As for homogeneous lenses, for axial gradients the analysis of the Seidel and chromatic aberration coefficients can be very useful in lens design. However, at present few commercial optical design programs list the Seidel aberrations of GRIN lenses and none of them lists the chromatic aberrations. In order to facilitate the computer implementation of the chromatic aberrations of axial GRIN lenses a new mathematical derivation for the axial and lateral color coefficients is presented. Also, new qualitative insight into the properties of axial GRIN lenses is obtained by introducing the thin-lens approximation in the aberration expressions. Within the domain of validity of this approximation, the primary aberrations of an axial GRIN lens are equivalent to those of a pair of homogeneous aspherical lens in contact, having a common plane surface and having refractive indices and Abbe numbers equal to the corresponding axial GRIN values at the two end surfaces.

Converting linear coordinates in the plane of the detector of an astronomical instrument to celestial coordinates involves in principle the equivalent focal length of the instrument. However, most methods in astrometry manage to reduce observations in a global manner without actually measuring a focal length. We point out a case for solar space observations where the long term stability of angular distance measurements is better than the ground calibration of the angular value of a pixel. We report and discuss this ground calibration.

This report describes the realization of an actuator for a high-numerical-aperture objective lens, as part of an experimental optical disk player. The player is capable of reading a disk with 10GByte density and is fully compatible with the 120 mm Digital Video Disk Read-Only Disk standard. The objective consists of two lens elements, having one aspherical surface, and a free working distance of 50 micrometers . A special active-tilt-control (ATC) actuator is required to achieve sufficient tolerance for disk cover layer thickness and tilt between objective and disk. The ATC-actuator, containing the objective, is as small as a standard CD ROM objective, and therefore fits in a standard 2D-actuator for focus and radial tracking. The manufacturing and assembly of the ATC-actuator requires specialized prototyping techniques, such as the use of alignment molds, and assembly in a specialized clean room. We have controlled the free working distance within 1.1 micrometers and tilt within 0.7 mrad at 3kHz, while being carried in a Philips actuator, operating at 2kHz. The ATC-actuator was developed to investigate new options for future optical storage systems.

The presented work is a versatile approach to time-dependent numerical modeling of active optical instruments. Based on a hybrid geometrical- and physical optics propagation code an optical modeling tool (OMT) has been developed. Mainly targeting at the simulation of astronomical telescopes it allows building linear and non-linear optical models for integration into dynamic end-to-end simulation environments with models for mechanical structure, control systems and various disturbances. The light propagation through an instrument is modeled by a sequence of polarization ray tracing and diffraction propagations. A radiometry algorithm based on a triangle grid interconnecting the rays computes the calibrated power flux. Recently the OMT has been implemented as an optical kernel within the End-to-End Model for the Very Large Telescope Interferometer (VLTI) developed at the European Southern Observatory. There it performs the dynamic computation of the electric field in the exit pupils of the VLTI including polarization, radiometry and diffraction effects.

Refractive indices and dispersion values of optical glass melts deviate from the catalog data. The difference must be considered during the optical design of precision optics to avoid significant performance losses. The melt data are supplied as tables with refractive index and dispersion values for a few wavelengths in the visible range of the spectrum. Several numerical methods for the inter- and extrapolation of melt data are examined. Good performance is achieved with procedures, that do not 'forget' the catalog behavior of the glass. They use the melt data only for corrections of the catalog values. Best results are obtained with a refractive index correction formula with only two free parameters. A modified version of this method calculates the melt coefficients for the Sellmeier dispersion formula which can be entered into the user glass catalog of commercial optical design programs and allow an ease access to the melt data.

Now raster surfaces and arrays of microlenses are widely applied to image generation, animation of images, shaping of specific distribution of an optical radiation, including in quality homogenization of a excimer laser radiation, in optical lighting and telecommunication systems, and also system of a safety, coding of an optical information and optical computers.

We are interested in calculating precisely the PSR far from its maximum, where the maxima of the irradiance are falling to 1E-06, or less. The first and most used method consist in calculating the Fourier transform of the wavefront using the Fast Fourier Transform algorithm (FFT). Another method is using the beam superposition technique (BST) to decompose the wavefront in Gaussian beams, propagate those beams, and recompose to obtain the result. The third method is to apply the exact equations derived at the end of last century and described in reference books like Born and Wolf or Marechel and Francon. We shall compare the result obtained with the three methods, FFT, BST, and exact calculation in the case of a F/3 system working at 4000 nm, in focus and in presence of small defocusing.

Fundamentally, the process of refraction is the change of energy, direction or speed of a light beam which is propagating through a medium. In the one case, the change in direction is a continuous bending of the light beam and the subsequent change of speed of the light beam which is propagating through a medium. In the one case, the change in direction is a continuous bending of the light beam and the subsequent change of speed of the light in the medium which is referred to as the index of refraction of the material. In the second case, there is the abrupt change in the index, polarity or phase of the medium which directs the energy out of the medium, or changes the ability of the light to pass through the medium, thereby absorbing the energy. The second case is the technique employed in Optical Refractive Synchronization. The light is passed through a crystal which has the refractive index changed abruptly, and subsequently the electric field, by mixing a radio frequency signal into the crystal which then creates a modulation on to the wavelength of light passing through, or absorbing, in the crystal at the frequency of the radio signal that is to be modulated onto the light beam. This Optical Modulation is performed, therefore, through the application of the refraction of the optical signal.

In optical design is desirable that simulation and experimental set-up are as close as possible. We have developed our environment to simulate and to model complex optical systems (ROSA), which could contain non-optical elements. This environment is a robust tool for simulation, analysis and optimization of complex optical systems with an easy custom modeling by designer. ROSA has four basic ideas: geometrical description of the elements involved, electromagnetic ray description, free-full modeling by designer of geometrical and optical descriptions, and the possibility to use source structure. These concepts allows to consider non-optics elements in the simulation process and to follow the flux propagation around the optical system. With this tool it is possible to obtain this flux and different kind of information at every point of the optical system. In this work, we present this tool and also some simulation examples. In those examples we have obtained dray tracing taking into account multiple reflections, energetic distribution at different wave lengths, and the photometric distribution of a light source.

The MTF is a parameter used for quality analysis of a system in optical design. In optical design, this parameter is usually obtained without taking into account energy losses and ghost and narcissus effects. The proposed method to calculate MTF with this contribution has the same structure than traditional method. This one is based on ray tracing to obtain the PSF of the optical system, and then apply the Fourier transform to obtain MTF. The method we propose has three modifications from the traditional method: it uses a non-sequential ray tracing, it includes samples structures in the process to obtain the PSF and it also includes energy looses in the PSF function. In this work, we present the influence of and ghost and narcissus effects in MTF for a triplet system proposed by M. Laikin. We have obtained the traditional MTF with commercial available software Beam4, and our method without inclusion of ghost and narcissus effects. Also we have compared all results obtained with those that M. Laikin gives. Finally we have obtained the MTF with the contribution of ghost and narcissus effects using our proposed method.

The several dozen versions of waveguide acousto-optical devices (WAOD) are used as components of photonic system. The quality of the WAOD essentially determines the limiting parameters of photonic system. The characteristics of WAOD are defined by the Bragg cell and the lens system. A particular emphasis was laid upon computer analysis of frequency and dynamic characteristics of Bragg cell with different types of interdigital electro-acoustic transducer. The temperature and radiation effects upon the interference phenomena in the Bragg cell were investigated. The planar lens system with high numerical aperture should be used for a high resolution and dynamic range (DR). To increase the numerical aperture the optical system included several planar refractive lenses have to be used. We have been design the optical systems included planar refractive lenses and modified topology Fresnel lens. Therefore the elements of Fresnel lens can be of different thickness and to several Fresnel zones. The surface of the eye's pupil should be aplanatic lens design. In the case of WAOD the DR for two resoluted signals is defined by a laser optical beam aperture function, its frequency spectrum, optical losses, displacement and geometry of a CCD detector array. In the case the computer simulation is shown that the DR depend on autocorrelation length for Rayleigh and Mie scattering, scattering on scratches. The scratches give local maximums in scattering function.

Optimization methods have long been used for computer-aided optical design. In most cases, the problems to treat are 1D. Furthermore, the number of parameters we can vary is relatively small. Ophthalmic lens design, and in particular progressive addition lens (PAL) design, is quite different from classical optical design. PAL design requires the use of nonsymmetrical diopters defined by geometrical, optical or physiological quantities calculated for each point of the lens by ray-tracing methods. The large number of parameters, the complexity of the cost function and the large number of constraints, require to implement specific descent, optimization and differentiation methods.

For optimization and for image analysis of optical systems it is necessary to calculate derivatives of aberrations. The main task is to calculate a derivative matrix. This has to be done repeatedly during optimization. The conventional finite difference method suffers form two major drawbacks, i.e. inefficiency and inaccuracy. Since some years a new elegant differential technique for analytical calculation of the derivative matrices was developed here first by the senior author and later competed by co-workers. We represent the central parts of the differential technique in this paper, and the concrete application possibilities will not be given in details. A comparison of differential derivative and the conventional finite different method is made at last. The analytical formulas have been derived for the following types of variables: surface radius, axial distance, refractive indices and aspherical coefficients. With the help of an optimally organized program structure we realized an efficient tool for optimization and system analysis.

Conventional definitions of aberrations in optimization programs are based mostly on single rays. But the corresponding ray aberrations do not describe the real image structure in a satisfactory manner. This is so even if the designer optimizes the optical system under consideration with many selected single rays in the merit function.

This paper is in tune with our efforts to develop a systematic method for multicomponent lens design. Our aim is to find a suitable starting point in the final configuration space, so that popular local search methods like damped least squares (DLS) may directly lead to a useful solution. For 'ab initio' design problems, a thin lens layout specifying the powers of the individual components and the intercomponent separations are worked out analytically. Requirements of central aberration targets for the individual components in order to satisfy the prespecified primary aberration targets for the overall system are then determined by nonlinear optimization. The next step involves structural design of the individual components by optimization techniques. This general method may be adapted for the design of triplets and their derivatives. However, for the thin lens design of a Cooke triplet composed of three airspaced singlets, the two steps of optimization mentioned above may be combined into a single optimization procedure. The optimum configuration for each of the single set, catering to the required Gaussian specification and primary aberration targets for the Cooke triplet, are determined by an application of genetic algorithm (GA). Our implementation of this algorithm is based on simulations of some complex tools of natural evolution, like selection, crossover and mutation. Our version of GA may or may not converge to a unique optimum, depending on some of the algorithm specific parameter values. With our algorithm, practically useful solutions are always available, although convergence to a global optimum can not be guaranteed. This is perfectly in keeping with our need to allow 'floating' of aberration targets in the subproblem level. Some numerical results dealing with our preliminary investigations on this problem are presented.

A new Monte-Carlo ray-trace (MCRT) environment has been created and used for the conceptual design of a next- generation radiometer for monitoring atmospheric energetics form space. A multi-band, two-mirror reflecting telescope illuminating an array of thermal detectors is under active consideration as a follow-on to the Clouds and the Earth's Radiant Energy System instruments. Future instruments must provide narrower spectral resolution without concomitant sacrifices in radiometric accuracy and spatial resolution. Strategies are under study for obtaining tow or more spectral channels from a single telescope without significant optical cross-talk between channels. Differential filtering based on different combinations of interference filters will be used to achieve spectral separation. Filters are potential thermal noise sources because they may absorb and re-radiate varying amounts of power in response to changes in scene spectral radiance. The MCRT design environment is used here to study the optical performance of a candidate instrument.

Electro-optic data links are of increasing importance due to their high bandwidth, low losses and intrinsic immunity to electromagnetic interference. Nevertheless as most data processors are using electrical signals electro-optic devices like laser diodes are required to convert electrons to photons. In radiative environments encountered in satellite applications or large physics experiments, this conversion can be perturbed which results in information lost. Most previous works investigate the behavior of electro-optic devices under total dose effects, in connection with the determination of device lifetime. Transient irradiation effects, that could affect data transmissions, are rarely considered. To induce transient effects in laser diodes, we used a 30 picosecond tunable laser. Tuning wavelength near the III-V semiconductor energy bandgap allows us to generate selectively electron-hole pairs in the various materials and regions of the device. By pumping carriers with this method, we have been able to observe differences between bulk and multi-quantum-wells laser cavities. When the whole device is irradiated, we also observe a strong dependence on device structure and technology. These data are useful for the manufacturers, because they evidence the intrinsic limitations of a laser diode technology that can not be investigated by standard electrical and optical characterizations.

Starting from the minimum pixel number 1 k X 1.3 k for the high resolution digital photography, the camera development is dominated by the progress of matrices. Basic relations for the lens adaptation to actual detector developments are presented. Resolution losses by color interpolation and by optical ow pass filters in the one shot photography are quantified by special MTFs. Relations for he admissible blue circle, defining the depth of field in the digital photography, are deducted. Consequences of the lens adaptation to matrix properties are presented by several examples. Further developments in the semiprofessional digital still photography with nonchangeable lenses, in the digital use of classic SLR-cameras and in the professional digital still photography with bellows cameras are presented. New viewfinder concepts are discussed.

After six years of existence, Achromatic Three-Wave Lateral Shearing Interferometer (ATWLSI) is currently in use in wave-front analysis of high-intensity ultra-short laser pulses. The purpose of this paper is to compare ATWLSI to the well-known Hartmann-Shack wave-front sensor (HSWFS) for different generic applications: optical testing, atmospheric turbulence and ultra-short laser pulses analysis and correction. This qualitative comparison is made on the basis of a description of HSWFS, seen as a lateral shearing interferometer.

Atmospheric aerosols play an important role in determining the Earth's radiant energy budget and hence its climate. Aerosol measurement are needed both for intensive aerosol/climate field studies and to validate satellite measurements of aerosols and radiation. Solar aureolemeters measure the angular distribution of sunlight scattered by atmospheric aerosols in the circumsolar sky. The data obtained are interpreted in terms of aerosol single- scattering phase function, aerosol size distribution, and aerosol index of refraction. Recently interest has turned to tracking airborne instruments capable of sounding vertical profiles of these quantities. A significant engineering problem inherent to practical aureolemeters is the need to occult the solar disk while viewing the circumsolar sky. This is accomplished with an occulting disk mounted a meter or more in front of the instrument aperture. It is clear that such a long protrusion into the air stream is unacceptable for a tracking airborne instrument. The novel concept reported here uses two-mirror reflective optics in which radiation from the solar disk is captured by a cooled cavity behind an aperture at the center of the secondary mirror. This innovation makes it possible for the first time to implement a compact aureolemeter whose physical length is on the order of centimeters rather than meters.

Optical Instruments require high precision structures, under varying and often severe environmental conditions. If such instruments are movable, or carried on spacecraft or aircraft platforms, low mass is essential. Stabilization requirements and flight environment demand high dynamic stability, usually specified as high vibration frequency. Those 3 qualities - dimensional stability, high stiffness, low mass - present severe problems to the designer, if he is constrained by the use of conventional materials. Advanced ceramic material like SiC offers great potential, due to its extremely high stiffness, at very reasonably low mass, and thermal expansion. But technologies are not yet available to manufacture parts of 1 m dimensions or above. A special C/SiC material developed by Dornier Satellitensysteme GmbH and partners allows just that, today only limited to 3 m sizes by existing facilities. Mechanical properties are comparable to SiC, and the manufacturing process is far more economical. Advanced composites, in particular ultra-high-modulus carbon fiber materials, offer dimensional stability commensurate with Zerodur, at significantly lower mass. Those fibers exhibit ultra-high stiffness at negative thermal expansion and very low mass. THe paper presents an introduction into material properties and manufacturing processes of those two materials, and high-lights the design approach for a number of high performance structures for satellite borne optical instruments.

The banana mirror system is an alternative approach for the design of telemetric laser scanners with a large scan format instead of using an f-(theta) scan lens. We developed an analytical model and a combination of a hyperbolic and a parabolic cylindrical mirror. This model is called the Ideal Scanner Model. We will introduce the concept of conical deflection and present the basic features of the ISM theory.

A design study for a compact 3D scanner, called Coplan, is presented. The Coplan is intended to be used for high speed, in-line coplanarity and shape measurement of electronic components, like Ball Grid Arrays and Surface Mount Devices. The scanner should have a scan length of at least 2 inches and a resolution of 5 micrometers in all 3 dimensions. First an analysis of two different scan schemes is made: a so-called pre-objective scheme using an F-(theta) scan lens and a post- objective scheme using a so-called banana field flattener, consisting of a convex, cylindrical hyperbolic mirror and a concave, cylindrical parabolic mirror. Secondly, an analysis of height resolution requirements for triangulation and confocal depth sensing has been made. It is concluded that for both methods of depth sensing a synchronous scheme with a 50-60 degrees detection angle in cross scan direction is required. It is shown that a post-objective scheme consisting of a banana mirror system combined with triangulation height detection offers the best solution for the optical requirements.

A compact coaxial optical system is described that employs a Cassegrain telescope with switchable primary mirrors plus a catadioptric relay. The system can operate in the visible, near/thermal IR, and millimeter wavebands, is athermal, and provides multispectral compensation for a protective dome.

This paper illustrates the impact of using hybrid elements in mechanically athermalized objective lenses designed for use with uncooled focal pane arrays in the 8-14 micrometers waveband. Hybrid and conventional refractive lens designs are compared in terms of primary chromatic aberrations, MTF performance, transmission, mass, and cost.

This paper describes the configuration of a DFOV objective intended for use with a linear detector in the LIR band. The implications of the presence of the scanner are evaluated, including a definition of distortion in the scanning direction and a study of cold stop efficiency. The rear part of the objective is redesigned to deal with a focal pane array. Criteria such as the improvement of the cold stop efficiency are kept in mind. The new arrangement introduces a binary surface to control pupil aberrations maintain the volume envelope as in the previous case.

Tilted component systems are known to be characterized by aberrations with unusual field dependences, such as decentered coma and binodal astigmatism. Often, a computer optimization of a tilted-component system will yield a solution having astigmatism that grows approximately linearly from a value of zero at the field center, i.e., one of the astigmatic nodes has been placed at the center of the field. For system with substantial field angles, this linear dependence is as detrimental to image quality as ordinary coma, but it is often difficult to avoid this form of solution. In this paper, the origin of binodal astigmatism in a multi-element system from the contributions of individual surfaces is explained in an intuitive manner, as a logical extension of the 'ordinary' aberrations known to all optical designers. The insight provided by this graphical model allows an understanding of why the astigmatism of any given system behaves the way it does, and what remains can be corrected by a final, rotationally symmetric subsystem. Examples of tilted component system are given in which astigmatism and coma have been reduced to 'ordinary' forms.

Derived from the SPOT series, the new SPOT-5 instrument, called HRG, is now in development phase for a launch in 2001. The HRG instrument will perform Earth mapping still with 60km swath, but with considerably improved resolutions: 5m and 3.5m in the panchromatic band, and 10m multispectral, to be compared with 10m, respectively 20m for the SPOT-1 to SPOT-4 camera series. This improvement is obtained by the implementation of a new focal pane concept and also by a telescope MTF significant enhancement. This paper describes how the optical quality of the SPOT-5 camera has been improved for meeting the new resolution requirements, while still using the same type of telescope as in SPOT-1 to SPOT- 4. First the technique of computer assisted polishing of the mirrors has been adopted to reach a telescope image quality compatible with the demanding resolution. Moreover, for reducing mirror optical surface distortion, specific isostatic fixation devices have been developed. The telescope structure has been also optimized in terms of thermo-elastic and hydro-elastic behavior to ensure stable performances.Lastly, significant progresses have been made in telescope alignment and testing.

In this work, the photolithographic method with the improvement of the stretch-and-write technique is applied for the design and the fabrication of fiber-Bragg gratings distributed on different lengths of fiber and with different operating wavelengths. A proper apparatus was set-up, which allows to easily change the fiber position behind the mask; moreover, by suitable setting the stage displacements, it is possible to stretch the fiber to a given strain value. In this condition all written gratings compress and the peaks move towards shorter wavelengths. To the purpose to obtain grating arrays, working at pre-established wavelengths, strain calibration curves was obtained. Two different types of applications were investigated. Arrays of up to five gratings with different peak position and distributed over a 1 m length of fiber were fabricated and characterized for sensing purpose. Adjacent gratings spectrally concatenated were also produced in order to obtain pass-band filters to be applied in photonic systems. An interesting field of application of FBG arrays was considered for strain sensing in the automotive industry, to monitor various critical components of vehicles. Another example of application was the construction of a pass-band filter applied to suppress the first side lobes of a laser diode spectrum.

An instrument used for measuring the length of cable as it passes form one reel to another is described. The optical portion of the instrument comprises two distinct components a beam delivery unit and a collector assembly. The package is capable of performing length measurements on cables having an assortment of shapes, including those with corrugations.

The polarizer and the analyzer of the polarimeter are realized by Glan-Thompson-prisms which are characterized by a very high extinction. In this set-up only the object under test is located between the prisms, i.e. the polarization properties of the light are not distributed by optical components and high angle resolution is achieved. The disadvantage of these prisms is the use of the extraordinary ray causing an axial astigmatism. In the paraxial domain this astigmatism can be corrected by a simple cylindrical lens. However, this leads to a distorted scaling in the image, because the scaling in the active and the inactive direction of this lens is different. This disadvantage can be omitted by using a cylindrical optic which consists of at least two lenses having opposite sign of their focal length. The calculated result for this optic are verified experimentally.

This paper presents a systematic study of aplanatic cemented doublets acromatized with normal glasses in the visible spectrum in order to answer some questions concerned with residual aberrations such as zonal spherical aberration, oblique spherical aberration, spherochromatism and secondary spectrum. Two of the questions concerned with these residual aberrations are: (1) is it possible to reduce even by a small amount any of these aberrations by selecting an appropriate pair of glasses, and (2) is there any advantage in having the crown in front of the flint when designing a doublet. To answer these questions a study is being carried out for a doublet with an aperture of 2.0 inches and a semi- field of view of 1 degrees. The doublets are designed for six f-numbers: f/5.6, f/4.0, f/2.8, f/2.6, f/1.8 and f/1.6 when the crown is in front of the flint. All solutions have the same thickness on axis for the flint and the same thickness on the edge for the crown. This analysis is also performed for a double having the flint in front of the crown. The results are presented and discussed.

In this paper the principle of CLA-target system to obtain focal line with homogenous intensity distribution was described. And tow new structure modal CLA used for improving the homogeneous of focal line was described and the numerical results of the classical CLA and new type CLA was also given. Those result showed that the focal line long-range intensity distribution can be improved greatly by using CLA with optimized unequal cylindrical lens element for beam with Gaussian intensity distribution and by using hybrid element CLA for the case of super-Gaussian distribution. The optimal process was treated by simulated annealing method. The intensity modulation decreased to 0.7 percent for optimized 4-element unequal width CLA system when incident laser with Gaussian section distribution.

This paper introduces a new type of flexural pivot, which is a substitute for cross-stripe flexural pivot in the servo- reflector in ICF Laser Driver in China for higher stability and resolution. This paper presents force analysis model of the new flexural pivot. On the basis of force analysis, the torsional stiffness and rotational center drifting are calculated theoretically. In the meantime, FEM and a prototype test were carried out to verify the theoretical result. The integrated test shows that the new flexure pivot can provide sensitively adjusting with low center drifting. The resolution of the stepper-reflector system reaches 2 (mu) rad. And the repeatability of the reflectors with this new type flexural pivot is no more than 0.1 (mu) rad.

In many consumer and professional plastic lenses have potential applications because of cost, weight and aspherical shape. However they suffer from a big disadvantage: large amount of focal shift as function of temperature. In particular for bar code scanners, focal shifts due to temperature changes have huge impacts on the function of the scanner. One possibility to improve the temperature behavior of such lenses is to turn them into so- called hybrids: a combination of a refractive and a diffractive surface. This way a temperature compensation can be achieved that reaches the level of glass lenses. In this paper design and manufacturing considerations for such a lens will be given. This includes proper material choice and mechanical design. The lens is temperature compensated over a range from -230 degrees-+60 degrees C. Operating at 650 nm and having a focal length of 4 mm, makes it extra difficult to produce such a lens with sufficient image quality and diffraction efficiency. Results from the design will be compared with measured values from an injection molded sample of the designed lens. Quality parameter such as wavefront quality, focal shift with temperature and diffraction efficiency will be given.

We present the first semiconductor p-i-n photodiode with excellent sensitivity in the VUV range and high rejection of visible radiation. The device is based on the thin-film technology of amorphous silicon and silicon carbide and can be integrated in large area arrays on glass or flexible substrate. Its internal quantum efficiency is over 50 percent in the VUV and decreases with wavelength. In the visible range the sensitivity can be tuned by variations to the technology parameters. Solar blind photodiodes have been fabricated, with 1 percent quantum efficiency at 400 nm and 0.1 at 650 nm. Working bias voltage is very low since its best sensitivity is achieved when reversely biased with 0.3V. Linearity of the photocurrent was verified with incident UV light in the range 5nW to 4mW. Response times under UV illumination was tested with a N₂ laser: 500 ns rise times and 6microsecond(s) FWHM were measured. The excellent behavior of the photodetector in the UV range was explained in the UV range was explained within the hypotheses that generation of hot carriers in the p-doped layer occurs and that a pure diffusion mechanism rules transport, being the thickness of the p-doped layer comparable with the effective diffusion length of electrons.

Aberration properties and correction capabilities of objectives containing two or three cemented radial gradient- index lenses are analyzed. It is shown that the simplest radial gradient-index system, which can be corrected for all third-order monochromatic aberrations, is the cemented doublet with flat external and spherical cemented surfaces. Aberration properties of the cemented component made of two different inhomogeneous materials and having only four flat surfaces are analogous. It is also shown that the simplest radial gradient-index system, which can be simultaneously corrected for all third- and fifth-order monochromatic aberrations, is the cemented triplet made of three different inhomogeneous materials and having spherical surfaces. The methods and examples of aberrations-free objectives design are given.

Often the digital resolution of optical systems is limited by the size of the pixels of detector arrays. To increase this lateral resolution an architecture with a new spatial light modulator is presented. A microstripe is moved across a detector. The microstripe shades off a small part of the detector surface thus providing an inverse opto- micromechanical scanning. Additional virtual subpixels are generated. The lateral resolution of the detector increases by the number of lateral shifts, which is experimentally demonstrated up to factor of 30. The concept includes a throughput or multiplex advantage. For enhanced resolution the signal to noise ratio nearly does not decrease in the case of thermal like noise. The microstripe array is prepared by micromachining technology, the thickness of the stripes is 1...2 micrometers , the width is 3 micrometers ...1 mm and length is up to 2 mm.

A new approach is proposed for the design of wide band-pass multilayer optical elements for the hard x-ray spectral region. The method, based on the combination of analytical and numerical methods, solves the inverse problem consisting of inferring the composition profile of a depth-graded multilayer coating. First, assuming the multilayer d-spacing profile to be a monotone function of the depth and the d- spacing gradient to be large enough, we derived the differential equation that describes the change of period necessary to guarantee a given spectral reflectivity profile. Then, a computer code using an algorithm of steepest descent was used to refine numerically the multilayer period profile, each layer thickness being treated as an independent variable. When using the solution to the differential equation as a starting point of the direct problem, a many-fold decrease of computer time could be obtained. At each step, the spectral dependence of reflectivity was accurately computed using a standard matrix method. Simulations of the particular case of constant reflectivity and maximum integrated reflectivity over a wide spectral range are presented. The best choice of material pairs for comprising a depth-graded multilayer structure is discussed from the viewpoint of maximum achievable reflectivity and least number of bi-layers. Features of depth-graded multilayer mirrors, which are distinctive from conventional periodic mirrors, are examined.

The high throughput x-ray spectroscopy mission XMM is the second cornerstone project in the European Space Agency (ESA) long-term program for space science. This observatory has at its heart three large x-ray telescopes, which will provide a large collection area with a spatial resolution around 15 arcsec. Five flight models of the XMM x-ray telescope have been delivered to ESA in 1998. They show optical performance, which is far better than the specifications, especially in terms of optical and x-ray stray light reduction. The low level of x-ray stray light will be an important benefit for the observation of the extended faint sources such as super nova remnants or clusters of active galaxies. This reduction of x-ray stray light is due, in particular, to the implementation of a very complex and accurate x-ray baffle mounted at the entrance of the telescope. In this paper, we present first the need, the design, the manufacturing and the integration of the x-ray baffle. Then, we concentrate on the verification of the performance of the baffle at the Centre Spatial de Liege. Finally, we will present the excellent results obtained with these baffles.

High-resolution spectrometer was designed to resolve the fine structure of discharge emitted radiation near hydrogenous line 4648.8 A. The device consists of two concave diffraction gratings with 2700 grooves per mm and the radius of curvature 1000 mm. Optical mounting is calculated in such a way that the second grating compensates aberration of the first one for one wavelength. Using slight nonequidistancy of grooves we reduce aberrations in narrow region near this wavelength and achieved limit of resolution about 0.015 A for the spectral region of interest: 464.18- 465.15 nm. Diffraction gratings for this spectrometer have been produced mechanically in Sate Vavilov Optical Institute, St. Petersburg, Russia, by EA Yakovlev. Gratings show good spectral and energetic characteristics at previous laboratory tests and will be used in spectrometer, which is under mounting now. Area of these gratings is limited by mechanical way of production. The limit size is 50 by 50 mm. To detect weak signals it could be good to increase the are of gratings. To do it we try to calculate optical mounting of recording of these gratings holography. Since classical method of recording using homocentric beams which go to the grating blank from the same side of it does not provide aberration compensation conditions, we calculated recording mounting using recording in opposite directed beams.

A novel resonant grating filter has been designed and constructed for the red part of the visible spectrum. A multilayer waveguide structure underneath a subwavelength grating has been used to reduce the reflectivity of the grating in the vicinity of the resonant peak.

The modification of the transmission and reflection of a Fabry-Perot resonator by the inclusion of an angled Bragg- grating is treated. A combination between wavelength selectivity and angular selectivity occurs. The results are a generalization of Airy's formulae.

The main feature of a semiconductor (alpha) -laser is the codirectional small angle Bragg-reflection in a medium with gain. Within the framework of the coupled wave formalism for Bragg reflection an asymmetrical filtering characteristic occurs in dependence on the coupling constant, the ground gain and the gain coupling coefficient. The asymmetric far- field distribution of (alpha) -lasers is comparable with that filtering process.

A novel optical pickup based on DOEs is proposed and first optical key elements are designed and fabricated. The DOE- pickup enables multi-focus imaging and speeds up the data transfer rate. Parallel reading of many tracks and two or more superimposed memory layers is possible. Our measurements revealed, that the efficiencies and the optical performances of the DOEs are suitable for the implementation in an optical DVD-pickup.

We report the results of the analysis of the elastic field structure in the region near the Y-plane of the BaTiO₃ crystal. THe assumption of given interference light pattern with a fringe spacing (Lambda) and an independent on y modulation index m at steady-state is used. The photorefractive grating vector k_g is assumed to be parallel to Z-axis of the crystal. Taking the crystal surface to be traction free we consider tow cases: (a) dielectric boundary and (b) short-circuited boundary.

It is important for a laser beam with divergence angle as small as possible and large mode volume. For the fundamental mode of the common laser resonator, in which the reflective mirrors are spherical, the beam waist is very small, so the output power is very poor. The separation of adjacent transverse modes is often small. Maximizing the discrimination to gain a single mode output with larger power is necessary. It is very difficult to meet these requirements for the common laser resonators. So it is necessary for the laser resonator to perform the mode selecting.

Many experiments and industrial applications require a laser beam irradiance that is nominally constant over a specified area. Such applications include surface treatment, drilling and welding, as well as the processing and recording of optical information. So in many case it is desirable that the beam-shaping operation conserves energy. For a beam with Gaussian profile, it is possible to map the beam into a uniform intensity profile with steep skirt.

A laser beam with uniform intensity and plain phase is advantageous for many applications. Based on diffractive theory, a binary optical resonator was developed according to phase-conjugate principle in this paper. Replacing the sphere mirror of a semiconfocal resonator with a 16 levels binary optical mirror, having square aperture, a square- cross-section 10th order super-Gaussian bema is designed as the eigenmode of the new resonator. A few different original beam distributions mirror can select the desired beam profile or not. THe resulting square-cross-section 10th order super-Gaussian fundamental mode reproduced itself after some roundtrips in the laser resonator successfully and the other modes were attenuated.

To establish the theoretical basis for providing a better design method of synchrotron radiation beamline optics, we have developed a third-order aberration theory of a double- grating system and derived analytic formulas for spot diagrams and aberration curves. We describe an analytic merit function and a new definition of the resolving power. The former closely represents the variance of a very large number of ray-traced spots in the image plane and takes into account the dimensions of a source and optical elements. The latter takes into account the effects of an asymmetric line profile and a finite exit-slit width. The equations of aberration curves, merit function, and the definition of the resolving power are evaluated by taking three designs of a Monk-Gillieson varied-spacing plane grating monochromator as testing optics. The analytic merit function is used for these designs. The result show that the features of ray- traced spot diagrams can be analyzed by means of aberration curves and that realistic resolving power can be predicted by the new definition. The results also show the relation between the formation of coma-free images and the choice of design wavelengths. All these findings support the effectiveness of the analytic merit function in the design work.

Laser light modes are beams in whose cross-section the complex amplitude is described by eigenfunctions of the operator of light propagation in the waveguide medium. The fundamental properties of modes are their orthogonality and their ability to retain their structure during propagation for example in a lens-like medium, in free space or a Fourier stage. Novel Diffractive Optical Elements (DOEs) of MODAN-type open up new promising potentialities of solving the tasks of generation, transformation, superposition and subsequent separation again of different laser modes. Now we present new results obtained by synthesis and investigation of beams consisting of more than one two-dimensional Gaussian laser modes with the same value of propagation constant formed by DOEs. The exploitation of these phenomena could enhance the fiber optical system transfer capacity without pulse enlargement.

In this paper, we will discuss the theoretical model that provides for the transient temperature distribution in all three orthogonal axis of a transmissive optic in a high power laser beam train. The mathematical transforms are set out for one, two and three dimensions for a time temperature history and the resulting optical deformation and subsequent loss of beam quality. The transforms will also provide maximum temperature rise, i.e., temperature differential, as a function of the laser power to allow for the transient thermal shock. Different optical materials are evaluated for providing trade-off of laser flux density, optical distortion and thermal shock. A great deal of pace is devoted to determining the temperature transient in an optic wherein the laser beam does not fill the whole aperture and the distortion arising from the different techniques of mounting.

Microcameras for computers, mobile phones, watches, security system and credit cards is a very promising future market. Semiconductor industry is now able to integrate light reception, signal amplification and processing in a low- power-consuming microchip of a few mm² size. Active pixel sensors supply each pixel in an image sensor with an individually programmable functionality. Beside the electronic receptor chip, a highly miniaturized lens system is required. Compared to the progress in microelectronics, optics has not yet made a significant step. Today's microcamera lenses are usually a downscaled version of a classical lens system and rarely smaller than 3 mm X 3 mm X 3 mm. This lagging of optics is quite surprising. Biologists have systematically studied all types of natural eye sensors since the 18th Century. Mother Nature provides a variety of highly effective examples for miniaturized imaging system. Single-aperture systems are the appropriate solution if the size is a free design parameter. If the budget is tight and optics limited to size, nature prefers multiple-aperture systems, the so-called compound eyes. As compound eyes are limited in resolution and night view, a cluster of single-aperture eyes, as jumping spiders use, is probably a better solution. The recent development in micro- optics offers the chance to imitate such natural design concepts. We have investigated miniaturized imaging systems based on microlens array and natural optical design concepts. Practical limitations for system design, packaging and assembling are given. Examples for micro-optical components and imaging systems are presented.

A programmable arrayed-waveguide grating demultiplexer is presented. The device shows new functionalities, like a tunable center frequency and a variable transmission characteristic. The measured crosstalk was lower than -30 dB.

Matra Marconi Space (MMS) has designed, built, aligned and tested a 200-mm bi-telescope demonstrator, which both structure and mirrors have been manufactured with silicon carbide. Thanks to the unique properties of sintered silicon carbide developed by C and C, the measured performance of our demonstration show the great interest of such approach for space optics applications. This paper describes the main innovative points and performance which have been drawn up during demonstrator development: (i) a very few number of pieces, thanks to an innovative architecture and a very simple mirror attachment concept, made our concept cost effective; (ii) a high optical quality of primary mirror telescope; (iii) a huge optical stability over large environmental constraints, either after mechanical stress or thermal stress; (iv) design compatible with a serial production.

Prototypes of compact lensed fiber connectors have been fabricated by LIGA technique that provide multimode connections for parallel optical interfaces. Contactless embossed microlens arrays were introduced as collimating and focusing elements in order to achieve a simplified connector assembly. As an alternative ball lenses were inserted in a second type of expanded-beam connector ferrule. Fibers, microlens arrays or respectively single microlenses, and two metal guiding pins are possibly adjusted in high precision alignment structures. The ferrules are injection modeled and the modular mold insert has been fabricated by means of microtechnology: LIGA technique and electro-discharge machining. Insertion loss values of 4.5 dB have been measured for assembled mated couples of ferrules with contactless embossed microlens arrays and 2.3 dB for ferrules with ball lenses, both at 1310 nm including reflection losses of typical 1 dB. Even though commonly used butt-coupling connector show lower insertion loss values, the introduced compact expanded-beam connectors could offer an attractive solution for applications in harsh or dirty environments of for micro-optical components e.g. compact 90 degrees optical interfaces for backplane connectors or switches by deflecting the expanded optical beam by a mirrors or prisms.

For the two-wave interaction in a cubic photorefractive crystal under square-wave electric field we analyzed the self-consistent interdependence of the space charge field and modulation index of the light field. Analytical dependency on the interaction length and on the time of the space charge field amplitude and modulation index of the light field. Analytical dependency on the interaction length and on the time of the space charge field amplitude and modulation index is obtained for the case of the periodical time dependency of the both value and small modulation index. The analysis of the kinetics of the space charge field amplitude and its dependency on the frequency of the applied field are made at the arbitrary interaction length for parameters corresponding to the Bi₁₂SiO₂₀ crystal. It is shown that the time dependency of the space charge field amplitude can strongly vary at the increase of the interaction length. Behavior of this change is determined by the orientation of the grating vector relatively the crystallographic coordinate system. It is demonstrated that the frequency dependency of the space charge field amplitude varies at the rotation of the grating vector on 180 degrees.

The integrity of oil pipeline is always a major concern of operators. Pipeline leak not only leads to loss of oil, but pollutes environment. A new pipeline leak detection and communication system based on optical fiber technology to ensure the pipeline reliability is presented. Combined direct leak detection method with an indirect one, the system will greatly reduce the rate of false alarm. According, to the practical features of oil pipeline,the pipeline communication system is designed employing the state-of-the-art optic fiber communication technology. The system has such feature as high location accuracy of leak detection, good real-time characteristic, etc. which overcomes the disadvantages of traditional leak detection methods and communication system effectively.

Optical alignment is a crucial step in the commitment of a telescope. The accuracy in which it is accomplished has a deep impact in the future life of the telescope. The Galileo Telescope, sited in La Palma, is a 3.58 meters telescope with active optics and has recently undergone its final optical alignment. The result of the alignment, obtained in the so-called 'passive' mode, that is just before switching- on the active optics system, are here presented. The alignment consisted in the definitions of the mechanical axes of the structure and mirrors supports and of the optical axis of the entire telescope, using three high precision alignment telescopes and their relative targets. The final step has been to take some images on the sky looking at point like objects and to measure the point spread function in terms of full width at half maximum. The first star imaged in our 'passive alignment' test on the sky had a FWHM of 0.8 arcsec, well inside the range of the active optics system correction, making it totally usable for the following fine-tuning of the optics.

Sometimes during a scientific data acquisition the focus of a telescope may change, especially for medium- and long-time exposures. This is mainly due to temperature changes inducing an expansion of the serrourier truss, and more generally, due to elastic structural flexures. Modelization and control of defocusing effect is an important topic in telescopes with great magnification ratio. In the Telescopio Nazionale Galileo case, a 3.5 meters class telescope located in La Palma island, a temperature change of 1 degree induces a 0.9 arcsec image blue. In such a case a control of defocus during an acquisition is essential to obtain sub-arcsec images, thus exploiting the site seeing. The secondary mirror of Galileo telescope is actively controlled via a hexapod actuator. Both systems, the hexapod secondary support and the control system, have been completed and tested at the telescope. The results show that positioning of the mirror is smooth enough, introducing an image movement of about 0.1 arcesc and allowing in such a way the on-line correction also during scientific operations.

The VLT M2 Unit is an optomechanical system constituted by the M2 mirror and the mechanism used to control its position and orientation along 5 degrees of freedom. Of these the control and design of the tilt/chopping stage is the most challenging one. The tilt/chopping stage influences the pointing of the telescope' LOS, especially to allow observation in the IR range. This is achieved by chopping the M2 mirror up to 10 times per second with a maximum throw of 120 arcsec about an arbitrary axis. During this chopping the 'residual forces' are introduced into the telescope structure. The acceptance tests of the first M2 units showed, that the residual forces excited some resonances of the telescope structure and the performance requirements were not met in the beginning. DSS developed an adaptive control that is able to minimize the amount of residual forces automatically during chopping. This presentation is focused on the developed Adaptive Control and its results shown up during the acceptance test for unit 02. The finally achieved performance and the gained experience are presented.

The high throughput x-ray spectroscopy mission XMM is the second 'Cornerstone' project in the ESA long term Programme for Space Science. This observatory has at its heart three heavily nested Wolter I grazing incidence x-ray telescope. The telescopes are equipped with non-dispersive spectroscopic imaging instruments and medium resolution dispersive spectroscopic instruments. Because of the sensitivity of the XMM instruments x-ray detectors in the visible wavelength range, a high suppression of the visible radiation emitted from out-of-field sources must be ensured. The straylight reduction capability is quantified by the PST. The experimental verification of the PST on the XMM flight model mirror modules for off-axis angles between 1 degree and 85 degrees is presented in this paper. For the first time a straylight test of a compete telescope was performed in air measuring the telescope PST over a range of 9 orders of magnitude.

We demonstrate experimentally and theoretically that the sign of two-wave coupling gain in sillenite crystal at some polarization of light changes with the increase of the amplitude of square-wave field applying along the axis. It is shown that the nonunidirectional energy exchange is the reason of this effect in Bi₁₂TiO₂₀ single crystal. Such energy exchange is bound with the contribution of the self-diffraction gyration effect into the efficiency of the two-wave interaction. At the theoretical analysis we used the mode obtained on the basic of the mode approach. Made the numerical calculation of the dependency of the two-wave coupling gain on the amplitude applied field has god agreement with the experimental data. This calculation has allowed estimating the material parameters of the investigated samples of the crystal.

Investigations in the field of optical system quality assessment mostly are dedicated to the concrete methods of measurement and calculation of the system and to concrete qualimetric experiments. These investigations are supplemented with the reviews and the discussions on general problem of substantiation of criteria of quality. Our communication is a contribution to such a discussion. We consider an optical image forming system. If the optical scheme of the system is chosen, then L variable parameters of the scheme p1...pL should be optimized to retrieve the global maximum of some criterion of quality of the system Q. We discuss the methods of solution of three interconnected fundamental problems, namely, the choice of the measure of quality Q, the choice of the set of the parameters p1...p1, and the representation of the criterion as the function Q.

Misalignment modes are combinations of rigid-body perturbations to the optical elements that comprise an optical system. Comparison of misalignment modes associated with metrology data and projection-camera performance can be used to increase the sensitivity of metrology measurements to specific camera-performance specification such as chief- ray distortion. Selection of measurable misalignment modes in the case of metrology and interesting misalignment modes in the case of camera performance is based on a determination of whether a mode can 'fit' into a projection camera given actuator-stroke and mirror tilt bounds. Measurement and interest subspaces are next compared using distance between subspaces. As an example of this type of analysis, we find that exit-pupil wavefront measurements can be made more sensitive to chief-ray distortion if these measurements are collected at field positions outside the ring field of view of an extreme ultraviolet lithography projection camera.

For comparability and replacability of optical component for lasers and laser system an international standard was developed. In this standard codes for the single components were laid down as well as preferred substrate materials. The most important dimension and dimensional tolerances and the material and surface equality were standardized. In the following paper the contents of the standard will be shown. Besides this some critical notes will be given.

The high throughput x-ray spectroscopy mission XMM is the second cornerstone project in the European Space Agency (ESA) long-term program for space science. This observatory has at its heart three large x-ray telescopes, which will provide a large collecting area with a spatial resolution better than 15 arcsec. In 1998, the three Flight Models and the two spare models of the x-ray telescope have been delivered to ESA, after verification and calibration at the Centre Spatial de Liege and at the Max Planck Institute near Munich. They show mechanical and optical performances much better than the specification. Their performance will undoubtedly bring an important benefit for the astronomers. The most challenging part of the development of these telescopes was the design, the manufacturing and the testing of the x-ray mirrors, during four intensive years. In this paper, we will first summarize the development and the excellent results of the mirrors. Then, we will discuss the lessons learned during this development, mainly in terms of management and technical aspects, including design, manufacturing and testing. These lessons will be drawn in perspective of the future x-ray missions such as Constellation X, Xeus and ASTRO-F.