This paper describes various analytical and numerical tools for evaluating optical system designs under thermal-mechanical environments. 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 predictions 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.Upon closer evaluation of these applications, it is clear that a major portion of the lens mold market will be satisfied by the ability to grind aspheric surfaces up to a maximum diameter of 50mm. Also, to fulfill other requirements of these molds, a grinder must be capable of producing accurate alignment diameters and shoulders which are concentric and square to the optical axis of the aspheric surface. (see Figure 1.) This paper will discuss the design of a Grinding Attachment for a standard turning lathe, which is being used for fabrication of the lens molds previously described. It focuses on grinding of a silicon carbide mold. The following key areas will be discussed in detail: - Process Development a. grinding wheel selection b. wheel dressing c. wheel setting d. cutting parameters - Restrictions/Limitations - Accuracies Achieved a. form error b. surface finish

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 component 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 unphased 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 dia-meters 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 requirements 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 re-assembled by bonding with an angle of 29 degrees, with a final wavefront distortion of lambda / 60 RMS. The final optical performances of the telescope can be summarized by a loss of MTF better than 7 % with respect to the diffraction 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.

Since Scanning Acoustic Microscopy (SAM) has reached and exceeded light microscopical resolution more than 6 years ago, its systematic application and realization by commercially available instrumentation has started. For a better understanding of the possible contribution of SAM to applied microscopy in general, the nature of information obtained by SAM in comparison with modern light microscopy, i.e. the fundamental character of the interaction of acoustic waves with the elastic properties of microscopical properties under investigation is discussed. After explaning the essential elements of SAM systems in comparison with conventional and scanning optical microscopes (SOM), typical examples of SAM applications to material sciences, microcircuit inspection and living cells are given

General corner cube reflectors are represented in 'dihedral angle' space to provide for a means to evaluate their acceptability when a maximum deviation angle between incoming and exiting beams is known. Deviations as well as dihedral angles may be derived from interferometric measurements or from autocollimation methods.

Narcissus, imaging of a cold detector onto itself, is usually disturbing in scanning thermal imaging system. But it can be used as a cheap and effective testing tool for complete thermal imaging systems. A mirror placed in front of the system induces narcissus. This set-up is examined, and three examples are given, one in the 3 - 5 μm range and two in the 9 - 12 μm range.

The use of cylindrical test plates for measuring the surface figure of cylindrical optical surfaces is accompanied by several practical problems due to the absence of rotational symmetry. A method to test cylindrical surfaces with spherical test plates is presented.

Modern electro-optical components and design approaches allow superior multi-angular scatterometers and highly accurate transmissometers to be fabricated. Various design approaches are discussed and their several aspects contrasted. Calibration procedures, tests methods, performance deficiencies, and correction methods are discussed theoretically and practically for a semiconductor-laser-based instrument.

An imaging sensor specifically designed for passive naval surveillance of passing vessels is described. The sensor, containing an infrared and a visual channel, is part of the IVISS system. This land-based system is optimized for the identification of passing vessels by remote control. The generated images are transmitted via ordinary telephone lines to a headquarters. In principle the numberof sensors to be controlled from a headquarters is unlimited. The infrared (8-14 μ) and visual channels of the sensor are to ensure identification by day and night and in poor visibility. The sensor is based on a slow scan principle thus obtaining high sensitivity and adaption to the bandwidth of the transmission channel. The sensor generates images in the infrared and the visual spectra. The format of the generated images is 1:4 which is due to the adaption to naval objects. The general field of view of the sensor is 3° vertically x 12° horizontally. This general field of view can be moved round the horizon by means of a simple mechanical positioner. Through a digital zoom function it is possible to select three magnifications of the general view from one scanned picture. In contrast to optical zoom systems these three fixed zoom fields of view can be placed at random positions in the general view.

A concept for a new spectroscope device is presented working on longitudinal chromatic dispersion of a properly made lens. The lens design characteristics are first reported, and interferometric testing results on a fabricated prototype lens are then comparatively produced. After calibration, the actual system performance is discussed.

CROUZET has developed since 1978 under contracts from the French Ministry of Defense (DRET and STTE) the laser Doppler technique to provide an equipment for aircraft air data calibration. A CW CO2 laser sensor performs a coherent detection of the light scattered by the aerosols sustained in the air. The instrument has successfuly flown in the vibrating environment of helicopter and airplane.

Key features of the opto-mechanical designs for two high performance objective lens assemblies of similar focal lengths and relative apertures, but significantly different configurations and applications are discussed. The first lens is a 25.4 cm EFL, f/1.5 catadioptric lens designed for a ±2.8 degree field and intended for use with a detector array in a spaceborne star mapper. The second example is a 22.8 cm EFL, f/1.5 refractor covering a ±10 degree field intended for distant target observation in an airborne low light level visual periscope and featuring an integral laser channel for target designation and ranging. The logic behind critical materials choices and the techniques applied in mounting the optics in their mechanical surrounds are described.

The use of optical systems for data acquisition and transmission is becoming increasingly popular for aviation applications. Features such as weight and immunity to high levels of E.M.C. are distinct advantages over conventional electronic systems. In some cases optical transducers provide a means of measurememt which would otherwise be impossible. One such transducer is the Turbine Blade Pyrometer Transducer. This instrument determines gas turbine blade temperature by measuring emitted visible and near infrared radiation. The transducer is an engine mounted electro optical system which provides a voltage output proportional to turbine blade radiance. As such it must be designed to withstand the demanding environment of a gas turbine engine.

A fast and versatile interferometric system for measuring surface profiles of flat optical surfaces without the need of a separate reference surface will be presented. The instrument is capable of resolving height variations of about 50 Å, while lateral resolution is 3 m. The profile measurement takes 20 seconds, and statistical properties like rms height, slope and spectral density can be calculated from the profile. No extensive alignment of the sample is needed, and scan lengths of 100 micrometers to several millimeters are obtainable.

A new multiple wavelength interferometer makes use of stabilised helium-neon and argon ion lasers to measure the length of engineer's gauge blocks. The combination of television and computing techniques to analyse the resulting interferogram makes the instrument less dependent on operator skills and is able to provide data about the gauge surface.