Two key criteria govern the characterization of nominal shapes for aspheric optical surfaces. An efficient representation describes the spectrum of relevant shapes to the required accuracy by using the fewest decimal digits in the associated coefficients. Also, a representation is more effective if it can, in some way, facilitate other processes - such as optical design, tolerancing, or direct human interpretation. With the development of better tools for their design, metrology, and fabrication, aspheric optics are becoming ever more pervasive. As part of this trend, aspheric departures of up to a thousand microns or more must be characterized at almost nanometre precision. For all but the simplest of shapes, this is not as easy as it might sound. Efficiency is therefore increasingly important. Further, metrology tools continue to be one of the weaker links in the cost-effective production of aspheric optics. Interferometry particularly struggles to deal with steep slopes in aspheric departure. Such observations motivated the ideas described in what follows for modifying the conventional description of rotationally symmetric aspheres to use orthogonal bases that boost efficiency. The new representations can facilitate surface tolerancing as well as the design of aspheres with cost-effective metrology options. These ideas enable the description of aspheric shapes in terms of decompositions that not only deliver improved efficiency and effectiveness, but that are also shown to admit direct interpretations. While it's neither poetry nor a cure-all, an old blight can be relieved.

The theory of coherence and propagation of light through imaging systems is well established. For coherent and incoherent sources, the intensity in the image plane can be predicted numerically using a straightforward convolution calculation. Image formation becomes more complicated when dealing with partially coherent light, as treating two-dimensional intensity fields (described by the four-dimensional mutual coherence function in the time domain or the cross-spectral density in the frequency domain) requires evaluating four-dimensional integrals. Thus, calculations are complex, slow to process and place demands on system memory. We present a variation of a method recently introduced [Wald et al, Proc SPIE, 59621G, 2005], in which elementary functions are used to reduce the integrals to two dimensions for light of relatively high degree of coherence. The method resembles the coherent-mode expansion, but the elementary functions are easier to find and work with than the coherent modes. We outline the method and present some numerical results. This approach has applications in modelling of photolithographic systems in which partially coherent excimer lasers operating in the Deep Ultra-Violet (DUV) regime have been used for the last decade. An accurate numerical model of such systems could prove useful in solving the classic inverse imaging problem of lithography reticle design.

The paper analyses the vignetting phenomenon for optical systems that have the objects placed at finite distances from them, e.g. microscopes. Three possible definitions, only two of them existing in the literature, are used and discussed in the paper. The characteristic circles and zones in the object plane are ascertained with regard to the vignetting, that is, with regard to the stop of the incident beams produced by the various diaphragms of the optical system, i.e. by the entrance pupil and by the entrance stop. These zones are mathematically analyzed and a geometric vignetting coefficient, with two expressions, a linear, classical, easy-to-use one, and a non-linear, more precise one, that we propose, are obtained. We demonstrate that the latter is better one from the point of view of the precision of the mathematical model that characterizes the physical phenomenon, while using it proves not to be essentially more difficult than the previous, less precise one.

The optical response of nanostructures that exhibit pronounced plasmonic effects is studied and analyzed. Various approaches to solve light scattering problems in the time domain and in the frequency domain, using both the domain and the boundary discretization methods were used. Far-field and near-field characteristics of plasmonic nanostructures are investigated with several numerical algorithms to study the shape effect and the effects of the illumination angles on the resonance behavior. Numerical results with high accuracy, reduced complexity and reduced computational time due to extensive use of semi-analytical solutions are obtained. This set of numerical experiments demonstrates significant differences in the performances of different numerical methods. We observed that even simple geometries of plasmonic nanostructures may pose severe problems for various methods. We identify a strong need to select and modify numerical simulation algorithms according to the plasmonic effects, in addition to the standard selection of numerical method according to the geometrical settings and length scales.

Machine Vision systems for manufacturing quality inspection are interdisciplinary solutions including lighting, optics, cameras, image processing, segmentation, feature analysis, classification as well as integration with manufacturing process. The design and optimization of the above systems, especially image acquisition setup is mainly driven by experiment. This requires deep know-how and well equipped laboratory, which does not guarantee the optimal development process and results. This paper proposes novel usage of rendering, originating from 3D computer graphics, for machine vision prototyping and optimization. The invented technique and physically-based rendering aids selection or optimization of luminaires, tolerancing of mechanical construction and object handling, robustness predetermination or surface flaw simulation. The rendering setup utilizes mesh modeling, bump and normal mapping and light distribution sharpening with IES data files. The performed light simulation experiments for metal surfaces (face surface of bearing rollers) are validated.

Traditional zoom lens designs employ multiple moving lens elements to provide simultaneous control of focal length and focal plane. We present an example of a simplified and compact zoom lens design by employing a single moving element to control only the focal length. In this zoom lens, wavefront coding is used to control the defocus. We describe the principles of operation with special attention to image processing. We simulate imaging and image restoration capabilities and present that the zoom lens provides high imaging quality.

The antireflection coatings which are used on lenses and other optical interfaces can have a profound effect on the image quality formed by an optical system. This paper evaluates the effects on optical performance of s- and p-phase shifts due to coatings. Coating design and lens design are usually treated as separate tasks, since the coating-induced wavefront aberrations are considered insignificant. As demands on optical systems increase (NA>0.9, wavelength <400nm, strehl ratio >95%), it is shown, that coating induced-wavefront aberrations can be the dominating aberration within an optical system. The wavefront aberrations induced by different antireflection coatings on an optical imaging system are numerically evaluated as an example. It is concluded that coating design and optical design have to be optimized in one task to achieve the best optical performance.

Tolerancing an optical design is vital when optical modules are produced in tens of millions. In these cases the production yield is all-important: it will decide if the product will be a success. While optical design softwares provide powerful tolerancing tools, to get an idea of what the production yield will be, we will have to go a step further. A way of taking this step consists in a tolerancing procedure that will use these tolerancing tools and a dedicated analysis software: - A list of specifications that the lenses will have to fit into has to be established. - A merit function that will calculate each of these specs will have to be written. - For the tolerancing itself, a script will have to be used to write to an output file all these values for each lens created during tolerancing - The analysis software will read the output file, make all the desired statistics and then give the production yield and other relevant informations (e.g. yield and behavior of any spec)

There is need in the media industry to scan moving film images into computer systems for subsequent image processing. Scanning is used today mainly for the "digital intermediate" process - the whole film gets scanned and digitally processed. The industry demands projection lenses that are made in small quantities to very high specifications. This paper will describe an implementation of both projection lenses and associated illumination optics. Optical design theory, computer optimisation and production methods will be discussed.

The importance of condenser optics is the fact that it is the bottleneck limiting efficiency in commercially available projection systems. Efficiency is a key parameter of projector performance, since it augments screen luminance, enabling the system to perform well under increasing levels of ambient light. Conventional condensers use rotational symmetric devices, most of them being elliptic or parabolic mirrors. They perform very far from the theoretical limits for sources such as arc lamps or halogen bulbs. Typical small displays in the 5-15 mm² etendue range have geometrical efficiencies about 40-50% for the best condensers; although theory allows about 100% (no reflection nor absorption losses are considered). Two basic facts are underlying this effect: The coma aberration of the reflectors and the rotational symmetric image of the source making the source projected image to unfit with the target. Thus, the only way to improve this performance is to generate a free form design that is able to control the shape and rotation of the source projected images. As yet, this can only be done with the SMS3D design method. We present here one of such designs achieving a geometrical efficiency that is 1.8 times that of an elliptical condenser for a 4:1 target aspect ratio and for the range of target etendue with practical interest and 1.5 for 16:9 target. This design uses only 1 additional reflection, i.e., uses a total of 2 reflections from the source to the target. A prototype of this free form condenser has already been built.

A lens that incorporates an internal optical pan and tilt mechanism using a Risley prism has been designed. A zoom mechanism that provides various ratios up to 10x has also been incorporated. The design of the lens allows any object in the field of view to be brought into the centre of the field and then zoomed onto. The lens design is scalable. The first variant was designed with a focal range of 2-10mm with a pan/tilt of 46° within a field of view of 90° in a pinhole lens configuration. Importantly the lens has an external stationary entrance pupil that leads to a compact form. A technology demonstrator has been built and its performance is discussed. Further developments of the lens technology are also discussed, including a 120° field of view variant with a 10x zoom.

Chromatic Aberration plays a part in modern optical systems, especially in digitalized and smart optical systems. Much effort has been devoted to eliminating specific chromatic aberration in order to match the demand for advanced digitalized optical products. Basically, the elimination of axial chromatic and lateral color aberration of an optical lens and system depends on the selection of optical glass. According to reports from glass companies all over the world, the number of various newly developed optical glasses in the market exceeds three hundred. However, due to the complexity of a practical optical system, optical designers have so far had difficulty in finding the right solution to eliminate small axial and lateral chromatic aberration except by the Damped Least Squares (DLS) method, which is limited in so far as the DLS method has not yet managed to find a better optical system configuration. In the present research, genetic algorithms are used to replace traditional DLS so as to eliminate axial and lateral chromatic, by combining the theories of geometric optics in Tessar type lenses and a technique involving Binary/Real Encoding, Multiple Dynamic Crossover and Random Gene Mutation to find a much better configuration for optical glasses. By implementing the algorithms outlined in this paper, satisfactory results can be achieved in eliminating axial and lateral color aberration.

The simultaneous multiple surface (SMS) method has been used to design nonimaging devices, such as solar concentrators and collimators, which work near the thermodynamic limit at highest efficiencies. The very high compactness of these devices is obtained through the simultaneous design of two high-order (above 30^th) aspheric surfaces. In imaging optics, low-order aspheric surfaces were introduced to correct Seidel aberrations. The ease with which the SMS method calculates higher-order aspheric surfaces offers great advantages in imaging design. The SMS method can design N rotationally-symmetric surfaces that, by definition, form sharp images of N one-parameter subsets of rays. The design strategy consists in finding the best configuration of these subsets of rays in phase-space, one that ensures that image-quality specifications will be met by all non-design rays. As a first example of an SMS imaging device, a new video projection optics system is presented, featuring extremely short throw distance, high compactness and wide angle projection.

Today's high performance cine lenses rely more and more on the use of aspheres. These are as powerful in correcting aberrations as they are expensive if it is not possible to use high-volume manufacturing processes. One possible solution to meet the increasing demands of design to cost is the use of identical parts in several lenses. The biggest gain is possible with the most expensive parts: the aspheres. In this presentation a successful as well as an ineffective way of incorporating the same asphere in three lenses which differ by a factor of 1.5 in focal length will be shown.

The Schmidt-Cassegrain configuration has advantages from the point of view of the packaging constraint but doesn't provide enough optical quality through the full field of view when a larger F-number (3.6) and a FOV of 1° are necessary to reach the minimum illumination threshold in the sensor. Moreover, to improve the global performance the telescope's window must be spherical instead of flat. All these factors produce a poor image optical quality that must be increased. We had overcome those problems introducing two changes in the traditional Schimdt-Cassegrain configuration. First, we had changed the spherical primary mirror to a Mangin mirror. This introduces a second surface and an extra thickness that can be used to optimize the system without adding new elements. Secondly, as the Mangin mirror is the entrance pupil of the system with a 200 mm diameter, the use of aspherical surfaces on it is too expensive. Instead we have aspherized the telescope's secondary mirror to obtain the required image quality. This aspheric coefficient of the secondary mirror, introduced in an element with a diameter not larger than 50 mm, replaces the third order coefficient of the second surface of the telescope window.

The retina camera is a very classical setup, which is mainly caused by the complex functional demands of this kind of systems. A lot of knowledge and experience is necessary in order to get the system parts working perfectly together at all multiple settings, so major changes in design will cause a new learning process. In example a lot of effort is paid to avoid undesirable reflected light, since the response of desired information of the retina is very weak and every direct reflex even from antireflection coated surfaces will overlap the desired information. The most disturbing undesirable reflected light is introduced by the so called ophthalmic lens, a refractive optical element dealing the double pass characteristics of the setup. Substituting the refractive optical element by reflecting surfaces will avoid the undesirable reflected light just by choice of the setup. It will be discussed the optical design concept of such a reflecting ophthalmic group, including the core idea and the steps leading to the final solution using reflecting free form surfaces. Furthermore, it will be shown the results of the related optical design study dealing the demands of the application retina camera.

A new principle of panoramic annular lenses (PALs) design and a new calculation method based on this principle are described. Six PAL new configurations designed with the help of this method are presented and discussed. In particular, the PAL configurations that form a real image and might help to design a very compact but simple system for panoramic surveillance are discussed as well. The analysis of the output characteristics of new PAL configurations have shown that they can provide high image quality, especially in the infrared spectral range.

Similar to human's binocular vision, stereomicroscopes are comprised of two optical paths under a convergence angle providing a full perspective insight into the world's microstructure. The numerical aperture of stereomicroscopes has continuously increased over the years, reaching the point where the lenses of left and right perspective paths touched each other. This constraint appeared as an upper limit for the resolution of stereomicroscopes, as the resolution of a stereomicroscope was deduced from the numerical apertures of the two equally sized perspective channels. We present the optical design and advances in resolution of the world's first asymmetrical stereomicroscope, which is a technological breakthrough in many aspects of stereomicroscopes. This unique approach uses a large numerical aperture and thus an, so far, unachievable high lateral resolution in the one path, and a small aperture in the other path, which provides a high depth of field ("Fusion Optics"). This new concept is a technical challenge for the optical design of the zoom system as well as for the common main objectives. Furthermore, the new concept makes use of the particular way in which perspective information by binocular vision is formed in the human's brain. In conjunction with a research project at the University of Zurich, Leica Microsystems consolidated the functionality of this concept in to a new generation of stereomicroscopes.

Digital taking systems for HDTV and now for the film industry present a particularly challenging design problem for rear adapters in general. The thick 3-channel prism block in the camera provides an important challenge in the design. In this paper the design of a 1.33x rear anamorphic attachment is presented. The new design departs significantly from the traditional Bravais condition due to the thick dichroic prism block. Design strategies for non-rotationally symmetric systems and fields of view are discussed. Anamorphic images intrinsically have a lower contrast and less resolution than their rotationally symmetric counterparts, therefore proper image evaluation must be considered. The interpretation of the traditional image quality methods applied to anamorphic images is also discussed in relation to the design process. The final design has a total track less than 50 mm, maintaining the telecentricity of the digital prime lens and taking full advantage of the f/1.4 prism block.

Instruments intended for use with the human eye almost always suffer from field curvature, because nearly all the components in them are of positive power. This paper will look at some standard eyepiece designs, and also one of the designs undertaken by Ancient and Modern Optics, comparing the calculated dioptre variation across the field with the subjective impressions of the user. Finally a design methodology for visual systems will be proposed which takes into account the asphericity, as well as the curvature, of the field presented to the eye, and the ability of the eye preferentially to select the best of the two astigmatic fields presented to it.

A THz time domain imaging system is optimized and analyzed with ZEMAX. The requirements to the optical design of time domain imaging systems in the THz spectral region are deduced. A system is presented, which is diffraction-limited for wavelengths down to 838 μm and field points up to ±4 mm. In the optical system a 90° off-axis parabolic mirror is combined with an aspheric plastic lens. The lens was made from ZEONEX E48R®, and it was manufactured by ultraprecision machining. A resolution test of the system shows that on time domain analysis of the pulse maximum on-axis 1 LP/mm can be resolved with an intensity contrast of 0.22. The resolution of the outermost field point is 0.67 LP/mm with an intensity contrast of 0.23. An outlook of an optimized system for imaging a field of ±10 mm in x- and y-direction is given.

The optical layouts incorporating binary phase diffractive grating and a standard micro-objective were used for femtosecond microfabrication of periodical structures in fused silica. Two beams, generated in Talbot type interferometer, interfered on a surface and in the bulk of the sample. The method suggested allows better control over the transverse size of the grating pitch, and thus control the reflection strength of the waveguide or fibre grating. We present the examples of direct inscription of the sub-micrometer periodical structures using a 267 nm femtosecond laser radiation.

A power density model is introduced into the Delano diagram. The correlation of the system length and the peak power density are outline especially for 2-f-systems with a low Lagrange invariant and high energy transfer.

The collimator in BD/DVD/CD compatible optical pickup unit has been designed to motivate and translate along the optical axis by the motor, for multi kinds of disc compatibilities of spherical aberration compensation incurred when reading and writing. The driving motor is huge and not easy to activate. Another technical obstacle to be handled is the alignment so that the reflective mirror should be adjusted and rotated along two axes. In this paper, this kind of optical pickup unit might be minimized, and realize dynamic focus control by micro machined deformable mirror. The optimal sensitivity should be achieved when the focusing spot size is equal to the diffraction limited diameter of the focal spot of the reflected beam.

Lens design is a continually expanding field being driven by applications with increasingly difficult packaging and imaging constraints. In order to meet the challenges posed by current and future design tasks, axisymmetric aspheric optical surfaces deviating from conicoids are required. Practical use of such surfaces is being enabled by ever-improving manufacturing and metrology methods. In this paper lens design with Forbes' orthogonal aspheres is investigated. The significant advantages of such an orthogonal representation for design of systems with good performance and manufacturability are highlighted.

We present the results of the utilization of a Spatial Light Modulator Liquid Crystal Display for the implementation of wavefront codification procedures in an imaging system. The light modulator works in transmission mode at the pupil of the instrument. The main disadvantage is that the procedure implies a calibration of the device as well as an inherent image processing. The more interesting feature we can obtain is the versatility related to the use of an electronic device at the pupil, as compared with conventional (fixed) manufactured ones.

The imaging system of a head-up display of production-vehicles in automobile industry includes the windshield which is different for each automobile type. Thus, the the imaging system has to be matched to it. This requires an effcient optic design procedure in order to minimize the development costs. One challenge is the layout of the freeform surfaces of the imaging reflectors because there is a lack of procedures comparable to classical imaging systems like first order design or aberration theory. Additionally, reference systems are not published. Onother big issue is consistent data management. It is usual practice in automotive industriy that the surface data of the imaging surfaces will be imported in CAD systems. Often, from these systems manufacturing code is automaticall generated. Importing surface date is delicate, because the surface describtion in CAD systems is done by NURBS (non-uniform rational B-Splines) which are not or insufficently implemented in commercial optic design software. Thus, a conversion of the surface is performed by the software tools. This conversion is normally not much documented and problems with e.g. accuracy, surface continuity often arrise. In this contribution some methods for the design of an imaging reflector for a head-up display and some resulting designs are presented. Additionally it is shown that already in the design phase the freeform surface can be described by NURBS without any lack of performance. This kind of describtion can then easily be transfered to CAD systems by standardized formats like IGES or STEP without any error-prone conversion.

An investigation is described in which asphericity is used to correct the spherical aberration of a high numerical aperture system comprising a sphere followed by a plane parallel plate. This scheme, first devised by Van Heel¹ for use as a monochromatic test device, provides a model to investigate the aberration contribution from coefficient terms of the reduced Feder equation for asphericity on a plane surface. Analysis and manipulation of surface profiles is facilitated by use of a closed form of the Feder formula: [see Formula in manuscript].

A unique collimated display concept has been developed by INO and its partners for wide angle immersive display applications. The concept involves the reflection of scanned beams inside a reflective dome having a symmetry of revolution and an elliptical profile. The axis of revolution of the reflective dome coincides with the axis of rotation of the scanning mirror. The nominal position of the observer's eyes is also located on the reflective dome's axis of revolution. The scanning mirror is centered close to one of the foci of the ellipsoidal reflective dome while the eyes of the observer are located close to the other ellipsoid focus point. The system projects only one line at the time and the full image is constructed by rotating the image line around the observer by means of the scanning mirror. Light is generated by a linear array of individually addressable light elements such as a linear array of deformable micro-mirrors illuminated by a laser line or an array of LED. The beams of light produced by the linear source are conditioned using specialized optical elements and introduced into the system from the outside by transmission through the dome shell.

In many imaging applications, the objects of interest have broad range of strongly correlated spectral components. For example, the spectral components of grayscale objects such as media printed with black ink or toner are nearly perfectly correlated spatially. We describe how to exploit such correlation during the design of electro-optical imaging systems to achieve greater imaging performance and lower optical component cost. These advantages are achieved by jointly optimizing optical, detector, and digital image processing subsystems using a unified statistical imaging performance measure. The resulting optical systems have lower F# and greater depth-of-field than systems that do not exploit spectral correlations.

The NIRSpec imaging spectrometer, which forms part of the James Webb Space Telescope instrumentation, will include an integrated field unit (IFU). The IFU will be tasked specifically with efficient analysis of extended objects, including galaxies; it will accept a square image area at the spectrometer entrance field, dissect this area into 30 parallel sub-slits, and image the sub-slits end-to-end, forming a single virtual entrance slit. The IFU, uses all-mirror optics to operate over the spectral range 700nm to 5000nm. 95 mirrors and the main support structure are made in a common aluminium alloy, to achieve athermal performance down to an operating temperature of around 30K. Relatively complex mirror surface shapes are produced by diamond machining. The IFU has been designed and constructed by SSTL, with optics produced by CfAI; the unit is currently undergoing performance tests. This paper describes the IFU optical design and performance, and outlines the mirror manufacturing methods and alignment procedures.

Linearly variable filters, also called wedge filters are special optical interference filters with a shift of the spectral characteristics along one axis of the filter. These optical components have the huge advantage of allowing simple and small volume spectroimager designs. But they also have drawbacks such as their sensitivity to the instrument design (F number, distance between filter and detector), and to the stray light, especially stray light between the detector and the filter. And performances of such spectro-imagers are difficult to model because of the angle dependence of the filter response (as every interference coating show) and because of the spatial dependence of wedge filters spectral response. These variations make purely geometric stray light calculation unusable because the stray light spectrum can be very different from the nominal beam spectrum, and because of the mixing between imagery and spectrum aspects. A MatLab code has thus been developed to be able to take into account a non uniform filter with both spectral and imaging aspects. The purpose of this study was, using this code, to evaluate the achievable performances of a spectro imager using a wedge filter, and to quantify the sensitivity of these performances with respect to instrument design.

Imaging spectrometers featuring a grating disperser allow for a compact system design. However, due to the limited diffraction efficiency of the grating these instruments suffer from low throughput and high sensitivity to polarization. Prism spectrometers do not have these disadvantages, but they show a low angular dispersion with noticeable non-linearity, which is the main driver of the overall spectrometer dimensions. The envelope of a prism spectrometer can be significantly decreased when prisms with curved surfaces are used. They allow for a reconfiguration of the concentric Offner relay which is well known for its good imaging quality and its low distortion. In the document at hand a novel type of compact Offner spectrometers with curved prisms is presented. As an example the optic design of EnMAP, a German space born hyperspectral imager is given.

Since April 2008, the International Space Station (ISS) is supplied by the Automated Transfer Vehicle (ATV) developed by EADS-Astrium for ESA. This ATV is the first entirely automated space docking system based on optical devices. Its guidance was possible thanks to a device of the ATV developed by EADS-SODERN and named Videometer (VDM). The VDM delivers range, line of sight (LOS) and attitude (among which roll) to the guidance and navigation system of the ATV from 300 meters to docking. During the development steps, tests and studies showed that the measurement of the ATV roll by VDM includes a bias due to the diffraction of the emitted light by corner-cube retroreflectors located on the ISS. The sign and the magnitude of this bias are linked with the distance ISS/ATV. Since the accuracy of the VDM measurements determine the quality of the docking, it was important to evaluate with precision this bias and and check that this bias is compatible with the required docking accuracy.

High precision space optics requires ultra stable lightweight platforms, which have to survive the launch loads and to maintain their stability under space environment. Such benches require a high planarity, small roughness and are usually made of the same material as the carried equipment. For space systems mass is a penalty, thus optical platforms are lightweighted by machining features. Besides of being not too mass efficient, this reduces significantly the load carrying capability of the base material. The challenge for us was to develop, qualify and deliver optical benches, providing a high mass reduction, while maintaining the load carrying capacity of the base material. Such an optical bench has been developed and built by Oerlikon Space and was equipped together with SESO with the high performing optical components for the flight model of the Aladin Mie Spectrometer for Astrium Toulouse. All tests have proven the high strength and stability of the adopted concept.

In this paper we propose and analyze a novel racetrack resonator based vibration sensor for inertial grade application. The resonator is formed with an Anti Resonance Reflecting Optical Waveguide (ARROW) structure which offers the advantage of low loss and single mode propagation. The waveguide is designed to operate at 1310nm and TM mode of propagation since the Photo-elastic co-efficient is larger than TE mode in a SiO₂/ Si₃N₄/ SiO₂. The longer side of the resonator is placed over a cantilever beam with a proof mass. A single bus waveguide is coupled to the resonator structure. When the beam vibrates the resonator arm at the foot of the cantilever experiences maximum stress. Due to opto-mechanical coupling the effective refractive index of the resonator changes hence the resonance wavelength shifts. The non uniform cantilever beam has a dimension of 1.75mm X 0.45mm X 0.020mm and the proof mass has a dimension of 3mm X 3mm X 0.380mm. The proof mass lowers the natural frequency of vibration to 410Hz, hence designed for inertial navigation application. The operating band of frequency is from DC to 100Hz and acceleration of less than 1g. The resonator has a Free Spectral Range (FSR) of 893pm and produces a phase change of 22.4mrad/g.

New types of sounders dedicated to selected species could be used on small satellites to monitor atmospheric chemistry with simpler instruments. A new kind of Fourier transform spectrometer has been patented by CNES a few years ago. Based on a static configuration, two projects are being studied at CNES with laboratory breadboards. One is dedicated to CO2 concentration monitoring in near infrared. The other one works in thermal infrared to study CO and O3 atmospheric profiles. MoLI breadboard, with a new highly integrated interferometric core, will be used for a long time measurement of CO2 concentration. MOPI is another breadboard under development to transpose this concept in thermal infrared during the SIFTI phase A study. These new generation spectrometers consist in a Michelson interferometer with staircase mirrors assembled by molecular adhesion. They are adapted to narrow spectra sounding from space and could lead to totally static and highly stabilized instruments.

The design limits of grating array spectral sensors are discussed. The limit of a grating spectrometer with respect to the resolution is given by the diffraction limit of the grating. To approach the limit for the visible spectral region the entrance slits should reach a width of 2 μm and larger depending on wavelength and numerical aperture. The detector pixel sizes should be in the same range, which is achieved virtually by the discussed double array arrangement with a transmissive, static slit array and detector array. A number of techniques are applied for optimizing the performance as well as for miniaturization. A sub-pixel imaging including a sub-pixel analysis based on the double array arrangement virtually reduces the detector pixel sizes down to about 20%. To avoid the imaging aberrations the spectra is imaged from different entrance positions by the entrance slit array. The throughput can be increased by using a two dimensional entrance slit array, which includes a multiplex pattern or a fixed adaptive pattern. The design example of a UV-Raman spectral sensor is presented including spectral measurements.

Jenoptik Laser, Optik, Systeme GmbH has developed a new mounting technology for optical elements. It is free of any glue or other organic material whereby it is excellently appropriate to the use for DUV Systems, especially if high intensity occurs as it is to be found in illuminating systems. The new technology has been successfully applied in high quality lenses e.g. in a high NA inspection lens @266nm and several ultra high quality imaging systems @193nm. The so called Clamp Mount Technology is characterized by high accuracy and stability under environmental influence such as shock, vibration or thermal effects. There is no limitation in use with any optical material e.g. fused silica or calcium fluoride. The lens cells are routinely optimized by finite element method. Thus in advance clamp force is optimized having regard to deformation of optical surfaces, lens shape, lens weight, gravity and shock load. Additionally stress induced polarization effects are predictable. The FEM simulation results can be transferred to optical design tools which are used for lens design as much as for comparing design data with experimental results.

The BepiColombo Laser Altimeter (BELA) shall profile the surface of planet Mercury and operates on the day side as well as on the night side. Because of the high thermal loads, most interior surfaces of the front optics are highly reflective and specular, including the baffle. This puts a handicap on the straylight performance, which is needed to limit the solar background. We present the design measures used to reach an attenuation of about 10^-8. We resume the method of backward straylight analysis which starts the rays at the detector and analyses the results in object space. The backward analysis can be quickly compiled and challenges computer resources rather than labor effort. This is very useful in a conceptual design phase when a design is iterated and trade-offs are to be performed. For one design, we compare the results with values obtained from a forward analysis.

The report discusses operation principles of a hyperspectral imaging acousto-optic system intended to process optical images in visible and infrared regions of spectrum. A diffraction grating induced by ultrasound in a birefringent crystal selects color of transmitted light and also controls polarization of the incident radiation. In the developed system, arbitrary polarized divergent or convergent optical beam is split at output of the system into two orthogonally polarized optical beams that are simultaneously scattered into symmetrically situated +1 and -1 diffraction orders. If the incident beam forms an arbitrary polarized non-monochromatic optical image then as much as two images are observed at output of the device. Application of two CCD cameras provides registration in real time of the filtered images possessing orthogonal polarizations. Optical wavelengths selected by the filter are tuned by means of driving ultrasonic frequency. The transmission coefficient of the acousto-optic device is regulated by magnitude of the driving RF power.

This paper presents a statistical method for determining the dimensions, tolerance and specifications of components for the Laser MegaJoule (LMJ). Numerous constraints inherent to a large facility require specific tolerances: the huge number of optical components; the interdependence of these components between the beams of same bundle; angular multiplexing for the amplifier section; distinct operating modes between the alignment and firing phases; the definition and use of alignment software in the place of classic optimization. This method provides greater flexibility to determine the positioning and manufacturing specifications of the optical components. Given the enormous power of the Laser MegaJoule (over 18 kJ in the infrared and 9 kJ in the ultraviolet), one of the major risks is damage the optical mounts and pollution of the installation by mechanical ablation. This method enables estimation of the beam occultation probabilities and quantification of the risks for the facility. All the simulations were run using the ZEMAX-EE optical design software.

Triggered by the roadmap of the semiconductor industry, tremendous progress has been achieved in the development of extreme ultraviolet (EUV) sources and high-quality EUV optical coatings in recent years, opening up also new fields of applications apart from microlithography, such as metrology, high-resolution microscopy, or surface analysis. The Laser-Laboratorium Göttingen e.V. has developed a laser-driven plasma source for generation of soft X-rays in the spectral range 2...20 nm. A Nd:YAG laser (1064 nm, 800 mJ, 6 ns) is focused into a gas-target leading to plasma formation which in turn emits characteristic soft X-ray radiation. Depending on the employed target gas, narrow-band as well as broad-band spectra can be obtained. For focusing a Kirkpatrick-Baez optics is used, providing broad-band light steering due to grazing-incidence reflection. The mirrors of the arrangement are formed by bent silicon wafer slices allowing continuous tuning to the desired curvatures. The motorized control offers active adaption of surface shape and incidence angles even in high vacuum, to various experimental demands (e.g. focusing on different sites, beam collimation). For reduction of aberrations the optical system was fine-adjusted with the help of a Hartmann-Shack wavefront sensor in the visible spectral range. The wave propagation properties were determined and compared to calculations performed with ZEMAX. From the difference between calculated phase and measured wavefront direct information about the figure error between perfect and real mirrors could be obtained.

In the context of a virtual retinal display, the exit pupil of the optical device is small, and for this reason, even small eye movement of the user will induce losing the virtual image. In order to increase pupil size, we work on devices such as diffuse surfaces, intended to expand emission angles of sources. Unfortunately, because of laser coherence, this type of device will create speckle noise, which will degrade image quality[1]. In previous papers we have described in details how this noise is generated by a classical diffuser plate, and how to specify devices in order to decrease this noise. In this paper, we analyze another type of pupil expander: faceplates. In addition to this modeling, we compare both devices and conclude that the faceplate is a better device than a classical diffuser.

Ground-based optical telescopes are still the fundamental tool in observational astronomy. Building future extremely large telescopes featuring AO systems is on the way with a prime goal to reach the diffraction limit in resolution with a few milliarcseconds over extended field. Current difficulties in manufacturing large deformable mirrors (DMs) limit their direct use in the main telescope system, yet it might be feasible in the future. The present paper deals with optical systems with integrated 2-3 DMs into the telescope design. Using DMs of larger diameter in the telescope, one could minimize the number of reflecting surfaces and increase the number of actuators across the DMs, hence improving throughput and reducing the AO fitting error. We present several optical designs with fully-integrated AO that provides conjugations to various heights. A comparative analysis of the imaging quality is given together with recommendations for optimal pupil diameter for each optical configuration.

Integral field spectroscopy (IFS) is extremely useful for high-contrast imaging purposes and integral field units (IFU) based on a matrix of lenses are suitable to guarantee low level of differential aberrations among the array of light footprints reaching the detector. To this purpose a new optical concept (BIGRE) for the lenses array adopted in integral field spectroscopy is here fully described, and characterized in the working case of two IFS instruments devoted to high-contrast imaging of extrasolar planets: SPHERE and EPICS, respectively for a 10 meter class telescope (VLT) and a 40 meter class (E-ELT) telescope. The aim of this work is the explanation of the BIGRE optical concept and its implementation on two IFS optical designs, optimized respectively for SPHERE and EPICS.

The food industry is keen to have new techniques that improve the safety and shelf life of food products without the use of preservatives. The use of UV light and ozone (O₃) gas are becoming increasingly popular as methods to decontaminate food and thus extending its shelf life. A microwave radiation device that is a novel source of both germicidal UV and O₃ suitable for the food industry has been developed, which offers speed, cost and energy benefits over existing sources. With this system comes the need to monitor a number of conditions, primarily UV intensity and ozone gas concentrations. An optical fibre sensor system is being developed to analyse these properties, in order to control and optimise the outputs of the microwave plasma UV lamp.

Spectral Hemispherical Reflectance data, covering both VIS and SWIR wavebands, from 400 to 1800 nm, obtained by the investigation of laboratory controlled polluted water samples, are presented. In the frame of the article, the description of a dedicated equipment, consisting of a wide band illuminator based on a super quite Xenon lamp and a colour corrected NSF6-CaF2 objective, a dedicated tank, a custom integrating sphere coated with Zenith^TM diffuser interfaced to a ASD Field Spec spectrometer, is given. With such an equipment, spectral hemispherical reflectivity data have been achieved on water samples, "polluted", under controlled conditions, with known quantities of oils, as examples of some typical oil pollutants of the marine environment. The experimental data obtained by means of the proposed apparatus, collected in a controlled way, allow to get fundamental measurement necessary to evaluate optical properties of liquids and materials to be used for optical modelling and spectral reflectance behaviour. Such a data are difficult to be achieved in literature in such a wide spectral range. They will serve to set up inversion algorithms for remote sensing applications. The wide variety of possible features that can be explored through the proposed equipment, jointed to its flexibility, constitute a reference point for future investigations on the characterisation of the reflectance properties of liquids.

In this contribution we present a compact system to create an illumination distribution with a constant aspect ratio 3:4 and FOV from 0.4 to 1 degree. Besides, the system must delivery 40 W from 170 individual laser diodes placed in a regular 2-D array distribution of 10 x 20 mm. The main problem that must be solved is the high asymmetry of the individual sources; emission divergence's ratio 3:73 (0.3 vs. 7.4 degree) combined with the flux holes due to the laser's heat drain. In one axis (divergence of 0.3º) the best design strategy approach is a Galileo telescope but in the other axis a collimator configuration is the best solution. To manage both solutions at the same time is the aim of this contribution. Unfortunately for the Galileo strategy, source dimensions are too large so aspheric surfaces are needed, and the collimator configuration requires an EFL that must change from 573 to 1432 mm. The presented solution uses a set of three fixed anamorphic lenses, two of them pure cylinders, combined with a wheel of anamorphic lenses that have the function to change the FOV of the system. The most important contribution of the design is to obtain a constant final ratio 3:4 from an initial ratio of 3:73 with no losses of energy. The proposed solution produces an illumination pattern with peaks and valleys lower than 40%. This pattern distribution might be unacceptable for a standard illumination solution. However, the actual FOV is used to illuminate far away targets thus air turbulence is enough to homogenize the distribution on the target.

Circular diffraction gratings (also called diffractive axicons) are optical components producing achromatic non-diffracting beams. They thus produce a focal line rather than a focal point for classical lenses. We have recently shown in the visible spectral range that this property can be used to design a simple imaging system with a long depth of focus and a linear variable zoom by using and translating a diffractive axicon as the only component. We have then adapted this principle for the mid-wavelength infrared (MWIR) spectral range and the long-wavelength infrared (LWIR) spectral range. A LWIR low-cost micro-camera, called MICROCARD, has been designed and realized. First images from this camera will be shown. Moreover a way to design a compact MWIR micro-camera with moveable parts integrated directly into the cryostat will be presented.

Electronic speckle pattern interferometry (ESPI) is a full-field measurement technique, capable of displaying vibrational mode shapes. Two electronic speckle pattern interferometers using reflection holographic optical elements (RHOEs) are presented. In the first ESPI system the RHOE is designed to create the speckled reference beam. A partially reflective glass plate provides illumination of the object along the normal to its surface, ensuring that the system is sensitive only to out-of-plane displacement of the object. It is demonstrated that the HOE-based system can be used for vibration measurements. Phase shifting can be implemented for fringe analysis. In the second ESPI system a reflection holographic optical element of a flat diffusely reflecting surface serves a dual purpose. On reconstruction, a diffuse beam of laser light is produced to act as a reference beam in the ESPI system. Undiffracted light passing through the RHOE serves to illuminate the object. This system is not completely insensitive to in-plane displacement but the illumination and observation directions can be made nearly collinear. The systems are compared in terms of flexibility in their adjustment, sensitivity, suitability and limitations for different applications. The introduction of holographic optical elements in ESPSI systems gives the advantage of using high aperture optical elements at relatively low cost. Both systems are suitable for out-of-plane vibration studies. The results obtained are promising for future applications of RHOEs in alternative laser Doppler vibrometry systems.

In this article the results of experimental investigations of photo anisotropy in organic dyes embedded in different polymer matrices are reported. All the matrices used in this work can be subdivided into those entering into a chemical reaction with dye molecules and those that are chemically inactive. The results of this investigation are suggested that the matrix is of crucial importance of the creation of photo anisotropic materials.

Cat-eye-array retro-reflectors, combining a lenslet array with a reflective surface at the common focal plane of the lenslets, are widely used due to their simple structure and low cost. While for many applications the performance (brightness, acceptance angle range and directionality) is acceptable, others could benefit from better performance. Improving these retroreflectors is difficult because their simplicity results in too few degrees of freedom. Here, we show how the use of one or two diffractive surfaces can significantly increase the brightness of the reflected beam and/or the acceptance angle while still allowing inexpensive manufacturing by molding or replication. Specifically, we focus here on one potential application of cat-eye-array retro-reflectors: semipassive optical communication units. Semi-passive communication units combine a retroreflector with a light modulator. The directional auto-aligned retro-reflected signal enhances security and power efficiency. Furthermore, many modulators use very low power: far lower than light emitter. Modulated retro-reflectors have already been demonstrated for space and military communication. Here we focus on a different application: optical smart cards. These devices described elsewhere, can be used, for example, for access control identification or as non-contact secure teller machine ID. Such devices must have an optical modulator in the optical path, so the effect of the modulator must also be accounted for in the design. As a consumer product, low cost manufacturability is another requirement. Design examples are presented.

The wavelength division multiplexing (WDM) technology effectively increases the bandwidth capacity of a communication line without installing additional fibers and increasing data bit rate to high levels. Optical add-drop modules are key components in WDM optical networks. We propose two types of all-optical tunable filter with a photorefractive planar waveguide. The photo-induced index grating in the PR waveguide by control beams drops off a part of wavelength components in the WDM signal beam. It make possible to select the wavelength components of the signal beam by optically adjusting the wave vector of the grating. It is also possible to control bandwidth of the output signal by adjusting the broadening of the grating in the waveguide. The photorefractive effect is known as one of the most efficient nonlinear effects, and therefore the device is controllable by the relative low beam power comparing with the conventional devices using non-linear optical effects. The channel crosstalk is generated by using uniformly broadened index grating. We note that the nonreciprocal energy transfer between the two control beams via a photorefractive two-wave mixing causes the nonuniform index grating like Gaussian profile. We therefore suggest the suppression method of channel crosstalk by adjusting the incident intensity of the control beams.

Standard polymer optical fibers (POFs) are used in various fields of applications. As a medium for communication systems, they offer many advantages in comparison with copper or glass. POFs are applied for short-distance communication in the automotive. They are also used for communication in the house. All these applications have high demand on bandwidth. Standard communication via POF is limited in bandwidth, because only one wavelength is used to carry information over the fiber. One promising attempt is to use wavelength division multiplexing (WDM). There instead of one wavelength many wavelengths carry information over one single fiber. So WDM over POF has the power to force this limitation. Therefore the design and the development of a demultiplexer, which is required for WDM, will be shown in the paper. The development is done by means of an optical simulation program. This is a fast and inexpensive way to obtain satisfying results. The principle structure of the MUX/DEMUX element is a Rowland spectrometer. This device separates the monochromatic parts of light by means of a high dispersive grating on a mirror. The shape of the mirror and the parameters of the grating have to be developed and optimized in several steps to reach the demands. These process steps will be presented.

In this paper we present analysis on three different coupling systems, i.e., butt, single ball lens, and two ball lenses between the tips of two coupled single mode fiber in semiconductor optical amplifier (SOA) module. The coupling components inside the module can be aligned in an active alignment process and attached by means of dual beam from an Nd: YAG laser welding system. The tips of the coupled fiber are ferruled inside metallic tubes to enable the attachment to the substrates through saddle-shaped welding clips. Investigations of the variations of coupling efficiency with the with working distance for the three schemes showed that two ball lenses is more efficient with coupling efficiency of 75% followed by single ball lens at 55% and butt coupling mode at 20% maximum. In addition dual ball lens configuration have shown to have better longitudinal tolerant even with an elliptical beam profile from the source fiber. This is however not the case in single ball lens and butt coupling scheme. We also observe however the optimum separation between the two lenses at in the range between 0.35 mm - 0.45 mm. This is to ensure the coupling efficiency is the highest possible within the acceptable tolerant misalignments.

We develop a new type of X-ray lens system which is achromatic in a limited energy range. For such achromats we combine different types of refractive and diffractive elements. For example, Fresnel zone plates and planar parabolic concave SU-8 lenses are combined with lenses with a biconvex parabolic shape and with Fresnel lenses, respectively. We present numerical results from a theoretical study of such optical systems. We determine the focal spot size for an energy range of about E ± ΔE with ΔE/E ≈ 17%. Amongst other results we find that, compared with conventional lens systems, the spot size can be reduced by several tens of percent by using such achromatic lens systems.

In this paper a new optimum design method of anisotropic acousto-optic deflector (AOD) with ultrasonic beam steering is introduced for two kinds of crystals: Tellurium Oxide (TeO₂) and Lithium Niobate (LN). First anisotropic acousto-optic (AO) interaction geometric relationships in the two crystals are calculated. Then optimum design method and results, including design parameters and design curves of the two anisotropic AOD, are given through calculating Bragg loss vs acoustic frequency. Final curves of relative bandwidth vs relative length for the two anisotropic AOD are given. Compared with non-steering AOD, when relative bandwidth is equal to octave bandwidth, the relative length of steering AOD will increase 34.7% for TeO₂ anisotropic AOD and 73.4% for LN anisotropic AOD, when relative length is satisfied condition into Bragg region, the relative bandwidth of steering AOD will increase 9.1% for TeO₂ anisotropic AOD and 17.7% for LN anisotropic AOD.

Lithium Niobate (LN) and Quartz. crystal are good piezoelectric crystals, they can be used bases of surface acoustic wave (SAW) devices. In this paper, SAW elemental equation and corresponding mechanics boundary condition equation are deduced. For the above two crystals, SAW velocities are calculated systematically, and curves of the acoustic reciprocal velocity are drawn using a new circle iterative method in decoupling acoustic sagittal plane, that is yz plane. Calculation results lay a good theoretical base for design of SAW devices and have research signification and practice value.

TMA (Three Mirrors Anastigmatic) can simplify the configuration of telescope and lighten the weight, so it is very popular to the design of space-based optical system. According to this concept, an off-axis unobstructed TMA is calculated. Based on initial configuration parameters, automatic optimization is executed in ZEMAX program, and a new telescope is obtained with parameters as follow: aperture is 2000mm, f/number is 2.25, FOV is 5°, angular resolution is better than 7 μrad and image quality meets limited performances.

The phase information of the thin heated air cylinder transection was acquired with a self-collimated interferometer and line CCD camera at the frame rate of 27kHz , based on the presumption of axial symmetry ,using addition algebraic reconstruction algorithm , 2-dimension index-of-refraction distribution of the heated air in the transection was acquired ,and the 2-dimension temperature distribution was calculated, the temperature shift was observed, the central temperature of the air cylinder changed between 330K and 430K. The results show the method could be used to the measurement of near axial symmetry aero-optical medium.

Coherent combination of fiber lasers through mutual injection locking is demonstrated experimentally in this paper. By moving the mutual injection couplers from the output port to the high reflection feedback port of the lasers, a modified combining configuration is constructed with obviously enhanced slope efficiency as compared with the conventional one. The laser efficiency increases from 29.7% to 37.8% by this modification. The corresponding maximum output power enhancement of the combined laser is 26.6%. This modification increases not only the individual child laser powers but also the combining efficiency. The physical connotation of the modification on the improvement of the laser performance has been discussed.

Anisotropic change of the absorbtion edge of seleno-cadmium glass under the action of linearly polarized monoimpulse of a ruby laser of great power has been investigated. The spectral width of the area of anisotropic bleaching of the sample which is being radiated has been estimated. The dispersion curves of photoinduced birefringence and the anisotropy of the absorbtion on the absorbtion edge of the glass of RY-19 type have been obtained in the interval (6500-6700 A).

Wavelength measurement or monitoring can be implemented using a ratiometric power measurement technique. A ratiometric wavelength monitor normally consists of a Y-branch splitter with two arms: an edge filter arm with a well defined spectral response and a reference arm or alternatively, two edge filters arms with opposite slope spectral responses. In this paper, a simple configuration for an integrated ratiometric wavelength monitor based on a single multimode interference structure is proposed. By optimizing the length of the MMI and the two output port positions, opposite spectral responses for the two output ports can be achieved. The designed structure demonstrates a spectral response suitable for wavelength measurement with potentially a 10 pm resolution over a 100 nm wavelength range.

X-ray prism lenses have been defined with the aim to collimate X-ray radiation emitted from an X-ray tube working as a condenser lenses. Such a lens must have a large aperture as low absorption as possible. X-ray prism lenses combine low absorption and large apertures. They are made up of a large array of equilateral triangular prismatic microstructures. The intent by using these structures is to obtain as many refracting surfaces as possible in the smallest volume. The higher surface-volume-ratio in comparison to standard lenses reduces absorption significantly at the expense of focus quality. A first lens has been fabricated by X-ray lithography out of PMMA, with a designed aperture of up to 1.4 mm working distances of 325 mm to the point source and X-ray energy of 9 keV. The edge-length of the prismatic microstructures is 10 μm. The lenses have been tested at the ESRF in (Grenoble, France) and at ANKA (Karlsruhe, Germany). The results show an influence of the imperfections of the lens structures (bended prismatic microstructures) on the focal spot along the focal line. The measured gain was 28 at a focal width of 8 μm at full width at half maximum. Due to these imperfections the relevant aperture is currently limited to 500 μm.

We report the development of a 3GHz bandwidth Bragg cell designed for operation at 488nm with a peak optical diffraction efficiency of 2.3%/RF Watt. This device has the highest bandwidth ever reported for an optical polarisation switching Bragg cell. The device is manufactured using an optically rotated cut of single crystal rutile (TiO₂). Three prototype devices have been built and each have an acousto-optic response centred on ~5GHz that is flat to better than 3dB. Excellent electrical match to the device transducer has been demonstrated on all three devices. The best device had a VSWR of 2:1 over a bandwidth of 5.55GHz centred on 5.15GHz. These new devices exhibit low acoustic attenuation across the optical aperture and also have low optical scatter. They will permit the development of ultra-wide band acousto-optic spectrometers.

Noise Equivalent Temperature Difference is a key point for the evaluation of IR detectors and imaging systems. Our theoretical model of temporal noise predicts the NETD and responsivity of detectors with an accuracy better than 3 mK and 5 %, respectively in a large range of scene temperatures and integration times. This study clearly shows that we are able to estimate the temporal noise in any configuration and particularly for scene temperatures not easily accessible in standard laboratory conditions. Also, we can measure the amplitude of different noise contributions (1/f, white noise) and the FPA leakage current.

The high level of accumulated expertise by ULIS and CEA/LETI on uncooled microbolometers made from an amorphous silicon layer enables ULIS to develop 384 × 288 (1/4 VGA) IRFPA format with 25 μm pixel-pitch designed for low end application. This detector has kept all the innovations developed on the full TV format ROIC (detector configuration by serial link, low power consumption or wide electrical dynamic range...). The specific appeal of this unit lies in the miniaturization of the TEC-less (Thermo-Electric Cooler) package and its extremely light weight. The reduction of the pixel-pitch and the innovative package turn this array into a low cost product well adapted for mass production.

This paper presents a 64 x 64 pixel temporal contrast vision sensor for the 8-15 μm thermal infrared spectral range. The device combines microbolometer detector technology with biology-inspired ('neuromorphic') focal-plane array (FPA) processing circuitry to implement an asynchronous, 'spiking' sensor array. The sensor's individual pixels operate autonomously and respond with low latency and high temporal resolution to changes in thermal IR radiation (temporal contrast) by generating asynchronous, digital pulses ('spike' events). These spikes trigger the transmission of data packets containing the active pixel's array address via an asynchronous data bus. The output data volume of such a self-timed, event-driven sensor depends essentially on the dynamic contents of the target scene. The consequence is a near complete suppression of image data redundancy as compared to traditional, frame-based vision sensors. We discuss the bolometer properties and the different processing steps applied during fabrication and present a brief review of the implemented sensor architecture. A DFT-based approach to the characterization of asynchronous, spiking sensor arrays is introduced. We use a mechanical shutter (chopper) to generate a controllable and reproducible transient stimulus and evaluate the pixel response in time and frequency domain. Measurement results of pixel sensitivity, bandwidth and noise are shown.

A few years ago we have developed a patent pending method that allows to increase the reliability of the heater's tube temperature measurements through flames. The applications of this method showed additional potential for investigation of heating medium, i.e. mixture of various gases and aerosols inside flames and flue gases. This paper presents the recently developed, new version of the measuring system based on PtSi IRFPA commercial thermographic type camera. Two additional optical (8 filter wheel) and digital interfaces have been applied. The main special feature of elaborated techniques is the dynamic spectrally matched IR thermography, which bases on forming single images that consist of pixels of chosen statistical value, minimum and maximum, noted during adequately long sequence of thermograms with total independence to the moment of their capture. Sets of these data can be used either directly or as inputs to other artificial images. In this way, additive or suppressed interferences of fluctuating character could be minimized or exhibited, depending on the type of investigations i.e. studying tubes' temperature or energetic features of the flames and flue gases. Some of the results emerged as very promising - in the future they may help in creating a new field of thermal cameras application for furnaces control or steering to further enhance safety and efficiency of furnaces running.

Modern technology advances combined with unique physical properties of mercury cadmium telluride (MCT) material, empower low-signal applications in technical vision systems. Properties of MCT detectors manufactured from LPE and MBE epilayers and their dependences on thickness and doping both for IR and THz regions are discussed. It is shown by comparison of experimental data and modeling of I-V dark current characteristics that MCT photodiode ultimate electrical characteristics are limited by diffusion current in n⁺-n^--p junctions and by current via the deep traps in the gap with position E_t= 0.7 E_g above the valence band and concentrations N_t = (1.0-5.5)•10¹⁵ cm^-3 which are comparable with donor concentration in n^--region Nd = (1.1-1.8)•1015 cm^-3. Detector array parameters for a wavelength range 8-12 microns are: detectivity D*=1.9•10¹¹ cm•Hz^1/2/W, noise equivalent difference temperature NEDT ≈ 9 mK, dynamical resistance R ≈ 4·10⁹ Ohm for the reverse biases ΔV = 0.1-0.2 V. Also, it is shown that MCT layers can be successfully used as sub-mm or mm wave ambient temperature or moderately cooled hot electron bolometers. Thus, in addition to the wavelength range from SWIR to VLIR, where the MCT detectors are employed mainly as photodiodes or photoresistors, they can be used as sub-mm or mm wave detectors in the range from 190 microns to 8 mm. They can be employed here as semiconductor hot electron bolometers (SHEB). Measurements performed at electromagnetic wave frequencies ν = 37, 55, 77 GHz, and also at 0.89 and 1.58 THz with non-optimized Hg_0.8Cd_0.2Te bolometer prototype, has confirmed the basic concepts of SHEB. At ν = 0.89 THz, 77 GHz and 37 GHz the signal temperature dependencies were measured too. At 77 K the SHEB sensitivity at ν = 37 and 77 GHz is increasing up to two orders compared to room temperature data. The sensitivity S_ν ≈ 2 V/W at 300 K, and calculated both Johnson-Nyquist and generation-recombination noise values give estimations of SHEB NEP ~ 4•10^-10 W at band-width Δf = 1 Hz and ν = 37 GHz.

In ultra-low light conditions the presence of dark current becomes a major source of noise for a CMOS sensor. Standard dark current compensation techniques, such as using a dark reference frame, bring significant improvements to dark noise in typical applications. However, applications requiring long integration times mean that such techniques cannot always be used. This paper presents a differential dark current compensating pixel. The pixel is made up of a differential amplifier and two photodiodes: one light shielded photodiode connected to the non-inverting input of the opamp and a light detecting photodiode connected to the inverting input of the opamp. An integrating capacitor is used in the feedback loop to convert photocurrent to voltage, and a switched capacitor network is present in parallel with the light shielded pixel, which is used to satisfy the output equation to compensate the dark current. The pixel uses 150 μm x 150 μm photodiodes and is fabricated in a standard 0.18 μm, 6M1P, CMOS process. The results show that the pixel is light sensitive and has a linear output as expected. However, the dark current is not predictably controlled. Further work will be carried out on the pixel design, and particularly the switched capacitor circuit, to determine the cause of the non-predictability of the pixel output.

Plasmonics is an area of nanophotonic research involving the interactions of electromagnetic radiation and conduction electrons on a metallic surface, resulting in enhanced optical properties. Plasmonics is the mechanism behind Surface Plasmon Resonance (SPR.) Developing a sensor using SPR to monitor conditions within the built and natural environment is explored in this paper. A plasmonic sensor involves exciting surface plasmon polaritons (SPP's) present at the sensor interface by polarized light. SPP's have sensitivities that respond rapidly to changes at the interface through the presence of analytes, compounds or contaminants; this provides a real time label free detection method. This renders plasmonic sensors ideal as condition monitors. Possible applications include, microbial loading within airtight buildings, soil, water and air pollutant monitoring and structural deterioration monitoring. The advances and learning curves in the development of a new novel sensor for deployment within the built and natural environment are presented along with initial research findings.

Intrinsic Exposed Core Optical Fibre Sensors (IECOFS) based on step-index, silica fibres have been used to monitor surface crystallization processes. When applied to scale (CaCO₃) detection, the sensor is fully recoverable; requiring only immersion in a solution of dilute HCl. Unlike conventional scale sensors, the IECOFS responds only to heterogenous (surface) crystal growth and the optical response correlates to several crystal growth processes, offering a tool for monitoring surface crystal growth kinetics. Kinetic parameters extracted from the IECOFS response profiles are similar to those obtained from surface crystal growth on stainless steel surfaces indicating the potential for IECOFS as a sensor of scale formation in industrial processes.

In this paper, there are details of the continuation of the development of the previously designed multifunctional morphological system and a description of how the system has been upgraded by including soft morphological operators as their ability to compensate for noise by varying the k-value of the system and how this is of great importance in image processing. This paper will cover the details of the upgrade process to include a greater number of logical functions than its predecessor, how a biasing system was included to brighten or dim a certain quadrant of the image or the entire image, how images are combined in either a product, mathematical or logical block and finally how the control mechanism is interfaced so that there are no signal clashes and that complicated strings of possibly many merged or biased images can be processed and outputted. The testing process will be discussed where each layer is tested for k-value and extra operations which are then compared to MATLAB test images from the Image Processing Toolbox or hand written m-files as a basis for comparison. The paper will also include how certain areas have been made more efficient to make the system faster and to reduce space on the FPGA by reducing the number of convolution kernels compared to the latter.

Presented in this paper are the designs of several algorithms which enable the identification and tracking of various regions within a series of images using FPGA technology. Two example probLem domains in the areas of plasma physics and observational astronomy have been expolored. In the plasma physics application, an initial pixel extraction technique has been expanded to include spatial (related to the distance from a cathode) and value measurements (based on intensity values), which are subsequently merged in order to identify different intensity / emissivity regions within a plasma assisted deposition system. The optimum combination of these and other techniques are discussed, together with their reasons for selection. The control signals, decoding method and subsequent processing steps, associated with how a point within individual images is selected, will also be presented. In the astronomical application, a variation of a scene change detection mechanism is shown and how this system was adapted in order to track and chart the motion of Near-Earth Objects (NEOs).

In this paper, we present the results of rigorous electromagnetic broadband simulations applied to CMOS image sensors as well as experimental measurements. We firstly compare the results of 1D, 2D, and 3D broadband simulations in the visible range (380nm-720nm) of a 1.75μm CMOS image sensor, emphasizing the limitations of 1D and 2D simulations and the need of 3D modeling, particularly to rigorously simulate parameters like Quantum Efficiency. Then we illustrate broadband simulations by two proposed solutions that improve the spectral response of the sensor: an antireflective coating, and the reduction of the optical stack. We finally show that results from experimental measurements are in agreement with the simulated results.

The paper considers the possibility of realizing an image spectro-chroma meter by a scientific grade CCD camera and a tunable narrow band filter bench. The presented system allows at recording a multi spectral imaging of the scene, acting as a spectroradiometer with a high spatial resolution and a spectral resolution depending on the bandwidth of the filters. The characterization of the constituting components is briefly described and some evaluations of their performances are presented. In particular, the spectral transmission coefficients of the filters are evaluated together with the power spectral responsivity of the CCD camera. As an example of application, the light reflected by coloured sample is considered and both the spectral radiance and the correspondent colour coordinates are determined. A comparison between measurements obtained by the CCD spectro-chroma meter and by a spectroradiometer allows at quantifying the performance of the new system: for every coloured light, the measured spectral radiance differs less than 2%, so as the luminance value, when a light approximating the Illuminant A is considered. For the same white source, the errors on x and y coordinates are always less 0.002.The system is also used to measure the spectral reflection coefficient of the same coloured samples obtaining performances close to the ones of a good spectroradiometer. The error on spectral reflectivity is about 5% and the error on the CIE 1976 (L*a*b*) coordinates is of the order of ΔE*=3 under the Illuminant A.

Micro spectrometers have been realized by the use of MEMS based scanning grating chips several years ago. The main advantage is the requirement of a single detector instead of a detector array for micro spectrometers applying fixed gratings. Especially in the near infrared range beyond the detection limit of silicon detectors, this can help to reduce the system costs significantly. First measurements for test application have been performed successfully. Industrial applications require wide spectral range, high long term stability and sufficient computation power in the system itself to realize intelligent sensor heads for process monitoring and quality control. Through the recent time, many details have been improved. Extended InGaAs detectors have been used to extend the spectral range up to 2500nm. Improvements of the grating position readout improved the wavelength stability of the system even under tough operation conditions. The integration of faster digital signal processors opens the possibility to implement spectral evaluation algorithms into the system itself. Besides simple applications shown earlier like the selection of different kinds of plastic waste, now a more quantitative analysis can be achieved. For example the ethanol content of liquor samples has been measured and evaluated quantitatively.

The charpy impact is a technique used to evaluate the toughness of an engineering material that determines the amount of energy absorbed by it during fracture. Initially, measurements were estimated manually and later replaced by a PC version. This study reports the development of the Field Programmable Gate Array (FPGA) portable version. The FPGA based version allows easy analysis of samples without the need of sending them to a lab for analysis. The process, presented here, as the original, is based on measuring the percent of crystal in the test sample after impact, to determine if the material is ductile or brittle. The FPGA version, adapted under the MATLAB Simulink environment, shows a graphical block representation of the charpy impact PC version. An important asset of the FPGA version is its portability, it has to be easily modified and downloaded onto a device to estimate the percent of brittle fracture of the broken Charpy surface. The beauty of the DSP Builder programme is that it allows the model to be compiled to various types of optimised code for any Altera FPGA device. To provide a firm basis for scientific comparison to the new FPGA system, images already analysed via the PC based Java system were also used for testing and comparison purposes. The FPGA system converts the image into an 8 bit grayscale image and analyses it in a 5x5 sampling window. This produces texture features that can be used in a comparison system, similar to the Support Vector Machine (SVM) used in the original. The output is a signal that states the material being tested is brittle or not via an output of '1' for brittle and a '0' for ductile. A detailed pixel by pixel analysis of the various output images is then investigated to state the percentage difference between the PC and FPGA based systems.

In this paper, we discuss a Field Programmable Gate Array (FPGA) implementation of steganography for security applications such as anti-theft systems and forensic investigation systems. Our proposed method takes advantage of both conventional encryption/decryption algorithms and fragile image watermarking techniques to provide user-friendly interface. It could potentially be of benefit to financial investment companies, the military and security forces in order to keep certain information hidden within other content with a change so subtle that no one who does not know exactly where or how to look will not be able to obtain the data. In our proposed system, a steganographic message known as plaintext is first encrypted by conventional methods to give an extra layer of security, producing a ciphertext. The steganographic message can be either an image or ASCII text, both of which will be discussed. Then, the cover text or image is modified to contain the ciphertext, yielding a encrypted text or a watermarked image. Details of the circuitry for each stage are given with some of the encryption and randomization circuitry not included in full detail for commercial reasons. Test images before and after watermarking will be shown to demonstrate the validity and effectiveness of the proposed system.

Doped with Ga lead telluride was taken as a model object to explain the nature of group-III deep levels in IV-VI semiconductors and to elucidate the vapour phase doping mechanism. For this goal interaction of various gallium-containing molecules with defect-free crystal as well as with native defects in PbTe were considered. The first-principle density functional theory calculations using 216-atoms supercell were performed. Formation energies for different point defects created in PbTe as a result of interaction the Ga₂Te molecules, Ga₂ dimers and single Ga atoms with a host crystal were calculated. Particularly Ga_Pb and Gai together with formation of accompanied Pb_i and Te_i self interstitials in various charge states were examined. In addition we propose the new type of defects - the impurity complex (Ga₂)_Pb which looks like < 111 >-oriented gallium dumbbell. Calculations suggest the double donor behavior and DX-like properties of this defect together with extremely low formation energy values. Namely, Ga_Pb centers are preferably formed under Ga₂Te doping while (Ga₂)_Pb + Pb_i ones are formed under Ga₂ or Ga doping. In all cases formation energies are negative and resulting defect concentration is determined by the reaction kinetic only. Mechanisms of the lead vacansy compensation with the vapour phase doping is considered as well.