Although interferometry's earliest and most familiar use is with photons, the discovery of matter-wave (deBroglie-wave) interference for electrons demanded the development of quantum mechanics. Since then, matter-wave interferometry has been performed with neutrons, Cooper electron-pairs, and most recently, with whole atoms and diatomic molecules. This talk describes our recent high-flux atom interferometry experiments using the generalized Talbot-vonLau effect. Our interferometer consists of a sequence of three planar vacuum-slit diffraction gratings, microfabricated from silicon nitride membranes. DeBroglie-wave interference fringes are sensed by measuring the transmission of potassium atoms on a hot- wire as a function of grating relative position. Different spatial Fourier components (up to sixth) in the diffraction pattern are resonant in the interferometer at different atomic velocities (i.e., at different wavelengths). When a laser cooled slow atomic beam is incident, various different diffraction patterns are observed as a function of atomic velocity. In an alternative `Heisenberg Microscope' configuration an incident thermal beam produces a velocity average over different fringe Fourier components. AC modulated weak laser light passing through the interferometer interacts selectively with atoms at a specific velocity. The associated fringe pattern is then ac modulated and revealed by its selective destruction.

The paper reviews our recent studies on spatio-temporal heterodyne interferometry. The technique employs both spatial and temporal carrier frequencies to make highly efficient use of the limited spatio-temporal frequency bandwidth available for the fringe detection system. A new concept of a virtual wavefront is introduced, and the generation and detection of the virtual wavefront by a space-time degenerate scan-synchronized wavelength-shift interferometer are proposed and demonstrated by experiments.

A fringe analyzer has been developed which delivers phase distribution from an interference pattern having carrier fringes at the video rate. It is based on the generation of three phase- shifted moire fringe patterns through electronic multiplication with computer generated reference patterns having mutual phase shifts and subsequent phase calculation. After the principle and specifications of the analyzer are presented, applications to feedback control of a liquid crystal spatial phase modulator, measurements of large mirrors using synthetic aperture interferometry, and active phase shifting speckle interferometry are reported.

Neural networks are being increasingly used in the visual pattern recognition field. They have already been applied with some success to such problems as the classification of fingerprints, the recognition of facial expressions and the identification of hand-written characters. This would suggest the possibility of applying a neural network system to the conceptually similar field of interferometric fringe analysis. Although the algorithmic techniques of phase stepping and Fourier fringe analysis have been successfully applied to many fringe analysis problems, there exist some areas, notably with complicated and noisy images, where a different approach may be required. Here, the backpropagation paradigm is applied to two simple fringe analysis problems. Firstly, to find the radius of a one dimensional curved surface from its simulated intensity distribution. Secondly, to identify four lens shaped objects of different radii of curvature from fringe patterns obtained under different conditions. Both cases were met with reasonable success, but the overall implications of the results were that, when applied to fringe analysis, neural networks would function more successfully at identification, rather than precise measurement.

Photorefractive crystals are gaining importance as a recording medium due to the possibility of real-time operations. A BaTiO₃ crystal can be used as a recording medium in two configurations, i.e., when the phase shift of (Phi) between the dynamic grating and the interference pattern is (Phi) = +/- (pi) /2. The optical characteristics are different for the two configurations. We discuss the optical characteristics of BaTiO₃ crystal under the two configurations, and use the BaTiO₃ for speckle photography and image plane holography.

The interference method of two-frequency phase modulation has been investigated both theoretically and experimentally as applied to displacement measurement and wavefront testing. Analysis of errors caused by shot noise, piezoceramic modulator hysteresis, modulating oscillations phase shift and their amplitudes deviations has been carried out. It is shown that phase measurement error of 2(pi) /180 can be obtained at real conditions.

An analytical model of cascaded electron multiplication in the detectors with avalanche multiplication of charge is proposed. Functional equations for evaluation of output single electron impulse characteristics are obtained. Some results, concerning channel gain, pulse- height and time distribution of a single electron signal are introduced.

We present consistent theoretical studies of the optically heterodyned polarization interferometry (OHPI) of polarization-inhomogeneous media (initially isotropic materials) with collinear arbitrary polarized (partially or totally depolarized) interacting beams (pump-probe scheme) within the framework of the 3rd-order nonlinear susceptibility (3NS). Our analysis is based on a 4 X 4 Mueller matrix formalism. Some generalizations have been done over known approaches: the inclusion of an elliptically polarized pump beam, and the treatment of the observed OHPI signal taking into account the second order effects in the pump beam intensity and the realistic linear depletion of the interacting waves. In the light of new results obtained, we consider several practical cases.

The calculation and simulation of holographic fringe patterns by known object deformations can be used advantageously to solve numerous problems, for example the following: the investigation of the predictability of material defects by means of disturbances within the fringe pattern, or the optimization of holographic fringe patterns with respect to automatic evaluation. In this report the applications of simulated fringe patterns in 3D measurements are discussed, the new features of the enhanced program are described and some interesting simulation results are presented.

In this paper we show that interferometric systems with phase-conjugate mirrors (PCMs) the quantitative determination of the quality of optical elements (lenses, mirrors) and the measurement of optical wavefronts is possible with the same accuracy as with classical interferometric systems. With a view to a quantitative analysis we especially discuss the problem of applying an appropriate phase-shifting mechanism in an interferometer with a self- pumped phase conjugating mirror (SPPCM). Furthermore, we carried out first measurements of the accuracy of a Twyman-Green interferometer (TGIF) with SPPCM.

In quantitative investigations of heterogeneities in transparent media in such fields as experimental gas dynamics, ballistics, thermal physics, physics of plasma, control of large optical elements, etc. classical interference and holographic techniques are most effective. They make possible the a posteriori analysis of the objects waves reconstructed from holograms by shadow, color and interference methods with the change of initial tuning of the device and with the increase of measurement sensitivity. The recording of the object initial hologram or interferogram, for example on a gas-dynamic stand or during the control of large mirrors, can be hampered by the external vibrations or by difficulties of joining together the objects and the interferometers. This is conditioned, as a rule, by the off-axis location of the reference beam in the interferometer circuit, for example of Zehnder-Mach type, and by the existence of the relatively distant large optical elements. This paper presents a new interferometer, which hasn't the said drawbacks.

Optical techniques present useful tools for superresolution at 3D and surface inspection. Microscopic analysis of phase images has shown a higher diffraction stability of some field fragments, particularly wavefront dislocations. Diffractional stability is intent for contrast- and resolution enhancement and is generalized to the case of polarization imaging. This paper develops the morphological analysis of phase- and polarization images. Several practical algorithms for obtaining superresolution are discussed.

A brief description of specialized software tools for simulation and parametric estimation of optical radiation intensity is presented. Simulation of intensity decays is performed for the set of samples in the different experimental conditions with random and nonrandom distortions. The methods of estimation include least squares method, Laplace transform method, and Proni method. Statistical experiments have been done for investigation of these methods.

An algorithm for unwrapping noisy phase maps has recently been proposed, based on the identification of `discontinuity sources' which mark the start or end of a 2(pi) phase discontinuity. Branch cuts between sources act as barriers to unwrapping, resulting in a unique phase map, independent of the unwrapping route. Five methods to optimize the placing of the cuts are described. The most successful is one based on a global minimization of the total cut length, using a graph theory `maximum flow' algorithm. Computation time increases approximately as the square of the number of sources. With this approach, unfiltered speckle interferometry phase maps with very high discontinuity source densities (at least 0.1 sources pixel^-1) can be reliably unwrapped. An alternative method based on a one- dimensional unwrapping along the time axis is also described. The main advantages of this second technique are (1) it is inherently simple, (2) phase errors are constrained within the high noise regions, and (3) phase maps containing global discontinuities are unwrapped correctly, provided the positions of the discontinuities remain fixed with time.

This paper demonstrates the advantages of a recently reported improved technique of phase- shifted electronic speckle interferometry. The improvement extends the range and enhances the accuracy of measurements and thus unlocks many new applications. One of these is detecting various types of fatigue damage in carbon-fiber-reinforced plastics (CFRP). The optical measurements of surface matrix cracks and of delaminations agree very well with the results of other non-destructive testing (NDT) methods. We also demonstrate an improved contouring technique and present the theory behind the experimental procedure, leading to the improved results reported here.

An instrument capable of highly accurate, non-contact range measurement has been developed, which is based upon the principle of projected rotating fringes. More usually known as dynamic fringe projection, it is this technique which is exploited in the dynamic automated range transducer (DART). The intensity waveform seen at the target and sensed by the detector, contains all the information required to accurately determine the fringe order. This, in turn, allows the range to be evaluated by the substitution of the fringe order into a simple algebraic expression. Various techniques for the analysis of the received intensity signals from the surface of the target have been investigated. The accuracy to which the range can be determined ultimately depends upon the accuracy to which the fringe order can be evaluated from the received intensity waveform. It is extremely important to be able to closely determine the fractional fringe order value, to achieve any meaningful results. This paper describes a number of techniques which have been used to analyze the intensity waveform, and critically appraises their suitability in terms of accuracy and required speed of operation. This work also examines the development of this instrument for three-dimensional measurements based on single or two beam systems. Using CCD array detectors, a 3-D range map of the object's surface may be produced.

Interferometer fringe pattern analysis is a very precise measuring method. However, this analysis method has not received significant attention in industry as a result of the long calculation time for an operation. The majority of conventional computer analysis methods process an image in the spatial domain using sophisticated algorithms. A new time domain fringe analysis technique is discussed in this paper. Until fringe analysis data can be processed at high speeds using parallel picture processing systems, fringe analysis in the spatial domain is not practical. In order to reduce the calculation time, the fringes imaged on CCD sensor are processed as analog data in the time domain in this paper. The fringes are spatial information on a CCD sensor. The fringes on the CCD sensor are converted to a synchronous electrical signal by the CCD driving clock pulse. The analog signal, which corresponds to the fringes on the CCD sensor, is analyzed using an electrical circuit. The time-instantaneous frequency and phase of the fringes are detected by frequency-demodulating and integrating the signal, respectively. This proposed system can perform high speed fringe analysis operations in 10 msec a line of CCD. The experimental results show that the new fringe analysis is a very high speed processing method and equally as accurate as the FFT method and the fringe scanning method. It is likely that this new fringe analysis method will be a very useful technique for interferometric fringe analysis requirement in industry.

We have developed and numerically evaluated an iterative algorithm for interferogram processing including the Fourier-transform method, the Gerchberg-Papoulis algorithm and Wiener's filter-based regularization used in combination. Using a signal-to-noise ratio not less than 1, it has been possible to reconstruct the phase of an object field with accuracy better than 5%.

The generating algorithm is based on summation of the point-source waves diffracted on the aperture of the imaging system, with the phase as a random variable of uniform statistics and the intensity determined by a `non-speckled' image. Such an approach takes into account the speckle size and form determined by the size and shape of the imaging-system aperture. The computer program based on the algorithm generates the speckle pattern in the image captured or created by a computer. The `non-speckled' image belongs to the input data for the program and it supplies with mean value of the intensity at each pixel of the image. Other input data describe geometrical parameters of the imaging system, including shape and size of its aperture. As an output, the program generates a `speckled' image of the form like that obtained by means of a real imaging system with coherent-light illumination. Images with computer-generated speckle pattern can be used for testing different computer-aided methods of image processing, especially in optical metrology.

Various interferometric and fringe projection techniques may result in complex interferograms with the information about the phenomena tested. Recent applications require the analysis on the base of a single interferogram. Here, we address two problems: simultaneous analysis of the information about two events and analysis of interferogram with high phase gradients in both x and y directions. The analysis of an interferogram is performed by the spatial-carrier phase-shifting method used sequentially for x and y sampling directions. The error analysis of the two procedures proposed is presented.

Spatial phase-measurement interferometry techniques are affected by a number of sources of error. This paper focuses on the major limitations for phase calculations using standard N- point algorithms. These limitations are having the wrong carrier frequency, unequally spaced fringes, detector nonlinearities, and variations in the dc fringe intensity. Computer simulations reveal the character and magnitude of these errors.

Some preliminary results in analysis of statistical properties of computer-generated speckle pattern are presented. The probability density functions of the intensity and size of the speckles are determined. Statistical properties of the intensity have been investigated for two different approaches: at a separate pixel for a set of random-phase distributions on the object surface, and in the whole image (all pixels taken under consideration) for a single random- phase distribution. The influence of the radius of the point-spread-function domain taken for computations on the statistical properties is also analyzed.

Bioscan Optimas package from Bioscan, Incorporated of Edmonds, running under Microsoft Windows was used for acquiring and analysis of endoscopic images. The fiberoscopic endoscope was used for imaging of the tissue of the cat stomach and for imaging of the known reference plane. The illumination system of the gastroscope was substituted by the special ordered fiber bundle, allowing the projection of the Ronchi ruling onto the surface of the investigated objects. The intensity distribution in the image of the reference grating and deformed grating were analyzed in order to determine the shift between the two gratings for corresponding fringes. The deviation from the reference plane was calculated, thus providing a three dimensional (3-D) representation of the two dimensional (2-D) endoscopic images.

The method of spatial carrier synchronous detection of an interferogram, also called direct interferometry, has been developed by several authors. Besides reviewing this method, we present here two spatial carrier interferometric procedures using a spatial circular carrier and also a phase modulated carrier to compensate the aberration of aspherical surfaces.

The absolute contouring of diffuse objects is considered. Variable index holographic contouring is presented in terms of a thought experiment. Absolute moire contouring is discussed in some detail. Experimental work is presented. This work agrees well with the theoretical analysis outlined.

Many engineering applications of interferometry, such as fracture mechanics and stress analysis, require the extraction of the first derivative of some measured function g(x,y) which is in turn represented by a 2 dimensional, digitized fringe pattern I(x,y). The conventional approach is to obtain an intermediate function (phi) (x,y) which represents the modulo 2(pi) interferometric phase change related to some change in optical path. It is first necessary to `unwrap' this phase information to obtain a smooth and continuous function, which may then be numerically differentiated to obtain the desired quantity of g(x,y). This analysis process, while reasonably straightforward, may be computationally expensive and in any case sensitive to noise, bad data, and quantization error. In this paper, we investigate the use of gradient operators for the direct extraction of the derivative of the interferometric phase function. Our goals are to be able to apply local gradient operators directly to the wrapped phase data, thus removing the `unwrapping' part of the process, and to reduce the susceptibility to noise of such operators.

Automatic processing of interferometric fringe patterns using the phase step method only leads to relative values of the deformation vector components. Extending this method to two wavelengths absolute values can be gained as known from classical interferometry. The optical as well as electronical and software expansion of an ESPI is presented allowing the system to determine absolute deformation components by automatic evaluation of fringe patterns by means of the phase step method with two wavelengths.

This paper describes research into a non-contact system for the measurement of components and solder on printed circuit boards (PCBs). The objective of the system is the inspection of the PCB to identify faults in the manufacturing process. Two approaches are described: diffraction pattern analysis and fringe pattern analysis. For the diffraction pattern analysis, a diffraction pattern is formed by the lead array on a component. For fringe pattern analysis, a fringe pattern is generated on the PCB using either interferometric methods or projection of a grating. For both methods, an image of the pattern is captured and stored on a frame store. The pattern is then processed to provide data from which parameters which relate to solder joint integrity can be determined. Results demonstrate the feasibility of the methods.

In this paper we suggest an interferometer that allows us to obtain up to four high-quality interference images with relative phase shifts despite stray vibrations and an algorithm for fringe patterns processing.

Based on our experiences of absolute testing of flats and spherical surfaces we are developing methods for absolute testing of cylindrical surfaces. Three methods are presented and compared with each other. Method I determines the absolute deviations of three cylindrical surfaces from a mathematical cylindrical surface by five measurements. Method II calibrates the interferometer so that afterwards it can be used for absolute testing. Method III determines the absolute deviations of one single cylindrical surface by using two known flats.

The growing interest in microlenses and microlens arrays has created a need for measurement systems to characterize their performance, particularly important being the transmitted wavefront and focal length. A Mach Zehnder interferometer has been built into a microscope body to allow fast, convenient, and accurate measurement of these parameters.

Microlens arrays are now widely distributed and applied in many domains like public uses, optical communications, information processing, astronomy. Each lens of these arrays is geometrically and chromatically aberrant because of its shape defects which can be dependent on its position inside the array and on the chromatic variations of its refraction or dispersion. Quality testing of the surface limiting the lenses which are of small size can be affected by means of interferometric methods associated to microscopy. Two kinds of defects of different scales are then accessible. Surface quality like roughness and systematic manufacturing defects are displayed by means of reflection interference contrast. Shape defects like errors with respect to an ideal spherical surface which produce geometrical aberrations are given by two waves interferometry with a Linnik's microscope. Defects of sphericity are interpreted by errors of fringes distribution compared with that of Newton's rings and dissymmetry around the axis by their shape defects. Analysis of these fringes patterns gives sufficient information on the quality of lenses in terms of geometrical aberrations if it is considered that their refractive index is constant.

A reflecting system with tilt spherical mirrors is proposed, which from the definition is free of any chromatic aberration. The astigmatisms of both tilt mirrors are mutually compensated. Conditions of the construction of such an achromatic beam shaping optical system are presented.

In this paper the new modification of Hindle scheme for interferometric testing of convex hyperbolical surfaces is presented. It has a number of advantages and can be used to obtain undependable quality data of aspherical surface manufactured in another testing scheme. The advantage of the new Hindle scheme modification is the decrease of sizes in comparison with the classical Hindle testing scheme, the absence of additional compensators, the convenience of alignment and calibration, and the possibility of IR interferometers application during testing surface grinding. The suggested principle can be used during convex paraboloids testing.

The survey of questions concerning the influence of various factors on the measurement error is presented. In particular the following problems are brought up: telecentricity of the optical system on the detector side, propagation of the aberrated wave in free space, influence of aberrations of individual elements, local absorption center, and beam truncation by the aperture stop. On the basis of Fizeau interferometer the optimization of the aberration correction, compensation of the aberration influence, and influence of the configuration of the interferometer are considered.

Absolute interferometric flatness testing of the three-flat type has made remarkable progress within the last few years. These developments show improved lateral as well as depth resolution and easier handling.

This article is devoted to the holographic testing canal of an adaptive optical system. The results of mathematical modeling of interferometric testing of large telescope mirrors and that of the whole telescope system by holographical testing are presented. The problem of correspondence of errors of the primary mirror surface shape, determined during holographical testing, to real deformations of the primary mirror is investigated.

The method for interferometer quality testing and calibration is described. The theoretical analysis and measurement results of the Fizeau interferometer errors are presented and discussed.

Interferometric flatness testing of a large surface of 500 mm plus in diameter appears to be a complex problem which can be solved, in particular, by means of the oblique-incidence interferometer. The possibility of use of dumping least square method is considered in this paper. This method criteria are square sum minima both for wave front distortion function deviation and for mirror mounting errors in the three base points. The mathematical model has proved that the method proposed provides the original wave front reconstruction accuracy 2.5 ... 5 times better than by means of the former method depending on points number on a subaperture.

The plane parallel plate (PPP) and wedge plate (WP) interferometers are the simplest configurations for collimation testing. These elements are usually used in reflection due to high fringe visibility. The reflection coated wedge plate acting as a shearing interferometer both in reflection and transmission is recently reported. This multiple beam wedge plate lateral shear interferometer (MBWPLSI) used for collimation testing gives superior performance compared to an uncoated wedge plate interferometer. In this paper, some aspects of the multiple beam interferometer and its use in the double pass configuration are presented. Double pass results in a system of fringes in which adjacent fringes rotate and split in opposite directions for a non-collimated beam resulting in further improvement in the setting sensitivity.

New techniques in white light interferometry and their fringe analysis methods are described. These applications in thickness and 3-D shape measurement and defects detection are reviewed.

The spectral characteristic of a light source e.g. spectral linewidth, light wavelength, stability of frequency and output power are the most important performance parameters for an interferometer. The influence of the above mentioned effects on the performance of a two- beam interferometer was experimentally tested in a heterodyne interferometer which had been developed for this purpose.

A dynamic interferometer for range finding with directional discrimination is proposed. It uses a laser diode which is tuned in frequency by the injection current with a triangular modulation function. Both the reference and the target signal beams from a Michelson interferometer are combined and coherently detected. The beat frequency is proportional to the optical path difference. When a target is moving, the beat frequency is different according to the upward current ramp or to the downward one, respectively. Consequently, two unknown parameters can be measured: absolute distance and velocity of the target. The technique enables the directional discrimination of the velocity and it doesn't need polarizing components or a spectrum analyzer widely used for such applications. A description of the device, experimental results, and main measuring error sources are presented and discussed.

A scanning optical profilometer without sample displacement along the optical axis has been developed. Light coming from a wide spectrum light source is focused onto the inspected surface through a Fresnel lens. Because of its dispersive properties, the foci are distributed along the optical axis as a function of wavelength. The reflected light is focused on a filtering pinhole like in confocal microscopy. The only wavelength exactly focused on the surface is transferred through this pinhole to the detection unit. The detected light is analyzed through a spectroscopic device and the surface height is deduced from the wavelength for which the light intensity is maximum. This punctual measure is repeated for each surface point by a lateral scanning of the surface. With respect to other focus sensing profilers, we replace a mechanical z displacement of the sample by a spectral inspection of the detected light. The setup and some experimental results are presented.

We demonstrate a new type of a white light profilometer which combines a two-beam Fizeau- type interferometer with a grating spectrometer to realize absolute measurements of the surface profile with high accuracy. Two evaluation methods are discussed and the experimental results show that a measurement repeatability of 0.4 nm can be reached.

Interferometric measurements of wavefront phase distributions for laser diodes applied in optical disk memory units were carried out. The influence of laser diode wavefront astigmatism on the focused light spot dimensions was investigated.

Development of different branches of industry first of all, and expansion of construction of different kinds of buildings demand accurate measurements in length and angles-improvement of accuracy and reliability of measurement of profiles of complicated configuration. For making engineering and geodesic works more effective modern tools and instruments are needed. An optical distance-meter of a geometrical type used for taking measurements of length in range from 1 - 10 to 500 - 600 m, is also an instrument of that kind. In optical distance meters of geometrical type the measurement of distance is taken by contactless and indirect methods. The base and parallactic angle (gamma) are the fundamental parameters of distance meters of this type. We consider distance meters with a constant base or with a constant parallactic angle. We have constructed a distance meter-profilometer, in which a distance meter of the geometrical type is successfully combined with the method of projection of interference patterns.

The grating interferometer, used for analysis of the field of the refractive index in the inhomogeneous mediums, is described. The application of a space-frequency Fourier filtration for one of two interference light beams allowed us to transform a compact scheme of a shearing grating interferometer into an interferometer with an undisturbed based beam. Some experimental results are also presented, which illustrate a possibility of application of the interferometer for diagnostic of turbulent streams of stratificated fluid. A series of interferograms of the water flows were received under laboratory conditions. On the basis of measuring the phases of radiation, travelling through the investigated medium, the following statistic characteristics of streams were calculated: a standard deviation of the phases fluctuations, a spatial structural function and a function of mutual correlation of phases of radiation, travelling through different region of a water current.

The three-channel LIR scheme for the liquid absolute refractive index measurement and several of its modifications are described. The main sources of error are analyzed in detail and some methods are suggested for decreasing their influence.

The influence of optical and electronic parameters of digital laser anemometer on the accuracy of velocity measurements was investigated. The sizes and fringe number of the interference field of the anemometer was examined for circular and astigmatic entrance beams to verify the influence of the above parameters on Doppler signal parameters. The spectrum averaging procedure was applied to decrease the uncertainty of Doppler frequency measurements. The relative standard deviation of measurements was achieved < 0.1% for the best configuration of optical and electronic parameters of the anemometer.

In the paper, a description of a method of measuring little periodical movements involving laser interferometer is presented. The principle of this method is to use vibration table during contact verification instruments. The table is activated by periodical signal. All the movements of the table are measured by laser interferometer. Measurements of table movements are obtained thanks to interferogram which shows particular states of the table. Theoretical basis and measurement errors analysis of this method are presented in the paper. The measuring system, which has been worked out, consisting of vibration table, laser interferometer and measuring signal transforming unit is also described. During the studies its field of application has been defined. Comparative studies and practical tests have proved the effectiveness of the system. The research stand makes it possible to measure displacements of the mobile element of a vibration table, which can perform oscillations from 0.1 Hz to 500 Hz frequencies. Harmonic vibrations amplitude range is from 0.15 micrometers to 7.5 micrometers for vibration frequencies lower than 50 Hz. For vibrations of frequencies higher than 50 Hz, the lower limit of measuring amplitudes range is 0.15 micrometers and the upper limit of this range decreases with vibration frequencies increase. Displacements measuring error in harmonic movements depends mainly on laser light wavelength reproducing error and on interference signal measuring errors. While using the worked out method one more error appears. It arises from not performing Abbe's postulate. Value of displacement measuring relative error in this method does not exceed 3% and it decreases with vibration amplitude increase. Value of this error can be decreased by appropriate vibration table amplitude setting.

A construction and results of basic parameters of laser wavelength meter with digital processing of data are presented. The instrument designed for measurements in the 400 - 1100 nm range of spectrum consists of the optical head including quartz or glass Fabry-Perot resonator, a system of filters and lenses and detection and data processing blocks. The last two blocks include linear CCD camera, buffer memory, 8-bit A/D converter, an interface and PC/12 MHz 80286. The meter allows one to measure the wavelengths and spectral line widths of both cw and pulsed laser. The preliminary results of the investigations are presented.

The form of a crater, appearing during interaction of laser pulse with the surface of a metal sample, was obtained by stripe projection method. The factors that determine the topography of the crater were investigated. The model which permits us to describe the forming of the zone of destruction and to explain its relief was suggested. Velocities of the metal drops thrown out of the melted zone, the pressure which threw the drops and the gradient of pressure in the compressed gas at the surface of the target were evaluated. The increasing use of laser processing of materials is responsible for the growing interest in the elaboration of new methods of non-destructive diagnostics and control of the regime and results of technological process. That is why the physical phenomena resulting from the interaction of the radiation with solid excite a great interest. The processes that proceed in plasma cloud near the surface of the target (the `external problem') and in the melted zone (`the internal problem') are investigated rather completely. Less investigated are the processes proceeding directly on the surface of the irradiated sample. Moreover, a real shape of the melted area and of the crater appearing on the surface of the target was not radically investigated in detail. However, many parameters of both external and internal problems are determined exactly by the shape of the area of the interaction of radiation with matter. Our aim was non-contact (and, consequently, nondestructive) determination of the topography of the crater, appearing during the interaction of optical pulse with the surface of metal, investigation of processes proceeding during the forming of the zone of laser destruction and clarification of the factors that determine relief of the crater.

A new application of human back contouring by the projection moire method for the assessment of furniture design ergonomics is presented. The muscle-osseous system is analyzed in three planes and several characteristic points to find 6 basic parameters selected from 48 automatically analyzed ones for the standing and sitting positions. If the furniture dimensions are incorrectly selected with respect to the user height and body proportions the values of selected parameters differ for the two positions. The analysis indicates, with high accuracy, the places of the vertebral column exposed to the risk of postural deformities in the case of incorrectly chosen furniture.

Two basic optical triangulation systems for routine studies of postural deformities among youths and adults are described. They use projection moire with temporal phase stepping and grating projection with carrier frequency spatial phase stepping for the automatic analysis of fringe patterns. The operation parameters of both systems are discussed and compared. The special medical software developed for analyzing the back and front of the human body is presented.

The measurement of displacement of surfaces due to dynamic vibrating is very difficult, because of the high commutator velocity and the small translation. With the aid of the described procedure it is possible to detect surface displacement by non-contact gauging. It works on the principle of the diffraction of light in a slit. The theoretical foundations are explained and suitability for detecting surface displacement is shown by the example of a rotating engine commutator.

A study was made of the dynamics of crater growth when a millisecond light pulse with a complex temporal profile interacted with the surface of a transparent insulator. The effective growth of a crater was found to last no more than 100 microsecond(s) and it consisted of two stages. In the first stage the area of the damage region increased while its depth remained practically constant, whereas in the second stage the crater growth was three-dimensional. The increasing use of laser treatment of materials is responsible for the growing interest in the processes resulting from the interaction of high-power light pulses with the surface of a solid. Such investigations are essential for the selection of the effective technological regimes and for the development of new monitoring and diagnostic methods; moreover, such investigations provide results of purely scientific interest. The phenomena that occur in a plasma cloud formed at the surface of a target and in the bulk of an irradiated sample have been investigated thoroughly. On the other hand, much less information is available on the processes that occur on the surface of a solid, including primary (and, at first sight, trivial) phenomena as the formation of a crater and an inelastically deformed zone. The data are particularly scarce on the interaction of solids with relatively long (at least 1 microsecond(s) ) light pulses which have complex temporal profiles (these are the pulses typically emitted by solid-state laser operating under free-running conditions). The dynamics of such surface processes under the action of a light flux has been practically ignored in the case when the solid is not a metal but a transparent insulator. However, any optical component used in experiments involving high- power laser radiation is in fact a sample of this ki