This PDF file contains the front matter associated with SPIE Proceedings Volume 10842, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

In this paper, a Hermitian symmetry based orthogonal frequency division multiplexing (HS-OFDM) signal transmitter is proposed. It can be used in a digitized radio-over-fiber (DRoF) system to reduce the system complexity by transmitting a real digital sequence. In this HS-OFDM transmitter, differential pulse code modulation (DPCM) schemes are used instead of the traditional pulse code modulation (PCM) to quantify the bandpass sampled signals, which can improve the signal-to-quantization noise ratio (SQNR) by 4~7 dB. Moreover, a high-order pulse amplitude modulation (PAM) is utilized to increase the spectral efficiency of the DRoF system. Simulation results show that the digital code with PAM- 16 can improve the spectral efficiency by 3 times with the same error vector magnitude (EVM) performance.

In the process of laser excitation of the solid laser, the laser crystal is exposed to the cooling of the surrounding medium while being irradiated and heated by the pump light. So that an uneven temperature distribution is formed in the laser crystal, leading to the thermal stress, stress birefringence, thermal lens effects, partial refraction effects, and even fractures that seriously affect the stability of laser resonators, laser output power, output beam quality, conversion efficiency, and laser lifetime. Therefore, studying the distribution law of temperature and thermal stress in the laser crystal and its effect on laser performance has become one of the hot topics in the field of solid-state lasers. In this dissertation, based on the mathematical model of the thermal conduction and thermal stress of the orthogonal anisotropic laser, the temperature distribution and thermal stress distribution in the laser crystal are numerically calculated, and the location where thermal cracking occurs is analyzed. A solid self-Raman yellow laser was used to verify the experiment. The thermal cracking position of the laser crystal was consistent with the theoretical analysis. The changes of the laser output power before and after the thermal cracking of the laser crystal were measured, and the degree of influence of thermal cracking on the output power of the laser was qualitatively studied. The experimental results show that the maximum power of the 1064nm fundamental frequency laser output before and after thermal cracking is reduced from 2.2W to 1.7W, while the yellow laser power is reduced from 200mW to 26mW.

The negative capacitance (NC) Ge pFETs with different thicknesses of HfZrO_x (HZO) are investigated. Although NC transistors with 6.6 nm HZO exhibit a 56 mV/decade subthreshold swing, the hysteresis inevitably occurs. The hysteresis-free characteristics are demonstrated in NC Ge pFETs with 4.5 and 3.7 nm HZO. We also study the impact of annealing temperature on the electrical performance of devices, which shows that the hysteresis reduces with the increasing of annealing temperature. By tuning the parameters of HZO, the NC devices achieve better SS and on-current in comparison with the control transistors.

This paper is dedicated to feature extraction of acoustic emission (AE) signals from machining hard brittle materials. A diamond intender is used to scratch BK7 and sapphire. Typical characteristics of AE signals from the two materials of are all concentrated in [100-200]KHz frequency span, and band-filtered signals represent obvious local burst-type waveforms, which is closely related to the crack and fragmentation phenomena that occur when brittle material is removed. Locations and oscillation form of burst-type AE are useful information for process monitoring and quality prediction of machined surface. In order to acquire the information, the theory of shift-invariant sparse coding(SISC) is introduced to analysis AE RMS signals. Experimental results of the two typical hard brittle materials show that oscillation form and locations of burst-type AE can be sparsely expressed by a self-learned atom and the corresponding coefficients. From the aspects of machining process monitoring, taking burst-type AE event as a monitor parameter is more accurate and objective in the reflection of locations and scales of cracks on the machined surface induced by machining.

Additive manufacturing of metal parts in space is one of the potential means to realize on-orbit maintenance of aircraft. However, the basic phenomena such as the rapid melting and solidification behavior of metallic materials under the action of high-energy beams in space are unclear. It is necessary to observe those phenomena and reveal basic laws through space experiments. Therefore, an experimental platform for rapid melting and solidification of metal materials is developed. There are two parts included in this platform. A detailed design of the manufacturing system in space is described at first while the in lab experimental system on the ground is introduced also. In order to simulate the vacuum environment in space, a vacuum chamber is used to contain the core unit of the experimental system. Laser is used to melt a metal wire during the experiment while a positioning stage is adopted to shape the melted wire. The melting and solidification process is controlled automatically while it is monitored by a machine vision system at the same time.

As complex ceramic multicomponent materials, the lunar regolith and minerals still challenge people on onsite utilization technology limited to the lunar surface environment. In this paper, we investigate the suitability of lunar regolith simulants and ilmenite powders for 3D printing (aka Additive Manufacturing) of hypothetical brick aimed at lunar habitat construction. The first generation of laser 3D printing equipment (Lunar 1.0) for our experiments has been designed and assembled, which is suitable for selective laser sintering (SLS) process out of many kinds of ceramic powders to manufacturing samples with different geometrical shapes. The lunar regolith simulants and ilmenite powders are demonstrated obvious spectral absorbance from ultraviolet to near-infrared spectra, which are successfully performed during the SLS process in Lunar 1.0. The 3D printing technologies are constantly improved by adjusting the parameters of laser process and mechanical movement. The morphological features of 3D printed samples, including surface and porosity are investigated by using SEM. The evaluation of size and micro-hardness tests are also conducted to reveal the printing qualities of samples. The EDS and XRD results characterize the elements and components of 3D printed samples. Obviously, the strong heating process by laser source in Lunar 1.0 has a great impact on materials, because the complex multicomponent materials and solid state reaction in high temperature by SLS process for regolith simulants and ilmenite. However, this influence of heat treatment by laser source is quite different from continuously thermal treatment for ceramics such as normal high temperature furnace. In the future, the research for 3D printing of lunar regolith simulants and ilmenite powders for hypothetical brick in vacuum and low gravity will carry out for approaching the extreme manufacturing environment on lunar surface.

Micro-pits array structure, micro-gratings structure covered with finer nanostructures were generated on titanium surfaces using femtosecond laser pulse. The wetting behavior of the two types of surface structures were studied. Micropits array structure with a size of dozens of microns exhibits hydrophilic properties, and the hydrophilicity increased with increasing the number of laser pulses. Micro-gratings structure covered with finer nanostructures exhibits hydrophobic properties, and the hydrophobicity increased with decreasing the laser energy density. The results demonstrated that wettability of metallic surface can be facilely controlled by adjusting the femtosecond laser processing parameters. The formation processes of the two types of surface microstructures as well as the underlying mechanisms for their special wettability are also discussed. This research might provide a facile controllable strategy to realize special wettability for metal or other solid surfaces, even expand the functions and applications of metals.

Currently, periodic structures on lithium niobate crystal surface exhibit extensive application prospects in related fields of on-chip photonic-integrated platforms and nanophotonics. We fabricated periodic ripple structures on the surface of lithium niobate crystal by femtosecond laser pulses irradiation and observed the evolution of these structures irradiated by 50,100,500,1000 laser pulses respectively. The morphology of surface structure became more uniform with the increasing number of laser pulses. Especially fabricated by 1000 pulses, regular ripples were found over the ablation area. The direction of ripples is perpendicular to the laser polarization and the period is around 190 nm, which was calculated by 2D-Fast Fourier Transform. By Finite-Difference Time-Domain method, we simulated the effect of the initial periodic structure on subsequent energy distribution. Numerical simulation results show that energy is deposited in the grooves between the ripples. Therefore, the ablation of grooves is more efficient, and the ripples morphology resulting from subsequent laser pulses irradiation becomes more uniform. The simulation results are consistent with the experimental results. This research is considerably valuable for controlling precisely periodic micro- and nanostructures formation and providing innovative laser manufacturing technology for wide bandgap material.

In this work, we demonstrate a developed 3D printing based on two-photon polymerization for achieving millimeter-scale, micron-accuracy 3D structures (MM-3DS), which combines the femtosecond laser of 800 nm and low magnification objective lens of 10×. The commercial photoresist SU-8 is used in 3D printing system for improving mechanical strength and chemical stability of MM-3DS. The 3D microstructures are preprogrammed and optimized by considering the scanning mode and experiment parameters. During 3D printing process, micron features are written within the interior of SU-8 film via localized polymerization driven by nonlinear two-photon absorption process. By the 3D movement in ~1 mm scale of the focused beam, a customized MM-3DS can be produced. We have fabricated a customized MM-3DS with a size of 1.6 mm and an accuracy of 10 μm. The influence of volume for the printing structures V_s on the printing time T exhibits a linear behavior, indicating that the printing speed is 0.248 mm³/h under the current conditions. This technology offers a flexible and low-cost method of generating highly customizable, precisely controlled MM-3DS, which is promising for the manufacture of complex functional structures and devices for the microfluidics, microelectronics, photonics and so on.

Poly(ethylene) glycol diacrylate(PEGDA)-based hydrogel materials with the excellent biocompatibility are widely used not only for cell culturing and tissue engineering but also for damaged bone repairing. In order to guarantee the stability of PEGDA as cell scaffolds and the compatibility with the host tissue, a further knowledge of interaction between PEGDA micronanostructure and cells is indispensable. In this study, two kinds of three-dimensional PEGDA micronanostructures have been designed and fabricated by two-photon polymerization for fibroblasts culturing. The PEGDA (average molecular weight 700) used in our study can preferably reconcile with a quantitative crosslinker to enhance the mechanical strength of structures. The polymerized line width as a function of the experimental conditions such as laser power and scanning speed during the two-photon polymerization has been investigated. Through investigating the adhesion, proliferation, and spread of fibroblasts on PEGDA micronanostructures in vitro, a response between micro-structures and fibroblast has been investigated. This study would provide the potential application of PEGDA hydrogel in biophotonics and tissue engineering.

In this paper, a luminance measurement model of LED display using the image sensors was constructed, and the precision problems of this model were analyzed. We analyzed the parameters of the luminance measurement model of LED display from several aspects, including the spatial distribution of luminous intensity of LEDs with different viewing angles, the LED positioning error, the aberration of the optical measurement system, and the imaging as well as noise characteristics of the image sensors. Through the simulation, the influencing factors and the rules of the precision of the luminance measurement model of LED display were discussed. The results show that the LED positioning error and the noise level of the image sensors are the main influencing factors in the measurement model.

Here, we report a preparation method to fabricate 3D micro-cones with controllable morphology based on two-photon photolithography. Two-photon photolithography offers the unique ability to create arbitrarily complex 3D polymeric structures. The voxel shape of polymerization point is crucial for the topography of the micro-cone structure. Therefore, the relationship between focused voxel features of femtosecond laser and the shape of micro-cone were analyzed systematically, and a micro-cone structure with a cone height of 2 μm, cone tip of 50 nm, and a cone angle of 20° was successfully obtained in this study. In addition, 3D micro-cone structures with 10°, 20°, and 30° sharp corners have been fabricated by means of controlling the relative movement between laser focus and moving direction. Besides, the structures with a varied slope angle from 0° to 90° on the substrate surface can be obtained by controlling the post treatment process. Furthermore, a large array of 3D micro-cones has been achieved based on the proposed preparation method.

Metal nanoparticles fabricated from chemical methods exhibit various excellent properties with their unique physicochemical properties and structures. To address the problems of the complicated manufacturing process and the side products generation, laser ablation in aqueous environment is proposed as a facile and environment friendly method to fabricate nanoparticles, producing very limited impurities. Ag, TiO₂ and Ag/TiO₂ composite nanoparticles are fabricated under the irradiation of pulsed laser with surfactant dodecyl trimethyl ammonium bromide (DTAB) as the stabilizer. Assembly shape of surfactants could be tuned by controllable concentrations, resulting in different nanostructures of nanoparticles. The laser processing parameters and the stabilizer showed collaborative effect on the morphology design of metal colloid nanoparticles. SEM images showed different morphologies of Ag nanoparticles and evenly distributed TiO₂ nanoparticles are obtained. Typical silver crystals and rutile titanium dioxide crystals was characterized by XRD patterns. The UV-visible spectrum reflected the effects of Ag nanoparticles synthesized under different concentrations of DTAB on the absorption wavelengths of silver and titanium dioxide composites.

Multi-photon laser lithography (MPLL) is an economical maskless means for high resolution and intrinsic three-dimensional micro/nanostructures fabrication. Here, we report MPLL of AR-N 4340 photoresist, and a spatial resolution of 40 nm is obtained. The relationships between laser parameters and line morphologies are systematically investigated. In the MPLL process, standing wave interference generated by the reflected light from photoresist/air interface and the incident light could greatly influence the bonding capacity between the fabricated lines and glass substrate. Therefore, lines with width smaller than 150 nm can be easily taken away in the development process. In order to obtain line with higher resolution, two rectangular photoresist plates were fabricated for immobilization of the fabricated lines, and a nanoline with a feature size of 40 nm was achieved between them through carefully adjusting the incident laser power. This work is one of the evidences for high fabricating resolution characteristic of MPLL, and it exhibits the potential for fabricating high resolution semiconductor and electronic micro/nanostructures.

The explosive market growth of consumer electronic devices has made a great demand for the precise processing of sapphire by using ultrafast lasers. Ultrafast lasers can induce nonlinear multiphoton absorption, and thereby leads to the precise and defined microfabrication inside transparent materials with minimum heating effects. The induction of these structural modifications by tightly focused high intensity laser pulses is a versatile technique for the fabrication of three-dimensional photonic devices. Ultrafast lasers are therefore widely used for fundamental research as well as practical applications. This paper presents the laser induced damage mechanisms and absorption phenomena that lead to structural modifications in sapphire. For the given parameters, the electron density growth as a result of plasma generation through multiphoton and avalanche processes is predicted theoretically and is found to be greater than the critical electron density required to induce breakdown in sapphire. Structural modifications, from small change of refractive index to birefringence, cracks and voids are observed when sapphire was irradiated experimentally under the same parameters. Observations revealed the creation of a highly crack region at the focal volume surrounded by local refractive index change which enhances in radial as well as longitudinal direction with increase in the incident laser power and pulse number. Followed by this highly crack region, a birefringent region associated with the nonlinear propagation of laser beam is observed, length of which increases with increasing input power however no significant effect is observed with changing number of pulses. Depending on the input beam powers, this region has length of several hundred-micron and diameter smaller than two microns.

The starting and the stopping of the moving carrier can cause tens of thousands of gravitational accelerations of mechanical impact, which may lead to the damage of photoelectric detection parts, especially the optical system. For the study of the anti-overload ability of the optical system in strong impact environment, based on the finite element modeling method, taking the optical system with a diameter of 35 mm lens as the subject, the deformations and the stress nephograms of different materials of optical lenses under 10000g impact condition are obtained and the influences of different lens mounting structures on anti-overload ability of the system is analyzed. The consistency of the simulation results and the physical model test results, fully illustrates the correctness of the theory and the model. This paper explores an effective way for the analysis of the mechanical and structural evolution characteristics of optical system in strong impact environment.

In the development of microfluidic systems, conventional 2D processing technologies are increasingly difficult to meet the requirement of integration of multifunctional components within a microchannel. Recently, two-photon polymerization (TPP) technology has emerged as a novel alternative to fabricate 3D microdevices functionalizing conventional microfluidic chips. Here, the development of TPP microfluidic technology comprising parallel fabrication, holographic patterning method and real-time lithography in a controlled flow is reported. And a series of functional microcomponents containing microfilters, microsorters, microtrap, tunable microlens are fabricated by above methods. The results indicate that the processing of microfluidic devices is simple, timesaving, low cost and programmable designability. The functional microchips are further used in blood cells sorting, biomedical sensing, microparticle purification and trapping with successful test results.

There has been many models for material removal mechanisms of bonnet polishing (BP) based on the well-known Preston model. However, some experimental investigations have demonstrated that the relationship between process parameters and material removal are not linear at all, especially the relative velocity, which cannot be accounted explicitly by the classical model. Accordingly, in this paper, an analytical model is proposed to investigate the nonlinear relationship between relative velocity and material removal in BP based on the mutual interaction of the slurry, pad and workpiece among the BP interfaces with the micro-contact theory and the tribology theory. Good agreement between the predicted results of proposed model and the experimental data is obtained, and the nonlinear material removal with the change of relative velocity is attributed to the variation of the real contact area.

Additive manufacturing in-space is considered to have the potential for achieving logistical support in future space exploration. In order to meet the future metal additive manufacturing in-space, our research team is developing an advanced metal-wire laser additive manufacturing technology. The laser system is composed by 8 laser beams in an annular array. In the manufacturing process, 8 laser beams focus on the substrate to create molten pool and the metal-wire is vertically fed into the molten pool. This technology has been evaluated on ground environment and the metallurgical microstructure of the fabricated metallic parts is studied. In the immediate future, we are planning to evaluate the technology in microgravity environment using aircraft parabolic flights and carry out the comparison experiments. The experiments are used to study the effects of microgravity on the molten pool behavior, metal parts geometry, microstructure and mechanical properties.

In the field of harvesting robot control with vision feedback, hand-eye system calibration is very important which directly affects the precision of the task. Aiming at the feature that the vision of harvesting robot is fixed, a hand-eye system calibration method was developed. In the proposed method, by making use of the stereo vision to obtain coordinates of the target point in the robot coordinate system, and combining robot motion parameters, the calibration equations can be established first, and the eye-to-hand systems can be further calibrated based on improved least square method. This calibration process is simple, and does not need complex auxiliary devices. Related experiments have been done based on the suggested method to obtain the transformation matrix between hand-eye systems calibration, which has been shown to be of precision and efficiency.

More and more researches are focused on investigating the extremely wetting surfaces because of their applications in self-cleaning and anti-icing. However, aircrafts body panels and car glass windows were often exposed to harsh environment impact. In this paper, an electrochemical etching method were used to fabricate magnesium superhydrophobic surface with selg-cleaning property. Water contact angle (CA) of 165.8° and sliding angle (SA) of less than 3° were obtained after fluorination. The micro-structure of superhydrophobic surface were obtained by a scanning electron microscopy (SEM). The neutral electrolyte of electrochemical etching was an aqueous solution of NaCl and NaNO3. The superhydrophobic surface has water-repellent property. This study is also provided a potential method to fabricate the superhydrophobic surface. 1

Unstable thermocapillary convection in metal liquid bridge is a typical phenomenon during the laser metal-wire additive manufacturing process in microgravity environment. The evolution and dynamic mechanism of the liquid bridge will influence the manufacturing process and quality for the forthcoming on-orbit space metal additive manufacturing. Therefore, it is very important to investigate the evolution and instability of thermocapillary convection in liquid bridges in microgravity. In present investigation, a numerical model is developed to reveal the characteristics of thermocapillary convection. The effects of aspect ratio and gravity on the critical Reynolds number for convection instability of thermocapillary convection in metal (Ti6Al4V) liquid bridge are investigated numerically. The results indicate that the critical Reynolds number for convection instability decreases with the increase of aspect ratio number at first, and then increases both in the gravity or microgravity environment. The numerical results also reveal that the critical Reynolds number for convection instability under gravity environment with natural convection in metal liquid bridge is larger than microgravity environment. The research shows that the influence of microgravity leads to a distinctly different behaviour of thermocapillary convection in metal liquid bridge compared to the gravity environment. A more comprehensive study will be conducted to cover the parameter space more systematically to identify the factors which significantly influence the stability of the thermocapillary convection in metal liquid bridge under microgravity environment, which is important for the on-orbit space metal additive manufacturing.

Nano-CT provides a brand new tool for the research of biology, life sciences, archeology and artifacts, and new materials for its excellent nondestructive detecting capability, especially in the non-destructive testing of carbon and hydrogen polymer light element materials. However, typical conventional Nano-CT cannot perform high-resolution and contrast imaging on structure of materials with small differences in X-ray absorption, and the traditional color CT which can achieve this function has low ray intensity and poor image quality when observed on light-element materials. Therefore, a true-color Nano-CT based on FEI Quanta 600 SEM is proposed in this paper. Three different material targets, Cr, Cu, and W, are introduced to obtain different energy rays. High-sensitivity CCD detector and single-circle scanning method are used to acquire projection data and reconstruct three CT images with different energies. Finally, principal component analysis (PCA) algorithm is used to extract the three principal components as color and the three primary colors of the image are combined to form a true-color image. The true-color Nano-CT can perform high-resolution imaging of substances with similar attenuation coefficients but different compositions with high resolution.

The vertical heterogeneous integration structure of optical fibers and planar chips has taken on important functions in many MEMS devices and systems such as optical waveguide chips, MEMS vector hydrophones, and integrated optical fiber sensors. An optical fiber end face adaptive lithography method has been proposed in this paper to improve the alignment accuracy of fiber-to-chip integration. It uses the optical fiber to be integrated as the transmission medium for the UV exposure light source, and the optical fiber end face serves as a lithography pattern, thereby realizing highprecision pattern transfer of the optical fiber end face shape. We simulated the fiber optic adaptive exposure model using Zemax optical software, and analyzed the effect of light source power, exposure distance, and exposure angle on the experimental results. Finally, an adaptive fiber exposure experiment was performed, and the fiber end face shape and lithography pattern were compared and analyzed.

Transparent light-emitting devices based on organic optoelectronic materials and transparent electrodes can have broad impact on amount of areas including building decoration, smart displays and lighting system. In this work a transparent organic light-emitting device (TOLED) with a large area is demonstrated by using an inverted architecture. A polymer of ploy[(9,9-bis(3’-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctyl)fluorene)] (PFN) is utilized to modify the energy level and morphology between ZnO and organic optoelectronic material. As a result, a brightness of ~1000 cd/m2 is obtained from both sides of the transparent device with a working area of 1 cm2. This work might inspire a promising approach for the fabrication of TOLEDs for both information display and solid-state lighting.

Ion beam figuring(IBF) is commonly used during the process of fine optical fabrication. According to sputtering theory, material removal rate varies with the ion inject angle and the surface curvature. During the process of figuring high gradient aspherical surface, the removal function of ion beam figuring should be calibrated strictly to guarantee the accuracy of the figuring results. In this paper, we describe the influence of ion density distribution and surface curvature on material removal rate. Since the removal function varies from point to point within the ion bombed region for high gradient surface, rectification matrix was proposed to fix the disparity between the practical removal function and flat removal function. Experiments were implemented with high gradient aspherical surface to prove the rectification matrix can fit the variety of the material removal rate effectively.

A new class of semiconducting materials called organic-inorganic halide perovskites hereafter could lead to commercial photoelectric devices due to the ultrahigh-performance and low cost. Meanwhile, perovskite-based photodetectors also have a rapid evolution in recent years. On the part of optical sensors, visible light detection is crucial for many applications, including imaging, medical treatment, industrial auto-control and so on. However, it is difficult for traditional preparation techniques to reach large-scale preparation accompanied by splendid performance of the device. Herein, we reported a method for high performance photodetctor by brush-coating. The device structure of the photodetector is ITO/PEDOT:PSS/CH₃NH₃PbI_2.4Br_0.6/PC₆₁BM/C₆₀/LiF/Ag, and the composite perovskites are consisting of CH₃NH₃PbI₃ and CH₃NH₃PbBr₃ with optimized mixing ratio which is crucial for not only enhancing the photon absorption but also ensuring a adjustable detection range .The device shows an excellent detectivity of ~10¹¹ Jones under the illumination of 650 nm light at the bias of -0.5V. Due to the brush-coating process, the dark current is effectively suppressed down to 10^-10 A. The present results suggest a promising strategy for fabricating outstanding perovskite-based photodetectors and provide a potential strategy for large-area fabrication.

Slurry plays an important role in the material removal of computer-controlled optical surfacing (CCOS). However, in the high-speed and high-pressure polishing process based on traditional polishing tool, the distribution and flow of the slurry is uncontrollable and the update of slurry in the interface between the polishing tool and the workpiece is difficult, thereby affecting the polishing efficiency. Consequently, this paper proposes a novel polishing tool, which makes the slurry supply to the bottom of the polishing tool actively, thus ensuring the effective update and uniform distribution of the slurry and improving the polishing efficiency. The experimental results based on the novel tool shows that the removal efficiency of the internal slurry flow pattern (ISFP) is higher than that of the external slurry flow pattern (ESFP). In addition, with the increase of rotation speed of polishing tool, the removal efficiency of the ISFP increases approximately linearly, while the removal efficiency of the ESFP increases nonlinearly. Compared with the ESFP, the peak and volume removal efficiencies of the ISFP based on the novel polishing tool are increased by 44% and 40% respectively. The paper demonstrates that the removal efficiency can be improved based on the novel polishing tool, which plays an important role for the high-efficiency manufacturing of large-aperture aspheric optical elements.

For the purpose of ultra-precision grinding large scale and complex off-axis aspheric optics effectively and automatically, computer-aided NC programming system was developed in this article. First the mathematical model of aspheric parallel grinding was analyzed, and the manufacture process of aspheric grinding is designed. Then the system architecture was established, which included initial grinding module, on-machine measuring module and error compensation grinding module. After inputting process and aspheric parameters, the system could calculate the grinding wheel X/Z/Y coordinates precisely and simulate the grinding pathway automatically, and then create grinding CNC program, which could control the grinding wheel to move along the aspheric surface. And the on-machine measurement CNC program was created to acquire the form error by displacement sensor. By combining the form error with the aspheric surface coordinates, the grinding wheel coordinates could be calculated and compensation machining CNC program was created. Using this system to manufacturing one large scale and off-axis aspheric optics, the PV of final form error was below 3.0μm, and the RMS was below 0.5μm.

X-ray fluorescence analysis (XRFA) is a method which is widely used in measuring thin coating thickness. For metal coatings, the chemical and physical properties vary from metal to metal and their sensitivities to measurement parameters are also different. Thus, using the same parameters to measure different metal coatings would affect the measurement accuracy. In this article, the effects of the primary filter, substrate material and high voltage on different metal thickness measurement are presented. Six kinds of common plating materials (Au, Ni, Al, Sn, Ag, Zn) are used in the experiments. The experimental results also illustrate the differences in parameters selection of light metal Al and other heavy metals and analyze the reasons for this difference.

In this paper, Er-doped ZnO thin films were deposited on the substrates of slide and Si by sol-gel method. The effects of Er concentration on the structure, morphology and optical properties were studied in detail. The Er/Zn ratio were 1%, 2%,3%,All the samples were characterized by X-ray diffraction(XRD),atomic force microscope(AFM), ultra-violet spectrometer(UVS) and photoluminescence(PL). The AFM images illustrated the morphology of samples have uniform distribution and smooth surface, the grain size became smaller as the Er/Zn molar ratio increased. The PL spectra showed two emission bands located in the UV region and the visible region, both the positions and the intensities are affected by Er concentration. As the doping concentration increased, the transmission side had blue shife and the samples gradually increased ultraviolet light. This result was similar to the transmission spectra. The XRD pattern revealed all the samples had a hexagonal wurtzite structure.

The microwave phase modulation of liquid crystal depends on the rotation angle of liquid crystal molecules under the external electric field, and the alignment layer on the surface of liquid crystal drive electrode important influence on it. In this paper, the microwave phase modulation characteristics of non-chiral doped nematic liquid crystal under different materials with polar alignment layer and different rubbing alignment conditions are studied. The variation of different frictional strengths and microwave phase-shifts magnitude with the driving voltage of liquid crystal was tested through the test method. It provides a basis for the design of a liquid crystal microwave modulator and the selection of liquid crystal alignment materials.

MRF is capable of producing smooth surface without incurring serious mechanical defects. Thus it is employed to machine fused silica in the hope of reducing mechanical defects on the optical components. The MRF-polished surface was damage-tested with 355nm 8ns pulsed laser and it is found that the laser induced damage threshold was not improved (31.2J/cm² ) even if the surface contains almost no mechanical defects. However, the damage threshold is increased to 45J/cm² after slight HF-solution etching (~1μm material removal). On the other hand, the ion beam etching (IBE) was also investigated to find out the potential effects on the laser damage performance of fused silica. The laser damage threshold of IBE processed fused silica is 26.5J/cm² while the threshold rose to 55J/cm² after slight chemical etching (~1μm material removal) with HF solution. For comparison, the control samples finished with conventional pad polishing process were also tested. The thresholds prior to and following HF wet etching (~1μm material removal) are 29 J/cm² and 42 J/cm² , respectively. From the experimental results, it is clear that slight HF wet etching can enhance the damage resistance of fused silica irrespective of the finishing techniques. Neither MRF nor IBE finished fused silica surface behave better than conventionally polished surface whilst IBE-finished surface appears to have stronger damage resistance after HF etching. HF etching can improve the laser damage threshold by >107% for IBE finished fused silica.

Organic-inorganic hybrid perovskite solar cells have been widely recognized as an excellent candidate for next-generation photovoltaic devices because of their easy processing and rapidly developing power conversion efficiency (PCE). Owing to the fact that the interface is sensitive to photoelectric conversion properties, many strategies are used to improve the interface wettability between perovskite precursor solution and the hole transport layer (HTL). In this study, we report a method of argon plasma treatment on the poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) layer which could effectively enhance the wettability because of the improvement in the chemical compositions and film morphologies of PEDOT:PSS. In contrast to untreated films, the wettability of PEDOT:PSS is increased by 3.3, 3.6 and 3.7 times based on the optimization of plasma power, treating time, and pressure, respectively. We also systematically described the timeliness of wettability from 0 to 8 hours after plasma treatment. The interface wettability shows a down trend with increasing storage time.

With the science technology development, Electro-optical devices requires higher demands for optical lens. Less than 10mm small-sized cylindrical lens were fabricated and inspected. With conventional methods, custom designed fixture, cylindrical lens satisfies the designed demands were fabricated on classical polishing machine. A reliable processing procedure was acquired, which can guide the operator successfully fabricate the lens, and also be reference to the fabrication of similar optical lens.

The axicon is a rotationally symmetrical optical element along the optical axis of the focal line, including concave shaft cone and convex shaft cone. It is widely used in laser beam shaping, laser drilling, optical detection, laser resonator and lithography illumination due to the property of long focal length and narrow transverse width. The axicon has only one optical axis, and the curvature radius of each point of the surface is different in the direction of the optical axis, that is, the line is a straight line, but the points of the adjacent bus are really circular torus, and the traditional equipment is difficult to polish. A new process suitable for axicon processing is proposed, including forming, traditional polishing, Atmospheric Pressure Plasma Processing for surface correction, flexible asphalt discs for smoothing. With it, the convergence of the polishing process is significantly improved, and the PV is decreases from 27λ to 3λ. There are two main factors that affect processing efficiency: temperature and gas flow rate. An analytical method is selected to estimate the complex interaction between the temperature field analysis and the polishing efficiency during the polishing process, and it is possible to achieve efficient and determined process.

An analytical model for the pulsed laser generation of ultrasound in an adhesively bonded three-layered plate is presented. The model gives the time domain displacement of the plate as a function of laser characteristics and materials properties. Simulation of ultrasonic wave motion in three-layered plate is solved here with the finite element analysis. Detailed descriptions of ultrasonic waves are presented. The simulation allows a better understanding of the generation and propagation of laser-generated ultrasonic by creating a window of observation in the three-layered structure.

Industrial robots have great potential for efficient and flexible polishing of large optical components, but the low positioning accuracy and control stability limits the polishing form quality. A model is established to describe the pressure distribution at the edge based on FEA analysis, and the effects of form deviation between the workpiece and the polishing pad is also investigated, thus TIFs can be calculated reliably. Polishing paths are planned to avoid sharp turning angles and fast movement, which can lead to unstable material removal. The dwell time is calculated via deconvolution with the space-variant TIFs. Experiments are conducted and the results show that the edge-roll error is significantly reduced and the polishing time is saved by 80%. Hence the robotic polisher can be comparable to the conventional polishing machines, which has a great significance for the ultra-precision optical manufacturing.

The potential applications of organic materials in solar cells have been widely explored for the creation of inexpensive and flexible modules compared with their inorganic counterparts. However, the power conversion efficiency (PCE) of organic solar cells (OSCs) have been severely restricted on account of the insufficient light absorption in the organic active layers. A simple method to achieve higher absorption efficiency is to increase the thickness of the active layer, but considerable electrical loss can occur during charge transport to the electrodes. Therefore, it is necessary to seek some effective ways to enhance light absorption in active layer without increasing its thickness. OSCs with inverted configuration usually present higher PCE and longer lifetime than corresponding devices with regular configuration. In this study, we demonstrate an improvement in photovoltaic properties in inverted OSCs by introducing the patterned structures in the active layer (PTB7:PC₇₀BM) using a nano-imprinting technique with a PDMS stamp. By adjusting pressure of imprinting the active layer, the imprinted OSCs were optimized, showing the optimal optoelectronic performances. The results indicated when the imprinted cell was pressed by a 200 g weight, the absorption of the nanoimprinted cell dramatically increased compared with the control cell. Meanwhile, the fill factor (FF) also increased from 68.0% for the control to 70.0% for the optimal imprinted cell. In addition, the open voltage (V_oc) was maintained in 0.73 V. Overall, the PCE of 6.95% with a 6.0% enhancement compared to the control cell (6.54%) was achieved.

The Ta₂O₅ thin film is one of the most important high refractive materials in the band range from visible to near infrared. In this paper, Ta₂O₅ thin films were prepared by electron beam thermal evaporation(EBE) technology with different process parameters. The optical performance parameters of Ta₂O₅ thin films with different process parameters were tested, and the process parameters of the minimum extinction coefficient and the highest laser-induced damage threshold of Ta₂O₅ thin films were obtained. The results show that when the optimum process parameters are: electron beam current 110 mA, pressure 2.0×10 ^-2 Pa, substrate temperature 150°C, the extinction coefficient of the prepared Ta₂O₅ thin film is the minimum; when the optimum process parameters are: pressure 1.0×10 ^-2 Pa, substrate temperature 150°C, The laser-induced damage threshold (LIDT) of the prepared Ta₂O₅ thin film is the highest when the electron beam current is 90 mA. The research results have reference significance for the selection of process parameters of Ta₂O₅ thin film with different the laser-induced damage thresholds.

Additive Manufacturing (AM) technology is considered as one of the most promising manufacturing technologies in the areas of aerospace and defense industries. However, a lack of assurance of quality with AM parts is a key technological barrier that prevents manufacturers from adopting AM technologies, especially for high value added applications. Therefore, it is critically important to monitor the quality of products during the AM process. In this paper, current process monitoring especially the defects measurement for metal AM in Powder Bed Fusion (PBF) was firstly reviewed. And then, an optical in-situ inspection method based on multi-spectrum is proposed. The optical measuring system with infrared and white light imaging system is designed and optimized. Imaging data fusion algorithms is proposed to obtain the enhanced measuring results from infrared and white light imaging system. Simulation studies were undertaken to verify the validity of the proposed monitoring system. The research work is helpful for the optimization of process parameters so as to control the quality in the AM process.

Kilo-joule Laser System (KLS) is constructed as a X-ray backlighting resource, to provide X-ray for performing X-ray diagnostic experiments. As a crucial component of KLS, backlighting terminal system has such function as frequency conversion, color separation, laser transport, beam focusing, target alignment and debris shielding, enabling focal spot energy(2ω) of 500J in 1ns pulse, with target alignment accuracy of ≤±25 μm.

Computer-generated hologram (CGH) is an important component for high-precision aspherical surface testing. This paper puts forward a manufacturing method of amplitude-type CGH by femtosecond laser direct etching, and carries out detailed analysis and demonstration. Firstly, the demand of microstructure fabrication of amplitude-type CGH was analyzed by optical diffraction theory. Furthermore, we have established the theoretical model of femtosecond laser machining amplitude-type CGH fringe. Finally, we developed basic verification experiments, and analyzed the feasibility of fabricating CGH by direct etching process based on the testing results of processing fringe characteristics.

Near filed optical lithography has been a promising alternative to photolithography for its high resolution, low cost and high throughput. Bowtie aperture, one type of nanoscale ridge aperture, is widely used in near filed optical lithography. However, the bowtie structure milled by focused ion beam (FIB) usually suffers from non-vertical sidewall with taper and rounded corner due to Gaussian ion beam profile and redeposition effects. Here, we report a novel method to fabricate bowtie aperture with sub-15 nm gap, producing highly confined electric near-field by localized surface plasmon (LSP) excitation and nanofocusing of the closely tapered gap. Utilizing a passive flexure stage for contact control, we present our recent lithography results with a record 20 nm resolution (FWHM).

Maskless photolithography was proposed to achieve the conventional and low-cost micro and nano fabrication, the pivotal of such technology was the application of digital micro-mirrors devices (DMD). Based on maskless photolithography, we designed a specific bifocal compound eyes (BCE) which made up of an array of two superimposed microlens. However, during our experiments, we found the existence of nonlinear relationships among gray levels, exposure intensity and development depths. To precise control the surface profiles, we did several tests and interpolations were used on the data we gathered. Finally, we ascertained the development depth of each grayscale, a gray mask was designed and filled to 1024*768 to fit the size of DMD.

In the micro-nano structure manufacturing field, large field of view, flexibility, and single exposure are the advantages of laser interference lithography. However, this method can only produce periodic patterns. In this paper, laser interference lithography and optical field modulation techniques are combined. By adjusting the parameters such as the phase and amplitude of the incident light beam, a light field modulation interference model was constructed to study the relationship between the parameters of the incident light beam and the intensity distribution of the interference light field. We verified the feasibility of the method through simulation. Considering the performance of existing optical modulation devices such as the pixel size of spatial light modulators, we discuss the challenges of this approach and the actual resolution that can be achieved. There is no doubt that this provides a new direction for the preparation of multiscale, variable period micro-nano patterns.

Microchannel heat sinks have been widely utilized in micro fuel cells, micro medical equipment, high power cooling systems and so on. Fabrication of porous structures on the micorchannel surfaces provides an efficient method to enhance heat transfer, as it enlarges the heat transfer areas considerably. In the study, a laser micro-milling method is used to fabricate porous structures with micro-holes and micro-cavities on the microchannel wall surfaces. Three different shapes of micro-channels, i.e., U-shaped, V-shaped and rectangular ones, were utilized to process the porous structures, which demonstrated that porous structures can be formed on all the microchannels. Besides, the effect of laser fluence on the formation of porous structures on the rectangular microchannels was also explored. It was found that laser fluence played a vital role on the formation of porous structures. With the increase in laser fluence, the cross-sectional shape of the rectangular microchannels changed from rectangular to trapezoidal one. The channel depth and surface roughness of porous copper surfaces increased, whereas the channel bottom width decreased with increasing the laser fluence.