The requirement of not just survival but high performance operation in a hostile environment is a fundamental consideration in some optical systems. The paper details the effects of -- and compensation for -- deep-sea immersion, variable air-pressure and humidity, and a variety of thermal perturbations. The deleterious effects on optical materials resulting from a selection of hostile environments, including that of high radiation levels, are also considered and suggestions made concerning the optimum choice of materials.

A report is given on the contents and the structure of ISO DIS 10110 'Preparation of drawings for optical elements and systems,' including a comprehensive selection of important details. This future international standard gives rules for the indication of quality characteristics of optical elements and subsystems.

In recent years a lot of efforts were made to characterize laser beams and to describe their propagation in optical systems. For more than two years one working group of the International Organization for Standardization (ISO) worked in this field and has proposed a procedure to measure beam width and beam divergence. The Optical and Quantum Electronics Journal will publish a special issue on laser beam quality this year. What a waste of time for a single parameter one might think. What are the problems?

This paper describes methods of predicting the degradation of the performance of a simple imaging system in terms of the statistics of the shape errors of the focussing element, and conversely, of specifying those statistics in terms of requirements on image quality. Results are illustrated for normal-incidence x-ray mirrors having figure errors plus conventional and/or fractal finish errors.

Topographical measurements of surfaces yield a lot of data which are usually presented by tables of height coordinates or by contour maps. Here a method is described to characterize the surface geometry by just a few parameters which quantify the functional properties: sphericity, twist, and waviness. Examples of applications are given from the field of surface plate measurement. Some measurement techniques based on electronic levels, autocollimators and laserinterferometers are briefly discussed. A resulting accuracy of 0.1 micrometers on a one square meter surface is claimed. With the characteristic parameters, even small geometrical changes due to the environmental conditions temperature and moisture could be recorded and explained.

The microtopography of a certain surface is a complicated structure varying across the complete surface. Every surface has different elements of microstructure. In this paper, we consider roughness as a fine structure and defects as large structure elements. Roughness measurement on BK7-glass and CaF₂ samples is considered using different techniques. The comparison includes the automatic scatterometer STREUIX 2 and a TIS-measurement system, the ZYGO microprofilometer MAXIM (DOT) 3D, and the NANO SCOPE III of Digital Instruments. For the investigation of scattering characteristics of different surface defects, a special measuring device was developed. The scattered light distribution of different defects and contaminations measured with this set-up is discussed.

By means of image processing it is often difficult to detect minor defects of smooth surfaces such as glass and polished metal or ceramics. It was found that certain statistical moments of the bidirectional reflectance density function (BRDF) contain consistent information regarding different kinds of defects. Using Multivariate Discriminant Analysis with BRDF moments as feature variables the defect recognition and classification can be carried out in a straightforward way. Because the classification algorithm is very simple it is suitable for real- time application.

For overcoming the classical limits of resolution in optical microscopy it is necessary to detect the diffracted signal from the small details of an object in the near field. These light waves interact with the object details and then can be used for determining the object topology. The solution consists of frustrating the evanescent field by means of optical fiber probes. In this present communication a new super-resolution scanning near-field optical microscope using a diode laser ((lambda) equals 1.3 micrometers ) and optical fibers is demonstrated to measure the samples with submicron structure in a noncontact manner. A reproducible method manufacturing of the fiber probes is proposed. First, results dealing with the characterization of the device are reported.

An application of the Schlieren test method to evaluate scratches, digs, bubbles, inclusions, or any other kind of optical defects using the same simple equipment is reported. The system can be used in two different configurations, allowing the testing of mirror surfaces (reflection mode) and lenses (transparency mode) as well. The magnification is invariant and gives the opportunity to automatically count or compare defects with standards.

After being processed by an optical system, either in reflection or in transmission, a probe wavefront contains information on the induced aberrations that are conveniently reported by interferometry. Yet, the probe beam also includes diffuse light, mostly produced by scattering at the optical surfaces. The actual disturbance that is studied via interferometry is a partially developed speckle field, made of a strong bias phaser plus the weak random contribution due to scattering. The standard deviation of the random contribution, normalized to the modulus of the bias phaser, is assumed as a characteristic parameter of the speckle field. Such a parameter has been measured with digital phase-shift interferometric techniques on a series of selected samples, corresponding to different optical finish. In excess of 120 samples have been studied, referred to a traceable polishing process. The results are interpreted on the basis of available models of polishing mechanisms. Data fitting to the equation of the theory is reported; the results are in fair agreement with the theory.

Design and application of a rigid miniaturized phase shift interferometer is presented. The matchbox size instrument has a Twyman-Green setup and an integrated CCD camera. A standard HeNe laser supplies the light through a monomode fiber. The advantages in measuring big and small objects are discussed. The sensor-like instrument can even be integrated into manufacturing equipment.

Angenieux has developed a device providing a fast, accurate, 3-D analysis of a large range of aspherical and spherical surfaces and wavefronts, from diamond turned IR components to molded or polished lenses and up to large astronomical mirrors. Measurements are achieved without the need for compensating tooling such as null-lenses or holograms.

The absorbance of an Au/ZnS/Ge thin film system, Au/ZnS, Au/BaF₂, Au/PbF₂ film combinations, and of bulk Ge were measured as a function of increasing temperature in the infrared spectral range with a photothermal beam deflection (PBD) arrangement.

For quantitative photothermal investigation of both thermal and optical properties of thin films it is necessary to calibrate the observed signals. For thermoreflectance measurements this is the absolute surface temperature rise while for photothermal displacement measurements the slope of the sample surface deformation must be related to the energy absorbed from the heating beam. Such calibration is obtained by imaging the spatial distribution of ac current heating in metallic layers incorporated into a thin film system. We present experimental evidence that results from both techniques and can serve as a direct measure for the squared current density in the film. The surface temperature and thermoelastic response was calculated using simple one-dimensional models for the surface temperature and thermoelastic expansion. It is demonstrated that the method is well suited for an accurate absolute calibration of photothermal thin film measurements. The possible use of the Joule heating methods for thermal characterization of thin films and imaging of thin film microstructures is discussed.

Non-rotational aspherics offer new perspectives for the development of new concepts for high power laser resonators (e.g., CO₂-laser with unstable resonator). Furthermore, the intensity profile of the laser beam can be adapted to the needs of special working processes (e.g., cutting, welding, surface treatments). At the IPT a variety of mirrors with complex shapes are manufactured with a proprietary fast-tool-servo on a diamond turning lathe. For these mirrors an aspheric testing interferometer with computer generated holograms has been developed. Research work was done on the design of the optical system, the development of algorithms and software for the computation of the holograms, the techniques for manufacturing the computer generated holograms (CGH) and an appropriate strategy for adjustment of the measurement system. The hologram pattern is plotted using a CAD-plotter and photographically reduced in scale. To overcome this time-consuming technique and to improve the precision of the holograms a laser-based direct writing hologram-plotter is under development. We describe the concept of the measurement system, and discuss several systematic error sources. Some recent results are presented.

Microlens arrays made by engraving photoresist coatings are suitable for astronomical applications, especially in the Shack-Hartmann type of wavefront sensor. Their characteristics have to be carefully chosen to fit the turbulence strength. Our instrument, composed of a photon-counting device and a Shack-Hartmann sensor, allows synchronous recordings of short-exposure images and their corresponding wavefronts. In post-processing, the point spread functions (PSF) are calculated and used to deconvolve the direct images. A new real- time centroiding device transforms this experiment into a quasi real-time imaging corrective system.

We present a technique for interferometrically testing aspherical surfaces without the use of compensating elements. The method consists of recording successive overlapping phase maps from a set of annular interferograms of an aspherical surface, obtained using a conventional phase-shifting interferometer and a micropositioning translator stage. These maps are then sewn together with a suitable algorithm we have developed, and the whole surface error is recovered. Experimental results are shown to be in good agreement with the null lens test performed for comparison.

Zernike circle polynomials generally employed in interferometric mastermind fitting software fail on an annular dominion. Therefore, when testing catadioptric optics erroneous results may be obtained. We performed interferometric measurements on annular pupils at increasing obscuration ratios, and we fitted the resulting aberration wave-fronts using either Zernike circle polynomials and another polynomial set orthogonal over an annulus. The results obtained with the two different sets are compared and the limits of the standard interferometric fitting software are pointed out.

This new approach is based on optimization algorithms. In contrast to common techniques like fringe analysis or phase stepping methods the wave aberration can be evaluated from a single interferogram -- apart from the sign. Describing the wave aberration by a polynomial expansion, the coefficients of that polynomial are used as variables which are adjusted by iterative variations so that the corresponding computed interferogram is approximating the real interferogram. We discuss the special problems and demonstrate the practical meaning of the new approach.

The measurement of wavefront aberrations for optical imaging systems plays a major role in the field of modern optics. Measurements with a Fizeau type interferometer and a shearing type interferometer are described. The interferometric set-up for the shearing interferometer and the algorithms, in particular for the evaluation of the wavefront aberration, are described in more detail. Various methods for the measurement of wavefront aberrations are compared.

The attainable accuracy in interferometric surface testing is limited by the precision of the reference surface (relative testing). Therefore, this surface has to be measured independently with sufficient accuracy as compared to an ideal mathematical surface (absolute testing). The importance of further developments of methods for absolute interferometric testing for the optical shop and for standardization purposes is discussed and emphasized. Results of our own developments in absolute flatness testing are presented.

We have developed a technique for fabricating microlens arrays by engraving photoresist coatings. These microlens arrays are designed for astronomical applications for atmospheric wavefront sensors. First, we describe the apparatus and the manufacturing process. Second, we review the characteristics of the different photoresist types used in this process. Third, we report on the different optical testing methods to measure the microlens' performances. Then we deduce the several inherent advantages and limitations of this method. Fourth, we show how to produce monolithic arrays using ion beam milling with photoresist microlens arrays as a pattern and we demonstrate how these arrays can improve upon the performances of photoresist arrays.

In the paper the two systems developed at the Institute of Atmospheric Optics (Tomsk) are considered. The systems are intended for monitoring of wavefront parameters and phase control. These two systems supplement one another: one of them operates in the IR-range (8 - 12 micrometers ), the second one operates in the visible wavelength range. The second system is a multi-function original computer system for a contact less control of optical surfaces and a detailed analysis of laser beam parameters. It is intended for: (1) the investigation of shapes and quality of optical surfaces by the interferential method of control; (2) the reconstruction of the wavefront of laser radiation based on an interferogram; (3) modeling of interferograms with preset parameters; (4) the analysis of spatial characteristics of continuous and pulse laser beams.

Experience shows that very often a lot of similar elements have to be tested by the optician. Only a small number of input parameters are changed in a well defined manner. So it is useful to develop simplified software for special applications. The software is used in a compact phase shifting interferometer. Up to five interferometers can be controlled by a single PC-AT computer. Modular programming simplifies the software modification for new applications.

The uncertainty of optical transfer function (OTF) measurements of lens systems -- as one example of high-precision optical measurement technique -- can be greatly reduced by computer-aided measurement control and analysis. Improvements resulting in a high repeatability are described and the problems of some analysis concepts are discussed. With such a high repeatability (10^-3) and resolution possible, the influences of temperature and the resulting thermal expansion dynamics of the mechanical set-up and the measuring system itself become factors limiting the reproducibility. Realizations of temperature controlled or thermally insensitive designs are presented.

The analysis of point spread functions is important for the quality evaluation of imaging systems. Point spread functions are evaluated here through their moments. But two problems impede the use of this method successfully: the definition of the integration area and the assignment of adequate values to the limits of the area. The current presentation describes a method to overcome these problems: through clipping the background noise is suppressed, and the use of reduced coordinates introduces adequate scaling and normalization for the calculation of the moments. Associated density functions are defined to perform the symmetry analysis of the central disc and the ring structure of the point spread function separately. Their geometric parameters are determined from the moments and are used as symmetry descriptors. Experimental results of the evaluation of microscope objectives are presented.

Modern large telescopes are complex systems whose optical performances not only depend on their own optical properties but also on external factors such as atmospheric turbulence and local air conditions. Because angular resolution is mainly limited by these external factors, a simple geometrical approach is inadequate and efficiency criteria based on overall throughput and signal-to-noise ratio are preferable. The idea is to establish functional performance criteria which cover all aspects linked to the telescope efficiency. The result is that the user is provided with a realistic estimation of the final performance, while the manufacturer is given maximum freedom to re-arrange his own error budget according to his particular experience. Additionally, it reduces the risk of overspecification, with evident consequences for costs and leadtime.

The performance of an x-ray image intensifier (XRII) tube is usually expressed in numbers attributed to performance parameters, like conversion factor, image distortion, and entrance field size. As the values may depend strongly on the definitions used, standardization of the measurement methods is important. Within IEC SC62B, Working Group 16 actively pursues this standardization.

Techniques are described for measuring the MTF of imaging systems which use detector arrays. The methods can be applied equally well to visible, near-IR, and thermal wavelengths.

ISO-DIS 11254 specifies a test method for determining the laser radiation induced damage threshold of optical surfaces. It has been the intention to provide a method for obtaining consistent measurement results which may be rapidly and accurately compared between different testing laboratories. Measurements according to ISO-DIS 11254 were performed with a Nd:YAG-laser with 15 ns pulse duration. Five-hundred-forty-four test sites are included in the determination of the damage probability in dependence of the power density. An extrapolation of the damage probability to zero results in the damage threshold. Critical parts of the experimental set-up like beam diagnostics, beam attenuation, and damage detection are considered in detail. Some shortcomings of the specified testing procedure are discussed on the basis of selected examples.

The functional and perceived quality of an optical component depend on both the global and localized nature of its surfaces. While small departures in specification of surface form, roughness, and waviness occur as global errors, extending over the whole surface and being difficult to see, digs and scratches accumulated during manufacture and subsequent handling are highly localized. It is this characteristic that results in such flaws, which are usually extremely small in width and depth, being readily visible and therefore rated as an indicator of poor quality. Due to expansion in the use of electronic imaging and laser systems and heightened international competition, more effort has been devoted in the last few years to drafting new standards and the development of improved methods of measurement of all surface-related parameters. This paper concentrates on recent progress in the characterization, measurement, and standardization of localized surface defects. Particular attention is paid to both deterministic methods, needed for diagnostics and research, and the parametric approach more appropriate to control of quality in component production. The need for international collaboration in setting acceptance thresholds for localized surface quality, relating to different applications, is stressed to ensure the full benefit of increased yields is attained.

Measurement equipment is presented for the quick measurement of modulation transfer function (MTF), image field curvature (FC), and chromatic aberration (CA) of optical systems. The measurement device is based on a cooled CCD-matrix element as image analyzer and on a set of pinholes as objects. It is intended to be used in final quality control of optical systems and is thus incorporated into a system of computer aided quality assurance (CAQ) which has been developed in the last few years. After a description of the hardware modules and the interface constellation to the computer hardware (for the various control and regulation systems), the structure of the associated software and the function within the CAQ-System is described. An example of the test procedure for a fixed focal length optical system is given.

The application of the PST-function to radiometric thermometers demands some specifications: a finite object distance and the extension of disturbing sources. Therefore, the typical appearance of the PST can be changed. An example demonstrates this effect. A new model calculates the irradiance in the sensor plane by means of the PST-function. This method permits the user to determine limit-values for the PST to guarantee the required thermal resolution.

Advantages to using coded information in general are presented. For illustration purposes LEICA's digital levels are described in detail. Experimental data of the instrument's performance are given.

A basic relation in the diffraction theory of the image of a point source is that the distribution of complex amplitude in the PSF is given by the Fourier transform of the distribution of complex amplitude over a reference (or pupil) sphere at the exit pupil. For this relationship to be valid it is essential to express the complex amplitude over the reference sphere as a function of the rectangular coordinates of points on the exit pupil sphere, and not those of points in the exit pupil plane. I describe in what follows the advantages of using, also in geometrical optics, the reference spheres in the object and image spaces respectively as the surfaces of the entrance and exit pupils, rather than the pupil planes.

Recent progress in global optimization has raised new interest in the application of global methods to lens design. This paper has several goals. We describe the attributes of a new global algorithm, Global Synthesis (OS), and we distinguish it from previously reported methods on the basis of efficiency and the ability to handle many (i.e., >50) variables and comparable numbers of active, nonlinear, equality and inequality constraints. Many experienced designers doubt, often with good reason, that mu1ple minima exist for practical problems, so we present meaningful examples showing additional minima often do exist. These test cases, some with known optimal solutions, can be used to study and benchmark the performance of different methods, and we describe recent results with OS on these test problems. We discuss what is meant by "success" in global optimization, and point out the practical limits of current methods. Finally, we discuss what impact global optimization may have on optical design as it becomes a mainstream tool of designers.

The result of a lens optimization is critically dependent on the choice of the initial design, and this paper discusses ways in which starting points for optimization can be generated. Examples will be given showing how, in some cases, an optimization program can obtain results that are very different from the initial design. In other cases, the choice of the initial design severely restricts the potentiality for optimization, and this is also discussed.

The current two major non-numerica1 design methods equivalent layers and polynomial synthesis, are reviewed and compared. The equivalent layer method works well when only a small number of fixed refractive indices is available. This is the case when the coating is manufactured by evaporation. Polynomial synthesis generates a priori better designs but does not allow predetermination of refractive indices. So, for evaporation, the designs have to be translated from many refractive indices to a few. This process generally downgrades the design. This translation is not necessary when sputtering or chemical vapor deposition is being used. Here, in-between refractive indices can easily be generated by mixing or flip-flopping. As a consequence, superior designs can be implemented.

An outline is given of how advantages of conventional magnetic recording have been combined with those of compact disc technology to establish a method of high density magneto-optical recording, where information can be erased and freshly recorded at potentially very high superficial density and data rates. Application of the principles of thin film optics to the design of multilayer recording media with optimised magneto-optical "read" characteristics are emphasised, and possible future developments discussed.