The design of optical systems gains profit from the application of aspheric elements: to correct for image aberrations, to reduce weight or system length or to cope with other functional needs like the number of reflections or the field size. Manufacturing, however, is suffering in practice from problems resulting from the reduced symmetry of the components as compared to spherical optics. Almost all large optical companies in the world are working on solving the problem of fabrication of accurate aspheric elements at reasonable cost. In this paper fabrication and metrology aspects of aspherical elements in the IR, visible, UV and EUV at Carl Zeiss and other companies will be discussed. The specifications achieved presently are ranging between some micrometers to nm for figure accuracy and 100nm to 0.1nm for microroughness.

Aspherics up to 500 nm diameter in optical glass or in ceramic substrates have been fabricated using area- compensated polishing tools and conventional optical shop machines. The tool forms are derived starting from the actual shape of the part under figuring. The figure error is measured using an interferometer mounted on-line with the polishing machine. Measurements are taken after each polishing step to compute the new tool form. The process speeds up the fabrication of aspheres and it improves repeatability in the manufacturing of axisymmetrical optics using moderate cost equipment's up to astronomical requirements. In the paper we present some examples of polishing results using the above mentioned approach on different aspherics for space applications.

This paper report the development and production activities performed at REOSC during the years 1989-99 related to the VLT and Gemini large telescopes projects.

We describe the optical fabrication and testing of the 6.5 m f/1.25 primary mirror for the first Magellan telescope. Figuring was performed with a 1.2m stressed lap, which bends under active control to match the local curvature of the optical surface, and a variety of small passive tools. The figure was measured with RI and visible interferometers, using refractive null correctors to compensate 810 microns of aspheric departure. After subtraction of Seidel astigmatism and spherical aberration, the finished mirror is accurate to 14 nm rms surface error, and has an encircled energy of 80 percent in 0.06 inch diameter at 500 nm.

REOSC has supplied Indian Space Research Organization in 1998 and 1999 with two sets of eight lens assemblies to be used for the Ocean Color Monitor mission. First set will be launched on the Indian earth observation satellite IRS P4 during 1999. All lenses have a 20mm focal length and work with a very wide field of view angle. Each set of lenses covers the visible range using eight narrow spectral bands, one for each lens, distributed from 412nm to 865nm. The eight lenses of one set are matched for perfect registration: focal length better than +/- 0.01 percent, image format better than +/- 2 micrometers , distortion better than +/- 0.45 micrometers for each point of the field. In order to achieve these very tight requirements, REOSC has developed a specific spheroparabolic lens and particularly the process allowing to polish the parabolic surface with a very repetitive quality. A method has been settled to achieve the matching specifications of the lens assemblies by iterative correction of the optical design during the testing activities. The paper discusses the main points of these topics, reports this optical fabrication and testing challenge and presents the final obtained performances.

This paper reports the beginning of laser amplifier discs and spatial filtering lens polishing activities performed at REOSC for the Laser Megajoule project Ligne d'Intergation Laser prototype facility.

This paper reports on a new finishing process, Fluid Jet Polishing (FJP), that resembles the kinetic process employed in ASJ systems in that it is guiding a pre-mixed slurry to the surface, but within FJP low pressures are applied. Since FJP employs a fluid for machining, no tool wear occurs and the tool is cooling and removing debris in process. Using slurry that contained water with grinding abrasives, the FJP finishing process has been demonstrated. On flat glass samples, the surface roughness of a previously ground surface has been reduced from 475 nm rms to 5 nm rms and a prepolished surface has been shaped without increasing its roughness of 1.6 nm rms. Experiments are described showing that the final surface roughness depends on slurry characteristics and that the material removal spot can be adjusted by varying process parameters, e.g. the angle of the incident ray.

Magnetorheological finishing (MRF) is an innovative and powerful new polishing technology for fine figuring of high precision glass optics. MRF may be used to improve precision ground or polished lenses into optics having figure accuracy of better than (lambda) /20 p-v in a matter of minutes. The technique works extremely well for high precision flats and spheres, but its ability to produce high precision glass aspheres reliably, reproducibly, and affordably is its greatest contribution.

With 'Banana Technology' an unconventional hybrid fabrication technology is indicated for the production of very large parabolic and hyperbolic cylindrical mirror systems. The banana technology uses elastic bending of very large and thin glass substrates and fixation onto NC milled metal moulds. This technology has matured during the last twenty years for the manufacturing of large telecentric flat-bed scanners. Two construction types, called 'internal banana' and 'external banana; are presented. Optical figure quality requirements in terms of slope and curvature deviations are discussed. Measurements of these optical specifications by means of a 'finishing rod' type of scanning deflectometer or slope tester are presented. Design constraints for bending glass and the advantages of a new process will be discussed.

The use of lasers is more and more growing in industrial processing of different materials. Some examples of possible applications are the improvement of surface characteristics, drilling, welding, cutting and micro-structuring. An important aspect in this context is the necessity to adjust a specific intensity distribution for each application. This is usually realized by using special optics, which are able to form or shape the beam. These optics have complex geometries and in addition they have to fulfill high precision requirements regarding form and surface quality. The efficiency of laser system can be increased by using special designed optics with non-rotationally symmetric structures. Fabricating optics with these requirements is almost impossible using conventional manufacturing techniques. The only possibility for manufacturing is the use of fast tool servo system while the diamond turning process.

Long cylindrical mirror sections with an 'Alliptical' cross- section and an interfoci distance of approximately 1 m can be produced by means of diamond fly cutting. However, because of the finite tool radius, the generated profile is basically not an ellipse, but an equidistant ellipse or 'Allipse'. By numerical ray tracing analysis two unique conjugated 'A-points' can be found that are optically nearly equivalent with pure elliptical focal points. A reversed modeling procedure is used to predict the optimum machine configuration for producing just the required ellipse sections. Optical figure quality, focal line position and straightness are tested by a simple deflectometer set-up.

Today's optical manufacturing industry is facing increasing pressure on cost, quality, and delivery performance. There is also in an environment of decreasing batch sizes, a move towards higher tolerances - usually for very quality conscious customers. A frequent response is to invest in new manufacturing technology. The alternative discussed here is to focus on improving the underlying processes.

Ion beam figuring is a deterministic optical fabrication technique which efficiency has been mainly demonstrated on large optics these last years. One of the disadvantages of ion figuring is the high surface temperature of the workpiece. Temperature aspects have already ben mentioned by some authors but are weakly detailed. Therefore thermal effects on BK7 and Zerodur, mainly surface figure distortions and surface temperature measurements, have been investigated here in more detail.

An ion beam figuring facility is operational at the Centre Spatial de Liege since 1997. Its present capabilities are described. An extensive characterization program is running in order to determine the optimized parameters for various materials and operating conditions. In this frame, tests have been performed on a spherical gold-coated aluminum mirror plated in between the with nickel. The nickel plating was used to be super-polished to a BRDF of 1 10^-4 at 1 deg at 10 micrometers wavelength. Micro-roughness and etching rate measurements were realized and influence of ion bombardment on the coating has been established after removal of the gold coating. The gold coating removal of the gold coating. The gold coating removing was performed by using the ion beam flux. Finally, the mirror has been figure from the original sphere to a parabola. Surface characteristics evolution is also described in terms of micro-roughness and surface error. An overview of the research and development programs related to this facility is given. Results of this technique and potential impact on optics fabrication are then briefly exposed.

Matra Marconi Space (MMS) has designed, manufactured and tested a (Phi) 200 mm aspherical mirror to (lambda) /100 rms WFE for the purpose of a telescope demonstrator which both structure and mirrors are made from sintered Silicon Carbide. This outstanding performance has been achieved through a coordinated R and D program with the Insitut fuer Oberflaechen Modifizierung for the mastering of all the figuring aspects of any sintered Silicon Carbide telescope mirrors based on Ion Beam Figuring.

We have used a broad ion beam technique to generate cylindrical structures. Although limited to small dimensions, it produces potentially high precision smooth surfaces. As a first trial, four surfaces were produced for an industrial application, using a fairly simple mask; the 8 mm wide, 3 micrometers deep W profile cylinder was engraved on silicon substrates. Reproducibility was in the range of 1 percent when working in reproducible conditions, allowing refinement of the mask. We shall discuss the limitations of the method and improvement of the mask. We shall discuss a project extending the method to quasi-cylindrical figuring: the fabrication of a diffraction-limited off-axis ellipsoidal mirror at a 21 nm wavelength, with, as a first trial, the fabrication of a toroidal surface to a nanometric precision.

In 1994, REOSC took the decision to set up a large optics Ion figuring facility to be operational within 18 months. The equipment was designed to be able to accept components up to the maximum dimensions of 1.3 X 1.3 X 1.3 meters mounted in a high-vacuum chamber. After a period of design, fabrication, installation and validation, the Ion Beam Facility came is now, since more than two years, fully integrated in our production line as an efficient complementary technique to the mechanical polishing. We present in this paper some experimental results showing the maturity of the technology as well as some recent improvements and future applications.

Reactive ion beam etching (RIBE) has been demonstrated to be an efficient figuring process for the fabrication of optical aspheric elements with high asphericities as they are needed for high performance EUV - or x-ray optics and satellite communications optics respectively. Using specially designed broad and medium beam size ion sources a RIBE process based on fluor containing etching gases was developed resulting in high removal rates and very smooth surfaces. In two applications the RIBE figuring was applied for the fabrication of fused silica aspheric surfaces with nanometer accuracy at a figuring depth of some ten micrometers. A setup with a computer controlled two-axis shutter system for shaping of the ion beam was applied for etching of a linear parabolic aspheric surface. In a second application a medium diameter high current source with a fixed beam profile was scanned across the surface with the dwell time being proportional to the desired material removal.

Micro-electro-mechanical system technology offers a wide number of applications for the military, industrial, and consumer markets. The miniaturization of components is a common objective for all studies. Refractive microlens array with density 400 lenses per cm² are fabricated in three minutes by using hot embossing. The higher accuracy and lower cost of microlens fabrication methods are needed to meet the rapid growth of commercial devices. Higher density of microlens is achievable by a higher density mesh mold. Microlens diameters of 250-380 micrometers are shaped with various molds. Focal lengths of 185-225 micrometers are obtained by changing compression pressure and working temperature which are discovered in this experiment. Molding temperature effects on the surface tension in lens material as explored is essential. From accuracy of microlens arrays are less than Rt 0.1 micrometers that adapt to the form accuracy of the lenses. This article describes a mass fabricating method for microlens array by using hot embossing and the experimental results show its feasibility for practice.

This paper reports on the fabrication of prismatic microstructures on polymer films by a combination of KrF laser micromachining and hot embossing. Typical values of depth and pitch of prisms lie between 50 and 200 micrometers . Optical properties of such polymer surface sin the mid-IR are based on a geometrical optics mechanism. The UV ablation of V channels is achieved by projecting a (Delta) shaped mask onto the workpiece. Both poly(methylmethacrylate) and polyimide plates were machined. THe dependence of depth of grooves on mask shape, laser fluence, ablation rate of material, positioning table velocity and process gas has been investigated for both polymers. At 248 nm, the higher ablation rate of PMMA as compared to polyimide result in a close to 10-fold reduction in processing time. IR transparent polyethylene, films were replicated by hot embossing of either the polyimide master or a nickel shim electroformed on PMMA. Surface profilometry, optical microscopy and SEM measurements revealed that embossed PE replicas were produced with high fidelity. The angular distribution of IR transmissivity of the PE surface relief has been measured at 10.6 micrometers . Experimental results were compared to those calculated.

Optical surface gratings for surface emitting semiconductor lasers require extremely smooth functional surfaces, vertical step edges, a low sidewall roughness, and a high accuracy cover a large are. We report on the fabrication of binary patterns with a period of 1300 nm in GaAs and AlGaAs by electron beam lithography and different dry etching techniques, such as IBE, CAIBE and CARIBE. In order to improve the selectivity of the etch technique as well as the sidewall roughness three different etching mask techniques were applied. For grating depths of about 150 nm the best result with respect other geometrical grating characteristics have been achieved by using the e-beam exposed and developed PMMA as a direct etching mask. Comparing the different etching techniques, CAIBE on GaAs with chlorine shows the best etching behavior. A step edge angle of 90 degrees was achieved at an energy of 200 eV and a chlorine flow of 1.25 sccm. Optical diffraction measurements reveal a high efficiency for the gratings with vertical sidewalls and a line/space ratio of approximately 1.

A solution is described for replication of polymer microoptical elements on arbitrary substrates. The replication is done on wafer scale level and includes the adjustment step between the optical elements and the substrate. Demonstrators are various microlens arrays, structures for the efficient coupling between monomode waveguides or multimode fibers and photodiodes, and between multimode waveguides and LED's. Out of the many different replication techniques, UV-reaction molding is chosen for this application. This technique has advantages against hot embossing and injection molding. Network polymers which are stable against temperature changes can be used. The replication is made in thin layers on a solid substrate resulting in high mechanical stability and very good flatness of the samples. The process introduces mechanical stress nor thermal load on the substrate which can be a fully processed semiconductor wafer containing elements like diodes or LEDs.

Silicon is the mainly used material in the microtechnique and the crystal orientation wet chemical etching is a well known technological process in the production of microtechnical elements. The defined crystallographic faces prepared during etching and the shapes which can be created by combinations of them show properties of interest for applications in micro-optical elements. This will be demonstrated. First a systematic overview is given related to applications like fiber grooves, mirrors, beam splitters, gratings and prisms. As introduction in the crystal orientation dependent etching some basics to the process and design will be described which can be completed by many referencing. Properties like roughness, shape and inclination of the etched faces which are of relevance for optical applications are investigated. At last some special elements are described.

Recently, splices and connectors for fibers ribbons, optical cross connects and especially planar waveguide devices have been fabricated via LIGA in combination with precision engineering techniques. LIGA combines high precision and mass production capability, necessary for products designed for applications in the telecom and datacom market. In this presentation the fabrication of three-level molding and embossing tools is presented, which have been used for the manufacturing of waveguide prestructures consisting of waveguide channels and bier-to-waveguide coupling grooves. The precision of the tools is better than 1 micrometers in all directions, which allows for simple passive pigtailing. A first product, a precision of the tool is better than 1 micrometers in all directions, which allows for simple passive pigtailing. A first product, sixfold array of 4 X 4 multimode star couplers has been realized. The molding behavior of PMMA and COC material has been tested and compared. Production and assembly was tested by fabricating a series of 300 star couplers. The average insertion los has been found better than 9dB, the uniformity better than 3dB, both measured at 830nm. THe device is designed for application in optical backplanes for high-speed computers.

In total, more than 500 X-ray mirrors have been produced by Media Lario for the assembly of the six XMM telescopes. The x-ray performance of the individual mirrors has been evaluated both in terms of mirror shape and surface quality with the help of several metrology devices. In this paper we will present first eh metrology operations which were applied on the XMM mirrors to product their optical performance. Then, the metrology result will be analyzed and compared to the performance obtained during the verification and calibration campaigns. Finally, from the large XMM experience, we will conclude by giving some recommendations on the metrology tools to be used for the prediction of the performance of the next generation of x-ray telescopes.

An effective method to obtain the phase distribution is to use phase stepped interferometry. By recording a number of interferograms, all having a different phase step between the interfering beams, the phase distribution can be calculated. The accuracy of the phase distribution depends strongly on the accuracy of the applied phase step, i.e. the change in phase difference between the interfering beams. A novel scheme is presented that yields the change in phase difference between two recordings. It is shown that the calculation of the correlation between the two recording can directly be used to obtain the difference in phase stp between the two recordings. The accuracy in the obtained phase step value is better than 0.1 percent for all commonly used phase steps.

The Fritz's method using Zernike polynomials to assess the absolute planarity of test plates is revisited. Such method is based on four interferometric measurements, which are assumed perfectly correlated. In experiments, due to several instability sources, the data set is missing perfect correlation. Modifications of the Fritz's method are here presented, taking into account the residual uncorrelation of the data; such modified approach is demonstrated on a data set from experiments, achieving nanometer uncertainty level.

Laser MegaJoule and other large optical systems require the metrology of large components. MegaJoule's tilted amplifying slabs, for example, have a diagonal size of approximately 800 millimeters, thus requiring a large interferometer. Large interferometers, 600 millimeters diameter and above, are expensive. This is due, in part, to the large collimator and reference plate required. These parts, being large and heavy, also generate mechanical stability problems. Stitching interferometry is a method by which large optical components are analyzed using a standard 'small' interferometer. This result is obtained by taking multiple overlapping images of the large component, and stitching these 'subapertures' together. Previous papers have dealt with the subject.

A novel optical scanning technique for testing flats, aspheres and complex surfaces is presented, which offers ultra-precision for the measurement of slope and topography. The scanning technique is based on a combination of two principles, namely to perform difference measurements for slopes with large shears and to use only a single pentagon prism for the difference measurements, keeping the angular position of the pentagon prism constant in space. The combination of these two principles eliminates the influences of all first and second-order errors of the scanning facility, as this scanning technique is traced back exclusively to the units of angle and length. Especially whole-body movement of the artifact under test and distortion of the facility itself do not result in errors. The evaluation of difference measurements with large shears has become possible very recently with high accuracy and high lateral resolution because an error-free algorithm was developed. It is further a special feature of this technique that it measures differences of slopes and, consequently, allows the measurement of aspheres and complex surfaces with large asphericities.

Scanning Deflectometry is a powerful method to measure optical figure quality of various optical components and system in a simple way. This principle uses detection of slope deviations rather than optical path length variations. As an example, the design of a basic deflectometer for testing flat mirrors is presented.

Optical surfaces control poses a specific problem in the case of ophthalmic surfaces, particularly for progressive addition surfaces. Usual interferometry methods do not allow to measure easily such measurements but the duration and the sophisticated environment needed increase too much the testing cost. For that purpose, we have developed and patented a progressive addition surface measurement system using a deflectometry method. THe Ronchi method we use consists in illuminating the simple by a known wavefront and in measuring the slopes of the reflected rays. The main issue is then to compute accurately the surface topography. To solve this problem, we use an optimization method. Finally, the built instrument allows us to measure automatically deep aspheric surfaces in a few minutes with an accuracy close to 0.2 percent of its asphericity. It doesn't need a controlled environment.

The high throughput x-ray Spectroscopy Mission XMM is a 'Cornerstone' project of the ESA Horizon 2000 Science Program. The optical heart of this satellite consists in 3 Mirror Assemblies (MA). Each MA includes a Mirror Module (MM) containing 58 x-ray optical quality Mirror Shells (MS) and an x-ray (XRB) which reduces straylight. Two of the three MAs are equipped with a Reflection Grating Assembly (RGA) for spectral analysis. Tests are performed in the CSL FOCALX facility. The goal of the presented tests is to evaluate the x-ray effective area of a MM. These test are accomplished in a vertical configuration. An x-ray pencil beam is used for x-ray reflectivity measurements at Al, Au, Cu and Mo lines between 1.5 and 13 keV. A partial illumination collimated x-ray beam with a C continuous spectrum allows to measure the effective area of the MM over a 1.5-9 keV range. This paper gives a short description of the tested specimens, and presents the test configuration in CSL Focal X facility. The paper focuses on a compete and original way to work out experimentally effective areas of an x-ray telescope. Analysis of the achieved results is carried out.

Modern third generation storage rings, require state-of-the- art grazing incidence x-ray optics, in order monochromate the Synchrotron Radiation (SR) source photons, and focus them into the experimental stations. Slope error tolerances in the order of 0.5 (mu) Rad RMS, and surface roughness well below 5 angstrom RMS, are frequently specified for mirrors and gratings exceeding 300 mm in length. Non-contact scanning instruments were developed, in order to characterize SR optical surfaces, of spherical and aspherical shape. Among these, the Long Trace Profiler (LTP), a double pencil slope measuring interferometer, has proved to be particularly reliable, and was adopted by several SR optics metrology laboratories. The ELETTRA soft x-rays and optics metrology laboratory, has operated an LTP since 1992. We review the basic operating principles of this instrument, and some major instrumental and environmental improvements, that were developed in order to detect slope errors lower than 1 (mu) Rad RMS on optical surfaces up to one meter in length. A comparison among measurements made on the same reference flat, by different interferometers can give some helpful indications in order to optimize the quality of measurement.

Several critical aspects when testing aspherical surfaces by means of interferometry are reported. The aspheres are in the range of some microns to some 100 microns to some 100 microns of deviation from best fitting spheres. The required accuracy is a few nm. A compensating system has to be used to transform the interferometer's spherical wavefront to a wavefront that fits the asphere under test. Some special aspects will be discussed that are different to the test of spheres. Effects on the wavefront from lateral distortion, field curvature, and alignment of the compensating system need to be handled. The most problematic item up to now is the limited accuracy of the rotational symmetrical errors. The calibration of those errors still is much more uncertain than calibrations of unsymmetric errors or complete calibrations of spheres.

The first 1-m secondary mirror for the Gemini 8-m telescopes project was delivered by Zeiss in 1998, and 2nd mirror will be delivered in the summer of 1999. For first use during commissioning we produced an extreme lightweight Zerodur solution prefabricated at Schott. To reach the 85 percent weight reduction a novel etching technique was used. INterferometric testing was done performing full aperture measurements using a concave matrix. In progress with the fabrication process of the matrix we applied 3D-mechanical measurements, IR-interferometry, and VIS-interferometry using null lenses to reach the final intrinsic quality of 6 nm rms. For interferometric testing of the secondaries phase shifting interferometry with a tunable laser diode was applied. The optical test results of the secondaries show, that the mirrors are well within specification. The finally achieved intrinsic surface quality is 17 nm rms for Unit 1 and 13 nm rms for Unit 2, dominated by cutting effects which were introduced by removing the oversize at the inner and outer edge of the mirror after the final polishing step.

A mathematical algorithm is given and explained in detail that can be applied to a Ritchey-Common test in two angular positions to calculate deviations. The algorithm comprises a transformation form wavefront to mirror coordinates and a weighting function. Influences of the interferometer's misalignments are removed by fitting appropriate functions in the mirror plane. Functionality and accuracy have been checked by simulations and experiments. As an example one of the M3-mirrors of the Very Large Telescope fabricated by Carl Zeiss is shown.

We describe an interferometric method for measuring effective focal length of lenses. Measurement of the effective focal lengths of macroscopic refractive lenses and of a diffractive microlens are performed within the limit of paraxial approximation. The technique uses a reflective grating interferometer to produce a fringe pattern with a regular pitch. The lens under test is illuminated by the interference pattern and the focal length is obtained by the knowledge of the spatial frequency in a fixed aperture. Three imags of the interference pattern are stored by using a CCD camera: two of them are imaged by the lens under test placed at two different position, an one is the reference pattern with no lens inserted in the set-up. A 1D fast Fourier algorithm is applied to the digitized image and the phase modulo 2 (pi) is reconstructed. The phase is unwrapped and averaged to calculate the spatial fringe frequency inside the chosen aperture. The method has been applied for measuring the focal length of macroscopic refractive lenses and of a 1mm aperture diffractive microlens.

To test quality of the wavefronts number of arrangements are discussed in literature. Out of these the lateral shearing interferometers using diffracting elements are stable and simple devices. Lateral shear obtained by J.C. Waynt, rotation of two gratings by Hariharan et al and Rimmer and Waynt over come some of the drawbacks suffered by Ronchi interferometers. It has already been demonstrated that the two slightly displaced off axis zone plates acts exactly like a double frequency grating. This paper describes the holo-shear lens made on dichromatic gelatin for testing of off axis parabola. Joenathal et al investigate lateral shear interferometry with holo shear lens.

The surface roughness of polished glass substrates as well as metal an dielectric coatings is studied using atomic force microscopy, hard and soft x-ray scattering at the wavelength (lambda) equals 0.154 nm and 4.47 nm, and light scattering (LS) at (lambda) equals 325 nm. It is demonstrated that all the methods, permitting the determination of PSD functions in partly overlapping, partly different ranges of spatial frequency, are in a good agreement in spite of different physical principles underlying the methods. The possible reasons for some differences in the PSD functions determined form different measurements are discussed. The main of them are a more difficult interpretation of LS data when dielectric coatings are present and a limitation on the angular range of hard x-ray scattering measurements imposed by the applicability of the perturbation theory used for experimental data processing.

A variety of technical applications require surface roughnesses to be measured and characterized over a wide range of scale. Therefore, it is inevitable to combine different measurements methods, both optical and nonoptical. In this paper, we present results of white light interferometry, atomic force microscopy, and angle resolved scattering. In addition we use total scattering to control the surface roughness and its inhomogeneities over large sample areas. Power spectral density functions are used to combine the roughness data obtained from the measurements over difference scales and to characterize the surface by means of model PSDs. We present results from different statistically rough surfaces, such as quartz and black glass, Si-wafers, and polished brass surfaces.

The principle of scanning deflectometry is presented as a simple method for measuring optical figure finish quality of odd shaped high-gloss surfaces.

The surface microtopography and subsurface damage of fused silica have been examined after different stages of the manufacturing process. Results are presented of etching experiments and measurements performed by white light interferometry, atomic force microscopy and total light scattering.

The comparison of different methods of measuring surface roughness parameters, i.e. angle-resolved scattering (ARS) technique and atomic force microscope (AFM) profilometry, was performed for quartz precise optical surfaces, obtained by different polishing processes. The functions of power spectral density, calculated form ARS, using vector scattering theory, and form AFM data are in good agreement in the range of polar scatter angles 30..75 degrees. In this range the angular scattering is well predicted using the exponential autocorrelation function with parameters, calculated from surface profile. The autocorrelation length, calculated from ARS data in above range using exponential statistics, remains practically constant for different surfaces, obtained by the same polishing process. The latter allows to consider it as the characteristic parameter of certain polishing process.

Surface quality is an important issue for KDP crystals implemented in high power lasers. Single Point Diamond Turning is the only way to get the required transmitted wavefront and damage threshold, especially in the UV band of the laser Megajoule. The aim of the process development was to reach an rms roughness lower than 3 nm using a vertical fly-cutter, an appropriate cleaning equipment and an interferometric microscope for measurements. A Taguchi Design of Experiment method has been used to optimize the fly-cutting process parameters on 100 X 100 mm² KDP crystals.

We propose to extend x-ray scattering method to the investigation of concave surface roughness. Our approach is based on the use of the whispering gallery effect, which consists in that an x-ray beam falling tangentially on to a concave surface slides along a surface due to successive total external reflections. During its propagation the beam gradually broadens because the scattering transfers some part of radiation to the range of larger glancing angles. Fitting of a simulated angular distribution of outgoing beam to a measure done enables the determination of statistical parameters of concave surface roughness. Possible experimental schemes are analyzed by using ray-tracing technique, radiation scattering by surface roughness being modeled by the Monte Carlo method. Results of experiments in x-ray spectral region are discussed. Carbon-coated cylindrical surfaces with the radius of curvature of 6 cm and the arc angle of 45 and 60 degrees are studied with soft x-rays. The measured angular distributions of outgoing radiation are shown to agree quantitatively with the theoretical calculations when the scattering of x-rays by the surface roughness are taken into account. The rms roughness and the correlation length of the studied surface are found to be about 1.2 nm and 0.3 micrometers , respectively. The possibility of the study of concave surface roughness with the use of hard x-rays is also discussed.

Centering of optical lenses is necessary for obtaining the required resolution of an optical system, especially minimization of distortion. Advantage is the systematic approximation of an minimized centering error of the individual lens in relation to its housing. A method by using stick-slip effect has been developed. The process has an automatic numerical control which operates during rotation of the lines. The adjustment tool is driven by electro-magnetic hammers in a step-by-step mode.

Light scattering measurements are important tools for characterizing optical surfaces can basically be divided into two main groups: total scatter measurements (TS) and Angle Resolved Scattering (ARS). Since TS measurements are fairly straight forward and widely used, international standardization has formulated an international draft standard on it, ISO/DIS 13696. ARS is a more complex method and not as common as TS measurements. However ARS data in form of the Bi-directional Reflectance Distribution FUnction (BRDF) can be used to predict stray light in Laser and Industrial Optical Systems. Because of increasing importance of this topic the EC is sponsoring a project regarding 'Standard procedures for stray light specification, measurement and testing - SLIOS'. During the project two of the activities are: performing a round robin experiment of measuring BRDF data at 5 different sites including some complementary techniques; compiling of an open access data base of measured BRDF data, measured according to procedures agreed upon between the SLIOS partners and proposed for 'Standard Procedures'. Results of these two activities will be presented.

The spot follow-on system is anew CNES Earth Observation program with reduced development cost as a major objective. In order to reach this goal, new methods for design optimization and performances assessment will have to be taken into account, with the aim to decreasing costly design safety margins. Present paper describes an original approach for rational assessment of image quality of spaceborne observation optical systems. This approach is based upon an overall end to end thermal, mechanical, optical modelization of the instrument which is submitted to both ground operations and space environment. Potential presence of ground and/or on-board active control loops can also be taken into account in that global chain. Based on this approach, a simulation tool has been developed, which allows statistical evaluation of the optical performance expressed as the RMS wave front error (WFE) using the Monte-Carlo method. Instrument modulation transfer function statistical budgets, including detector convolution effect, can be finally obtained as a simple post-processing of preceding WFE calculation step. Validation results and application to the 3S TMA instrument will be presented.

We present a design and new approach to certify a null corrector with tight manufacturing tolerances. This involves a diamond turned asphere and a hologram that provide certification redundancy.

Laser Megajoule is a very large laser system: 240 beams, each comprised of dozens of optical components size 400 X 400 millimeters to 400 X 700 millimeters, covering the area of a football pitch or two. Like any laser system, the various components must be computed and drawn. These drawings include specifications.

Laser Megajoule is a very large laser system: 240 beams, each comprised of dozens of optical components 400 millimeters squares, covering the area of a football pitch or two. Specifying the optics in Laser Megajoule is a complex matter, because of the large range of types of defects, classified by their lateral size or scale.

In ISO 10110-5 the rotational symmetric surface irregularity of an optical surface is determined form a set of rotational symmetric Zernike polynomials. For a large variety of aspheric optical surfaces which are manufactured by means of CNC-controlled machines this method leads to inadequate results. CNC-controlled fabrication methods often cause ring-shaped deviations described precisely by calculating the integrals over circles concentric to the axis of rotation. The final result is called 'average radial profile' and shows the cross section over the typical ring- shaped deformations.

The publication of a new ISO standard and the increasing need to tolerance the surface quality of laser components has created renewed interest in defining surface imperfection parameters. Assessment of the performance of conventional subjective methods using reference scratches stressed the importance of an objective approach. An analysis of the distribution of intensity in the image of the simplest imperfection in the form of a single step suggest that the eye could see such a feature with height of only 0.01 of the wavelength used. Various parameters for quantifying surface imperfections are reviewed leading to the selection of radiometric obscuration. This choice is justified on the basis of ease of measurement, traceability to natural standards for line width and a good range of sensitivity. The need for further work to relate the magnitude of this parameter to eh cosmetic appearance and/or function of a system is stressed.

A short review of the new standards relating to production and testing of optical systems that have been developed recently by the International Organization for Standardization (ISO) is given here. A more detailed account of the current status of the Neutral Optical Data Interface Format (NODIF), the proposed interface between computer- aided-optical-design programs and other computer-aided- design programs is also given. NODIF is one application of the standard for exchange of product model data (STEP) which is a standard for the smooth transfer of data files form one program to another with no loss of information or accuracy. STEP defines a set of protocols for each application, it is device independent and language independent and a reference model for each application is defined and interpreted. A set of conformance classes must be devised, to be used for testing any implementation of STEP in computer software. When implemented, NODIF will enable optical data to be exchanged between different optical or other design programs, or archived electronically, together with all other design data for a complex product. The latest information on the advancement of NODIF and its progress towards becoming an international standard is included.

Commercial interferometers are now routinely used to test optical components and systems and several such instruments are on the market. They usually incorporate very sophisticated software and produce a wide range of performance data at the press of a key. It is felt that there is a need to introduce an international standard to control the use of such instruments. As preparation for this standard, a round-robin project was carried out, in which six simple optical components were tested by eleven different laboratories. The results have identified some areas of concern in the use of these interferometers. For example, there is a tendency for operators to over-estimate the precision of the measurements and to be unfamiliar with the procedures for estimating measurement uncertainty. There is also evidence of unfamiliarity with the adverse effect that surface imperfections and misalignment can have on the measurements. It is suggested that more extensive interlaboratory test should be carried out and that the new standard should include advice on inspection procedures, the effect that surface imperfections can have on the measurements, the importance of mounting designs and procedures, the need for software verification, and calibration procedures.

The paper describes some measurements carried out in order to obtain reliable data for designing a passively athermalized MWIR telescope for observation of earth from a satellite and for finally evaluating the change of focus with temperature for the completed telescope. The telescope was a catadioptric system and the main body was a carbon composite structure, while the lens elements in the system were of either germanium or silicon. Reliable data was of course available for the coefficient of thermal expansion (CTE) of the metal components used in the structure, as well as for Ge and Si. However, the CTE of a carbon structure will to some extent depend on the exact form of construction that is used and therefore needs to be measured, or at least checked, on the actual structure. A survey of the published dn/dT data for Ge and Si as well as that provided by the material suppliers showed variations and uncertainties that were unacceptable.

In the IR system the surface cosmetic quality is generally more critical than in the visible because the materials have generally low hardness and they tend to be affected by digs and scratches. These defects lead to a worsening in the optical quality and the image uniformity. The degradation effects depend on their dimensions and the surface position in the optical path. When the surface is near the focal plane their effects can be very evident because the defect dimension can be comparable to the beam one.

An illuminated table intended for illuminating transmission test charts used for the optical testing of different image capture devices has been developed. It provides a diffusely luminous table face, 300 mm in diameter, in a compact set- up. The spectral distribution of the emitted light is similar to Planck radiation of about 3050 K as required, for example, for testing, digital photographic cameras. The luminance level achievable is about 15000 cd/m², the standard deviation of which is 1.8 percent within a circle of 300 mm in diameter. The illuminated table consists of an integrating hemisphere, with the large opening covered by an opal glass serving as the illuminated table face. Inside, a set of seven tungsten lamps is posited at locations such that the light output at the table face is as uniform as possible. Residual non-uniformities caused, for example, by slightly differing luminous intensities of the lamps are adjusted by controlling the currents of the seven lamps individually by means of a PC-controlled automatically running optimization process. This closed control loop uses a calibrated digital camera to capture the current spatial light distribution at the table face. The image is analyzed by an algorithm integrated in to the control loop.

Interferometric methods are widely used in metrology , quality control and optical systems alignment. In precision measurement it is usually required to recover the interference fringes phase by non-linear data processing. As known the inherent property of equispaced fringes, Newton's rings and some other kinds of interference pattern in the symmetrical form of the function that describes the intensity distribution. Using such a priori information it is possible to calculate the shift of interference fringes with high sensitivity and noise-immunity without phase recovering using the linear transform only by signal autoconvolution. We have applied the autoconvolution method to measurement of fractional part of interference order for equispaced fringes and to measurement of lateral displacement of Newton's rings. The first kind of interference fringes is usual e.g. for linear displacement measurement, the second one concerns the problems of lens centering and interferometer alignment. The autoconvolution method was realized by interferometric signal processing in spatial and spatial frequency domains. The accuracy and noise-immunity of autoconvolution method were verified.

The measurement of total scatter losses is a major prerequisite for the development, optimization and commercialization of high quality optical components. Especially in laser technology, optical scattering gained of importance in the source of the development of laser system with ever increasing output power and improved beam parameters. Besides its influence on the efficiency of laser systems and the beam steering arrangement, total scattering is an important safety aspect for application of these laser systems in materials processing, medicine and fundamental research. As a consequence of this global trend, working groups of TC 172/SC 9 initialized the development of an International Standard for the measurement of total scattering in optical components.