can enhance the process window about twice than that use conventional illumination. The process capability of semi-dense pattern is insensitive to optical parameters. The 100% attPSMs and altPSMs are strong phase shifting mask, so the process capability can be enhanced. By using the polarized light can enlarge the depth of focus about 4%~11% with specified exposure latitude. According to the rules of process windows, some methods to extend process windows are presented.
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Model-based Optical Proximity Correction (MBOPC) is used to make systematic modifications to transfer a pattern's design intent from a drawn database to a wafer. This is accomplished by manipulating the shape of mask features to generate the desired pattern (design intent) on the wafer. MBOPC accomplishes this task by dividing drawn patterns into segments, then using a process model to manipulate these segments to achieve the design intent on the wafer. The generation of an accurate process model is very important to the MBOPC process because it contains the process information used to manipulate correction segments. When corrected data are written on a reticle, the faithful and well-controlled reproduction of the data on the mask is critical to realizing the desired lithographic performance. This paper will explore methodologies to improve model accuracy using mask fabrication data and process test patterns. Model accuracy improvement will be accomplished using intelligent sampling plans and representative mask structures. The sampling plan needs to identify critical device and process features. The test mask used to generate the process model needs to have test structures to gather process data. The test mask also must have test structures that can evaluate model quality by testing the extrapolation and interpolation of the model to data that was no used to generate the process model. These methodologies will be shown to improve final mask pattern quality.
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A Very High Resolution Telescope (VHRT) is designed as a space-to-earth remote sensor and the polarization effect in this VHRT is analyzed in this paper. First, the theory of polarization effect is reviewed. Second, the Jones arithmetic of polarization aberrations in VHRT is presented. Then, CODE V software is used to realize the polarization ray trace in this system and the results of the polarization effect analysis are obtained. The output information includes the plot of Modulation Transfer Function (MTF), the plot of Point Spread Function (PSF), pupil map, relative illumination, illumination, distortion and Strehl ratio. Finally, effective methods to control the polarization effect in an optical system are given. According to the results of analysis, we have drawn the following conclusions. Polarization effect in an optical system shouldn't be ignored to improve the imaging quality; with the incident angle as small as possible to control the polarization effect. Coating design must be considered carefully for the optical design.
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Silicon Carbide (SiC) has been recognized as a leading material for optical applications. In this paper, grinding of RBSiC using diamond wheels on surface milling machine under various grinding parameters was investigated. Examinations of ground surfaces reveal that surface roughness increases with increase of depth of cut and decreases with increase of burnishing time, but a further prolonged of burnishing time did not work obviously to improve surface quality. Values of surface roughness swing with increase of work-piece rotation speed and exhibit variety with the increase of the cumulate removal volume under different depths of cut. The Vickers hardness of ground RBSiC decreases with the depth of cut. Scanning electron microscopy (SEM) observation revealed that brittle fracture and plastic flow removal mode coexist during grinding process. The percentage of ductile-mode grinding area decreased with increasing of depth of cut.
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Optical microstructures are very important for the realization of multifunctional optics and photonics devices. In the last decade, with the development of commercial femtosecond laser, it has been proven that micro-structuring with femtosecond laser pulses is an excellent tool for free design micro-fabrication of almost all kinds of materials. With the filament, spatially scanning and other methods, many types of 0 to 3-dimensional optical microstructures, including optical memory, waveguides, gratings, couplers and photonic crystals, were produced successfully inside a wide variety of transparent materials of solid state and also liquid state. Here we reviewed the proceeding of the micro-fabrication technology by femtosecond laser pulses in the last few years.
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The ultra-weak photon emission is an intrinsic and spontaneous process in biological objects without any external excitation and is referred to as "biophoton emission". This paper reports the design of the rotation ellipsoidal cavity that was used in detecting ultra-weak photon emission from biological objects. The cavity can assemble the photons from biological sample at one focal plane of the rotation ellipsoidal cavity to the photomultiplier tube at another. The paper discusses the mathematical model of the cavity and the efficiency of collecting photons with the cavity. The measuring results for biological sample are given. The results are shown that the efficiency of collecting photons for the system with the cavity is evidently raised.
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The profilometer for on-line and non-contact measurement of the fine optical surfaces is described in this paper, which works on the principle of the differential interferometry with coaxial interference arms. The optical part of that is isolated and easy to install on the machine tools or the measuring machineries ea. This profilometer has excellent resistance to disturbance, especially to mechanical vibration, when the amplitude of vibration is about 300nm. So it still can be used to measure the micro-profile with sub-nanometer resolution. The vertical resolution of the profilometer is better than 0.05 nm rms. and need not add any condition or pretreatment
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With the development of the optical technology, wavelength division multiplexing (WDM) is becoming an important technology for the enhancement of bandwidths of fiber-optical networks. Bragg gratings utilize the fact that light is diffracted from a grating only if the Bragg condition is fulfilled. In the paper a new kind of measure called directly layered multiple VBGs (volume Bragg gratings) is presented, which is fabricated by photorefractive volume holographic technology, and the multiple VBGs fabricated by this method with layered structure is more compact, the corresponding system could, more sufficiently, utilize the volume of photorefractive lithium niobate crystal. In our experiment the VBGs can be formed by illumination of interference field of two thin sheet beams expanded and collimated through two cylindrical lenses, and then multiple VBGs can be accomplished at the same location by angle-multiplexing technique. And then the layered structure can be formed by space-multiplexing holographic technique, i.e. after the fabrication of the previous layer, the following layer is able to be created by above multiple illuminations through moving crystal along the sheet beam normal with a certain space. The steady layered multiple VBGs in LiNbO3:Fe crystal can be achieved through thermal fixing technique. Several layered structures are fabricated, that are respectively composed of four superimposed VBGs in LiNbO3 crystal. The spectrum distribution of each layer gratings transmittance was measured by utilizing Ando AQ6317C optical spectrum analyzer
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A new sensing unit structure of the uncooled infrared detector based on the multilayer lithium tantalite (LiTaO3) pyroelectric functional thin film is introduced in this paper. An innovative sol-gel process using lithium acetate and tantalum ethoxide as starting materials to prepare the multi-layer LiTaO3 functional thin film on two different substrates is described in detail. The glacial acetic acid addition in the tantalate ethoxide sol results in a new type molecularly modified precursor. And the LiTaO3 thin film was fabricated by spinning coater at 3000 r.p.m. To prevent the coatings from cracking, two-step "slow preannealing" was used to thermally treat the LiTaO3 thin film samples. The gold black infrared absorbing layer of the LiTaO3 thin film sample was evaporated about 300 nm in a clean evaporating chamber charged with nitrogen gas under a pressure of about150 Pa. The voltage response of the LiTaO3 thin film sample was obtained by the infrared device measurement system. The specific detectivity peak of the LiTaO3 thin film sample is near 6.1×108cmHz1/2W-1 from 1Hz to 100Hz.
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Defects in thin film are the most important factors resulting in laser-induced damage of far-infrared laser thin film components, and always a major concern. The defect is a primary problem for infrared thin film of 3.8um in some optical systems. In this paper, single layer of ZnS YbF3 and multilayer coating is produced by thermal evaporation, and species, properties and derivation of defects in these thin films are introduced firstly, Then, the influence of material and evaporation rate on the surface defect density of laser thin film is analyzed. Finally, this paper put forward the appropriate deposition rates of thin film. The result shows that the nodule and concave hole defects are the mainly in the infrared thin film of 3.8um, and YbF3 has a great effect on the defect density in thin film. Also, the deposition rate of YbF3 has a large effect on the number and area of particles deposited on the substrate, as the evaporation rate increases, the number of particles increases markedly. It is possible that the spitting change of fused deposition material increases when the rate increases, since the centre temperature of fused deposition material increases. The defect density from 7.3X10-3 reduces to 6.8X10-4 through reducing the rate. Finally, the authors found it was appropriate when deposition rates were 4Å/s for ZnS and 2Å/s for YbF3, respectively.
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In this paper we analyze the change of polarization state for a laser optical system which includes a Cassegrain beam expander and several fold mirrors. First, this system operates over a broad spectral band and is with several separated wavelengths, therefore, strong polarization effects will occur at certain waveband. The polarization state changes of different wavelengths at the exit pupil are discussed mainly based on the comparison of their Point Spread Function (PSF) and Strehl Ratio respectively. Then, fold mirrors cause large angles of incidence and can rotate in azimuth and zenith. The amplitude diattenuation and retardance are calculated at different azimuth and zenith of the beam director assembly. In this paper, Code-V commercial optical-engineering software is used to model the polarization behavior for the system. The factors mentioned above, which are spectral bandwidth, angle of incidence of surfaces and systemic coatings, are taken into consideration in the process of simulation. The result of the study shows that the polarization properties at certain wavelength are satisfactory except some other wavelengths are not. This laser system is more sensitive to retardance than to diattenuation. It is concluded that polarization is an important factor that affects the performances of the whole system and the design of laser optical system should take into account the polarization effects.
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By using the Gaussian light beam approximation and from the viewpoint of mode matching, the optical coupling theory between single mode fiber and optical antenna, which is based on the matrix optical theory and the ABCD law, is employed to present a universal designing method for transmitting optical antenna of a terrestrial line-sight optical communication system .The physical meaning and choosing method with its relative parameter are also discussed in detail, and an experimental example of the transmitting optical antenna for a terrestrial line-sight optical communication system is given as well. Through the testing of the designed transmitting optical antenna with the help of a laser light beam analysis instrument, the incident Gaussian light beam waist spot radius is 4.7μm, while the divergence angles of the transmitting Gaussian light beam in the two perpendicular directions are 1.9mrad and 1.5mrad, respectively, which can almost agree with the parameters of the designing theory above. In the end, the possibility of improving the quality of transmitting optical antenna and the reliability of space optical communication through applying technologies such as converting the elliptical Gaussian light beam into the round Gaussian light beam, the plane coupling into the spherical coupling and film-plating the optical antenna etc is discussed.
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An optical system for free space optical communication is designed, which are composed of three parts: Optical sender are designed as Schmidt-Cassegrain antenna to collimate the laser beam. λ/2 plate and polarization beam splitter are used to decrease the interference of astigmatism and reflection. The dense-lines Fresnel lens as an optical receiver, and further an automatic tracking system is employed to eliminate the pointing error between communication terminals. Experiment shows that the laser divergence of 2 mrad is obtained for the communication system at the wavelength of 850nm, with pointing error less than 5 μ rad, and laser power of 10dB. The detector can receive -17.5dB even in middle fog condition 2 km ranged. The system can be used for free space optical communication in 2km distance except under especial atrocious weather.
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A simple method of broadband distributed Raman amplifier is presented based on Chirped Fiber Bragg Grating Filter. C+L band gain flattened distributed fiber Raman amplifier with bandwidth of 50nm (1520nm~1570nm) and 15 dB averaged gain and ± 0.6dB gain ripple using single pump has been demonstrated. Compared to design methods of other existing Raman amplifier, our method has a substantial improvement in simplifying system.
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In this work, we reported the fabrication and characterization of an AlxGa1-xN /GaN hetero-epitaxial front-illuminated visible-blind UV photodetector with very high external quantum efficiency. This device was grown on one side of polished sapphire substrate using a low-temperature AlN buffer layer created by three-pocket multi-wafer system metalorganic chemical vapor deposition (MOCVD) with a vertical reactor. This device consisted of a 2.5μm thick GaN n-layer, a 0.4μm thick GaN i-layer and Al0.1Ga0.9N "window layer", followed by a 10 nm GaN:Mg p+ contact layer. In order to investigate the effect of p- Al0.1Ga0.9N thickness on the characteristics of the photodetector, three samples only with different p-AlGaN thicknesses of 0.1μm and 0.15μm were fabricated. All of the device processing was completed using standard semiconductor processing techniques that included photolithography, metallization and etching. Compared the results of these three samples, the sample with 0.15μm thick p-AlGaN possesses the highest quantum efficiency and its zero-bias peak responsivity was found around 0.20A/W at 365 nm, corresponding to an external quantum efficiency of 85.6%. Moreover, this device exhibits a low dark current density of 3.16nA/cm2 at zero-bias.
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Detection of fluorescent microarray slides can be divided into two categories: one is confocal scanning detection in which a photomultiplier tube is used as fluorescence sensor, and the other is flood illumination of the entire microarray slides and uses a Peltier cooled CCD as fluorescence sensor. CCD can afford high quantum efficiency, simultaneous illumination and detection of multiple pixels, and easy mechanical design, but its dynamic range and sensitivity are not as good as those of photomultiplier tube. At the same time, the Peltier cooled CCD camera is much more expensive than a high performance photomultiplier tube. Confocal scanning provides high dynamic range, good sensitivity and high signal-to-noise ratio, but the system design is difficult when considering rapid scanning speed, high resolution and large numerical aperture. There are three typical confocal scanning apparatuses which are mechanical scanning, optical scanning and optical-mechanical scanning. Their scanning mechanism, advantage and disadvantage are analyzed respectively. With the former understanding, a new optical-mechanical scanning apparatus is described in detail. It employs two lasers to excite the Cy3 and Cy5 fluorophores on the microarray slides. The emitted fluorescent signal is detected using a photomultiplier tube sequentially. One dimension scanning of the slides is performed by a telecentric f-θ objective with a moving coil optical scanner; the other dimension is scanned through a stepping motor driving a precision guidance. This apparatus is low-noise, economical and fast in scanning speed.
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Effects of residual stresses on mechanical properties such as voltage vs. displacement response, pull-in voltage and structural resonant frequency of segmented micro deformable mirrors were investigated with both finite element method (FEM) and analytical method. A simplified model was adopted to study the structural spring constant on the existence of residual stress and two methods for imposing residual stress on structures were utilized for the purpose. Both results of analytical method and FEM show that larger structural spring constant can be obtained by introducing tensile residual stress. Consequently, mechanical properties relevant to spring constant are also greatly affected. The higher the tensile residual stress is, the stronger the structural stiffness will be. That means in order to induce the same structural displacement of mirror plate as stress-free state, higher voltage is demanded. Meanwhile, with higher tensile residual stress, larger pull-in voltage and greater structural resonant frequency are achieved. For the situation of compressive residual stress, totally the opposite influences can be observed. In conclusion, residual stress (no matter tensile or compressive) can greatly affect the mechanical properties of segmented micro deformable mirrors. Accurate control of it is needed for optimizing the structural design and improving the performance of devices.
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This paper presented a bicubic uniform B-spline wavefront fitting technology to figure out the analytical expression for object wavefront used in Computer-Generated Holograms (CGHs). In many cases, to decrease the difficulty of optical processing, off-axis CGHs rather than complex aspherical surface elements are used in modern advanced military optical systems. In order to design and fabricate off-axis CGH, we have to fit out the analytical expression for object wavefront. Zernike Polynomial is competent for fitting wavefront of centrosymmetric optical systems, but not for axisymmetrical optical systems. Although adopting high-degree polynomials fitting method would achieve higher fitting precision in all fitting nodes, the greatest shortcoming of this method is that any departure from the fitting nodes would result in great fitting error, which is so-called pulsation phenomenon. Furthermore, high-degree polynomials fitting method would increase the calculation time in coding computer-generated hologram and solving basic equation. Basing on the basis function of cubic uniform B-spline and the character mesh of bicubic uniform B-spline wavefront, bicubic uniform B-spline wavefront are described as the product of a series of matrices. Employing standard MATLAB routines, four kinds of different analytical expressions for object wavefront are fitted out by bicubic uniform B-spline as well as high-degree polynomials. Calculation results indicate that, compared with high-degree polynomials, bicubic uniform B-spline is a more competitive method to fit out the analytical expression for object wavefront used in off-axis CGH, for its higher fitting precision and C2 continuity.
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Metallic mesh has been widely used in electromagnetic interference windows. While the duty ratio of curved mesh equals to planar mesh', the theory of planar mesh may be applied to curved mesh according to equivalent-circuit model. So the idea that latitude lines intersect latitude lines to form isometric mesh on the concave of a sphere is put forward, and the method of fabricating the mesh by concentric optical scan is introduced. The movement parts of equipment consist of an erection turning, a horizontal dividing and a pitching dividing spindle. Firstly, a spherical substrate is fixed on the horizontal dividing spindle that has been set horizontally on the erect turning spindle, the substrate revolves around the axis of the erect spindle, the tube of object lens that is fixed on the pitching dividing spindle steps at pitching direction, and a revolving circuit of the substrate corresponds to a step of the tube. Gradually, a set of latitude lines is attained. Afterward, the substrate makes a quarter turn around the horizontal spindle, another orientation latitude lines are also gained. Thus, the isometric mesh on the concave of a spherical substrate is gained. The process comprises surface cleaning, coating photoresist, laser direct writing, development, evaporated film, dissolving photoresist and plating. The fabricated spherical mesh has a line width of 7μm and a period of 600μm. Experiment shows that infrared transmission and electromagnetism shield efficiency of the metallic mesh are relatively consistent with theoretical value.
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Schmidt system is a famous optical system. The corrector equation based on the third-order aberration theory has been acknowledged all along. When the previous equation is confirmed in characteristic of the aspheric surface equation and optical design program ZEMAX, it is found that the equation of the corrector has some errors. Analyses of this problem are given. A new corrector equation is established. The new equation is confirmed seriously by the optical design program ZEMAX again, it can be deduced that the coefficient α=1/2r02, and the spherical aberration coefficient ΣS1=0. This improvement is very useful for the optical design of Schmidt system, which quickens the optimization and easily reaches the optimal design data.
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CCD noises and their causes are analyzed. Methods to control these noises, such as Correlated Double Sampling (CDS), filtering, cooling, clamping, and calibration are proposed. To improve CCD sensor's performances, the IC, called Analog Front End (AFE), integration of CDS, clamping, Programmable Gain Amplifier (PGA), offset, and ADC, which can fulfill the CDS and analog-to-digital conversion, is employed to process the output signal of CCD. Based on the noise control approaches, the idea of chip design of linear CCD drive pulse generator and control interface is introduced. The chip designed is playing the role of (1) drive pulse generator, for both CCD and AFE, and (2) interface, helping to analysis and transfer control command and status information between MCU controller and drive pulse generator, or between global control unit in the chip and CCD/AFE. There are 6 function blocks in the chip designed, such as clock generator for CCD and AFE, MCU interface, AFE serial interface, output interface, CCD antiblooming parameter register and global control logic unit. These functions are implemented in a CPLD chip, Xilinx XC2C256-6-VQ100, with 20MHz pixel frequency, and 16-bit high resolution. This chip with the AFE can eliminate CCD noise largely and improve the SNR of CCD camera. At last, the design result is presented.
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Since Deb's experiment in 1973 on the electrochromic effect, transmissive electrochromic devices (ECDs) exhibit outstanding potential as energy efficient window controls which allow dynamic control of the solar energy transmission[1]. These devices with non-volatile memory, once in the coloured state, remain in the same state even after removal of the field. The optical and electrochemical properties of electrochromic windows using magnetron sputter deposition tungsten oxide thin films and titanium oxide doped tungsten oxide thin films are investigated. From the UV region of the transmittance spectra, the band gap energy from the fundamental absorption edge can be determined. And the impedance of these thin films in 1 mol LiClO4 propylene carbonate electrolyte (LIPC) are measured and analysed. Equivalent circuit of thin film impedances, and correlative resistances and constant phase angle element are gained. SEM and XRD of the tungsten oxide thin films and (1-x) WO3xTiO2 thin films are studied. These performance characteristics make tungsten oxide thin films and titanium oxide doped tungsten oxide thin films materials suitable for electrochromic windows applications.
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In the field of microelectromechanical systems, a challenge to MEMS designers is to create low-order dynamic device models that can accurately capture the complex behaviors which may be discovered only through experiments or full three-dimensional simulations. Computer aided design (CAD) tools allow modeling and simulation of devices that may not have been constructed yet, but now only few softwares are available for modeling and analysis of microsystems. In this paper, we attempt to use MEMSPRO and ANSYS to fulfill the modeling and simulation of silicon micromechanical electrostatic comb drive resonators. A 3D model is constructed. Then the model is analyzed by a finite element analysis tool, ANSYS. We implement the static responses and harmonic responses of the model so that the static and dynamic characteristics of the resonator can be obtained to help improve design quality and efficiency. Based on the analysis results, low-order dynamic device model of the resonator can be tuned and further optimized. The effectiveness of the CAD/CAE technology in the development of MEMS is demonstrated in the paper.
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Reactive magnetron sputtering can be used to prepare graded index coatings. In this paper the relationship between the refractive index of the coatings and the partial pressure of reactive gas is discussed by experiment, in which A, O2 and Si are taken as sputtering gas, reactive gas and target material separately. And we have come to such conclusions that with the increase of partial pressure of reactive gas the color of the coatings turns shoal, the transmittance minimum of the coatings increases and the refractive index of coatings decreases according to the fitting rule of cubic polynomial. From XRD analysis, it can be seen that the coatings are identified to be amorphous.
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In an adaptive-optical (AO) system, the wavefront of optical beam can be corrected with deformable mirror (DM). Based on MicroElectroMechanical System (MEMS) technology, segmented micro deformable mirrors can be built with denser actuator spacing than continuous face-sheet designs and have been widely researched. But the influence of the segment structure has not been thoroughly discussed until now. In this paper, the design, performance and fabrication of several micromachined, segmented deformable mirror for AO were investigated. The wavefront distorted by atmospheric turbulence was simulated in the frame of Kolmogorov turbulence model. Position function was used to describe the surfaces of the micro deformable mirrors in working state. The performances of deformable mirrors featuring square, brick, hexagonal and ring segment structures were evaluated in criteria of phase fitting error, the Strehl ratio after wavefront correction and the design considerations. Then the micro fabrication process and mask layout were designed and the fabrication of micro deformable mirrors was implemented. The results show that the micro deformable mirror with ring segments performs the best, but it is very difficult in terms of layout design. The micro deformable mirrors with square and brick segments are easy to design, but their performances are not good. The micro deformable mirror with hexagonal segments has not only good performance in terms of phase fitting error, the Strehl ratio and actuation voltage, but also no overwhelming difficulty in layout design.
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Double layer films of SiO2/Si3N4 were prepared on sapphire (α-Al2O3) by radio frequency magnetron reactive sputtering in order to increase the transmission of infrared windows of sapphire. Composition and structure of each layer of the film were analyzed by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), respectively. The refractive index of deposited films was measured and effects of the coatings on optical properties of sapphire have been studied. Transmittance spectrum of uncoated sapphire and the sapphire coated on both sides with double layer films of SiO2/Si3N4 have been measured using a Fourier Transform Infrared (FTIR) spectrometer. The results show that the designed SiO2/Si3N4 films can increase the transmission of sapphire in mid-wave infrared greatly. The average transmittance of sapphire coated with the double layer films of SiO2/Si3N4 on both sides, at wavelengths from 3 to 4.5um, can be increased to 96.3%, 10.9% higher than uncoated sapphire sample with 85.4% in average transmittance at room temperature. What's more, sapphire uncoated and coated on both sides with double layer films of SiO2/Si3N4 were heated to 1000oC and the transmissions at high temperature were measured. The results show that the transmission of coated sapphires was higher than that of uncoated ones at high temperature. The decreases in average transmission were less than 2% for the sapphire coated with the designed double layer films at 1000oC.
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In this paper, high quality DLC coatings on large area (φ=150 ~ 250mm) infrared elements have been prepared by radio frequency enhanced plasma chemical vapor deposition (RF-PECVD) method. The microstructure has been studied by using Raman spectroscopy and FTIR spectroscopy. These DLC coatings show good uniformity, high infrared transmittance and resistance to harsh environment. The relations between RF power density, the microstructure and properties have been discussed
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Fundamental optical constants of porous silicon, which refer to the effective refractive index neff, the extinction coefficient K, the real parts εer and imaginary parts εei of the effective dielectric functions, and the absorption coefficient α, are calculated using the effective medium theory named the Modified two-phase Maxell-Garnett and two-phase Bruggeman models separately in the range of 400-1000 nm. In the model, the microstructure of porous silicon is considered as a two-phase granulated compound medium with identical silicon inclusions, placed at random inside a homogenous air matrix. To do the calculation the calculated reflectance spectra from two models are fitted with experiments corresponding to samples with porosities of 39%, 45%, 51%, 59%, and 67% in order to determine the involved parameters in dielectric function called Wemple-DiDomenico oscillator of the remaining silicon. Best results of both models are obtained using spheroidal inclusions of 0.9 eccentricity. Effects of the wavelength of incident light and the porosity of porous silicon on these optical constants were studied systematically.
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GLAD ZnS films prepared by electron beam evaporation method with glancing angle deposition technique are reported. The influence of different oblique angle on the structure and optical properties is investigated using atomic force microscopy and transmittance spectra. The GLAD ZnS films exhibit a porous structure with isolated island and columnar formed. The surface roughness increases with the increase of oblique angle. The refractive indexes of GLAD ZnS films are lower than that of corresponding bulk materials. The maximal birefringence is obtained at oblique angle α=80o, which is ascribed to the orientated growth and anistropic structure of GLAD films. Therefore, the glancing angle deposition technique is a promising technique to obtain enhanced birefringence property.
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Multi-layer dielectric grating is a key element used in chirped-pulse amplification technique. It includes high reflectivity film and periodic gratings on its top. Design of HR coating and top layer film (called multi-layer dielectric grating film) to produce gratings is important to fabricate such element with perfect optical properties and high laser induced damage threshold. In this paper, needle method is employed to synthesize the HR film with non-quarter wave coatings. The top layer is constructed by Fourier modal method, which is a rigorous method to analyze gratings. The synthesized multi-layer dielectric grating film shows good optical properties and electric intensity distribution.
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Mo/Si multilayers have been gaining industry interest as a promising choice for the next generation soft-x-ray projection lithography. Usually, an asymmetrical interlayer transition zones is formed in sputtered Mo/Si multilayers and Mo-on-Si interface is thicker than Si-on-Mo one. In order to study the influence of interface asymmetry on soft X-ray reflectivity of Mo/Si multilayers, a four-layer model is used to simulate soft X-ray reflectivity of Mo/Si multilayers at a given wavelength. The simulation study shows that interface asymmetry is not always disadvantageous to reflectivity of Mo/Si multilayers. When the sum of thickness of Mo-on-Si interface and Si-on-Mo interface is fixed, soft X-ray reflectivity of multilayers can be improved through increasing the thickness ratio of Mo-on-Si interface to Si-on-Mo interface. As the thickness of Si-on-Mo interface is fixed, only by increasing the thickness of of Mo-on-Si interface, soft X-ray reflectivity of multilayers can be improved. While the thickness of Mo-on-Si interface is fixed, only by increasing the thickness of Si-on-Mo interface, soft X-ray reflectivity of multilayers can be basically invariable.
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When used at oblique angles of incidence, the reflectance and transmittance of thin films exhibit strong polarization effects, particularly for the films inside a glass cube, which result from the fact that the tangential components of the electric and magnetic fields are continuous across each layer interface. However, for many applications, the polarization effects are undesirable and should be reduced. Therefore, the concept of non-polarizing beam splitter is proposed. Up to now, however, most of the reports of non-polarizing beam splitters are suitable for visible light. Therefore, it is necessary to find out some methods to reduce the polarization effects for infrared applications. A design method of infrared non-polarizing beam splitter in a cube is proposed, the theoretical analysis is given, designs for different substrates are demonstrated and the simulations of their optical properties are presented in this paper.
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The fabrication technology of refractive microlens array (MLA) with self-assembly of drops of various thermoplastic optical polymer solutions is reported. In order to develop a conventional drop-on-demand type ink-jet printing method for fabricating high quality microlens array, Firstly, we tried to prepare a series of optical polymer inks. These inks compose of high quality optical polymers, polymethylmethacrylate (PMMA), dopant, and functional organic molecules such as laser dye, nonlinear organic dye, and rare earth ion chelates with a suitable organic solvent. Effects of surface tension on the polymer solution drops induced the self-formation of microlenses. This process exhibited a completely self-assembly characteristic without any chemical and photochemical post-treatment. The resulting microlens array displayed diameters varying from 1mm to 5mm and focal lengths from less than one millimeter to a few millimeters. Observation with an atomic force microscope reveals that the surface roughness of the lens is 0.9 nm. The transmittance spectrum of the lens is also measured.
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The factors affecting the removal rate and surface shape in CMP is introduced. The edge effect is a critical problem in CMP process, which behaves on the global planarization of workpiece-pad interface and change on local planarization and results in collapse or rise in workpiece edges. One of the main factors of edge effect is Von Mises stress, which is a composition stress. The main affecting factor of Von Mises is the axial stress component. The factors affecting the material removal rate (MRR) of workpiece surface and surface nonuniformity include shape, material properties and thickness of pad and polishing media. Factors of load and relative velocity in CMP are also discussed.
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According to the requirement for output coupler in Nd:YAG laser resonator, the way of designing graded reflectivity mirror is researched. Three methods for designing formula are put forward, accordingly, each formula structure is got respectively. The designed variable reflectance profile can satisfy the single transverse mode Nd:YAG laser resonator. The tolerance error of the varying layer along the radius in the formula is computed,and the robustness and special technics for film deposition of the three formulas are compared synthetically. The method of changing all layers thickness along the radius is confirmed as the best and feasible designing way for depositing.
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By means of transfer matrices, the transmission spectral of random medium thin film is calculated, which consists of two-type medium. It is found that the thin film has selective transmission effect to the light within ultraviolet region, and that the larger the strength of randomness, dielectric constant and thickness of random layer (are), the narrower the half-width of transmission light becomes. Otherwise, no matter how the other parameters change, the light, whose wavelength is equal to the thickness of first layer, can transmit the thin film when the dielectric constant of first layer is one.
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ZnO thin films are prepared on sapphire (0001) substrate by laser molecular beam epitaxy (L-MBE) and the optical properties were studied. It is found that the growth conditions and the treat process have obvious effect on the optical properties of ZnO films. With the increase of the growth oxygen pressure, the concentration of the structural defects in ZnO films caused by the disbalance of Zn and O stoichiometric proportion is depressed effectively. As a result, the UV emission intensity grows much higher, but the deep level (DL) emission is depressed. Sample 1#, 2#, and 3# were grown at oxygen pressure 2.0E-3Pa, 8.0E-3Pa, 2.0E-2Pa respectively, and the ratio of the UV emission intensity and the DL emission intensity were 1.00, 2.34, 3.31 respectively. The effect of annealing treatment on the transmission spectra of ZnO films was also studied. Sample 1# was cut into three parts and annealed at 500oC, 600oC, 700oC respectively in the air atmosphere. The transmittivity in the visible range become much greater after annealing and the higher the annealing temperature is, the higher the transmittivity becomes. When annealed at 700oC, the transmittivity has nearly doubled.
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Deformable Mirror (DM) is a key element in Adaptive Optics (AO) system for correcting light wavefront aberration. A new DM actuated by liquid drops is proposed. The drop array is confined within hydrophilic areas, covering an electrode array and supporting a membrane mirror. Along with the change of the voltage between center electrode and edge electrode, the liquid drop can be deformed, pulling or pushing the membrane mirror. The DM model with water drops and aluminum membrane is analyzed with Finite Element Analyzing (FEA) software. The membrane thickness is first chosen by trial calculation. The deforming picture of the membrane driven by certain drop is obtained. Smooth deformation and a maximal altitude difference of about 33μm in pulling actuation confirmed the feasibility of the principle. Simple fabricating process, low cost, good wavefront correction ability can be expected with such a new DM.
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A novel nano-scale alignment technique based on Moire fringe for room-temperature imprint lithography in the submicron realm is proposed. A pair of special slant gratings is used as alignment marks on the wafer and template respectively. Moire signals generated by alignment marks are projected onto a photo-detector array, then the detected signals are used to estimate the alignment errors in x and y directions respectively. Test results indicate that complex differential Moire signal is more sensitive to relative displacement of the pair of marks than each single Moire signal, and the alignment resolutions obtained in x and y directions are ±20nm (3σ) and ±25nm(3σ) respectively. They can meet the requirement of alignment accuracy for submicron imprint lithography.
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In this experiment the microwave absorption and phase-sensitive detection technique was used to detect the time-resolved signal of photoelectrons generated by 35-ps laser pulses in AgCl emulsions uniformly doped with different concentrations of formate ions (HCO2-). According to photoelectron decay signal, the photoelectron decay properties and the trap-capture properties, influencing the efficiency of latent image formation of the cubic AgCl grains, were discussed. The results indicate that when its concentration is 10-5mol/molAg, the formate ions act as hole traps obviously, enhancing the escape of electrons from pair recombination, but when its concentration is more than or less than 10-5mol/molAg, the formate ions may not act as hole traps effectively. We find that the optimal concentration of uniformly doped formate ions which can increase the photoelectron lifetime effectively is 10-5mol/molAg.
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A new integrated LiTaO3 pyroelectric infrared fire detector and its characteristics are investigated in this paper. A novel multilayer infrared detector structure and its operating principle are presented. The detector is fabricated based on the pyroelectric effect of LiTaO3 film by the technology of MEMS based on silicon technology. A detector response parameter measurement system is built to measure the infrared response of the fire detector. The voltage response and the specific detectivity of the detector are also studied.
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We report a new technology to fabricate microstructured polymer optical fiber (MPOF, also named polymer photonic crystal fiber, pPCF) preform rods by in-situ polymerization of monomer in a mould. Series of pPCF preform rods including elliptic core fiber preform rod, single-mode fiber preform rod and ring-type holes structured preform rods have been fabricated. The optimum conditions for monomer-based fabrication of pPCF preform rods were investigated. Then, drawing from primary preform rods to secondary preform rods was carried out in a home-made furnace. Finally, optical and thermal properties of these pPCF preform rods, such as transmittance, a glass transition temperature, and the distribution of molecular weight were investigated. Optically functional dye-doped pPCF preform rods, rhodamines-doped PMMA preform rods were successfully fabricated.
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A novel X-ray source with micro-beam has been studied in theory and experiment. The source is composed of three portions: LaB6 crystal cathode electron gun emitting system, electrostatic focusing system, and permutable metal target system. The electronic current emitted by the electron-gun are controlled by modulating cathode temperature and Wehnelt grid voltage and ratio Dw/H, two-equal-radius-cylinder-electrodes focusing system concentrates electron beam, the X-ray photons are irradiated by high energy electron beam bombarding the metal target. The new x-ray source's general-purpose capabilities such as continuous radiation and pulse radiation, focus size and luminance, are also tested. When the temperature of LaB6 cathode is about 1900K and partial pressures being kept below 10-7 torr, the minimal focus diameter is merely about 10 microns. The new micro focus x-ray source has other lots of advantages such as economy, safety and facility.
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The optical constants and thickness of Nb2O5 optical thin film deposited by a reactive magnetron sputtering technique have been retrieved by all measurement data of the normal incidence transmittance. A computer program written in FORTRAN for determining the refractive index, extinction coefficient and thickness of this film has been developed and tested on two examples. This method can also calculate the optical constants and thickness of the film with a thickness thinner than a quarter wavelength optical thickness. Moreover, the optical constants calculated by this method are more accurate than those calculated by the envelope method. We also suggest that this method should be able to apply to other optical films, such as TiO2, SiO2 and Ta2O5.
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Large size pulse compression grating (PCG) with needs high adjusting precision in the light path of PCG fabrication. Note that the longitudinal error is the most error source of diffraction wavefront aberration of grating. It is difficult from conventional light path regulation to obtain such small longitudinal regulative error. A simple and practical method for regulating light path of PCG with big size is introduced. Rotate the grating fabricated by conventional light path adjustment and place it on the original recorded plane. The real grating and the imaginary one produced by two constructive beams interference overlap to produce the moire fringe pattern. Generally speaking, conventional regulation generates longitudinal error that results in cirques. Regulating the pinhole till Moire fringes become parallel and straight, and then backtrack with half of the regulating quantity, which is called Moire fringe method (MFM). With that, the problem that longitudinal precision of conventional light path adjustment is low is solved. To begin with the imaging formula of holographic lens, the principle of MFM is deduced theoretically. From results generated by ZEMAX software, the diffraction wavefront aberration of grating can be reduced to the least by MFM effectively. Proceeding with the relationship between optical system of holographic grating and the diffraction wavefront aberration of grating, the aberration of moire fringes obtained by analyzing the deviation of the fringes from parallel straight lines is about twice as the diffraction wavefront aberration of grating by reference to primary aberration theory.
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On an experimental apparatus employed for laser heat treatment, a specific optical device (image-overlapping waveguide cavity with a square aperture) is mounted in order to homogenize the energy distribution of a high-power CO2 laser beam which is used as a heating source. After the laser beam is transformed by this device, a square homogeneous beam spot with trim edges is got on the surface of heated materials. Based on Fourier optics, a mathematical model has been developed to calculate the power density distribution of the beam spot. Simulation has been done through programming on a computer in this model. By comparing theoretical simulation with experimental thermal spot, this model is validated. Conclusions of this work also demonstrate that the energy distribution of converted beam spot in the image plan, obtained through segmentation-recombination, shows local drastic variations due to interference. To suppress the interference fringes existed in converted beam spot and improve its local homogenization, a further study of the device is made. The optical parameters of the device which effect the final power distribution of converted beam spot are analyzed. An optimized scheme of the device is given through modifying its parameters. According to the scheme, the local homogenization of converted beam spot is improved by one order of magnitude.
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Based on the solution of energy equation about thermal conduction, a semi-analytical method to calculate the temperature field in a thin metallic plate irradiated by CO2 laser beam was presented in previous study. By means of this method, the simulation of temperature field can be completed on a personal computer with less calculation burden. In this paper, this method is studied further. The problem existed in the current model is pointed out. Via simplifying mathematical formulas rationally, an improved practical model to simulate the temperature distribution is given. According to the model, a set of simulation software is developed to calculate temperature distribution under laser heating opaque materials. The simulation with respect to a thin stainless steel sample plate heated by CO2 laser beam is carried out. The comparison of theoretical simulation and experimental data is made. The calculation error is less than 10%.
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When a small reflecting membrane is paralleled to a special Fresnel diffractive lens, the light intensity at the focal point of the diffractive lens is highly sensitive to the position of the membrane. Based on this principle, the authors put forward a new optical acceleration sensor which can largely meet the development of the fly-by-fight system used in flight control system. In addition, the sensing principle is described and the computer simulation of the sensor is carried out. The results show how the light intensity depends on the membrane position and the influence of error on conclusion. The sensor has realized the mutual supplement with each other's advantages of optical fiber and Micro Electro Mechanical System (MEMS).
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A viable green manufacturing method is provided. The theory and application of laser machining interior contour are proposed. The interaction physics theory between laser and transparent material, the knowledge of CAD/CAM and ultrasonic vibration are combined to manufacture the transparent material and remove chips. Adopting the method in manufacturing, the distortion of machine, noise and chemic pollution can be eliminated.
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Aiming at several problems existing in micro-aspheric component manufacture field in china recently, this paper brings forward a new complex grinding and lapping method that is used in producing micro-aspheric optical workpiece. This method adopts a complex wheel which integrates micro-grinding and MRF technique. The structure and parameters of the new pattern-grinding wheel are analyzed. The course of processing is summarized and every steps of controlling system are introduced. Methods about solving technical difficulties of process are put forward. The new complex processing method can increase flexility, processing efficiency and precision of the manufacture system, and provide a feasible way to resolve shortages of the micro-aspheric component manufacture domain.
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To generate axisymmetric aspheric surface function rapidly, virtual quadratic curves are adopted. Mesne constant, peak to picked length L, half parietal angle α and inclination between section & axes Φ are adopted in the selection of suited curves. The relationship between L, α, Φ and idiocratic parameter p, eccentricity e is analyzed with Matlab. Then machining locus is generated and optimized. Research results showed that, with the mathematical model found on the basis of virtual quadratic curves, the axisymmetric aspheric function and its machining locus could be generated rapidly.
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We deposited indium tin oxide (ITO) films on glass substrates with DC magnetron sputtering system and the experiments were scheduled by orthogonal test table L32(48). Sheet resistance, surface morphology and transmittance of films were tested. Effects of eight parameters on electrical and optical properties of ITO films, were discussed in detail. Deposition pressure, flow ratio of argon to oxygen and annealing temperature will greatly affect conductance of ITO films. The best parameters for sputtering ITO are: deposition pressure 2mTorr, flow ratio of argon to oxygen 16:0.5, annealing temperature 700K, distance between target and substrate 15, annealing time 1h, sputtering power 300W, annealing atmosphere pure nitrogen and deposition temperature 500K. Sheet resistance, transmittance in visible region and resistivity of the film prepared with above parameters are 17Ω/, 85.13%, 1.87×10-4Ω•cm, respectively.
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This paper presents theoretical analysis and experiment results of four different fibers transmitting 10MW peak power Nd:YAG laser pulse. The main factors limiting to optical fiber transmission of high power laser pulse is pointed, including air breakdown at focus area and surface damage of optical fiber. The theory of air breakdown and the fiber coupling conditions is described briefly. The results of study to the transmission properties and damage conditions are presented on the basis of four different types of optical fibers. The results of the experiments are further analyzed in the aspects of transmitting efficiency, air breakdown and surface damage. The local and foreign optical fibers, with plastic-cladding and silica-cladding, and step- index and graded- index fibers are tested separately in the experiments. The experiments showed that the imported fibers are able to transmit up to 10MW peak power laser pulse with no any visible damage, while energy density at the fiber output end surface is 3.54GW/cm2. For local fibers, damage on the input surface of both plastic-cladding and silica-cladding, step-index fibers was found obviously. The column damage to the graded index fiber was also found and investigated in the research. Damage mechanisms of fiber at high peak power laser pulses are summarized. High quality finishing of fiber end surface will improve damage threshold tremendously. The conclusion of the study is that transmitting Q-switched Nd:YAG pulses of 10MW peak power is feasible for the domestically made fibers if their end surfaces are properly processed.
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The key technology for aspheric machining offers exact machining path and machining aspheric lens with high accuracy and efficiency, in spite of the development of traditional manual manufacturing into nowadays numerical control (NC) machining. This paper presents a mathematical model between virtual cone and aspheric surface equations, and discusses the technology of uniform wear of grinding wheel and error compensation in aspheric machining. Finally, a software system for high precision aspheric surface manufacturing is designed and realized, based on the mentioned above. This software system can work out grinding wheel path according to input parameters and generate machining NC programs of aspheric surfaces.
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In this work, electrochromic tungsten oxide thin films doped with terbium were deposited by radio frequency magnetron sputtering deposition. The samples were analyzed with scanning electron microscopy (SEM), atomic force microscopy (AFM) and x-ray diffraction (XRD). The films were amorphous and the thickness of the films is about 250 nm. From the result of AFM, the WO3 films doped with terbium are porous and the sample doped with 1.95% Tb has more porosities than undoped sample. Cyclic voltammetry experiments were performed to investigate the influence of terbium content on the electrochromic performance of the films. When the terbium content is equal to 1.95%, the cell capacity owns the best electrochromic capability. Measurement of optical transmission measurement for W-Tb-O thin films was carried out by a double-beam UV-VIS-NIR spectrophotometer with a wavelength range from 380 nm to 900 nm. In the different wavelength ranges, the films have different transmittance changes for the bleaching and colored state.
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Some investigations into preparation of silicon coating on SiC mirror by Electronic Beam Physical Vapor Deposition (EB-PVD) are introduced in the paper, which include adhesion strength of coating to substrate, pattern of coating, and residual stress etc. According to the investigations, it was found that only when the temperature of substrate in the optimization temperature range, the excellent thermal-shock resistance and adhesion strength of coating to substrate are obtained. Furthermore, the coating has the column crystal structure. surface finish, deposition rate and gravity direction may have important influences on properties of coating-substrate system.
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Demands on large off-axis aspheric mirrors with high precision have propelled innovations of new effective and economical fabrication techniques as well as ultra-precision machining systems. A new generation of forming method for large off-axis aspheric surface is introduced. Linear motion guides are employed in the tool feed systems on most of diamond turning machines. For a rotary spindle can be made easier and less expensive than a linear guide at the same accuracy level, especially in manufacturing of a large size component, a rotary arm that carries a diamond tool combined with fast tool servo is used to replace the straight line. Therefore a new structure of a rotary feed machine is developed. Combination of two rotating movement of workpiece and diamond tool, and the micro linear feed of the fast tool servo controlled by CNC system synchronously, ultra-precision large aspheric surfaces can be turned. The corresponding geometric models are presented based on constituting appropriate coordinate systems and giving equation of the off-axis aspheric surface. By computer simulation it is verified that the processing method for the large off-axis aspheric component is simple and feasible. According to the geometric models provided in this paper, the 3-D machining is achieved. This new fabrication method allows equipment investment be decreased.
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A series of optical thin films of organic semiconductor materials including tri-(8-hydroxyquinoline) aluminum (AlQ3), bis-(2-methyl-8-quinolinolato)-4-(phenyl-phenolato)-aluminium-(III) (B(AlQ)), and N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine (NPB) were prepared by the vacuum sublimation technique. The optical properties in the UV-visible region of the thin films were investigated through measurements of optical transmittance and absorbance spectra. The optical band gaps were obtained from direct allowed transitions at room temperature by means of the Tauc plots. The Urbach energy and the slope of Urbach edge were calculated, respectively according to the Urbach-edges method. In addition, the single-layer structure devices of glass/metal/organic layer/metal were fabricated, and electrical resistivity of the materials were evaluated in term of the measured the current-voltage characteristics of the prepared devices.
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This paper describes a gradient-index planar waveguide (GIPW) coupler, its design and, structure in detail, and carefully analyzes its operating principle. Because mode-dimension and emission-angle of a semiconductor optical amplifier (SOA) can be converted with a selected direction by a gradient-index planar waveguide coupler, a high-efficiency fiber-chip coupling application is realized. The minimum coupling loss is less than 3dB.The gradient-index planar waveguide coupler can be used to replace a cylindrical lens sometimes due to their equivalent optical properties.
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In this paper, an experimental instrument for large-scale optics grinding is introduced, which is a three-axis CNC precision grinding machine. After resolving several essential technological problems (grinder dressing and dynamic balancing, positioning of large-scale optics and profile measurement) in precision grinding of large-scale optics, many experiments are carried on the workpiece of 330mm square K9 optics by applying the experimental instrument. Typical process values in grinding flat and spherical optics include: X-axis feed rate is 15-200mm/min, grinding depth 2-30μm, 1400-2000 rpm spindle speed for grinder and workpiece spindle speed of 40-150 rpm. The grinders are 250mm diameter resin bond with 8-10μm to 80-90μm diamond abrasives, used in rough or finish grinding. Experiment results are presented. The PV surface form of flat and spherical optics is 3-4μm, 4-5μm respectively.
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In this paper, the laser damage of transmissive optics used in high power Nd:YAG laser was studied in details by use of Nd:YAG damage testing system, the damage experiment was taken by 1-on-1 damage measurement method, and the damage morphology was observed by 200X Normaski microscope. The wavelength of laser is 1064nm and the duration of pulse is 10ns. Experiment result shows that the damage morphology of transmissive optics such as AR coatings and polarizer has same damage shape-pinhole, which is notable different from that of HR coatings. The pinhole is about round with diameter 10-50um, separated on the damage area of coatings and deep to the surface and sub-surface of the substrate. Specially, the damage pinhole exhibits on the rear surface of AR coatings and on the front surface of the polarizer respectively. On certain range of the laser energy density, the density improvement don't increase the size of the pinhole, just only increases the amounts of the pinhole. We think the pinhole is mainly induced by standing wave electrical field formed by laser and the defects near the both surface of the substrate.
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The compressor grating is a kind of reflective grating used in the ICF system for the pulse compressing or expanding. Nowadays, most of the compressor gratings are dielectrical reflecting gratings. According to the request of the ICF system, the compressing grating is difficult to fabricate because of its characteristics, such as high reflectivity, high diffract efficiency, high damage threshold value and the large aperture. So it is very important to study on the designing simulation method of this kind of grating. The performance of the simulation process should be discussed in detail. In this paper, differential method is used in the simulation process and several simulated results are given.
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A novel manufacturing method that is different from the traditional method for off-axis parabola is described. Generally, the figure error between the best-fit sphere and the parabola is many microns. It cannot be measured by high-precision interferometer and traditional hand finishing is not efficient. An advanced technology is introduced and the desired off-axis parabola is produced directly from the best-fit sphere. In this paper, magnetorheological finishing (MRF) technology is employed. The character of polishing spot, the material removal rate and the major manufacturing parameters are described. Fabrication parameters are optimized and the problems of fabricating off-axis parabola in practice are also discussed. A 150 mm diameter part was produced in a period of time in the experimentation with new deterministic polishing method. The final results show that the manufacturing ratio is more obviously improved than the traditional manufacturing method. It is a valid means to fabricate off-axis parabola with high efficiency and high-accuracy.
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A theoretical model for the backscattering from thin film deposited on super-smooth optical surface is established, based on which, a solid-angle integrated scattering (SIS) characterization system is built. The SIS measurement collects backscattered light in a limited solid angle by using an integrating sphere. The characterization system consists of three major parts: mechanical system, photoelectric conversion system, and control software. The scattered flux is spatially integrated by the integrating sphere and is detected by a photomultiplier and lock-in amplifier. The lock-in detection offers excellent noise rejection and is the key to the sensitivity. The measurement can be performed completely under the control software based on the Labview. Experiment results of the measurement are presented, sources of error are analyzed. Results showed that the backscattering down to 10ppm could be characterized with a resolution of 1ppm. The system can be used to measure the backscattering for an incident angle between 25o and 50o.
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This paper presents an optimal design of the waveguide separation and the orientation angle of the slabs for the arrayed waveguide gratings (AWGs) with low-crosstalk and low-loss. To demonstrate the effectiveness of the proposed method, a 16×16 AWG using silica-based sol-gel material is designed as an example to meet our prescribed specifications. The performance of the designed AWG is perfectly verified by simulation usingbeam propagation method (BPM). And the methodology of determining the optimal waveguide separation and the orientation angle of the slabs is simple and useful to obtain a low-crosstalk and low-loss AWG.
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Ptassium dihydrogen phosphate (KDP) crystals are used as key components in high power density solid-state laser for Inertial Confinement Fusion. Surface quality is an important factor for KDP crystals implemented in high power lasers. At present Single Point Diamond Turning(SPDT) is the only way to get the required transmitted wavefront and damage threshold KDP. The paper introduces something about the defects of KDP crystals fabricating and analyses some reasons. Based on the analysis of the reasons, the process parameters can be adjusted to meet the critical requirements of high energy density application. A piece of 320X320 mm2 KDP is acquired. The roughness of the 320X320 mm2 crystal surface was already to reach an rms about 5 nm. Data were measured by an interferometric microscope. The wavefront p-v is lower than 0.5λ(λ=632nm).
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Many researchers are interested in AlN films because of their novel thermal, chemical, mechanical, acoustic, and optical properties. Many methodsincluding such as DC/RF sputtering, chemical vapor deposition (CVD), laser chemical vapor deposition(LCVD), molecular beam epitaxy (MBE), thermal vapor deposition, can be used to prepare AlN films. In this paper, a new method, DC arc deposition, is used to deposite AlN films. It is an anti-reflective, protective film on optical elements. FTIR are used to determine the ALN structure and measure the transmittance spectrum. Ellipsometry is used to determine the films' refractive index, extinction index and thickness. The films' anti-wear properties are tested by pin-on-disc way and the anti-corrosion(anti-acid, anti-alkali, anti-salt) properties are also tested. The results show that the films is AlN films by the 670cm-1 typical peak, the films' extinction index is near to zero in the range of visible and infrared waveband, the films' refractive index is varied from 1.7 to 2.1 at range of visible and infrared waveband. The films have better anti-wear, anti-acid and anti-alkali properties, but their anti-salt properties are not good.
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Very strict requirements need to be met for producing a high-quality single-layer antireflection coating on laser diodes facets, In order to obtain a facet reflectivity of the order of 10-4, the index of refraction and the layer thickness of single-layer coatings have to be controlled for better than ±0.02 and ±2nm. In this paper, a mixed source material composed of Zirconium Oxide(ZrO2) and Titanium dioxide(TiO2), whose index is appropriate to the single-layer antireflective coating for 1.5μm InGaAsP laser diodes is described, A new method to control the index of refraction; and a simple and accurate method to control the thickness of deposited layer as well as a novel measurement method of low residual reflectivity of Si wafer are also proposed. One facet coated LDs is driven and ASE spectra are measured. The center wavelength shifts about 50 nm from 1610 nm to 1560 nm and the ripple in the gain is less than 0.2 dB and the broad-band is about 35 nm when the reflectivity is less than 4×10-4 by single layer.
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We report a photoluminescence (PL) study of nanometer Si-based films deposited by Pulse Laser Deposition (PLD).The surface appearance and microstructure of the films were characterized by Atomic Force Microscope (AFM), X-Ray Diffraction (XRD) and Raman scattering spectroscopy (Raman).The effects of several experimental parameters such as gas pressure, atmosphere and anneal temperature on the luminescence properties of the films were studied. The mechanism of PL property of the Si-rich Si02 films was discussed, we suggest that the PL is derived from quantum confinement effect of Si nanometer grains and the non-bridge oxygen vacancy defects of silica.
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In order to increase the reflection of incidence light which its wavelength is less than 350nm and higher than 1120nm (λ<350nm and λ>1120nm) on the surface of silicon solar cell and show no influence on the transmission of the light in spectral response range (350nm<λ<1120nm) of silicon, the IR/UV cut-off filter on encapsulation glass of silicon solar cell was designed. It can make silicon solar cell absorb the incidence light with selectivity. According to the theory of optical film, a computer program was designed. The IR cut-off filter of A[1.05(LMHML)]6[1.15(LMHML)]1.15LG on the top surface of encapsulation glass for solar cell was obtained. The transmission curve was plotted for IR cut-off filter. The curve shows: the IR cut-off filter has good selective transmission, most of the light (λ>1120nm) is reflected and all of the light (350nm<λ<1120nm) is almost transmitted to the solar cell. In the range between 350nm and 1120nm, the weighted transmission coefficient of light is 98.17%. Similarly, the UV cut-off filter of G H/2 L H/27 S on the rear of encapsulation glass for solar cell was obtained. The transmission curve was also plotted. The curve shows: the UV cut-off filter has good selective transmission, the most of light (λ<350nm) is reflected and all of the light (350nm<λ<1120nm) is almost transmitted to the solar cell. The weighted transmission coefficient of light (350nm<λ<1120nm) is 98.65%. The whole coating that combined IR and UV cut-off filter has the best selective transmission, the most of light (both λ<350nm and λ>1120nm) is reflected and all of the light (350nm<λ<1120nm) is almost transmitted to the solar cell. By calculation, we gained the weighted transmission coefficient, TW=97.49% (350nm<λ<1120nm).
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Crystal growth is dynamic coupling of transportation process and growth process between interfaces. Convection during crystal growth will tend to changes of liquation component and the defect of impurity stripe. The convection and stability should further be studied to obtain the crystal of high quality. It is necessary to obtain surface configuration and distribution of temperature around liquation phase and solute concentration. The technique of in-situ and real-time observation is a brand new technique, which is widely applied to production and scientific research. Information of crystal growth will be obtained from the observation. But the in-situ and real-time observation is uncharitableness for the experiment equipment, some conditions matched to the character of crystal must be provided. In the paper a design with ingenious and cheap crystal growth cell and circulation system of constant-temperature water which is suitable for the experiment of observation is developed, and a combined light path based on the technique of flowing visualization is designed to match to the crystal cell. The combined light path which is made up of the schlieren method and the principle of Mach-zehnder interference is non destructive, high sensitivity and observable, so it is an effective method to study the crystal growth.
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Hydrogen-free carbon films were deposited and synthesized by unbalanced magnetron sputtering (UBMS) using a graphite target in Ar atmosphere. The ion beam flow density was measured by a Langmuir probe under the condition of deposition DLC films. The results indicated that this unbalanced magnetron sputtering system can obtain ion beam density as high as 2.0 mAcm-2 even at low pressure of 0.5 Pa with an excitation current of 120 A, far larger than 0.3 mAcm-2 in a conventional balanced magnetron sputtering (MS) system. Hydrogen-free carbon films were deposited by PVD method with a rectangle graphite target of 480×120 mm. The Raman spectrum of carbon film was presented. It was proved that the film's structure is a typical diamond-like carbon. The Raman intensity of diamond and graphite peak ID/IGis as high as 2.26. Surface morphology was investigated by using an Atomic Force Microscope (AFM). The image indicated that the surface of carbon films is smooth; with the grains size about 10 nm and the surface roughness Rα about 2.5 nm, respectively. IR spectrum presented high optical transparency of 61.4% coated on single side of Ge sample, and no obvious absorption peaks were founded between 5000 and 1000 cm-1 owe to lack of hydrogen.
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As the shortcoming and insufficiency of CNC systems applied in optics manufacturing, a design and application based on Windows DNA-OM is presented. After introducing the prime principles and logic structures of Windows DNA-OM, a specific solution of optics integrated manufacture based on this framework is discussed in detail. In this solution, the OPC(OLE for Process Control) technology based on COM(Component Object Model) of Microsoft company is used for CNC equipment in the workshop, and this could provide a general interface for communication of hetero-structure CNC equipment of workshop and so all hetero-structure CNC can be accessed in a simple way. The experience and knowledge of optic manufacturing is stored and integrated in Windows DNA-OM Data part, this data part can guide optics manufacture. By completing this data part, an optics manufacture expert system can be realized. Then the prime characteristics of the integrated manufacture system are given. Finally this system is proved to has a good flexibility and opening, ease realizing, low cost and high feasibility.
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Ion beam enhanced deposition method was adopted to prepare In-N co-doped and Al-N co-doped ZnO films on Si, SiO2 and glass substrates. ZnO mixed with In2O3 or Al2O3 powder sputtering target was used and during the deposition N+/Ar+ mixed beam with an energy of 40KeV and a beam current of 2mA implanted into the deposited films. The XRD results showed that all polycrystalline In-N and Al-N co-doped ZnO films deposited on Si, SiO2 and glass substrates have a preferred (002) orientation. The as-deposited In-N co-doped ZnO film showed p-type and had a resistivity of 2.4Ωcm on SiO2 substrate. After annealed in N2, the lowest resistivity of p type In-N co-doped ZnO films was 0.8Ωcm. While Al-N co-doped ZnO film showed n type.
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For scanning and projection exposure, the image quality is decided by many factors, in which synchronization of wafer stage and reticle stage during exposure is a key one. Extreme Ultraviolet Lithography(EUVL) requires a much higher precision and speed for exposure, so the error that wafer stage tracking the reticle stage must be stringently controlled. This paper mainly deals with the control of the magnetic levitation stages of EUVL. The wafer stage and reticle stage used in EUVL are composed of dual stages respectively, namely a coarse stage and a fine stage, with which long distance and accurate positioning can be achieved. Feedback controllers are employed to compensate the positioning errors and solve the synchronization problem. The wafer stage is defined as the master stage and the reticle stage is defined as the follower stage. The slave stage tracks the master at velocity and acceleration at a required reduction ratio at anytime. To each stage, disturbance force is considered in the stage control loops; therefore the disturbance can be eliminated within the loop.
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For the fast and shade-free shape measurement of 3-D objects with large discontinuous height step, a new 3-D shape measurements based on the function of modulation is proposed. To avoid the shadings we adopt a coaxial optical system for projection and observation. A sinusoidal grating pattern is projected onto the surface of a testing object. Instead of phase information, we use the fringe modulation of the detected fringe pattern to determine the height distribution. Different modulation values correspond to different distances from the point of the object to the projecting system. Established the look-up table of modulation and position, only one frame of projected sinusoidal fringe is obtained and the height distribution of object can be calculated according to the value of modulation for the specified pixel of interest. The measurement result shows that the proposed 3-D shape measurement technique will be a promising method for fast acquiring 3-D data of complex objects.
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To solve the problems of manufacturing large aspherical primary mirror, an innovative idea was put forward: According to the characteristics that ultra-thin mirror can be easily deformed, a spherical mirror which is easier to fabricated and test, is employed to replace the aspherical mirror, then it is deformed into an aspherical one by adaptive optics technology. The predigested model, i.e., bended beam used in qualitative analysis was proposed, its deflection formula under the freely supported condition was set up. Based on an off-axis aspherical primary mirror, the relationship of
aspherical surface error (RMS) in tangential plane with bended beam's radius R, position S of concentrated load P and geometry length L of arc was analyzed. The range of R and S satisfied surface accuracy were calculated. Otherwise, aspherical surface error in sagittal plane was found, and bended beam's radius R, position S of concentrated load P and length L of arc which were suited for aspherical figure accuracy of both tangential plane and sagittal plane were given.
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The line width and period of the shield film were designed and optimized based on the principle of microwave transmission. The photolithography technology has been used to generate a photo mask. Then the mask was duplicated on the anti-refection coated fused silica substrate by adding metal and protective coatings with RF sputtering technology, followed by photoresist removing and other procedures. Finally, a high precision and dense metal shield film were developed on the substrate. A transmission of about 97% has been tested in the final result. A surface resistance of 30Ω/square has also been obtained. The microwave of 2.45GHZ has been completely shielded from radiation.
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The fabrication of volume holographic gratings (VHGs) has been investigated for many years. According to the photorefractive properties of LiNbO3:Fe crystal, the VHGs with the grating vector normal to c-axis of the crystal are obtained hardly. A new method for fabrication of above gratings in the planar waveguide array (PWA) in LiNbO3:Fe crystal based on the light erasing effect is presented. This light erasing technique is divided into two steps: the fabrication of PWA and the light recording of VHGs in the PWA. A PWA is formed firstly in the LiNbO3:Fe crystal through interference field of two red laser beams. The alignment direction of the formed PWA is parallel to c-axis of crystal. Then the VHGs are recorded using periodical erasing to the formed PWA by the bright fringes of interference, here the vector of the kind of gratings can be perpendicular to c-axis of LiNbO3:Fe crystal. Furthermore, the VHGs with the period of micron order are created in a PWA employing the light erasing method. The experiment results demonstrate that the light erasing method for fabricating VHGs with the grating vector perpendicular to c-axis in LiNbO3 crystal is feasible.
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In the procedure of printing progress epically for multicolor printing, better ink controlling is very necessary and important to obtain high printing quality products and presswork and it is very crucial to monitor the ink on-line in the printing procedure. Automatic printing inking-up has become one important research topic in the field of printing industrial production and automatic control. This paper presents a method for monitoring and controlling the printing ink in the press ink fountain automatically using one controlled system based on ultrasonic sensor. Firstly, physical properties and the installation location of the ultrasonic sensor is explained and analyzed and one monitoring system consists of ultrasonic emitter, ultrasonic acceptor, voltage-magnified circuit, detecting circuit and alarming circuit is designed; then an improved on-line monitoring method is put forward and a system which can give alarm to add the printing ink while the ink in the ink fountain reaches the minimum position is developed. Lastly, the quantity of ink in the ink fountain can be displayed on-line and the new system using on-line monitoring method can realize the automation of inking-up in printing process. Experimental results in our laboratory show that this on-line monitor method can improve the automatic degree of most presses in our country, which will bring great economical and commercial benefits to our country's printing industry.
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In computer controlled optical surfacing (CCOS), edge effect is a problem that needs to be solved as soon as immediately. When the polishing tool moves along the edge of the workpiece, the theoretical removal function model is not suitable for the machining practice. The pressure distribution is studied when the polishing tool goes beyond the border of the workpiece. The pressure distribution along the radius of the workpiece is presented and the calculation formula is given. The character of the pressure distribution is analyzed. On the basis of the analysis of the pressure distribution and the Preston hypothesis the amendment model of the removal function is established. The calculation formula of the amendment model is given and numeric analysis of the amendment model is processed. Using Matlab, the 3D simulation result of the amendment model is obtained. The removal profiles along X-axis and Y-axis are plotted. The characteristics of the amendment model are analyzed. Comparing the experiment results with the simulation results verifies the accuracy of the amendment model. Typical phenomena in experiments are analyzed and appropriate removal performance is illustrated. Our model correctly predicts that a greater amount of material is removed from the edge of the workpiece.
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The Laser Confocal Scanning Microscopy (LCSM) system is one kind of modern microscopic instruments characterized by its depth discrimination capability. Nevertheless, the quality of confocal microscopy images suffers from two basic physical limitations. The image produced by LCSM can therefore benefit from post-processing by deconvolution methods designed to reduce blur or noise. In this paper we present an improved blind deconvolution algorithm in which the initial value of parameters of PSF is determined based on error analysis. The results show that this method can effectively restore the degraded image acquired from the LCSM system.
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Photoresist spherical microlens array pattern can be fabricated by using multiple mask photoengraving and thermofusion forming process. By reactive ion beam etching, the spherical photoresist microlens array can be transferred effectively to a quartz substrate. The experimental parameters of the fused quartz microlens are the mean curvature of 40μm, mean bottom size of Φ56μm, mean apex height of 10.6μm.Scanning electron microscope (SEM) and surface contourgraph show that the pattern of spherical microlens array prepared is regular and well distributed, the configuration of each
fused quartz microlens is clear. Its surface is smooth and sleek. Experimental results show that by controlling amount of exposure according to spatial distribution, any surface structure which meets demands can be fabricated on photoresist of a certain thickness. In the process of microlens array pattern transfer by using reactive ion beam etching, etching parameters can be adjusted independently and controlled accurately. In the process, various technical processes can be schemed according to various demands, the best etching technique can be selected. In this paper, main process of microlens array fabrication is narrated. Main factors with influence on fabrication are analyzed.
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In recent years, interests have been growing for fast tool servo (FTS) systems to increase the capability of existing single-point diamond turning machines. Although piezoelectric actuator is the most universal base of FTS system due to its high stiffness, accuracy and bandwidth, nonlinearity in piezoceramics limits both the static and dynamic performance of piezoelectric-actuated control systems evidently. To compensate the nonlinear hysteresis behavior of piezoelectric actuators, a hybrid model coupled with Preisach model and feedforward neural network (FNN) has been described. Since the training of FNN does not require a special calibration sequence, it is possible for on-line identification and real-time implementation with general operating data of a specific piezoelectric actuator. To describe the rate dependent behavior of piezoelectric actuators, a hybrid dynamic model was developed to predict the response of piezoelectric actuators in a wider range of input frequency. Experimental results show that a maximal error of less than 3% was accomplished by this dynamic model.
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Based on the physical mechanisms of femtosecond laser-transparent materials interactions, three kinds of micromachining including three dimensional data storage, optical waveguide network and grating with an amplified Ti:sapphire laser system are presented. These optical devices on different transparent materials by femtosecond pulses are featured. The effect of laser machined parameters such as irradiated energy, the scanning speed and the recording material upon fabricated optical devices is studied in detail. From examples, the versatility of femtosecond laser precise micromachining technique is demonstrated. Practical application of femtosecond laser materials processing is illuminated.
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The requirements for ITO glass used in OLED are higher than those for LCD used. It has to keep much strict control on the process for making ITO glass because of the numerous impact factors. An orthogonal analysis method is used to deal with those factors, and the ITO glass good enough for OLED used by the DC magnetron sputtering has been got. The glass properties are 17Ω/, 81% transmittance in visible region. By the orthogonal analysis method, we just use limited materials and take experiment times to finish the crafts research.
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This paper mainly discusses the Si film which is deposited on the GaAs substrate with the IBAD E-beam coating system. By changing the technical conditions to get Si film with different parameters. Further studied on the test, and optimized processing parameter to get final Si film with more dense structure, higher index and minimum absorption. At the same time, considering the better stress matching of the substrate, selected minimal possible layers but realized even more reflection in the process of matching lower index materials. The mainly parameters are temperature of substrate, vacuum pressure, deposition speed and different gas flow, etc. Detailed analysis and evaluation based on the measuring curves and result of the Si test are presented.
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Nano-TiO2 powder and TiO2 optical films with photocatalytic activity were prepared by sol-gel progress.
Eu3+,Nd3+,Tb3+,Dy3+ were adoped to enhance the photocatalytic activity. The modality of the films was observed with AFM morphology; Three-dimensional picture of TiO2 by AFM (RMS=2.83nm) showed its fine quality. Samples
annealed at different temperatures were analyzed with UV-VIS spectroscopy. The results indicated that the absorption of the sample annealed at 500oC is strong because it is composed of anatase and rutile sized about 10~100nm (ref. XRD). XRD was used to analyze the structure of TiO2. The results showed that rutile phase is precipitated as well as anatase of TiO2,and anatase is about 66wt%,and the average dimension is 26nm; Alumina-supported vanadium oxide catalyst (V2O5/Al2O3) was prepared conventionally by impregnating alumina with an aqueous solution of ammonium metavanadate(NH4VO3). Cyclohexanol and cyclohexanone are key reactants for the production of adipic acid and caprolactam. The photo-oxidation of cyclohexane on titanium dioxide and over V2O5/Al2O3 was investigated in neat cyclohexane to synthesize cyclohexanone and cyclohexanol. The reaction also features the photocatalytic activity of Nano-TiO2 and V2O5/Al2O3. The results indicate that titanium dioxide doped with Eu or Tb exhibits the high selectivity to partial oxidation compounds. The characteristic of the reaction over V2O5/Al2O3 is a reasonable (K/A) ketone/alcohol ratio.
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This paper analyzes the principle of liquid crystal display backlight system illuminating by light emitting diode (LED) and serial kinds of structure of light guide plate. The density of diffusion dots on the light guide plate is an important factor to determine symmetric luminance and percentage of light transmission of LGP surface. Through changing the structure of light-guide plate, we can decrease the loss of light and improve the distribution of light.
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Soft X-rays has applications in many fields because of its special characters. Therefore the focusing and imaging is important to those applications. The traditional refractive lens to focus soft x-rays has some shortcomings. Fresnel zone plates can overcome these shortcomings. However, it presents new problems, that is, the resolution is limited by the width of the outermost zone. Kipp et al2 developed a novel diffractive optical element called the photon sieve. It can overcome the limitations of Fresnel zone plates. According to Fresnel-Kirchhoff diffraction integral, one can present the far field model3 and obtain the radius and the central position of pinholes on the conditions of far field and near field correction. We show the simulated figures and the diffraction pictures when the number of pinholes is 20, 40 and 80 respectively by imitating this model. Then we compare some diffraction pictures of the photon sieves with different number of pinholes to monochromatic light, and analyze the influence of the number of pinholes to the ability of focusing. The result indicates that the pinhole photon sieve has higher precision focusing ability than zone plates. This model is simple in theory and it has facility in operation.
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An optical configuration design is presented for the ground testbed. The system includes three sub-telescopes as the collecting elements, and a combination telescope. The goal is to produce an image with a "quality" equivalent to a filled monolithic aperture. The system has a diffraction limited field-of-view of 0.1 degrees. The subsystem utilizes non-spherical primary and secondary mirrors. Also, several image restoration techniques are analyzed in details, which are applied to sparse-aperture imaging system in frequency domain. The performances of the restoration techniques are compared under different circumstances, such as the aperture configurations, the fill factors, and the level of noise. The correlation coefficient is proposed as a criterion to determine optimal parameter, and evaluate the performance of algorithms. Simulation results demonstrate its possibility. Some suggestions are given for better restoration(resolution) of sparse-aperture imaging system.
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The fast qualitative analysis of textile fiber is a crucial step in textile manufacture, export and inspection. This paper presents a near infrared spectroscopy classification method based on SVM for fast qualitative analysis of textile fiber. SVM is a new automatic classification tool and it has successfully been applied to standard classification tasks, such as text classification, pattern identification, bioinformatics and medical diagnosis. In this paper, SVM is extended into near infrared fast qualitative analysis of textile fiber for the first time. In this paper, eight kinds classification algorithms which are composed of two classifiers(C-SVC and ν-SVC) and four kernel functions (linear, polynomial, RBF and sigmoid) are used to do classification experiments and comparison analysis for ten kinds familiar textiles fiber. Experiment results show that it is feasible to apply SVM in fast qualitative analysis of textile fiber, and the optimal classifier algorithm and the corresponding experimental results are reported.
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Stress birefringence caused by assemblage stress can change the light through the glass into tow beams in different polarization mode, so the magnitude of the stress birefringence can be measured by a polarimeter. The Modulation Transfer Function (MTF) curve can be looked as the accurate result of image quality of an objective, in this article, we make an analysis of the correlation in theory, and list the result of the experiment. The MTF curve shows the obvious difference before the stress caused by assemblage was released and after. The stress caused by assemblage produces the additive wave aberration of the light. This additive wave aberration then cause the image quality loss of the objective. Measurement data indicates another objective as contrast has no stress in any of its units, so the MTF curve was almost the same as it was designed. The most serious loss of the image quality by assemblage stress is the falloff of the vertical curve and the horizontal curve of MTF, especially at the edge of the view field of the objective, and once the stress of the lens was released, this falloff disappears at the same time. So our conclusion is before an objective was assembled, each lens must be test by a polarimeter. If the stress can't be accepted, the stress should be released forwardly. And, this kind of test should also be implemented before the stickiness of each lens of the objective for the final image quality.
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Numeric control machining and on-line compensation for aspheric surface are key techniques for ultra-precision machining. In this paper, conformal cubic B-spline interpolating curve is first applied to fit the character curve of aspheric surface. Its algorithm and process are also proposed and imitated by Matlab7.0 software. To evaluate the performance of the conformal B-spline interpolation, comparison was made between linear and circular interpolations. The result verifies this method can ensure smoothness of interpolating spline curve and preserve original shape characters. The surface quality interpolated by B-spline is higher than by line and by circle arc. The algorithm is benefit to increasing the surface form precision of workpiece during ultra-precision machining.
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When femtosecond laser pulses are tightly focused on transparent material, high pressure caused by temperature increase in a confined volume of material will result in microexplosion. Thus the materials in such area will be densified, which causes the variation in refraction index. Continuous explosive lines that are just under the surface of quartz crystal wafers are micromachined by femtosecond lasers. These lines can serve as optical waveguides. Surface morphologies and nanomechanical properties in the area above the explosive lines were measured. The surface irradiated by laser beam is much rougher than that of the unirradiated zone, and there is a clear boundary between laser-induced rough and smooth areas. The size of the rough areas is much smaller than the laser spots that are irradiated on the surface. Nanomechanical changes occur in the area that has no observable damages in microscope and AFM. The position dependent variations of mechanical properties around the surface area that is just above the irradiated line were described in this paper. The values of elastic ratio changes significantly in different positions, which reveals the position dependent variations of femtosecond laser induced stresses and structural changes. Shocks generated during microexplosive process response for such changes. The changes can cause the variation in the degree of densification in different positions, which is corresponding to the modification of refractive index. By focusing the femtosecond laser pulses into the bulk of quartz crystal, internal waveguides and grating structures were fabricated.
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As the rapid market need of micro-electro-mechanical systems engineering gives it the wide development and application ranging from mobile phones to medical apparatus, the need of metal micro-parts is increasing gradually. Microforming technology challenges the plastic processing technology. The findings have shown that if the grain size of the specimen remains constant, the flow stress changes with the increasing miniaturization, and also the necking elongation and the uniform elongation etc. It is impossible to get the specimen material properties in conventional tensile test machine, especially in the high precision demand. Therefore, one new measurement method for getting the specimen material-mechanical property with high precision is initiated. With this method, coupled with the high speed of Charge Coupled Device (CCD) camera and high precision of Coordinate Measuring Machine (CMM), the elongation and tensile strain in the gauge length are obtained. The elongation, yield stress and other mechanical properties can be calculated from the relationship between the images and CCD camera movement. This measuring method can be extended into other experiments, such as the alignment of the tool and specimen, micro-drawing process.
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Tightly focused femtosecond laser, which can induce two-photon absorption (TPA) in photosensitive resin, has been regarded as a unique kind of technology for three-dimensional micro and nano fabrication. This technology provides the ability to fabricate precise micro optical devices such as three-dimensional photonic crystal and micro lens. In this paper, the characteristic for micro lens fabrication, and demonstrate some numeric simulation result about the lens to make sure how the fabrication parameters, such as laser power, scanning step distance and scanning path method, effect on micro lens surface such as its profile and roughness is presented. With the guidance of the simulation conclusion, by optimizing those parameters, good experiment results are obtained.
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In the technique on the detecting and the identifying of infrared target, the infrared target and the background can be distinguished by the difference of the gray-scale, i.e. the difference in temperature between them. Firstly, FPGA was used to pre-treat the infrared image including the threshold segmentation of two-apex and the threshold segmentation of maximum between-cluster variance. Secondly, the figure of the target was obtained, and then the binary image was transferred to the DSP which identified it. The high efficiency of FPGA in simple-shape computing of digital signal processing was stood out.
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Microwave absorption and dielectric spectrum detection technology, with high time resolution (less than 1ns), was used for non-contact measurement of electron property in solid materials. In this paper, the photoelectron decay time-resolved spectra of free electrons in cubic AgCl emulsion sensitized by different concentrations of green-sensitive cyanine dye were measured by dielectric spectrum equipment. At the same time the absorption spectra were obtained by spectrophotometer. Experiments show that when the sensitive concentration is less than 0.02ml(5.0mg/ml)/40g emulsion, the dye J-aggregate is not formed on the surface of silver chloride microcrystals; The photoelectron decay is slower than that of pure cubic AgCl emulsion. when the sensitive concentration is more than 0.2ml (5.0mg/ml)/40g emulsion, the dye J-aggregate is formed on the surface of silver chloride microcrystals; compared to the M-state of dye, the maximal absorption peak of J-aggregate is shifted to longer wavelength about 50nm. The photoelectron decay is faster than that of pure cubic AgCl emulsion.
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A novel light absorption layer for liquid crystal light valve is developed by VOPc and a new structure of liquid crystal light valve by using a three-sources evaporation system is proposed. CdTe is a typical absorption layer for liquid crystal light valve, but its absorption coefficient is not so good, especially at 400nm-500nm. However, the absorption of VOPc is very good at this range. So VOPc is introduced to the multi absorption layer. Then a double-layer absorption layer with a good absorption at whole visible light range can be got. To increase the adherence to the substrate, an SiO layer is introduced to wrap the CdTe layer and VOPc layer like a sandwich structure. At first SiO layer is evaporated and then the CdTe layer and the VOPc layer at the same time. After finishing the CdTe layer, VOPc is continuously evaporated for a while and then evaporating the CdTe is again made. After finishing CdTe and VOPc layer, SiO layer is used to cover the whole layer. At last, a multi light absorption layer with 8000Å thick and the structure of SiO:CdTe:VOPc:CdTe:SiO is deposited on glass by evaporation technique. Dependence of light absorption coefficient of multi film is measured. The resistivity of novel absorption layer is 5.5 108Ω•cm. The absorption coefficient of R=7.8 105 cm1, G=6.8 105 cm1, and B=7.2 105 cm1 is obtained with the optimum technics through experiment, and it can meet the needs of the liquid crystal light valve.
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The MRF system is designed and the principle is analyzed. The structure of the electromagnetism polishing wheel is generally designed, and the cross section of electromagnet is simulated by ANSYS. The points on the 2D flux lines that are used in the MRF are picked by an equal step. Data processing is used in the points by MATLAB. The equation of the polynomial fitting algorithm of the points on the 2D flux lines is gotten, and the area between the 2D flux line and the polishing wheel is figured out. Then the polishing curve is well controlled.
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The Nanosys-300 aspheric optics ultra-precision machining system is the main research achievement of the Ninth-Fiveyear Plan period key advanced research, namely the aspheric optics ultra-precision machining and measuring technology. The ultra-precision machining system, machining technology and measuring technology are investigated in this paper. The corresponding research achievements are as follows: comprehensive design and manufacturing technology of
aspheric optics ultra-precision machining system, high speed ultra-precision aerostatic air bearing work spindle system, ultra-precision fully constrained hydrostatic oil bearing slides, high speed ultra-precision aerostatic air bearing electrical grinder spindle system, open and high quality CNC system integrating technology, etc. The precision test and practical application shows that the concerned system has reached the world advanced level.
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In the area of astronomy and space camera, the application of silicon carbide (SiC) will have a good future for its specific stiffness and quickly thermal diffusion. However, SiC as a new material of optical mirror is difficult to process efficiently because of its specific characteristics such as stiffness and material structure. To manufacture the aspheric SiC mirrors of a R-C system with aperture 520mm in diameter, we starts to research on optical surfacing of SiC. Some small SiC parts are used to do serial surfacing experiments for finding a technology to improve the surface roughness of SiC. Test result shows that the surface roughness (RMS) of the best plate is better than 1.0nm. Finally, the surfacing results of the ellipsoid primary mirror with aperture 520mm in diameter and the hyperboloid secondary mirror with aperture 114mm in diameter of the R-C system are measured. The surface error (RMS) of them is less than 15nm, and the surface roughness of them is better than 1.8nm. The results meet the requirements of optical mirrors.
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Because of the isotropic energy band structure of the Γ electrons in N type GaAs/AlGaAs quantum well infrared photodetector (QWIP), normal incident radiation absorption is impossible so that the optical grating becomes key requirements for such QWIPs. The development of very long wavelength infrared GaAs/AlxGa1-xAs quantum well Infrared photodetectors (QWIPs) is proposed in the paper based on optimization of 2-d period grating design, processing of detector, and a 16μm cutoff wavelength QWIP has been demonstrated at 40K. The blackbody responsibility Rv=3.4847×106V/W is obtained. The peak detectivity reaches D* λ=2.962×1010cm•Hz1/2/W.
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