With deliveries of optical glass lots measurement data are given for the visible range usually from 436 nm (g-line) to 656 nm (C-line). Sometimes the question arises if refractive index values in the near infrared can be calculated from these data. With near infrared we mean the range from the C-line up to 1700 nm in this publication. The reason is that up to 1700 nm most optical glasses have hardly any reduction in their transmission. On the basis of a large amount of production data obtained over more than ten years with precision v-block refractometer evaluations are possible up to 1014 nm. The precision spectrometer URIS developed by SCHOTT enables to analyze the refractive index with measurement uncertainty fairly below 10^-5 for even longer wavelengths up to 2325 nm, however on a much smaller data basis. The variability of the IR dispersion is shown for selected glass types. Frequency distributions for the different deviation shapes give information how reliable extrapolations are from the visible range to the near IR. The precision refractometer data were used to simulate such extrapolations employing partial dispersion data from catalog data sheets and to check the consistency of simulated with real data. For some glass types extrapolations seem to be possible. However, there are also glass types, where the method using catalog partial dispersions leads to significant deviations from reality. So if extrapolations are intended to be done, a general check should be performed if this is justified for the glass type of interest.

Most of optical systems are axially symmetric. But axially asymmetric systems are necessary in some cases, for example, to avoid the vignetting of a mirror surface, or to eliminate the keystone distortion of the tilted object surface. The freeform surface is a surface without the axis of the symmetry. The surface profile is expressed as a function on a 2 dimensional coordinate system. The subject of this paper is a construction method of axially asymmetric lenses, which consist of freeform surfaces and spherical surfaces. The fabrication and the alignment of the freeform surface are much more difficult than those of the spherical surface. To minimize the fabrication cost, the total number of freeform surfaces should be as few as possible. Freeform surfaces should be used at the most efficient position. The question arises, how the optimal position of the freeform surfaces can be found. One way to find the optimal position of freeform surfaces is to include the surface numbers of freeform surfaces in the independent variables of the optimization. The surface number is the integer. If the surface number is extended to the real number, in other words, if the optical system with the realnumber surface numbers is consistently defined, the real-number surface numbers can be treated as ordinary independent variables of the optimization.

Today, both military and civilian applications require miniaturized and cheap optical systems. To reduce their size and their mass, imaging systems have to be as simple as possible, which means that they have to involve a minimal number of optical elements. The simplest system can be defined as a system which is composed of only three elements: a single optical component, an aperture stop and a detector. However, these elements can be complex if needed: for instance, curved detector, optics with aspheric surfaces or diffractive optical elements, microlens array with a complex shape... This paper aims at presenting the range of optical architectures available for a simple system. Thanks to the formalism of third-order Seidel aberrations, several strategies of simplification and miniaturization of optical systems are examined. This approach leads to a classification of existing miniaturized imaging systems which are described in literature (such as multichannel systems). Figures of merit are also introduced to assess the performance capabilities of such systems, showing the necessary trade-off between simplicity, miniaturization, and optical performance.

The objective of this paper is a new accommodating opto-mechanical model of the aging human eye for basic simulations of presbyopia, especially of the lens. The lens, consisting of cortex and nucleus, of the aging human eye is mechanically simulated by a FEM model with the program ANSYS. The model results in physiologically correct parameters, and is used as input for a complete optical eye model, implemented in the software ZEMAX. The optical performance of the model corresponds fully with clinical data and the model represents the changes in the mechanical and optical parameters during accommodation and due to the aging process. It is suitable for optical and mechanical simulation; therefore, for example, different possible treatments for presbyopia can be simulated. Furthermore first investigations of stray light due to the laser treatment and their impact on visual performance are presented.

Considering the sine condition or the physical meaning of imaging, pupil coordinate should be defined by direction cosine of ray. Using the pupil coordinate defined by the direction cosine of ray, Marx and the author had derived the sine condition in the presence of spherical aberration independently. Also we had confirmed its validity by practical lens designing. On the other hand, in order to deal with the object imaging and pupil imaging equivalently, conventional aberration theory (theory of image error) uses the pupil coordinate defined by the cross point between the ray and the tangential pupil plane. However, by using this pupil coordinate, Focke had deduced the wrong result that there exists no spherical aberration when the isoplanatic condition is fulfilled (when coma aberration does not exist). Therefore one might think that the conventional aberration theory has less meaning. However, in this paper, we find that there can exist 3rd order spherical aberration with no 3rd order coma aberration even when we use the conventional aberration theory. Namely the conventional aberration theory is effective at least for 3-rd order aberration from the viewpoint of the sine condition.

LEDs are a promising alternative to existing illuminants for a wide range of lighting applications. Besides efficiency and high durability, the small light source dimensions compared to conventional light sources open up new possibilities in optical design. In many lighting setups, it is desired to realize a prescribed intensity distribution, for example homogeneous irradiance on a given area on a wall or floor. This can be realized using LEDs in combination with specially designed freeform lenses and/or mirrors. For high efficiency, it is necessary to collect at least 70 - 80 degrees half-angle (measured against the z axis) of the light that the LED emits into a 90 degree half-angle. This results in a lens that resembles a hemisphere. The numerical design problem thus requires a mathematical description that can handle such strongly curved surfaces with strongly varying surface slopes. Surface parametrizations with a rectangular topography, like e.g. Cartesian tensor product B-splines, have severe drawbacks when handling such surfaces. We report on the use of an alternative surface approximation scheme that uses a triangular mesh. We describe an algorithm that optimizes the two surfaces of a lens for a wall washer that generates homogeneous irradiance on a wall area of 2.8 × 2.8 m² while mounted to the ceiling. The homogeneity is better than 80% and the optical efficiency including Fresnel losses is about 85%.

Recent lithographic technologies allow for the fabrication of high period diffractive structures on planar and curved optical surfaces with high precision. Such diffractive surfaces offer the optical designer extra degrees of freedom, which are of special importance for optical systems, where light collection efficiency is important. We illustrate the usage and benefit of diffractive elements within fast optical systems in various applications. For these hybrid design classes it is mandatory to include the realistic as-built performance of the employed diffractive elements into the design phase. Correspondingly we present simulation techniques to include fabrication specific diffraction efficiencies and stray light into the optimization and evaluation process.

In this work a vectorized and parallel version of the Finite-Difference Time-Domain method (FDTD) is applied to Volume Holographic Gratings (VHG) and Thin-Film Filters (TFF). In particular, in this work gratings with a grating period vector forming an arbitrary angle with the perpendicular to the plane of incidence are analyzed. Angular and wavelength selectivity are obtained by means of the normalized diffraction efficiency. These parameters are positively compared with experimental values and also with analytical closed expressions, thus validating our method. Furthermore, analysis of the performance of the parallel method is shown obtaining a severe improvement with respect to the classical version of the FDTD method. This improvement of the algorithm provides a feasible and accurate scheme for simulating a wide range of optical devices.

We developed a new mathematical formalism to model highly aspherical optical surfaces opening the possibility to explore innovative optical designs. This formalism is based on Bernstein polynomials allowing to describe from low to high order deformations of the optical surface. It has been implemented into Zemax making use of the User-Defined Surface (UDS-DLL) Zemax capability. In this case, the mathematical definition of the surface is imported into Zemax then allowing to apply classical optimization and analysis functionalities. This paper presents the UDS-DLL tool based on Bernstein polynomials together with an initial optical analysis performed to evaluate the gain obtained in using such a new formalism.

An artificial method of replacement reflecting surfaces by thin "mirror" lenses gives us the opportunity to create analytical equations as the base for subsequent parametrical synthesis of optical system consisting of two and three reflecting surfaces. In this case optical powers of the components are determined by required image field curvature. The ratios of back focal lens to the distances between the components are considered as parameters. In one particular case we've got a variant of three-mirrors system with acceptable aberration correction when one mirror has a spherical shape. Constructions of three-mirrors optical systems are presented.

The real aberration properties (all orders) and correction abilities of optical aspherical surfaces of arbitrary shape are insufficiently investigated due to the lack of exact aberration theory. Here we derive and investigate an exact analytical distortion function for axis-symmetric aspherical surfaces of arbitrary shape that describes correctly image distortion for the whole object space without any approximations. We prove that in the object and image spaces of every aspherical refracting or reflecting surface at fixed stop position there is in general one orthoscopic object surface and one conjugate image surface. In addition we offer formulae for determination of object and image orthoscopic surface coordinates in every refracting or reflecting axis-symmetric optical surface with known coordinates and continuous first derivative on the whole profile. To verify the distortion correction we use the commercial program OSLO. The differences between our results and these obtained by OSLO are less than 1.10^-8 mm. Using these exact formulae we investigate the real shape and location of the orthoscopic object and image surfaces as a function of stop position in different reflecting and refracting aspherics. The results can be used by optical designers in the process of synthesis of orthoscopic optical systems.

The process of optical design today is both an art and a science mainly due to the lack of exact and suitable aberration theory. In this paper we propose an exact (without any approximations) analytical aberration theory. It describes exactly the relations between the on-axis image aberrations and on-axis object aberrations via so called relative parameters, real aperture incidence angles, real aperture slope angles, refraction indexes and object distance. The image field aberrations (distortion, astigmatism, tangential curvature, sagittal curvature and field curvature) are described in a mathematically exact way by means of relative parameters, real incidence angles and slope angles of the chief rays, refraction indexes, object distance and corresponding object aberrations. For the image tangential coma and image sagittal coma we propose differential formulae. To verify the correction of every single aberration we use the commercial program OSLO. The differences between our and OSLO results for each aberration (except for the tangential and sagittal coma) are less than 1x10-8 mm. In addition we propose some exact aberration's correction algorithms for a very distant object and variety of constructive design solutions which confirm the truth of the proposed theory.

Optical designers typically use aberration diagrams based on ray tracing to analyze the chromatic aberration performance of their optical system. However to evaluate the impact of chromatic aberrations on color fringes in images optical imaging simulations are necessary including the effect of spectral response of the sensor or film, exposure time, Gamma corrections, etc. We have analyzed the correspondence of classical chromatic aberration measures versus analysis based on image simulations. We propose a metric directly linked to color fringes in images which can be used to constrain and specify the chromatic aberration performance of an optical system.

Within this paper, we present a novel approach for an optical system for a near infrared (IR) line camera, which exists of only one monolithical optical element with 3 optical free form surfaces. The optical design was performed with respect to the following requirements given by the application: wavelength range 0.9 μm to 1.7 μm, field angle 75° x 2°, horizontal angular resolution 0.5°. Within the design process one of the three optical surfaces is formed biconic, two are realized as cylindrical surface. The calculated component was realized by means of diamond UP manufacturing. Two of the optical surfaces were metallized to work as mirrors for the above mentioned spectral range. The realized element has a size of less than 8 cm³; it was finally characterized.

Here we present a novel optical design of the high concentration photovoltaics (HPCV) nonimaging concentrator (>500x) with built-in spectrum splitting concept. The primary optical element (POE) is a flat Fresnel lens and the secondary optical element (SOE) is a free-form RXI-type concentrator with a band-pass filter embedded in it, both POE and SOE performing Köhler integration to produce light homogenization on the target. It uses the combination of a commercial concentration GaInP/GaInAs/Ge 3J cell and a concentration Back-Point-Contact (BPC) silicon cell for efficient spectral utilization, and external confinement techniques for recovering the 3J cell's reflection. Design targets equivalent cell efficiency ~46% using commercial 39% 3J and 26% Si cells, and CPV module efficiency greater than 38%, achieved at a concentration level larger than 500X and wide acceptance angle (±1°). A first proof-of concept receiver prototype has been manufactured using a simpler optical architecture (with a lower concentration, ~100x and lower simulated added efficiency), and experimental measurements have shown up to 39.8% 4J receiver efficiency using a 3J with peak efficiency of 36.9%.

This paper developed an optical design approach to combine the auto-focusing and image sensing in the 2D inspection system. The focusing principle here employed the chromatic confocal microscopy due to the one-shot focusing capability. The system held a special issue that the chromatic confocal microscopy has the higher optical dispersion characteristic than the 2D image sensor which captures a clear image for the optical inspection. Hence, the system here must be designed to be characterized with both the higher and lower optical dispersion, which was called as the common path optical design in this study. That is, an optical approach must be developed to divide and switch the above totally different dispersion conditions. Accordingly, the higher dispersion device, the chromatic confocal sensor, examined the object surface height to vertically vary the focused position of the 2D inspection system. Furthermore, the lower dispersion device, the 2D image sensor, can be adjusted to focus onto the object surface so that a clearly focusing image can be acquired. The experimental results were also provided to ensure this approach can automatically focus the object surface and then the clear image can be captured to perform optical inspection to obtain the position, dimension or area.

Lately the short-wave infrared (SWIR) has become very important due to the recent appearance on the market of the small detectors with a large focal plane array. Military applications for SWIR cameras include handheld and airborne systems with long range detection requirements, but where volume and weight restrictions must be considered. In this paper we present three different designs of telephoto objectives that have been designed according to three different methods. Firstly the conventional method where the starting point of the design is an existing design. Secondly we will face design starting from the design of an aplanatic system. And finally the simultaneous multiple surfaces (SMS) method, where the starting point is the input wavefronts that we choose. The designs are compared in terms of optical performance, volume, weight and manufacturability. Because the objectives have been designed for the SWIR waveband, the color correction has important implications in the choice of glass that will be discussed in detail.

While multichannel configurations are well established for non-imaging applications, they have not been used yet for imaging applications. In this paper we present for the first time some of multichannel designs for imaging systems. The multichannel comprises discontinuous optical sections which are called channels. The phase-space representation of the bundle of rays going from the object to the image is discontinuous between channels. This phase-space ray-bundle flow is divided in as many paths as channels there are but it is a single wavefront both at the source and the target. Typically, these multichannel systems are at least formed by three optical surfaces: two of them have discontinuities (either in the shape or in the shape derivative) while the last is a smooth one. Optical surfaces discontinuities cause at the phase space the wave front split in separate paths. The number of discontinuities is the same in the two first surfaces: Each channel is defined by the smooth surfaces in between discontinuities, so the surfaces forming each separate channel are all smooth. Aplanatic multichannel designs are also shown and used to explain the design procedure.

In this work, two SMS algorithms are presented for an objective design with different selected ray-bundles: three meridian ray-bundles (3M) and one meridian and two skew ray-bundles (1M-2S), the latter from pin hole point of view, provides a better sampling of the phase space. Results obtained with different algorithms will be compared.

We have succeeded in designing a portable virtual display system based on a virtual projected optical design with 0.44"LCD panel. We have optimized the optical performance using a 2D optical multi zoom so that we should obtain a comfortable eye motion box area. Furthermore, it is designed to mechanically adjust the system tilting angle in considerations for different height of head positions. It is also able to display navigations maps and DMV in full color using RGB 3in1 LED sources. We believe that this is developed as an alternative to conventional built-in type HUD system targeting the high volume aftermarket at an affordable price.

Two new optical structures are designed using the Simultaneous Multiple Surfaces (SMS) method, comprised of 2 reflecting surfaces and 2 refracting surfaces, 800mm focal length, f/8 (aperture diameter 100 mm) and 1.18⁰ diagonal field of view in the SWIR band. The lens surfaces are rotational symmetric and calculated to have good control of non-paraxial rays. We have achieved designs with excellent performance, and with total system length of less than 60 mm.

Micro-optical systems, that utilize multiple channels for imaging instead of a single one, are frequently discussed for ultra-compact applications such as digital cameras. The strategy of their fabrication differs due to different concepts of image formation. Illustrated by recently implemented systems for multi-aperture imaging, typical steps of wafer-level fabrication are discussed in detail. In turn, the made progress may allow for additional degrees of freedom in optical design. Pressing ahead with very short overall lengths and multiple diaphragm array layers, results in the use of extremely thin glass substrates down to 100 microns in thickness. The desire for a wide field of view for imaging has led to chirped arrays of microlenses and diaphragms. Focusing on imaging quality, aberrations were corrected by introducing toroidal lenslets and elliptical apertures. Such lenslets had been generated by thermal reflow of lithographic patterned photoresist and subsequent molding. Where useful, the system's performance can be further increased by applying aspheric microlenses from reactive ion etching (RIE) transfer or by achromatic doublets from superimposing two moldings with different polymers. Multiple diaphragm arrays prevent channel crosstalk. But using simple metal layers may lead to multiple reflections and an increased appearance of ghost images. A way out are low reflecting black matrix polymers that can be directly patterned by lithography. But in case of environmental stability and high resolution, organic coatings should be replaced by patterned metal coatings that exhibit matched antireflective layers like the prominent black chromium. The mentioned components give an insight into the fabrication process of multi-aperture imaging systems. Finally, the competence in each step decides on the overall image quality.

Typical optical metrology systems for surface and shape characterization are based on a separated camera and projection unit, yielding to a limitation concerning the miniaturization of the sensor. We present a compact, highly integrated optical distance sensor applying the inverse confocal principle using a bidirectional OLED microdisplay (BiMiD). This microdisplay combines light emitting device (AM-OLED microdisplay) and photo sensitive detectors (photodiode matrix) on one single chip based on OLED-on-CMOS-technology. Comparable to conventional confocal sensors, the object is shifted through the focal plane (±▴z) and the back reflected/scattered light is collected via an special designed optic and detected by the photo sensitive detector elements. The detected photocurrent depends on movement (▴z) of the measurement plane. In contrast to conventional confocal sensors, our inverse confocal sensor detects a minimum of reflected/scattered light if the object is positioned in the focal plane. We present a novel sensor concept as well as system and optical simulations that demonstrate the principle of the novel inverse confocal sensor setup.

A new optical design inclusive of zoom optics and optical engine system is proposed in this paper. Traditionally, there is trade-off between F-number of projection optics and contrast, which seems that super high-contrast image from commercial projector was simply a dream. Some ideas of adaptive optics were announced before for the improvement of high contrast. However, few reach success or cost will be high. Traditionally, there is nothing to do with optics of projector and optical engine of projector if lens meets the specification. In this paper, a new optical design for optics and optical engine is studied with liquid optics arrays. Thanks to advanced optical design and LED light luminance, simulation results show that 50% improvement for image contrast could be made without sacrifice of volumetric size.

Although skin is easily accessible to optical methodologies, biopsies are at present a widely used procedure in dermatologic diagnostics. However fluorescence confocal laser scanning microscopy (F-LSM) is a non-invasive imaging technique that allows depth resolved investigations of inflammatory and neoplastic skin disorders in vivo and at high resolution. By applying substances onto or into the epidermis F-LSM is well suited to obtain information regarding the morphological structures of the skin down to a hundred micrometers below the skin surface. Compared to conventional light microscopy of histological sections this optical method has a clear advantage in the case of kinetic measurements. To this end, we have designed a portable confocal fluorescent microscope for future dermatologic studies, offering a field of view of 600μm x 600μm. Based on a dual-axis MEMS mirror (Fraunhofer IPMS, Germany) the confocal character of the system resides in the use of the same path for illumination and detection with spatial filtering of the signal collected from the subsurface analysis plane. Illumination is provided by a 488nm laser and the backscattered fluorescence light is separated from the illumination light by a filter, before being detected behind the pinhole. To reconstruct the image the measured intensity and position information is correlated. The ability to perform crosssectional imaging in the skin will be given by an integrated z-shifter.

As scientific quests and engineering applications reach down to a nanometer scale, there is a strong need to fabricate three-dimensional nanostructures with regularity and controllability in their pattern, size, and shape, including chirped pitch. Interference lithography is considered to be the most efficient way to make submicron-scale periodic patterns over a large area with superior control of pattern regularity. In order to make a chirped nano-patterning with interference lithography technology, we propose a zoom-chirped interferometer as a novel manufacturing tool with more flexibility for 3-D nano-patterning fabrication. The optical concept of this novel zoom-chirped interferometer is based on the Fresnel division-of-wavefront (DOW) interference combined with a pair of half-cylindrical zoom lenses, which are located in front of a Fresnel 90°-mirror, to generate a cylindrical wavefront interfering with a plane wavefront in the system. The collimated beam will be used as the incident beam for the interferometer. The interference patterning between the cylindrical and plane wavefront is fully controlled, and the variation of the required chirped rate can be adjusted by moving one half-cylindrical lens in the system. This novel zoom-chirped interferometer is more flexible and stable than conventional interference-lithography systems for micro and nano-patterning fabrication.

Contact- and proximity lithography in a Mask Aligner is a very cost effective technique for photolithography, as it provides a high throughput and very stable mature processes for critical dimensions of typically some microns. For shadow lithography, the printing quality depends much on the proximity gap and the properties of the illumination light. SUSS MicroOptics has recently introduced a novel illumination optics, referred as MO Exposure Optics, for all SUSS MicroTec Mask Aligners. MO Exposure Optics provides excellent uniformity of the illumination light, telecentric illumination and a full freedom to shape the angular spectrum of the mask illuminating light. This allows to simulate and optimize photolithography processes in a Mask Aligner from the light source to the final pattern in photoresist. The commercially available software LayoutLab (GenISys) allows to optimize Mask Aligner Lithography beyond its current limits, by both shaping the illumination light (Customized Illumination) and optimizing the photomask pattern (Optical Proximity Correction, OPC). Dr.LiTHO, a second simulation tool developed by Fraunhofer IISB fro Front-End Lithography, includes rigorous models and algorithms for the simulation, evaluation and optimization of lithographic processes. A new exposure module in the Dr.LiTHO software now allows a more flexible definition of illumination geometries coupled to the standard resist modules for proximity lithography in a Mask Aligner. Results from simulation and experiment will be presented.

At the Institute of Microstructure Technology (IMT) at Karlsruhe Institute of Technology (KIT), refractive X-ray optics are developed. These optics are proposed to be used as condenser optics in X-Ray spectroscopy and microscopy applications with an X-ray tube as a source. To produce the lenses, a thin structured foil with equidistant fins in triangular form is casted from a structured silicon wafer. The foil is then wound around a glass fibre core. Due to this fabrication method, it is possible to produce large-aperture lenses with low absorption in comparison to other types of refractive X-Ray optics, like X-ray lenses with continuous parabolic shape or prism lenses. The first are limited due to their absorption while the latter are limited due to their mechanical stability of the prism columns. The optimisation of the so called X-Ray rolled prism lenses (RXPL) is underway at the institute and involves several parameters. One important property of the lenses is the correct form of the wound foil layers. This determines the number of necessary refractive elements at a given radius, which in turn determines the refracted slope and focal position of the transmitted beam. The spatial extent of the x-ray source is also being accounted for in the lens design. Another important point is the diameter of the winding core, which should be as small as possible due to the fact that the winding core reduces the active area of the lens. The rolling process itself is also revised to produce lenses with the above-mentioned small diameter winding cores and bend foil layers while sustaining a tight- fitting foil bundle. The lenses are studied at different energies and types of X-Ray tubes, as well as synchrotron sources, to gain additional information of the internal structure of the lens after the winding process. In this paper the current status of the lens development and results at X-Ray tube sources for use in diffractometers is presented.

Several approaches have been demonstrated to build focus tunable lenses. The additional degree of freedom enables the design of elegant, compact optical systems, typically with less mechanics. We present a new range of electrically and mechanically focus tunable lenses of different sizes and tuning ranges and discuss their characteristics. We show how tunable lenses can be used to improve optical design for auto-focus and zoom in terms of size, quality and speed. Furthermore, we present an LED-based spot light with variable illumination angle, which shows optimal performance in terms of spot quality and optical efficiency.

Integral 3D television based on integral imaging requires huge amounts of information. Earlier, we built an Integral 3D television using Super Hi-Vision (SHV) technology, with 7680 pixels horizontally and 4320 pixels vertically. Here we report on an improvement of image quality by developing a new video system with an equivalent of 8000 scan lines and using this for Integral 3D television. We conducted experiments to evaluate the resolution of 3D images using this prototype equipment and were able to show that by using the pixel-offset method we have eliminated aliasing that was produced by the full-resolution SHV video equipment. As a result, we confirmed that the new prototype is able to generate 3D images with a depth range approximately twice that of Integral 3D television using the full-resolution SHV.

An object distance range within which fine image can be obtained by focus adjustment is limited since aberrations are caused by change of object distance. We have developed a novel optical design method to suppress variation of coma, astigmatism and field curvature induced by change of object distance. Variation of astigmatism and field curvature can be suppressed by introducing appropriate distortion. Also variation of coma caused by change of object distance can be suppressed by using spherical image surface which pivot is located at the center of exit pupil.

Recent advances have made it viable to fabricate optical surfaces that are not rotationally symmetric using a new generation of diamond-turning machines. This new fabrication capability allows for surfaces whose departure from a sphere varies both radially and azimuthally in the aperture to be machined into an optical surface. This new degree of freedom allows for the design of unobscured optical systems that are truly non-symmetric by tilting the optical surfaces themselves. With this new design degree of freedom, the aperture and field of view can be pushed to yield an order of magnitude increase in aerial coverage over current production while maintaining a compact solution. In one particular case, to be presented, a diffraction limited (< λ/10), long wave infrared (LWIR), F/1.9, 10° full field of view sensor telescope is designed by introducing these non-symmetric surfaces into the optical surface prescription.

Ingenio/SEOSAT is the flagship mission for the Spanish Space Plan 2007-2011, as is currently under development by a Spanish industrial consortium in the framework of an ESA contract. Ingenio/SEOSAT is a multi-spectral high-resolution optical satellite for Earth Remote Sensing, designed to provide imagery to different Spanish civil, institutional and governmental users, and potentially to other European users in the frame of GMES and GEOSS. SEOSAT/Ingenio is a Low Earth Orbiting mission. It features a Primary Payload (PP) with one 2.5 meter resolution panchromatic channel and four 10 meter resolution visible/near infrared spectral channels. The PP swath close to 55 km ensures a frequent revisit period, and offers quick accessibility to any point on Earth in emergency situations. In this paper are described the main characteristics and development status of the instrument from an opto-mechancial point of view, as well as the estimated performance data.

Wave-front correction in optical instruments is often needed, either to compensate Optical Path Differences, off-axis aberrations or mirrors deformations. Active optics techniques are developed to allow efficient corrections with deformable mirrors. In this paper, we will present the conception of particular deformation systems which could be used in space telescopes and instruments in order to improve their performances while allowing relaxing specifications on the global system stability. A first section will be dedicated to the design and performance analysis of an active mirror specifically designed to compensate for aberrations that might appear in future 3m-class space telescopes, due to lightweight primary mirrors, thermal variations or weightless conditions. A second section will be dedicated to a brand new design of active mirror, able to compensate for given combinations of aberrations with a single actuator. If the aberrations to be corrected in an instrument and their evolutions are known in advance, an optimal system geometry can be determined thanks to the elasticity theory and Finite Element Analysis.

We have developed diffractive primaries in flat membranes for space-based imagery. They are an attractive approach in that they are much simple to fabricate, launch and deploy compared to conventional three-dimensional optical structures. In this talk we highlight the design of a photon sieve which consists of a large number of holes in an otherwise opaque substrate. We present both theoretical and experimental results from small-scale prototypes and key solutions to issues of limited bandwidth and efficiency that have been addressed. Our current efforts are being directed towards an on-orbit 0.2m solar observatory demonstration deployed from a 3U CubeSat bus.

An imaging spectrometer in the 3-5 μm wavelength range is presented. This wavelength range reveals important information about scenes such as gas or landmine detection, but the amount of light is usually low and signal to noise ratio is a real issue. We selected a Fourier transform (FT) configuration, expecting an advantage in signal to noise ratio in the presence of detector noise. Radiometric and noise models are summarized. A Michelson interferometer with its mirrors replaced by twin mirrors arranged at right angles in a hollow roof was chosen for its nearly straight equidistant fringes localized at infinity. Because in such FT-based spectral imagers, the interferogram is acquired over the whole field of the camera while the scene of interest scans the path difference range, vignetting should be strongly limited while keeping the size of the interferometer as small as possible for manufacturability and cost reasons. The key point for that purpose is to put the entrance pupil of the imaging lens inside the interferometer and to make careful trade-offs between lens F number and angular field of view. The resulting system has a spectral resolution of about 25cm^-1 that fulfils the requirement for most targeted applications. Examples of absorption bands detection are shown.

MUSE (Multi Unit Spectroscopic Explorer) is a second generation VLT panoramic integral field spectrograph developed for the European Southern Observatory (ESO), operating in the visible and Near Infrared wavelength range (0.465-0.93 μm) with a 1 arcmin square FoV sampled at 0.2arcsec. It is composed of a Calibration unit, a Fore-optics and a Splitting and relay system that feeds 24 identical Integral Field Units (IFU); each one incorporates an advanced image slicer associated with a classical spectrograph. This article will present the optical design choices that have been done to optimize the costs, size and performances of the instrument as well as a detailed ghost images analysis of the whole instrument.

Optical MEMS (micro electro mechanical systems) have been used to reduce size, weight and costs of any kind of optical systems very successfully starting in the last decades. Scientists at Fraunhofer IPMS invented a resonant drive for 1-d and 2-d MEMS scanning mirror devices. Besides mirrors also scanning gratings have been realized. Now, rapidly growing new applications demand for enhanced functions and further miniaturization. This task cannot be solved by simply putting more functionality into the MEMS chip, for example grating and slit structures, but by three dimensional hybrid integration of the complete optical system into a stack of several functional substrates. Here we present the optical system design and realization strategy for a scanning grating spectrometer for the near infrared (NIR) range. First samples will be mounted from single components by a bonder tool (Finetech Fineplacer Femto) but the option of wafer assembly will be kept open for future developments. Extremely miniaturized NIR spectrometer could serve a wide variety of applications for handheld devices from food quality analysis to medical services or materials identification.

New immersed grating technology is needed particularly for use in imaging spectrometers that will be used in sensing the atmosphere O2A spectral band (750nm - 775 nm) at spectral resolution in the order of 0.1 nm whilst keeping a high efficiency and low stray light. In this work, an Ion-beam etched grating in a fused-silica substrate of 100 mm 100mm immersed on a prism of the same material is designed to obtain dispersions > 0.30°/nm^-1 and 70% efficiency. The optical performance of the immersed grating is modelled and methods to measure its efficiency and scattered radiance are described. The optical setup allows the measurement of an 80mm beam diameter to derive the bidirectional scatter density function (BSDF) from the immersed grating from a minimum angle of 0.1° from the diffracted beam with angular resolution of 0.05°.

We report on the grating development for the High Efficiency and Resolution Multi Element Spectrograph (HERMES). This paper discusses the challenges of designing, optimizing, and tolerancing large aperture volume phase holographic (VPH) gratings for HERMES. The high spectral resolution requirements require steep angles of incidence, of 67.2 degrees, and high line densities, ranging between 2400 and 3800 lines per mm, resulting in VPH gratings that are highly s-polarized that push the fabrication process to its limits.

The Multi Unit Spectroscopic Explorer (MUSE) is a second generation instrument in development for the Very Large Telescope (VLT) of the European Southern Observatory (ESO). The MUSE splitting and relay optics splits the corresponding telescope 1'x1' adaptive optics corrected field of view into 24 sub-fields and feeds each sub-field into a spectrograph. The design of the field splitter and separator unit and the performance of its prototype are described in detail in this paper. The relay optics builds a 24-channel fan-shaped bridge between the sub-fields and the corresponding spectrographs. An overview of the alignment procedure is given.

The UFFO (Ultra-Fast Flash Observatory) Pathfinder is a space instrument onboard the Lomonosov satellite scheduled to be launched in November 2011. It is designed for extremely fast observation of optical counterparts of Gamma Ray Bursts (GRBs). It consists of two subsystems; i) UBAT (UFFO Burst Alert & Trigger Telescope) and ii) SMT (Slewing Mirror Telescope). This study is concerned with SMT opto-mechanical subsystem design and optical performance test. SMT is a F/11.4 Ritchey-Chretien type telescope benefited from compact design with a short optical tube assembly for the given focal length of 1,140 mm. SMT is designed to operate over a wide range of wavelength between 200 nm and 650 nm and has 17 arcmin FOV (Field of View), providing 4 arcsec in detector pixel resolution. The main detector is 256 x 256 ICCD (Intensified Charge-Coupled Device) of 22.2μm in pixel size. This SMT design offers good imaging performance including 0.77 in MTF at Nyquist frequency of 22.52 /mm and 2.7 μm in RMS spot radius. The primary (M1) and secondary (M2) mirror are hyperbolic surfaces and were manufactured within 1/50 waves (He-Ne, 632.8nm) in RMS surface error. After completion of the initial integration, the SMT opto-mechanical subsystem reached to the system wavefront error better than 1/10 waves in room temperature. We then tested the opto-mechanical performances under thermal cycling and vibration. In this study, we report the SMT subsystem design solution and integration together with thermal and vibration test results.

A new software tool, called AWG-Analyzer, is developed to evaluate the simulated/measured transmission characteristics of optical multiplexers/demultiplexers based on arrayed waveguide gratings (AWG). The output of the calculation is a set of the transmission parameters like: non-uniformity, adjacent channel crosstalk, non-adjacent channel crosstalk, background crosstalk, insertion loss, polarisation dependent loss (PDL), etc. calculated for each output channel first and then for the whole AWG - the worst case value of each parameter over all the output channels. This set of the parameters is then taken as the AWG specification. The parameters are calculated for a particular channel bandwidth (also known as the channel passband or ITU passband), that is also an input parameter for the calculations. Additionally, the developed software tool, having a user friendly interface, offers the help where all calculated transmission parameters are explained and exactly defined. The tool also includes a brief overview about AWG functionality with a small animation and the information about various AWG types (CWDM and DWDM AWGs, Colourless AWGs).

We design and built a novel optical terminal specifically designed for free-space communication operating at light levels at the quantum limit, such as in quantum communication. Our system is particularly well suited for this task, as it is based on an all-spheric catadioptric design, which allows for large and un-obstructed apertures. This design offers an easier and cheaper approach to building high-quality optical terminals with large apertures than schemes based on offaxis parabolic mirrors. We utilized an off-axis version of the original Schwarzschild concentric design, and correct the spherical aberration by substituting the original on-axis secondary spherical mirror with an off-axis catadioptric secondary mirror. A prototype of the optical terminal was realized and tested and it meet the expected performance.

In a fibre-optic communication network, the wavelength-division multiplexing (WDM) technique enables an expansion of the data-carrying capacity of optical fibres. This can be achieved by transmitting different channels on a single optical fibre, with each channel modulating a different wavelength. In order to access and manipulate these channels at a node of the network, a compact holographic optical switch is designed, modelled, and constructed. The structure of such a switch consists of a series of optical components which are used to collimate the beam from the input, de-multiplex each individual wavelength into separated channels, manipulate the separated channels, and reshape the beam to the output. A spatial light modulator (SLM) is crucial in this system, offering control and flexibility at the channel manipulation stage, and providing the ability to redirect light into the desired output fibre. This is achieved by the use of a 2-D analogue phase computer generated hologram (CGH) based on liquid crystal on silicon (LCOS) technology.

The broadband mid-IR grating is required in the infrared spectrophotometer to keep the instrument compact. In this paper the optimization design of a type of broadband grating is studied by the rigorous diffraction grating electromagnetic theory. As a differential vector method, the rigorous coupled wave analysis (RCWA) has been widely used for the analysis and the design of diffractive structures. In this paper, firstly, the diffraction efficiency properties of the traditional broadband dual-blaze grating were analyzed by RCWA. Then a simple structure grating with broadband spectrum can be obtained to the dual-blaze grating. It is interesting that the designed grating only had one blazed angle which is more easily to made compared to dual-blaze grating. The optimization grating structure parameters were given. According to our design example of broadband, mid-IR metal grating, the grating with grating period 10.0μm and blazed angle 22 degree can obtain more than 80% diffraction efficiency within the whole broadest spectrum 8~18μm. The optimization design result demonstrates this simple structure grating is with broadband spectrum and more easily to produce than the dual-blaze gratings.

The objective of this work is to demonstrate the correlation between a simple laboratory test bench case and the predictions of the OOFELIE Multiphysics software in order to deduce modeling guidelines and improvements. For that purpose two optical systems have been analyzed. The first one is a spherical lens fixed in an aluminium barrel, which is the simplest structure found in an opto-mechanical system. In this study, material characteristics are assumed to be well known: BK7 and aluminium have been retained. Temperature variations between 0 and +60°C from ambient have been applied to the samples. The second system is a YAG laser bar heated by means of a dedicated oven. For the two test benches thermo-elastic distortions have been measured using a Fizeau interferometer. This sensor measures wavefront error in the range of 20 nm to 1 μm without physical contact with the opto-mechanical system. For the YAG bar, birefringence and polarization measurements have also been performed using a polarimetric bench. The tests results have been compared to the predictions obtained by OOFELIE Multiphysics which is a simulation software dedicated to multiphysics coupled problems involving optics, mechanics, thermal physics, electricity, electromagnetism, acoustics and hydrodynamics. From this comparison modeling guidelines have been issued with the aim of improving the accuracy of computed thermo-elastic distortions and their impact on the optical performances.

Manufacturing of miniaturized photonic devices based on diamond technology is possible by implanting the pristine material with highly energetic particles. Here we report on the spectral characterization of the optical constants of proton-irradiated diamond. Absorption of the irradiated zones was estimated in the UV-vis-NIR from direct transmittance measurement using a dedicated setup with enhanced spatial resolution. The OPD data providing an estimation of the thickness of the damaged area and its depth profile, have allowed then evaluation of the extinction coefficient from the transmission measurements. Simultaneous variation of dispersive optical constants makes the modeling significantly more complicated compared to the above cited monochromatic study.

We present an approach to an analysis of the third order monochromatic and chromatic aberrations of thin refractive fluid lenses with a variable focal length. A detailed theoretical analysis is performed for a simple variable-focus lens and formulas are derived for an optical design of such lenses. Aberration coefficients of the third order of the variable-focus lens can be completely characterized by three parameters which depend only on refractive indices of fluids forming the variable-focus lens. The calculations are provided for Varioptic lens Arctic-416. Potential applications for a primary optical design of modern liquid lens-based optical systems are emphasized.

IFS is one of the scientific channels of SPHERE, the new high contrast imager for the ESO VLT telescope. IFS is an integral field spectrograph for the near IR (up to 1.65 micron), using a Hawaii II detector. To simplify opto-mechanical design, IFS has no cold pupil. To reduce thermal background, a cold filter fabricated by JDSU has been placed about 30 mm in front of the detector. This filter allows reducing thermal background by more than a factor 10⁴. We describe the design and implementation of the baffling required for proper use of this system: this includes a combination of a cold and a warm baffles, and appropriate choices of the coatings of the surfaces. We present the laboratory results obtained, which show that this system has a thermal background below 10 e-/s/pixels in the SPHERE working conditions.

During the last months IFS, is the Integral Field Spectrograph for SPHERE, devoted to the search of exoplanets has been integrated in the clean room of Padova Observatory. The design of IFS is based on a new concept of double microlens array sampling the focal plane. This device named BIGRE consists of a system made of two microlens arrays with different focal lengths and thickness equal to the sum of them and precisely aligned each other. Moreover a mask has been deposited on the first array to produce a field stop for each lenslet, and a second mask is located on the intermediate pupil of the IFS to provide an aperture stop. After characterization of a previous prototype of BIGRE in the visible range, now the first measurements of the performances of the device in the IR range have been obtained on the instrument that will be mounted at the VLT telescope. These tests confirmed that specifications and properties of the prototype are met by state of the art on optics microlens manufacturing.

A dismountable and portable telescope with a large primary mirror (250 mm in diameter) and a numerical aperture of 5.6, is presented. The telescope has a all-spheric catadioptric optical design, consisting of a spherical primary and a group of spherical lenses, where the last surface is aluminized, as a secondary mirror. The group of lenses corrects all the optical aberrations, including the spherical introduced by the primary and the chromatic ones. The telescope has a very compact design, with a physical length of 600mm. This fact, joint with the all spherical design, make it a ligth portable and easy to align instrument: when dismounted it can be contained in a suitcase sizing 580x440x140 mm and the spherical surface for all the mirrors and lenses makes easy the final alignment of the optical train. We discuss here in detail the optical design and the realized prototype and will show the results, both in terms of theoretical and effective performances.&publicationDat

BepiColombo is the fifth cornerstone mission of the European Space Agency (ESA) foreseen to be launched in August 2014 with the aim of studying in great detail the Mercury planet. One of the BepiColombo instruments is the STereoscopic imaging Channel (STC), which is part of the Spectrometers and Imagers for MPO BepiColombo Integrated Observatory SYStem (SIMBIOSYS) suite: an integrated system for imaging and spectroscopic investigation of the Mercury surface. STC is a stereo camera consisting of two sub-channels, which are looking at +/-20° from nadir direction, that share the detector and some of the optical components. The main scientific camera objective is the 3D global mapping of the entire surface of Mercury with a scale factor of 50 m per pixel at periherm. Five different spectral bands are foreseen, a panchromatic and four intermediate bands, in the range between 410 and 930 nm. To avoid mechanisms, the technical solution chosen for wavelength selection is the single substrate stripe-butted filter in which different glass pieces, with different transmission properties, are glued together. This peculiar choice for the filter architecture, coupled with the fact that the filter is mounted very close to the detector, creates multiple ghosts which can affect seriously the quality of the images. The intensity and the position of the ghost images generated by each filter strip are discussed. An analysis of the ghosts impact on the imaging performance and the solution adopted to limit the degradation are presented.