The use of personal computers in Optical Design was first discussed widely at the International Lens Design Conference at Mills College, by Kidger , Sinclair, and others. Since then, the topic has been discussed at several International conferences, particularly the SPIE Conference at Geneva, in 1983, and the International Lens Design Conference at Cherry Hill, New Jersey, in 1985. Progress, both in terms of improvements in hardware as well as software has been quite dramatic, and this paper deals with some of the issues involved, with particular reference to the Optical Design software developed by Kidger Optics. Since the major advantages of using personal computers are now quite obvious, and have been discussed in detail in Refs 1, 2, 3 and 4, this paper will discuss new advances, since the last European SPIE Conference in 1983.

Even before the advent of computing technology, lens design was hardly a "user-friendly" activity. During the past decade, during which enormous computational power became widely available, this aspect of the process was seldom addressed -- and in the predominantly batch-mode environment that was common until the past few years, it reached its nadir. Now it is time for software vendors to reconsider the interaction of man and machine to a degree not previously attempted; widespread distribution of formidable computing power and the domination of interactive environments, together with hardware such as color graphic terminals, present new possibilities. We will outline the major directions of current research, and some of the possibilities for the future.

COMO is an optical design program of a special orthogonalization type, developed by Prof. H.Marx at Ernst Leitz Wetzlar Company. Not using a merit function, COMO corrects aberrations under equality and inequality constraints not simultaneously but sequentially, the order is chosen by the optical designer. The optimization procedure shows distinctive features compared to other programs. COMO is in use at Leitz since the early 1970's and is now running on HP-1000F and HP-A900 computer systems. In 1974, when it was implemented on a HP-2100, it was probably one of the very first "mainfrawe" optical design programs running on a minicomputer. H.Marx named this program COMO.

Approximate expressions for diffraction based image quality criteria like Strehl ratio or the relative Modulation Transfer Function in terms of the variance of the wave aberration function or the variance of the wave aberration difference function respectively have been used to obtain merit functions for lens design optimization. These merit functions are useful when the Strehl ratio or the relative M.T.F. of the optimized system is greater than 0.7. A few attempts have been made to develop techniques that extend the range of validity of the diffraction based criteria. This report presents a new approach to this problem. An expansion of the pupil function in terms of the orthogonal set of Block functions leads to an expression for the central intensity in terms of the average values of aberration over a finite number of subapertures. The range of validity of this expression depends on the number of subapertures used. It has been found that a rather small number is sufficient when the central intensity is greater than 0.25. A brief description of the use of this expression in least squares type optimization is presented.

As optical systems become more complex, it becomes increasingly difficult to design them using a general-purpose optical design program. At the 1983 conference in Geneva, we described a programming language, SCL, that could be used to extend the capabilities of such a program. In the present paper, we show some applications of this language to optical design problems.

A general ray-trace program has been developed for use on a desktop computer which traces finite rays through any non-rotationally symmetrical system. In particular any combination of decentred, tilted and rotated surface has been considered. Surface types such as Conic sections with and without Aspherics, Toric surfaces, surfaces of S and T Cylindrical sections, and Axicons, may be ray-traced. Each surface is defined in terms of a local rectangular co-ordinate system and has a particular aperture shape attributed to it. Aperture shapes may be defined as circular, elliptical, rectangular or quadrilateral. Also the centre of any aperture shape may be displaced from its local coordinate origin to facilitate the tracing of off-axis paraboloids. Before transferring to the next surface, the local coordinates are referred back to an initial reference coordinate system. Finally a means of assessing aberrations has been included. The main task here was to get a mathematical model of a non-rotationally symmetrical finite ray-trace running on an inexpensive desk top computer. The program was written for the BBC MICRO in order to investigate devices such as scanning systems for modern Thermal Imagers etc.

By employing Gaussian brackets, this paper derives formulae of paraxial ray propagation through an optical system which consists of plural sub-systems decentered slightly one another from the ideal centered position. As an application of the theory, compensation of the focal point shift caused by decentering is discussed.

The paper describes the results, in terms of speed increases, of replacing the usual finite-difference derivative calculation by analytical formulae. The advantage increases with the number of variables. In practical cases so far studied, computer run times have been reduced by almost an order of magnitude.

The importance and description of the control and suppression of stray light has been discussed and reviewed in several articles. The two basic methods of reducing stray light are by directional control and suppression through absorption. The added complexity of advanced optical systems due to more strigent requirements and longer lifetimes require an evaluation of the effectiveness of these methods. The type and accuracy of Bi-directional Reflectance Distribution Function (BRDF) databases will be addressed. Extra-polation of data to other wavelength regions will require credible scattering theories and scaling relations. An assessment of the type and need of facilities for stray light measurements at both the component and system level will be made. Contamination criteria are becoming increasingly important with longer lifetimes and will be discussed with respect to cryodeposition and outgassing of materials defined by system design. Approaches of evaluation of the stray light rejection characteristics of a total optical system will be compared and assessed. Tradeoffs and advantages of experimental measurements will be made. Trends in computer simulations will be identified.

The powerful ABCD-matrix method, originally devised in geometrical optics and later generalized for gaussian laser beams, is extended here into the domain of partially coherent, gaussian Schell-model beams. The method is then applied to derive the closed-form, coherence-dependent imaging laws for gaussian Schell-model sources. Several applications of the formalism, such as the evaluation of the focal shift in optical systems under partially coherent illumination, are pointed out. The fully coherent (laser) and the fully incoherent (geometrical optics) limits of imaging are discussed, and some equivalence laws between imaging of laser sources and gaussian Schell-model sources are presented.

The effects of manufacturing errors are numerous and varied. They range from simple phenomena such as changes in focal length, spherical aberration etc to the complex functions, RMS wave error and MTF drop. One or more of these will be used as a criterion to judge the 'success' or 'failure' of a lens. The manufacturing errors, a., will have some probability distribution fi(ai), which are determined by the tolerance anA workshop practice. These will, in turn, determine the distribution, f (y), of the effect, y, of interest. Given f_y(y) the designer can then predict the expgcted failure rate. Firstly we show how to predict the lower moments of f (y): mean, variance, skewness and kurtosis for linear effects of the errors: mean and variance for the non linear RMS wave error. Then we discuss approximations to the functional form of f (y), which we can specify by these moments. f_y(y) only tend towards gaussian form for linear process. The RMS wave error is better modellgd by a chi-square distribution. Comparisons with Monte Carolo simulations are shown. Small production runs will cause the expected failure rate to fluctuate. Simple equations are given which predict this scatter. Finally the effects of using compensators are predicted and compared with simulations.

The design of modern optical systems is not a trivial task; even more difficult is the requirement for an opticker to accurately describe the physical constraints implicit in his design so that a mechanical designer can correctly mount the optical elements. Typical concerns include setback of baffles, obstruction of clear apertures by mounting hardware, location of the image plane with respect to fiducial marks, and the correct interpretation of systems having odd geometry. The presence of multiple coordinate systems (optical, mechan-ical, system test, and spacecraft) only exacerbates an already difficult situation. A number of successful optical design programs, such as CODEV (1), have come into existence over the years while the development of Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) has allowed a number of firms to install "paperless" design systems. In such a system, a part which is entered by keyboard, or pallet, is made into a real physical piece on a milling machine which has received its instructions from the design system. However, a persistent problem is the lack of a link between the optical design programs and the mechanical CAD programs. This paper will describe a first step which has been taken to bridge this gap. Starting with the neutral plot file generated by the CODEV optical design program, we have been able to produce a file suitable for input to the ANVIL (2) and GEOMOD (3) software packages, using the International Graphics Exchange Standard (IGES) interface. This is accomplished by software of our design, which runs on a VAX (4) system. A description of the steps to be taken in transferring a design will be provided. We shall also provide some examples of designs on which this technique has been used successfully. Finally, we shall discuss limitations of the existing software and suggest some improvements which might be undertaken.

Gaussian beam optical system analysis by microcomputer with artificial intelligent has been studied. The analytic and symbolic forms by mu-LISP language of IBM pc microcomputer are very powerful for the purpose of Gaussian beam system analysis. The Gaussian beam optical model cosist of general model, refracting surface model, thin lens model. Using the forward chaining method the beam size locus, beam waist, sister surface are all easily be solved. The expert system consists of knowledge base with rules as well as built-in functions and the problem-solving mechanism with direct solver. The rules could be modified and adding in declarative approach, the program separates the knowledge base from the problem-solving inferance mechanisms, and could improve it performance in a dynamic manner, ie. the rules could be added and modified. Some learning mechanism are suggested in this paper also.

An automated technique has been developed for predicting square wave response of infrared optical systems. The method avoids conventional physical measurements of square wave modulation employing bar reticle images. As a result, the method can be applied to theoretical (modeled) infrared optics as well as real optical systems, and can thus be used as a standard tool for resolution evaluation during all phases of system development and production.

Relative illumination in an optical system is a function of many variables including distortion, vignetting and pupil aberration. It can be obtained by determining the size of the exit pupil in direction cosine space, using the appropriate coordinate system. In general, the calculation is done by tracing bundles of rays through the system. In many cases of interest, it is possible to calculate relative illumination accurately by tracing one on-axis ray and three off-axis rays.

The stray radiation analysis tool presented here is based on a general ray tracing program which is integrated with the "Euclid" 3-D solid modeling CAD system. It is an analysis/design tool whose main features are its highly accurate representation of mechanical structures, its interactivity, its visualization capability and the understanding it gives the user about the paths by which stray radiation propagates through the opto-mechanical system.

Asymmetrical aberrations also caused by decentration combined with symmetrical ones show a typical effect on the Modulation Transfer Function and the "Image Shift". As this effect on the Image Shift already appears at low spatial frequencies they can influence the image quality.

The early medieval scholar Maimonides wrote a famous book called "Guide for the Perplexed", which explained various thorny philosophical and religious questions for the benefit of the puzzled novice. I wish I had had such a person to guide me when I first started a career in lens design. There the novice is often struck by how much of an "art" this endeavor is. The best bet, for a beginner with no experience, should be to turn to optical aberration theory - which, in principle, should explain much of what goes into designing an optical system. Unfortunately, this subject is usually presented in the form of proofs and derivations, with little time spent on the practical implications of aberration theory. Furthermore, a new generation of lens designers, who grew up with the computer, often consider aberration theory as an unnecessary relic from the past. My career, by contrast, is based on the conviction that using the results of aberration theory is the only intelligent way to design optical systems. Computers are an invaluable aide, but we must, ultimately, bite the bullet and think. Along these lines, I have given several papers over the last few years which deal directly with the philosophy of lens design; the kind of guides for the perplexed that I wished I had had from the start. These papers include: "Lens design on a desert island - A simple method of optical design", "A modular method of optical design", "Optical design with air lenses", "Optical design with 'phantom' aspherics", "Optical design methods: your head as a personal computer", "Aberration theory and the meaning of life", and a paper at Innsbruck - "Some interesting correspondences in aberration theory". In all cases, the emphasis is on using your head to think, and the computer to help you out with the numerical work and the "fine-tuning" of a design. To hope that the computer will do the thinking for you is folly. Solutions gained by this route rarely equal the results of an experienced and/or intelligent human thinker. Other writers who have emphasized this same theme before me, and whom I highly recommend, are Bob Hopkins, Jan Hoogland, and Erhard Glatzel. This paper will not attempt to review the many different design methods set forth in the papers just listed. It will, however, "walk through" the thinking behind just one optical design in a way which will show the enormous power and versatility of aberration theory as a design tool. It is my strong conviction that just about everything worth saying about the results and implications of aberration theory (which is highly mathematical) can be stated in ordinary English, so there will be no mathematics in this paper.

Karl Schwarzschild (1873 - 1916)1 has set up the 2-mirror systems as a 2-parameter mani-fold. He constructed them for primary aplanatism with conic section surfaces, and for finite aplanatism with numerically determined surfaces of revolution. Developing from the still older 2-paraboloid telescopes, conceived by Marin Mersenne, the systems since designed fill three domains of existence. The grazing incidence systems too (the Wolter-Schwarz-schild systems) have their loci on this map. Martin Linnemann (born 1880), student of Karl Schwarzschild, designed the first lenses, made aplanatic with two general surfaces of revolution2. For later authors remained only to vary image scale to non-zero values, and to adapt the design method to computer use.

There are many correspondences between the behavior of monochromatic aberrations and chromatic aberrations. Usually the behavior of the chromatic aberrations is of a lower order than the corresponding monochromatic behavior. The cause of the 5th-order mono-chromatic astigmatism, for example, is similar in type to the cause of the chromatic variation of 3rd-order astigmatism. The stop-shift behavior of 3rd-order monochromatic coma is similar to that of first-order lateral color, and so on. These correspondences are interesting for two reasons. One is that they have not been commented on much before, despite the value of one's being aware of these relationships. Methods used to control a monochromatic aberration may also apply to the corresponding chromatic aberration, and vice-versa, for example. The other benefit to studying this topic is that the chromatic aberrations, which are of a lower order than their monochro-matic correspondences, are much easier to understand and visualize. A simple diagram can illustrate the stop-shift behavior of lateral color much more easily than trying to do the same thing with 3rd-order coma. Finally, the very important distinction between intrinsic and induced aberrations can be best illustrated with chromatic aberrations, because of their lower order.

A major area of concern when designing infra red systems is the defocus effect caused by the variation in temperature of the system from ambient. This paper outlines how this defocus affects the performance of the system and discusses in some detail techniques for overcoming this problem. The advantages and disadvantages of each technique are identified and a trade-off matrix shows the relative merits of each.

Hg short arc lamps combined with ellipsoidal concave mirrors are used today in illumination systems with a high radiant flux. The secondary focus of such systems can be considered as a "Secondary Light Source" which is quite inhomogeneous. The limits of such systems and the possibility of improvement will be discussed.

Any optical system transmits light from a radiating source through a number of optical elements up to a receiving surface (screen). This paper is intended to provide a method for calculating the local illuminance at the screen without any assumptions on the imaging properties (not necessarily 'Kohler Illumination' ). The concept is based on ray tracing and lies completely within the geometric optics model. The direction of the tracing calculations is against the direction of physical light flux. A differential illuminance is associated with each ray and the total illumination is calculated by integrating over the entrance pupil area. The main work lies in computing the differential illuminance; a few examples of illumination systems analysis are presented.

In the special case of optics for video discs we present an optical imaging system which is capable of giving the high resolution required for polychromatic radiation from a laser diode and an extended object field. A combination of an in-line holographic lens and a glass lens with a small coma, a small chromatic aberration and a very small spherical aberration giving almost diffraction-limited imaging over a relatively large object field and a relatively large spectral bandwidth, is here proposed and analyzed. Optimization programs yielded highly corrected imaging systems by comparably simple holographic means. The use of only two surfaces results in very compact and lightweight systems, the image quality of which is described for monochromatic and polychromatic illumination by means of optical transfer functions and wave aberrations.

A description is given of the correction of Seidel aberrations of zoom lenses. The procedure uses "bendings" of lens elements or groups with a thickness of 0. This procedure is of particular advantage if suitable examples of starting configurations are not available.

The technology of diamond turning of germanium, and the computational power of computer-aided mechanical design have now reached the point at which complex optomechanical layouts can now be considered for thermal imaging telescopes, with high confidence that the finished assembly will perform as predicted. This paper describes the specification, the optical design, and the mechanical design of a three-field telescope, designed to suit the tasks of parent vehicle guidance, target acquisition, and target identification.

The paper discusses the structure and the performance of the 10-100 mm f/1.8 Vario-Sonnar. This new Vario-Sonnar is a taking lens with continuous focus for the 16 mm format and combines high speed with compact design. The close range is marked down to 1.5 m, can however be set as low as 1 m (unmarked). A specific setting device permits macro mode with a reproduction ratio of 1:4. This device also enables the Vario-Sonnar to accept a wide-angle lens to change the initial focal length from 10 mm to 6 mm.

The design and breadboard of a very compact,f/1, CO₂ laser receiver lens are described. This optical system has been developed to fit a small CO₂ laser range-finder. Lenses are assembled in a fast, economical, self-centering technique. The first prototype has been tested by means of a CO₂ laser interferometer. Fringes have been analyzed by a numerical program that allows comparison between the realized and designed lens. Results of the analysis will be presented.

Merit functions are derived for non-imaging and imaging systems. In non-imaging (energy-collecting) systems it is essential to maximize the output signal of the detector, which leads to the well established criterion of maximizing system throughput. Imaging systems, on the other hand, require maximizing the spatial signal-to-background ratio. The merit function derived from this criterion is suitable for assessing different coating designs relating to their effectiveness in electro-optical systems.

This article describes the optical system design for the WAMDII instrument. WAMDII is an acronym for Wide Angle Michelson Doppler Imaging Interferometer. The function of the instrument is to determine upper atmospheric wind velocities, temperatures and volume emission rate over a wide visual field of view by measuring parameters such as Doppler wavelength shift, Doppler line broadening and emission intensities.

As is generally known, holographic gratings permit the construction of monochromators with only one optically effective element. Compared with the Seya-Namioka arrangement, our hologram pattern provides us with better means for aberration correction. The correction of aberrations is described. It is proven that the tangential focal curve passes through the exit slit at max. four wavelengths in the spectrum. This property of the tangential focal curve is used for a non-linear Chebyshev approximation. Methods and the pertaining correction parameters are given for the correction of astigmatism and coma. For concave spherical gratings, a classification into two monochromator classes is performed according to the correction parameters used. The results of the optimization are represented in the form of spot diagrams and inten-sity distribution curves. The spectral transmittance as a function of efficiency, aperture, resolution, magnification and astigmatism is discussed.

A system was designed and built for the reproduction of Braille originals by means of optical pattern recognition.

This paper describes various analytical and numerical tools for evaluating optical system designs under thermal-mechanical environ-ments. These analytical tools provide either direct input into optical design, heat transfer and finite element programs, or provide information for evaluating various aspects of optical component selection. Several case studies are presented demonstrating the use of these tools in a wide range of applications. These studies suggest an integrated approach to evaluating optical systems. Ultimately an integrated system of analysis programs with common data access is envisioned. This will enable the entire process of optical system design, component evaluation, and analysis, performance predic-tions and system optimization to be performed in a common environment.

This paper describes the transient temperature gradients in multilayer optical thin films when subjected to high energy continuous wave and repetitive pulsed lasers. Equations are described for use in evaluating the time-temperature history of each coating interface and subsequent energy distribution to the substrate. One and three dimensional equations are provided to examine the impact of thermal diffusivity, relaxation time and subsequent damage to the optical thin films. Coatings that are supported by cooled substrates are evaluated as a function of substrate material and cooling medium heat transfer coefficient. Coating temperatures and substrate temperatures are evaluated for conditions satisfying the semi-infinite plate model. A substantial number of curves are generated to provide the reader with an equation relationship of the response of the various coating and substrate materials. Key words: High Energy Laser, Optics, Optical Thin Films, Heat Transfer, Laser Damage.

This paper describes the temperature gradients in multilayer optical thin films when subjected to high energy continuous wave and repetitive pulsed lasers. Equations are described for use in evaluating the time-temperature history of each coating interface and subsequent energy distribution to the substrate. One and three dimensional equations are provided to examine the impact of thermal diffusivity and relaxation time and subsequent damage to the optical thin films. Coatings that are supported by cooled substrates are evaluated as a function of substrate material and cooling medium heat transfer coefficient. Coating temperatures and substrate temperatures are evaluated for conditions satisfying the semi-infinite plate model. A substantial number of curves are generated to provide the reader with an equation relationship of the response of the various coating and substrate materials. Key words: High energy laser, Optics, Optical thin films, heat transfer.

A summary is given for the evaluation of Optical Replication as a viable manufacturing process for optical components. Present limitations are discussed and suggestions for overcoming, or at least lessening, these limitations are offered. Practical design guidelines are presented for reflective and refractive imaging elements.

Through previous marketing surveys and discussions with many companies in 1984 and '85, it has become apparent that there is a growing need for a grinding machine capable of producing high quality, aspheric optical surfaces on various brittle materials that cannot be directly machined by single crystal diamond tools. Some of the materials of prime interest are ceramics and carbides, to be used as molds for plastic and glass lenses. Even though tool steel substrates with electroless nickel plating are being directly machined by single crystal diamond tools and used for injection molding of plastic lenses, the harder carbide and ceramic substrates have more desireable properties as molds for both plastic and glass lenses. Various applications of these lenses include use in: - Cameras and Photocopiers - Fiber Optic Connectors, and - Pick-up Heads for Compact Disc Players for both audio and read only memory (CD-ROM) applications.

Special design methods for optical systems with aspherical surfaces are worked out here. Short descriptions of the main features are given. It is tried to establish a systematic method for evaluating optimal solutions of optical systems with aspherics. Some examples are added.

A systematic procedure for initial glass choice in periscopic systems of contact doublets is described. The method yields comnonent surface curvatures for subsequent optimisation, and predicts some properties of the final system performance.

Recent technological advances in optical production methods have given the optical designer greater freedom in being able to solve problems in imaginative ways using devices that may not hitherto have been possible to construct. Complex opto-mechanical components can now be produced to a degree of precision that allows simplification of the overall systems. design. In addition, new materials offer many optical systems the possibility of a wider scope of use. Several such components are reviewed, with particular reference to the methods of production and the way in which they contribute to providing novel infra-red systems.

A compact, lightweight viewing system that provides a magnified, inverted image of the phosphor of an image intensifier tube is described. The compact dimensions have been achieved by repeated folding of the optical path by the use of a polarising beamsplitter. The approach taken to the design, its internal structure and method of operation are detailed.

A variety of highly non-conventional optical elements is being developed in laboratories around the world. Because these optical elements differ far more from conventional spherical dielectric reflective optics than do simple aspheres, they offer new challenges in both fabrication and testing. Some of the new kinds of optics to be discussed include fly's-eye lens, holographic optical elements, and panaramic lens.

The present status of MTF is reviewed and recent trends in the design of MTF measuring equipment described. MTF equipment can be used for other than MTF measurement, and some of these other measurements and the techniques for doing them are described. Finally some suggestions and comments are made regarding methods of assessing and specifying the performance of MTF equipment.

Single point diamond machining can now be used as a very effective production tool for optical components. Materials which have been successfully machined so far include various aluminium alloys, OFHC copper, brass, acrylic, germanium and silicon. This paper describes some of the work done within the Optical Components Group of Ferranti. Components manufactured to date range from flats to off-axis paraboloids. It has been shown that discussions with the customer at the early design stage can lead to simpler production techniques and, subsequently, faster turnaround times. Fixture design is also very critical when working to the tolerances demanded within the optics industry. Finally, the most important factor is probably cost. Care must be taken to ensure that the required specification is realistic. Unnecessary demands will usually lead to an escalation in cost which will certainly not be acceptable to the customer.

The results of an experiment designed to test the feasibility of optical testing using subaperture test flats are presented in this paper. This testing technique involves the replacement of the monolithic optical flat used in conventional double-pass optical system testing by an array of small flats, or subapertures. Subaperture testing was conceived previously by other authors as a low-cost means of testing future telescope systems with large apertures (ca. 10 meters). Previous work by these authors involved the development of analytical techniques for combining subaperture testing data such that the wavefront over the full aperture may be obtained; the present work provides experimental verification of these analytical techniques. A brief description of the algorithms used to analyze the data is given along with a description of the experimental procedure. An array of seven subapertures was used. The subapertures contained random tilts and phase shifts relative to each other; thus the possibility of performing subaperture testing with such an un-phased array was specifically tested. Control data were obtained with a monolithic flat. Experimental results are presented. Agreement among the subaperture data and the control data is good; thus it is found that subaperture testing is feasible. Knowledge of subaperture phases and tilts results in significantly increased accuracy. However, a lack of such knowledge may be compensated by increasing the amount of data collected. It is found that the diameters of the subapertures affect the accuracy more strongly than the knowledge of subaperture tilts. Data obtained with atmospheric turbulence deliberately introduced show that, in the presence of turbulence, subaperture testing is significantly less accurate than conventional testing.

The existing German industrial norms for flat surfaces date back to the precomputer age. To make them suitable for digital interferogram analysis, some refinements and additional definitions are necessary. An algorithm is described giving mathematically unique results that do not differ too much from the existing norms.

Ion milling was studied as a method for removing a well defined amount of material from a spherically shaped surface to fabricate high quality aspheric germanium lenses. The ion-current density of the beam was determined as a function of the acceleration voltage and argon-gas flow in order to find near optimum conditions for smooth etching of the lens surface. The sputtering yield was studied as a function of the angle of incidence of the beam with respect to the target surface. Based upon these data, a computer program was designed, which controls the dwell time and the corresponding position of the lens with respect to the ion beam such as to generate a prescribed surface shape.

The primary aim of the ESA's HIPPARCOS mission is to produce an astrometric catalogue of about 100.000 stars with an extreme accuracy (2 milliarc seconds). To achieve this goal, very severe requirements have been put on the payload. This paper concentrates on the short term stability requirements. In a first step, the link between the mission performances and the related hardware design and requirements is established. Then the methods used to verify these requi-rements are presented : - description of the methods and testing philosophies, - accuracies, constraints and limitations, - results of the tests already performed.

The design and the development of the HIPPAR-COS payload all reflective Schmidt telescope have been driven by the highly demanding challenge of reaching an accuracy of 2 milli-arcseconds (1.E-8 radians) in star position measurements. This achievement is made possible by an original optical arrangement of the telescope, based on the capability to develop the so-called "beam combiner", which consists in a reflective Schmidt corrector cut in two halves and reassembled by bonding with an angle of 29 degrees, with a final wavefront distortion of lambda / 60 RMS. The final optical performances of the tele-scope can be summarized by a loss of MTF better than 7 % with respect to the diffrac-tion limit and a chromaticity lower than 3 milliarc-seconds. After a short description of the principle of Hipparcos measurement and of the telescope optical configuration and a recall of the chromaticity concept, this paper gives a presentation of the development of the optics especially of the Beam Combiner, and technics used for the alignment and test of the telescope.

Electronic Speckle Pattern Interferometry (E.S.P.I) oftenly called Electronic Holography is a practical powerful technique in non-destructive testing. Practical capabilities of the technique have been improved by fringe betterment and the control of analysis in the time domain, in particular, the scanning of the vibration cycle, with introduction of: synchronized amplitude and phase modulated pulse illumination, microcomputer control, fibre optics design, and moire evaluation techniques.

The HIPPARCOS satellite, a project of the European Space Agency (ESA.), is devoted to very high accuracy astrometry for establishing a stellar catalog of 100 000 stars to an accuracy of about two milliarc-seconds. Optically the satellite consists in an all reflective SCHMIDT telescope of 29 cm aperture having the capability to image simultaneously two sky areas separated by a constant angle of 58 degrees called the Basic Angle. (A detailed desciption of this satellite and its requirements can be found in ref 1,2 and 3). The funtion of beam splitting is performed in the entrance pupil of the telescope by the BEAM COMLINER. This paper deals with the design of this mirror, the different steps of its fabrication and the procedure we used for the determination of its optical parameters.

A novel four electrode lens system was designed on the basis of axial potential distribution analysis and a new electrostatic lens design guideline. The properties' of the lens are investigated and some general comparisons were made with two and three electrode lenses. It is shown that the four electrode lens is more flexiale and easier to approach the optimized axial potential distribution with simple electrode shapes. With the lens system a 1nA Ga ion beam current in a o.o73-o.o57uM beam spot could be obtained under the following conditions: 14-40Kv acceleration voltage, 4mrad object side acceptance half angle, 20uA/sr angular cur-rent density and 10eV beam energy spread. Experiments were carried out on a focusing ion beam system using the designed four electrode lens and theoretical calculations were confirmed by the experiment results.

For use in large mirrors in outer space, where low mass is a critical need, carbon fiber developments are under our investigation sins six years. Our candidate for a successor to the Hubble Space Telscope will be here presented. The telescope mirror is a 10-meter diameter monolithic primary. In our option we use a Nasmyth Focus, because of mirror stability. The telescope is located in geosynchronous orbit to live out enviromental constraints and pusch observing efficiency.

The rapidly growing use of multichannel detectors in the design of analytical instruments has lead to the development of concave holographic gratings which produce a flat spectrum. These gratings are corrected from aberrations, mainly astigmatism, and are blazed for improving the signal. Spectroscopic instruments are subject to two forms of stray-light - diffuse scatter from the grating, a problem that can be significantly reduced by using holographic gratings and multireflections that may include the grating. This problem may be solved by calculating an aberration corrected grating that operates "off plane" and is, in fact, tilted. This paper describes the effect of these improvements for optimizing signal to noise ratio of flat field spectrographs.

The modern opto-electronic systems require infra-red zoom lenses for different uses. According to these uses, zoom lenses offer advantages with regard to bifocal lenses. This paper points out those advantages for five applications in the infra-red field which are: - thermal imagery - simulation - guiding on laser beam - tracking and ecartometry - coherent active imagery.