Coherence Multiplexing' makes use of the so-called `fringes of superposition' which are produced by time correlations of wave groups of light featuring a short coherence length. We show how such interference phenomena in broadband light can be used to imprint several signals simultaneously on light without crosstalk. This method can be advantageously used in a number of applications. We report new system architectures for distributed microsensors and integrated optics.

Modern Micro Electro Mechanical Systems (MEMS) place ever increasing dependence on miniaturization of components and rely on computational and experimental methods to reach their objectives. This miniaturization requires a detailed knowledge of micromechanical behavior of materials used in development of the components and emphasizes design validation of finished products. This information is provided by electronic holography and grating interferometry used as full field, noninvasive experimental techniques. The usefulness of these methods is shown on several examples including determination of local material properties, stress, relaxation of microelements and dynamic characteristic study of MEMS.

The addition of modern electronics, computers, and software to an interference microscope greatly increases the surface height measurement capability of the interference microscope. The RMS repeatability of surface microstructure measured using a computerized phase-shifting interference microscope can be less than 0.1 nanometer. While phase- shifting interferometry having sub-nanometer height precision has limited dynamic range, the dynamic range of an interference microscope can be extended to hundreds, or even thousands, of microns by using vertical scanning coherence peak sensing techniques. This paper describes the measurement capabilities of an interference microscope employing both phase-shifting phase measurement capability and coherence peak sensing. Typical measurements obtained using phase-shifting and coherence peak sensing are illustrated. Techniques for extending the measurement capability of computerized interference microscopes are discussed.

Phase shifting interferometry and white light interferometry are accurate techniques for surface analysis. These methods require an accurate scanning of the optical path difference for evaluating the phase at each surface point. Alternative techniques, avoiding the z surface scanning were recently proposed. They are based on a spectroscopic analysis of white light interferograms and were called Double Spectral Modulation (DSM). The interferometric set-up is associated to a diffraction grating and an image compression is performed. Thus absolute and unambiguous phase values are obtained along the spectral axis. This procedure allows nanometric resolution using two (or four) interferograms. In this paper we present a better approach to DSM which reduces by a factor of two the number of interferograms which must be analyzed. After data processing, a 3D image of the surface is reconstructed and any longitudinal or lateral scanning is avoided. This paper presents the principle and the data processing of the proposed method and experimental results as well.

Quality control in the production of rigid disk drives depends in part on accurate metrology of the read-write head. We review the established technologies for measuring the distance or flying height between the head and the rotating disk, and propose a new instrument based on polarization interferometry. The new instrument has excellent repeatability, high sensitivity at low flying height and in situ determination of the phase change on reflection.

The most established way to inspect machined surfaces is measuring with profilometers. Roughness measurements by these methods take plenty of time and an on-line integration in production facilities is not feasible due to different reasons. Over two decades ago, Goodman and Parry discovered the correlation between laser speckles of different light wavelengths and surface roughness. Since then several authors have been working on this topic. Nevertheless, industrial sensors based on the speckle correlation phenomenon measuring a roughness value are not available yet. In this article a new method is described, which is suitable for measuring the roughness of surfaces online under production conditions. The surface which is to be inspected is illuminated by a dichromatic laser beam. The scattered light is converted by lenses, and the far field speckles are detected in the Fourier plane of the lenses by a separate CCD-array for each wavelength. The CCD-data are captured by a frame grabber and stored for evaluation. A digital computer processes the data by calculating 2D-cross correlation functions of the two related speckle patterns for the different light wavelengths. The maximum values of the cross correlation function represents the correlation coefficient, which can then be translated into the root mean square of the surface heights of the workpiece. The main benefit of the method described is the feasibility of measuring roughness during processing. This is achieved by a time synchronous detection of speckle patterns of two different wavelengths, which are used to determine the roughness of a surface. The basic measuring time is determined by the shutter speed of the cameras, which is in the pilot project 1/10000 s. Therefore, only vibration frequencies above 1 kHz disturb the measuring results. A further reduction of the measuring time will be no major problem. Thus any realtime roughness measuring problem can be solved this way. This article describes the state of the art and the state of the experimental investigations measuring roughness by means of this new measuring process.

This paper describes a heterodyne common path differential phase interferometer which is resistant to the thermally and microphonically induced measurement errors of non-common path systems. The system utilizes a single probe beam which is focused onto the sample and then imaged onto the detector plane. Differentiation in any direction can be performed by altering the positions of the detectors. A theoretical derivation of the system transfer function is presented, the results from which show excellent agreement with experimental measurements. Initial theoretical results of the recovery of a sample profile from its differential profile are presented. Finally, a simplified and more stable differential system is introduced.

For some years we are studying the problem of the non invasive topographic characterization of rough surfaces of interest in the industrial world. We based our system on a simple and robust discreet triangulation procedure. The topographic information is obtained from the horizontal shift incurred by the bright spot created, by an oblique collimated light beam, on a surface when it is displaced vertically. A laser beam is focused onto a small, diffraction limited, spot on the surface and is made to scan it over the desired region. The sample is placed on XY high accuracy step motion table to perform the scanning of the sample areas of interest. At each sampled point the bright spot formed on the surface is perpendicularly imaged onto a photo-sensitive detection system and its position obtained. The horizontal spot's position shift regarding some reference is calculated. This shift is proportional to the vertical distance (height) between the surface and a reference plane. Obtained the surface's heights matrice the tridimensional reproduction of surface's can be performed and statistical characterization parameters calculated. Between the electronic spot's detection systems that can be used, in this communication we will present details about the characteristics and performance of the use of CCD's linescan (Fairchild 143A) cameras in comparison with the use of the so called PSD's (SiTek 1L10).

A novel application of the incorporation of an amplitude- locked loop (ALL) into a coherent optical sensing system is presented. The ALL is the mathematical dual of the phase- locked loop and is a unique circuit which operates on amplitude rather than phase. Current work on the ALL has concentrated on developing a simple free space Doppler velocimetry system whereby an object's velocity may be identified by analyzing the frequency content of coherent light reflected from the object. It is the purpose of this paper to highlight the potential advantages of using an ALL in the detection circuitry of a coherent optical sensing system in order to improve the detection sensitivity of such a system.

A new displacement monitoring system based on low coherence interferometry using standard telecommunication fibers is presented. The measuring system is especially designed for the needs and conditions encountered in the field of civil engineering. The system features a precision of 10 micrometers to 100 micrometers (depending on the sensor type) over a measuring length up to 100 m, an operational range of 70 mm, stability over long periods (at least two years) and insensitivity to aging of the fiber and connector losses. The results of laboratory and field tests show that fiber optic extensometers are promising tools for the long term monitoring and survey of civil engineering structures. The theory and the optical set-up are briefly described as well as different sensor types that have been developed for various applications (bridges, tunnels, retaining walls, piles, anchorage cables) and tested in the field and in the laboratory. To validate the technique and calibrate the sensors laboratory testing has been done for short sensors (0.5 - 2 m) at IMM and for long sensors (2 - 10 m) at LMS. The results of these tests are presented and discussed in detail. IMM made several tests with fibers embedded in concrete beams and slabs measuring deformations due to shrinkage, creeping, and imposing traction, pressure and bending to the structure. Field tests on a rehabilitated bridge are also presented. Using a 10 m long calibration bench, LMS tested several fiber set-ups using different fixation techniques and imposed displacements on groups of extensometers with different lengths.

Mechanical or structural changes on surfaces and in near- surface layers become detectable by photothermal measurement techniques, when they correlate with alterations of thermal properties. We apply this approach on the detection of variations in ceramic surfaces (silicon nitride, WIDIANIT or alumina) wherein a mechanical impact load or a thermal surface treatment have been induced. Vickers indentations model the mechanical load during grinding and a thermal surface treatment was performed by pulsed laser illumination. Afterwards, the treated areas are either scanned stepwise resulting in a lateral resolution comparable to microscopic images (thermal microscopy) or examined at different modulation frequencies. The photothermal images show remarkable changes near the marked areas depending on the different loading strengths. Proceeding from the photothermal signals' amplitude and phase the depths and profiles of thermal conductivity variations can be reconstructed. Certainly, mechanical changes on surfaces and in near-surface layers, cracks and plastic deformations as well as alterations of the microcrystalline structures are responsible for these effects. Finally, we intend improving the surface finishing by the applied laser and thermal treatments.

This paper describes some initial results of an evaluation technique, applied to composite plates, which effectively measures the ultrasonic transfer function of these plates and interprets these transfer functions in terms of damage thresholds within the material samples. The samples are probed using Lamb waves at frequencies in the region of 250 kHz. The detectors are interferometric optical fiber systems embedded within or mounted on the surface of the sample. The system is sufficiently sensitive to detect damage and/or structural deterioration before its magnitude is sufficient to compromise structural integrity.

Manufacturing and other industrial processes often require monitoring and control of temperature. Thermometry based on fluorescence properties of surface-bonded phosphors offers a number of advantages over traditional methods. The method is non-contact, remote, and independent of surface optical properties such as emissivity. Only a thin layer, less than 50 microns thick, is required of fluorescent materials that are temperature-active and chemically stable up to temperatures in excess of 1600 C. Phosphor thermometry has been developed from these high temperature extremes all the way down to cryogenic temperatures within liquid helium dewars. The fluorescence effects are stable in time, not subject to drift and need for repeated recalibration. Measurement techniques often involve use of optical fibers and other components that allow access into confined geometries and environments with high vibration, electromagnetic fields, or other extreme conditions. Uses include thermal management of cutting or shaping tools, monitoring of furnace and combustor walls or internal components, assembly components in automated lines, sheet metal surface thermometry, measurement of rotating components in motors, generators, turbine engines, and similar systems, fiber temperature measurement in textile fiber spinning, etc. Fluorescence measurement yields absolute temperatures, not dependent on references, and can have accuracies of less than 1 K, with precisions well below 0.1 K, providing opportunity for ultra high precision process control, life testing, and quality control.

This work deals with the use of ultra-thin thermoelectric couples as a mean for illumination control and investigation in the field of laser optics. After the description of the different sensors and their main characteristics, their different uses for measurement and imaging of laser beams or laser sheets profiles are presented, the spatial and temporal qualities of such sensors allowing the localized detection of light power densities. A more specific and versatile sensor is then proposed to be used in the field of laser Doppler velocimetry where special needs have appeared. Besides, the positioning and energy analysis of the measurement volume, this probe allows the precise determination of the fringes spacing under real conditions, this parameter governing the precision of the velocity measurement. Finally, such thermoelectric sensors appear to be an interesting alternative to the previous techniques of positioning and analysis of coherent light distributions because of a low cost, and a simple carrying out.

We present an AC original polarimetric method to study `Faraday rotation' of ferrofluids. The studied magnetic liquids are colloidal suspensions of Fe₂CoO₄ ferrite particles dispersed in various solvents. This method is based on an experimental device involving a Faraday modulator positioned between a polarizer and an analyzer with an angular uncrossing of a few degrees. From the detected light intensity we extract the various frequency components V_o, V_f and V_2f where f is the field frequency (h(t) equals H_o.cos2(pi) ft). We consider the origin of the Faraday effect, with AC magnetic fields, in magnetic fluids, as the result of the orientation of the particles towards the field, producing a macroscopic magnetization which can be described by Langevin theory. The theoretical harmonic components V_o, V_f and V_2f are calculated. We show that they depend on the physical characteristics of the magnetic liquids (concentration (phi) , saturation magnetization M_d, mean diameter d of the magnetic particles). They also depend on the amplitude H_o and the frequency f of the AC magnetic field h(t). We also relate the theoretical expression of V_f with the time constant of the Brownian relaxation in the ferrofluids. We compare the theoretical and experimental variations of V_o, V_f and V_2f with H_o and f for various ferrofluids. Finally we mention some applications concerning particles mean diameter and susceptibility measurement and magnetization curves determination.

This paper describes a systematic study of influences that have to be overcome for the application of interferometry in the high temperature range. A specially designed test facility including an optical arrangement is used for the investigation of CMC specimens. Verification tests are performed up to 1500 degree(s)C with combined thermal-mechanical load sets. The fringe quality achieved allows to evaluate a field of displacement and strain data. Experimental experience gained is convincing to reach even higher temperatures and to test CMC components as well.

In single crystal silicon microstructures produced by anisotropic etching, sharp notches are present. In order to investigate the material behavior and to define design parameters, measurements of the strain field in a micrometer-sized region at the notch tip are performed. The microstructure is loaded by bending and the strain is estimated by analyzing images obtained with a scanning ion microscope. The observed region has been previously marked with an array of square boxes spaced 500 nm center to center. The boxes are drawn by focused ion beam implantation. The image analysis is realized with a new algorithm with high superresolution capabilities which provides an estimation for a strain component and its standard deviation. The so-called `near field solution' for the infinitesimal strain field at the notch tip can be calculated analytically. The excellent agreement of the experimental values with the analytical as well as numerical calculations confirms the validity of the continuum mechanics approach for the mechanical characterization of micrometer-sized structures.

A new method is presented that allows continuous deformation measurements to be performed. It is based on the use of the deformation-induced phase change produced at each pixel to compute an instantaneous phase with a dedicated phase- shifting algorithm. Examples in holographic, speckle and decorrelated speckle interferometry illustrate the interest of the method which provides both relative displacement phase maps and absolute temporal phase evolution curves.

In the presented paper we show that--using appropriate image post processing--measurements with an accuracy and resolution far beyond the theoretical resolution limit of an optical sensor can be made. We demonstrate this based on the observation of tensile tests which are performed on micrometers - sized samples under a low numerical aperture microscope. Although the microscope resolves only about 4 micrometers , deformations of 20 nm can be observed. The measurement accuracy is in the same range. The algorithm achieving these results is an image matching technique combined with a diagnostic tool that automatically detects measurement errors and refines the parameter estimates applying a rigorous statistical testing framework. The paper focuses on the mathematical and physical aspects of this image processing algorithm. The use of image data from tensile experiments is motivated by the fact that we can find a ground truth--namely the linearity in the stress-strain relation in the elastic domain--even on the nanometer scale. Thus, we can test the algorithm on its performance. However, the matching technique has also the capability to estimate rigid body motion with the same accuracy and resolution. In addition, the algorithm is formulated independently of the microscope type. Therefore it is a straight forward task to transfer the procedure to other microscope types, i.e. Scanning Electron Microscopes.

An implementation of an optical distance measuring system by commercially available electro-optical products was tested experimentally. The system utilizes the spatial dependence of the intensity distribution in an astigmatic focus of a lens system on the distance from the latter. The system can either be used for fast distance measurements with a resolution of 1 in 500 or alternatively for position control with sub-micron resolution. The spatial intensity distribution was determined utilizing a four-quadrant silicon detector. The amplified signal was digitized and read into a PC for evaluation. A holographic lens was used as astigmatic element. A holographic lens has the advantage of easy control of the astigmatisms and the possibility of rescaling to suit the designed measuring range. Furthermore, a holographic lens can be used in an off axis arrangement with simultaneous suppression of comatic aberrations. The best recording geometry for the holographic lens was found by computer simulation. The four quadrants of the detector are arranged such that two detector elements are illustrated by either of the two astigmatic line foci. The detector was moved through the focal region. The intensity is shifted from one quadrant pair in the first focal plane to all detectors in the lane of least confusion and finally to the other quadrant pair in the second focal plane. The difference of the photo currents of the quadrant pairs is a measure for the distance from the holographic lens.

Holographic interferometry makes it possible to measure high precision displacement data in the range of the wavelength of the used laser light. However, the determination of 3D- displacement vectors of objects with complex surfaces requires the measurement of 3D-object coordinates not only to consider local sensitivities but to distinguish between in-plane deformation, i.e. strains, and out-of-plane components, i.e. shears, too. To this purpose both the surface displacement and coordinates have to be combined and it is advantageous to make the data available for CAE- systems. The object surface has to be approximated analytically from the measured point cloud to generate a surface mesh. The displacement vectors can be assigned to the nodes of this surface mesh for visualization of the deformation of the object under test. They also can be compared to the results of FEM-calculations or can be used as boundary conditions for further numerical investigations. Here the 3D-object coordinates are measured in a separate topometric set-up using a modified fringe projection technique to acquire absolute phase values and a sophisticated geometrical model to map these phase data onto coordinates precisely. The determination of 3D-displacement vectors requires the measurement of several interference phase distributions for at least three independent sensitivity directions depending on the observation and illumination directions as well as the 3D-position of each measuring point. These geometric quantities have to be transformed into a reference coordinate system of the interferometric set-up in order to calculate the geometric matrix. The necessary transformation can be realized by means of a detection of object features in both data sets and a subsequent determination of the external camera orientation. This paper presents a consistent solution for the measurement and combination of shape and displacement data including their transformation into simulation systems. The described procedure will be demonstrated on an automotive component. Thus more accurate and effective measurement techniques make it possible to bring experimental and numerical displacement analysis closer.

Material testing, quality control, and dimensioning of structures is related to deformation analysis of the considered objects. An important task is the 3D deformation measurement of an object surface. Optical field methods are suitable for solving this task. Due to the full field information, the results can be compared with finite element analysis. In this paper, an approach is described for measuring the 3D-displacement field of an object surface. It is an optical field method based on photogrammetry in combination with the object grating method. An important feature is that the measured objects can be small (in the range of a few mm²). In this paper, the main aspects (arrangement, calibration, measurement, displacement evaluation, strain calculation) are discussed and special problems measuring small areas are mentioned.

The problems connected with experimental and numerical controlling of laser beam welds are described. The methodology and instrumentation for determination of laser weldment properties based on automated grating interferometry are presented. The experimental procedure which includes the measurement of displacement/strain fields induced by residual stress released by cutting and the determination of local material properties in a weld under tensile load are shown. The experimental results have shown Poisson's ratio variations in a weld cross-section and the strain distributions at the surface of specimen after stress releasing in the weld and distant regions.

The grid method is a classical tool for displacement measurement, which provides field data. This method has benefited very much from the phase-shifting technique in recent years. Two examples of applications of this method in the nanometer range are presented. The first one concerns the materials science: it is shown that microgrids observed by SEM can provide displacement field data with an accuracy of a few nanometers. The second one concerns the measurement of a rigid-body displacement. In this case, displacement data can be averaged over the whole field, drastically increasing the sensitivity. It is shown that a sensitivity of 7 nm can be achieved by using a coarse grid with 8 lines per mm. This sensitivity corresponds to 1/18000 of the grid pitch.

The system of remote control for the fiber optic grating interferometer is presented. The principle of operation is based on the opto-electronic method of introducing the carrier frequency into interferograms. A full automation of the measurement process has been achieved by using the system of the smart recognition of carrier frequency with a feedback into the laser diode driver. Due to the reduction of the interferometer elements, the possibility to measure in-plane displacement maps in locations with difficult access is introduced.

We present newly developed, compact, self-contained fringe projection interferometer for use with phase step algorithms. The interferometer uses a polarization beam splitter and a computer controlled variable retarder to manage the phase shift. The well compensated path difference permits use of relatively low-coherence sources. The in-line setup contains no mechanical parts and provides a compact, rigid design and nearly perfect common path geometry. The phase shift is realized in a few milliseconds, which enables fast data collection. The interferometer can be used as a sinusoidal fringe projector for topography measurements, or as a shearing interferometer for testing optical elements. Other applications that use phase step technique and require similarly short data acquisition times, versatility and stability are also possible. Examples of surface topography measurements are presented.

The topographic measurement of high reflectivity test surfaces in a Fizeau interferometer using different two-beam phase-stepping algorithms (TBPSA's) is presented. Low pass- filtering the superposition of a multiple-beam Fizeau pattern and a Ronchi grid renders a pattern of sinusoidal profile (the moire image) that contains the Fizeau phase and that can be phase modulated by the in-plane translation of the grid. A set of these phase-shifted moire images can be combined in different TBPSA's in order to calculate the Fizeau phase making clear, at the same time, the sensitivity of the method to use the main phase error sources.

In common industrial environment, large deformation measurements of opaque bodies by means of holographic interferometry are often related to the problem of decreasing fringe spacing and contrast, causing the loss of the interference fringe pattern, which contains the whole information on the corresponding deformation. Therefore, the only way to determine the surface strain, rotation and displacement components of a structure element under load relatively to the unloaded state is first to recover the interference fringes--at least locally--and then to use the correct adequate relations to process the recovered fringe pattern properly. This paper explicitly the quantitatively presents the general equation system for a systematic fringe recovery procedure in the general case of a large unknown object deformation. The relations for the quantitative evaluation of the recovered fringes, i.e. the optical path difference and the exact fringe vector of the modified interference pattern, are also explicitly presented. All needed relations are first introduced in form of general vector and tensor equations. Then, equations for fringe recovery are written in cartesian components and used within a quantitative experiment to demonstrate the reliability of the theory. Some important points still should be considered in order to enable fringe recovery for general geometrical cases: (1) the holographic setup should allow a geometrical and/or an optical modification to adequately compensate the unknown mechanical deformation and the optical image aberrations; (2) the holographic method should be one of the type belonging either the real-time technique or the double exposure technique on two holograms (because not all holographic methods are suitable for this purpose); (3) the holographic images of the deformed and undeformed body must sufficiently overlap so that the fringe spacing must be large enough and the fringe visibility must have sufficient quality to be analyzed properly. The relations considered are general and may also be used in other application fields (with their related problems) of holographic interferometry, when the loss of fringe spacing and contrast should be compensated.

The holographic soundfield imaging technique combines the ultrasonic testing with the holographic interferometry. It makes possible the subsurface testing of components. The testing procedure results in an image that can be easily interpreted with regard to detected flaws. Ultrasonic surface waves are induced into the specimen and visualized by a real-time-image processing algorithm that subtracts the actual hologram from a hologram formerly stored without ultrasound. To get an image of the ultrasonic wave the intensity modulation of the illuminating laser beam is triggered by the ultrasound source. Former investigations of the holographic soundfield imaging produced satisfactory results concerning the lateral resolution for bonding flaws and cracks. Bonding flaws down to a diameter of 30% of the ultrasonic wavelength lying in depths down to 60% of the incoming ultrasound wavelength can be recognized. Recent development yields advantages with real-time holography mainly because of a shorter testing time. Furthermore, by this technique the processing of a single hologram allows the generation of several images with different ultrasonic frequencies and varying propagation directions. The sound wave is disturbed by the interaction between the ultrasonic wave and a flaw. Thus, with real-time holography the evaluation of components is possible during the propagation of the ultrasonic wave. Nowadays the real-time holography allows to perform two different irradiation directions with one hologram by using ultrasonic frequencies from 300 kHz up to 2 MHz. An ultrasonic amplitude of about 10 nm is required to attain a good contrast value for the visualized soundfield pattern.

Conventional holographic interferometric and speckle pattern interferometric techniques are tailored basically to compare the two states of the very same object, which may have optically rough surface or optically distorting transparent walls around. The direct comparison of the behavior of two different--but macroscopically quite similar--objects does not fit naturally in the process. At present, this type of extension can go three different ways. In holographic interferometry, one can mix the interferograms of the two objects at some sublevel of interferogram making and the moire effect of the individual fringe systems can be produced. In speckle pattern interferometry, the reference surface can be replaced by the other object itself and it serves as a live reference: changing according to the test object. Finally, although really first if time of birth is regarded, holographically recorded and reconstructed images of a master object can be used for illumination of test objects--in an otherwise conventional holographic or speckle interferometric arrangement. The present paper deals with this latter technique. Some new developments are reported in difference holographic interferometry and partly as a consequence of this--a really successful realization is introduced in holographically illuminated difference ESPI.

TV holography can be used to measure the small variations in refractive index found in acoustic fields in transparent substances. Projections of the amplitude and phase are imaged with an imaging interferometer, and several projections may be combined, using tomographic techniques, to form a volume mapping of the acoustic field. Both projections and reconstructions of acoustic fields in water are presented and discussed. Finally, some of the limitations of this technique are considered.

A stress in thin film SiO₂ was detected using high stability portable holographic interferometer. A stress relaxation phenomenon in this film thickness of 0.5 micrometers on Si wafer has been observed. This phenomenon does not exist in film with thickness of 1 micrometers . The advantages of the proposed measured technique and results are discussed.

Quick, reliable and inexpensive testing of products and components is needed in industry more often than not. Holography due to its intrinsic limitations and reasonably high costs yet is a method which is used comparatively rarely for industrial optical inspections. In the Laboratory of Technical Optics, Laser Technologies and Optoelectronics we produce holograms and interferograms on silver halide media in extremely unpromising conditions intentionally introduced to fit industrial ones. The main features of our processes are: (1) high speed of the whole process of data acquisition, storage and final presentation; (2) possibility to perform all these operations in strong daylight corresponding to industrial illumination levels or even exceeding recommended levels of illumination of industrial working places; (3) possibility to avoid any dark rooms; (4) high diffraction efficiency of holograms measured at the wavelength of recording, i.e. any wavelength shifts of holographic reconstruction are avoided for any types of holograms including reflection ones usually suffering from such shifts; (5) low costs due to low labor and equipment costs; and (6) easiness of performing quick checks in industrial environment. In our experiments we investigated various optical setups for recording holograms, double exposure and real time interferograms, in situ among them, and different types of holographic optical elements. We used different types of lasers: helium-neon (633 nm), argon (488 nm), semiconductor (675 and 685 nm), ruby (693 nm). Various silver halide media were used: Agfa Gevaert 8 E 75 HD films and plates, Russian PFG-03 and PFG-03 C (color).

Both electronic speckle pattern interferometry (ESPI) and holography are rather powerful tools for nondestructive testing of materials and products. ESPI and holographic interferometry allow to measure deformations and vibrations in the micrometer and submicrometer ranges. In spite of definite similarities they differ chiefly in the methods of acquiring and presenting optical data. Each method has its special advantages and drawbacks. The latter are severely limiting their applications especially in industry. It would be ideal to combine the advantages of ESPI and holography and to reduce influence of their drawbacks. As for ESPI, this method is very suited for large scale industrial optical inspections because the interferograms are acquired with a CCD camera and evaluated in quasi real time with a computer thus no media costs for the measurements arise. However current speckle pattern interferometers have rather complicated and expensive optical setups whose elements are aligned with difficulty. Moreover commercial ESPI devices lack flexibility in their optical setups. The negative influences of these drawbacks are drastically reduced in our method which is based on a very simple principle. We offer to use an unusual ESPI reference wave which is stored in a holographic optical element (HOE) as holographic object wave. In other words, a new method of ESPI is introduced which is a two stage process. At the first stage a HOE is recorded in a usual holographic arrangement. This HOE being illuminated later reconstructs an object wave which serves as ESPI reference wave. Well suited HOE's are produced on photothermoplastic or silver halide media. The latter are easily produced in an industrial environment. Experimental results and ready compact and inexpensive device are presented.

Recent progress in noise-immune phase unwrapping techniques for heterodyne interferometry and profilometry is reviewed. Following the statement of the phase unwrapping problem, some of the prevalent techniques based on different strategies are introduced, and their characteristics are compared.

The new approach to the shape measurement system by implementations of adaptive and feed-back elements for an automated fringe projection system is proposed. Specifically the fringe pattern evaluation module based on the assessment of fringe pattern parameters performed by Fourier analysis and new version of spatial-carrier phase shifting method based on sampling in two directions are presented. The functioning of the system in the calibration and operational modes is shown on a representative example.

An active two-beam interferometer has been developed which locks fringes in the presence of external perturbations such as vibration and air flow and enables measurement on an unstabilized table. Movement of carriered fringes caused by the perturbations are detected by a spatial filtering detector whose output signal is fed back to injection current of a laser diode to compensate for path variations by the resulting wavelength shift. The video image of the fringes is supplied to a real time fringe analyzer which delivers the phase distribution at the video rate. The analyzer is based on electronic moire principle for simultaneous generation of three phase shifted fringe patterns. The results from a spherical mirror of 130 mm- diameter have shown good coincidence in spherical errors with that obtained from measurement on an optical bench. Only its repeatability proved to be worse by 1.7 times.

For comparison to model predictions, measurement of the true response of weak polymeric materials requires that a non- contacting method be used. In particular, for compression tests on weak polymers it is necessary to obtain the full 3D displacement field for the specimen. In this work, the full 3D displacement field was measured using a combination of white light speckle correlation and projected fringes. To obtain the out-of-plane displacement field, a fringe pattern with frequency of 0.30 lpmm was projected onto the specimen surface using a standard slide projector. A phase-stepping algorithm was used to convert the optical fringe pattern in a contour map for the surface. Due to reflections and noise in the fringe pattern, the authors developed a robust phase unwrapping methodology based on fuzzy logic principles. Baseline tests have shown that the algorithm produces accurate contour maps even when noise and poor fringe contrast are present. For the measurements of the in-plane displacement field the polymer foam materials was illuminated with a white light source and the natural character of the reflected light was used to obtain speckle images of the polymer. The images were acquired at various load levels and stored in digital form. The digital images were correlated to obtain the speckle deformation field. To increase the range of measurement and to deal with high strain, additional processing of the images using fuzzy logic algorithms was completed.

This paper describes a new high speed 2D fringe analysis technique in the time domain using an electric circuit based on frequency demodulation. A 1D fringe analysis system based on this new technique has already been built, and its performance and characteristics were reported. With that system, a 1D fringe pattern could be processed every 10 msec. The accuracy was better than 1/20 fringe. In this paper, the principle of 1D fringe analysis is expanded to two dimensions. New electric circuits with which to process horizontal (x-) and vertical (z-) directional simultaneously were built. The paper proposes principles for the design of such circuits, which combine two outputs--one for the x- direction and the other for the z-direction. A new 2D fringe analysis system was then built using both analogue and digital processing circuits. Each fringe pattern was treated as an analogue signal synchronized with the CCD clock-pulse in the system. Using this new fringe analysis method, high- speed 2D image-processing can be realized. The system can process fourteen images a second. The characteristics of a laboratory prototype of this fringe analysis system were tested.

In this paper the application of classical tools for the characterization of building materials is criticized and the applicability of optical techniques in this field is investigated. Optical diagnostic techniques are particularly attractive for a non destructive evaluation of a surface's state and the detection of incipient damage. Non contact, high precision measurements and full-field of observation are features that can bring enormous advantages in experimental tests. Electronic Speckle Pattern Interferometry has ben preferred because it allows a real- time inspection of surfaces and is less sensitive to ambient conditions. The observation of fracture propagation, the full-field evaluation of deformations, the early detection of defects can help for a better understanding of the materials. Some experimental results obtained by optical tests are here discussed.

This paper describes the use of a non-destructive optical technique, digital speckle pattern interferometry, for the deformation analysis of a machine tool. An interferometric set-up has been designed and measurements of the milling head deformation have been made on the horizontal single spindle milling machine center.

For many years, speckle interferometry has proven its usefulness for measuring deformation and contours of objects with rough surfaces. Nevertheless, the influence of a parameter as important as the lens aperture of the imaging system on the result of the measurement is still not precisely known. Generally, it is stated that the speckles have to be resolved by the camera and that therefore the lens aperture number should be large enough (e.g. f/11 or f/16 for typical applications with a standard CCD). This contribution shows, theoretically as well as experimentally, that it is not necessary to resolve the speckles when making measurements in speckle interferometry. The joint probability distribution of the pixel modulation and the pixel background intensity, which determines the percentage of valid pixels, is investigated for different lens aperture numbers, i.e. for different numbers of speckles per pixel. The comparison between theory and the experimental counterpart allows a number of speckles per pixel to be determined for any given aperture number and pixel size. It appears that the average pixel modulation remains high enough even with a relatively large number of speckles per pixel. The results lead to the conclusion that--especially when the total camera noise is low enough--lens apertures up to f/2 may be used. Thus, measurements are less constrained by limited laser power and decorrelation effects.

Nowadays in mechanical material testing strains are measured only between two distinctive points on the specimen with probes or by optical analysis of two marked positions on the surface of the specimen. Information about eventual inhomogeneous strain distribution between these two points can not be obtained by these methods. A new laseroptic strain sensor overcomes these restrictions by using the principle of laser speckle interferometry for measurement. In the 1D measuring case the specimen is symmetrically illuminated by two bundles of laser light and the image recorded with a high resolution CCD-camera. Computer evaluation of the images shows deformations and strains on the surface of the specimen with high sensitivity. An extended design uses two of these optical set-ups to provide two inplane measuring directions. Special interest was laid onto the optical set-up which guarantees uniform measuring sensitivities in the whole measuring field and as well very limited adjustment requirements. The laseroptic strain sensor requires no marking on the specimen and gives full field measuring information without contact on nearly any surface. In this paper the operation principle of the laseroptic strain sensor is described. Typical application examples in material testing are given.

Optical techniques because there are no-contact and non intrusive methods are well suited for non destructive testing and for damage evaluation. Image correlation is well suited in mesoscopic approach between successive steps of deformation and can be achieved if the object under study is carrying a characteristic pattern. As a characteristic pattern the white light image of the object surface or the subjective speckle generated by coherent illumination of an optically rough object can be used. The image is then grabbed by a high resolution CCD camera. Instead of using a defined mesh on the object, image correlation allows dynamic link of a point to a pixels pattern called the correlation window. While applying stress or strain, points of the object surface are moving. Between each step of deformation the correlation window and the mesh are then updated. While using a tensile test apparatus the rigid body motion is compensated by moving the CCD camera on a parallel axis to keep the region of interest into the field of view. All the operations are computer-controlled under data acquisition and processing software. The results are presented as in- plane displacement vectors and allow the determination of some mechanical values by external computing. The method is applied to damage analysis from in-situ measurements in concrete manufacture.

Ambiguities can arise in measurements with interferometric profilers using monochromatic light in the presence of surface discontinuities larger than a quarter wavelength. In this case, surface profilometry can be performed by means of white light interferometry since the coherent function of the light source allows the identification of the fringe order. However, acquisition procedures and data treatments are more complicated than in the case of monochromatic phase-shifting interferometry. In this paper, the coherence function of the light source is considered as locally linear and new phase shifting algorithms can be derived, which are well adapted to white-light phase-shifting interferometry. First experimental results are presented.

When two beams of an interferometer are directed to the same object at different incident angles, the recombined, reflected beams generate an interference pattern with a large equivalent wavelength. This paper reviews the basic principles of these `desensitized' interferometers, and describes a novel diffractive geometry that is particularly well adapted to manufacturing applications, thanks to its large working distance, achromatism and high accuracy.

In high resolution optical reflection microscopy, one of the problems of using large numerical aperture objectives is that the depth of field is very narrow, for example only 0.4 micrometers for a X100 objective (NA equals 0.95). When working on microelectronic structures that may be many microns deep, this is a several imitation for analyzing possible defects or measuring linewidths etc. because many of the features are out of focus. In the case of analyzing deep rough surfaces, the image can become confused due to stray light from out of focus details. Coherence probe microscopy is a new method for automatic measurement of deep surface relief using white light interferometry. The nanometric depth discrimination due to the temporal coherence of the illumination beam makes it possible to profile deep structures while maintaining sub-micron lateral resolution. In this paper we demonstrate a new mode in which the maximum intensity of the fringe packet is noted at each pixel to give a full depth of field reflection image. The aspect of the image is similar to that produced by SEM (though not with as high a lateral resolution) but without the necessity for sample preparation or vacuum conditions. We show results on different materials and structures with a depth of field of up to 48 micrometers and a lateral resolution of less than 0.2 micrometers .

We present and describe two techniques used for optical detection of ultrasonic signals based on the photorefractive effect. These techniques used the wavefront adaptation properties of the photorefractive effect. In the photorefractive beam combiner, a local oscillator matched to the signal wavefront is created, leading to an homodyne detection system having a large etendue. In the double phase conjugate heterodyne detection system the signal beam wavefront is cleaned by a double phase conjugate mirror and transformed in a plane wave that is sent on a classical heterodyne detection system. Both systems are characterized and used to detect ultrasound.

In two-arms interferometers, spurious beams are often cause of instabilities. Resulting multiple-beam interference limit the probe sensitivity. Optical components are usually added to spatially shift or to suppress these `spurious beams' returning inside the interferometer. Experimentally, we have shown that the so-called `spurious beams' returning towards the laser can be successfully used to obtain stable interference. So, we have developed new structures of interferometers based on the reflection of a returning beam on the high-quality front mirror of He-Ne laser. The new structures present several advantages compared with classical interferometers (Michelson or Mach-Zehnder, e.g.). They are more simple and, at least, the same sensitivity has been measured. Alignment is simplified and power balancing is very easy.

C-scan images are presented of artificial defects in carbon fiber composite materials derived from a laser ultrasound imaging system. Detection of ultrasound has been achieved from natural material surfaces, by an actively stabilized Fabry-Perot interferometer in conjunction with an argon-ion laser source. Recent measurements have been made in what is known as the thermoelastic regime, so that the sample did not suffer surface damage from any plasma spark. However, signals were averaged in order to produce good quality images. These were further processed using a separable median filter to give images which compared favorably with X-ray radiography measurements. Using 0.25 mm pixel separation in the scanning process, images with size resolution better than 0.5 mm were achieved.

The photothermal deflection technique is applied to measure the surface deformation induced by laser absorption at the surface. The theory of the probe beam reflection due to the surface displacement is reviewed. The first experimental results show that this technique is able to measure displacements of a few Angstroms.

High sensitivity, grating interferometry system (AGI) with automatic fringe pattern analyzer is shown as the effective experimental tool for material macro and micro structure studies (the smallest grains which behavior may be monitored in this system reach 20 micrometers ). The applications of AGI system for non-homogeneous plastic strain studies of bicrystal and polycrystalline aluminum and steel materials are presented and discussed.

We present first results with a reflection mode SNOM, which uses a tetrahedral tip as an apertureless near-field probe. The SNOM was driven together with an STM to control the tip- surface distance in order to avoid mechanical damage of the tip.

One of the challenges for newly born probe microscopies is the estimation of their capabilities. The latter is closely related to the reachable resolution. We present a method adapted to these microscopies for determining resolution. It is applied to Reflection Scanning Near-field Optical Microscopy combined with shear-force (ShF) feedback but the method is quite general. The resolution is deduced from the comparison of the optical data spectrum to the shear force data one. Indeed, it is well known that spatial resolution of shear force is better than that of optical microscope and the optical resolution can thus be estimated through this comparison. Actually, the considered set-up uses ShF feedback. Quantitative results are given either with periodic or non periodic objects.

A new tip-distance control based on near-field acoustics is presented. The interaction between a vibrating tip and the sample enables high accuracy estimation of the distance variation (typically better than 1 nm with a fiber tip). The paper describes the physical interaction between vibrating tip and the object, the principle of regulation loop and shows experimental results obtained in the case of an optical fiber tip used in near-field optical microscopy. The proposed technique can be used to image the topography of the sample or to characterize coupling gas or fluid.

We propose a method of scanning near field optical lithography where the result of the process is controlled in quasi real time. Irradiation of the polymer involves a topographic modification of the layer. It is detected mechanically by the fiber tip, which plays the role of a nanosource and of shear force probe. A single snapshot gives an image of the intensity distribution around the tip. A resolution better than 100 nm is obtained even with dielectric tips.

The density of integration of magneto-optical devices is limited by diffraction of light. Recently some groups have proposed to use Near-Field Microscopy to overcome this limitation and some experiments have been performed both in transmission and reflection. In this paper we study theoretically magneto-optical effect in near-field. We consider a magneto-optical sample with details smaller than the wavelength. This sample is modelled as a multilayer rough structure. At least one layer has magneto-optical properties. The corrugation at the interfaces are very small compared to the optical wavelength. We do not consider the writing problem and the experiment is only modelled in the reading mode. Moreover, the magnetic properties are considered in the saturation regime. For this study we use an extension of the method that we used to describe near- field microscope with isotropic sample. The diffracted fields are determined in each layer by using a perturbative version of the Rayleigh method which leads to the resolution of a linear equation for each diffracted wave. The near- field above the sample is thus obtained by summing all the diffracted waves. We consider two geometries for the magnetization: polar effect where the magnetization is perpendicular to the sample and transversal effect where it is in the plane. We compare near-field images obtained in transmission and reflection by changing magnetization orientation. Comparisons with far-field results are also proposed.

Theoretically, it is well known that the classical optical microscope resolution, is limited to about 250 nm. Actually, the scanning near-field optical microscopy allow to get over this limit. Using a vibrating opaque metallic tip, which periodically and locally perturbs the electromagnetic field distribution of a focused laser spot in to the sample surface, we have observed with better resolution than the theoretical limit many topographic and optical test object.

It has been shown recently that a configuration combining near field detection and Fabry-Perot resonator offers a solution for increasing the signal to noise ratio. In this communication we use this conference as an interferometric imaging device. The basic idea behind this concept is that one way for enhancing the low sensitivity of such microscopes could consist of increasing the field intensity between tip and sample by either using a multi-reflection system such as a classical Fabry-Perot cavity or by using some more sophisticated multi-reflection devices.

We studied the fully-formed (80 angstroms) Pt/GaP and (140 angstroms) Au/GaAs interfaces by scanning near-field optics microscopy, internal photoemission, atomic force microscopy, and by x-ray photoemission electron microscopy. These complementary techniques enabled us to correlate the spatial variations of the diodes transport properties with the chemical and topographic inhomogeneities of the buried metal-semiconductor interfaces.

Fines are defined as the part of mechanical pulp which has lost its fiber like state. It is considered as an important fraction of the raw material, because it improves paper web properties, e.g. tensile strength and opacity. Our machine vision based measuring system is one of the first approaches to measure the fines fraction properties directly. Since a sample is imaged in flow, it is possible to collect a large quantity of images easily. The sample is then characterized by the statistics of its particle geometry.

A photogrammetric setup for measuring the working radius of drilling tools is proposed. A rotating device first holds a glass plate with a high precision cross grating. This serves for calculating the camera orientation, for deriving the spatial parameters of the rotation axis and for controlling the position of the CCD-cameras, if moved to the measuring position. Finally the drilling tool is inserted, its cutting plate is taken by the cameras and by a new algorithm the cutting radius and the inclination of the plate are determined from the edges in the images.

The paper is aimed at the description of an optical shape measuring technique based on a consistent principle using fringe projection technique. We demonstrate a real 3D- coordinate measuring system where the sale of coordinates is given only by the illumination-structures. This method has the advantages that the aberration of the observing system and the depth-dependent imaging scale have no influence on the measuring accuracy and, moreover, the measurements are independent of the position of the camera with respect to the object under test. Furthermore, it is shown that the influence of specular effects of the surface on the measuring result can be eliminated. Moreover, we developed a very simple algorithm to calibrate the measuring system. The measuring examples show that a measuring accuracy of 10^-4 (i.e. 10 micrometers ) within an object volume of 100 X 100 X 70 mm³ is achievable. Furthermore, it is demonstrated that the set of coordinate values can be processed in CNC- and CAD-systems.

The ability to measure the relief parameters and the absolute position accuracy of micrometer-sized structures is of obvious importance, not only to determine if the desired structure has been realized, but also to optimize the fabrication process. In this paper a simple characterization method is presented allowing fast and non-destructive testing of phase and amplitude gratings over large areas. Local line width and position errors can be detected. The theoretical modeling is based on rigorous diffraction theory.

Common path interferometric microellipsometry based on the Young's interference principle is presented. Interference of the pure p and s reflections at the back focal plane of a microscopic objective takes place by means of Young's interferometry. Therefore, the amplitude ratio, tan (psi) , and the phase different, (Delta) , of the two polarization components are represented as the contrast and the phase shift of the Young's fringe pattern. Hence, the complex refractive index of the sample can be calculated using well- known equations. This technique is particularly applicable in pure topography where the measured optical phase is actually a contribution of both the surface height change and material change as well.

Interferometric methods of sinusoidal, single-frequency phase modulation and two-frequency phase modulation have been investigated and compared as applied to displacement measurements and wavefront testing. A procedure of an experimental estimation of the periodic error which is a basic component of a systematic error of interferometric systems is developed. It is shown that the conventional single-frequency phase modulation method is preferable when it is desirable to have extreme resolution or maximum accuracy, while the method of two-frequency phase modulation will be more rational when small dimensions and weight of the device are of basic concern.

Food industry had begun to use lasers for improvement of effectiveness of production. We can clearly see three main directions: in the food technology, in the food engineering, and in the agriculture. The results of the work is given.

For more than a double photothermal measurement techniques offer the suitability for a non-destructive and contactless evaluation of coating thicknesses and for the investigation of boundaries between a surface layer and its base material. In the following sections, we want to describe in detail the use of the photothermal radiometric technique (which is the most promising photothermal method for an in-line manufacturing control) on different interfaces embedded in an optically opaque workpiece. Additionally, we will demonstrate the effect of adhesion defects on the photothermal signals, or, vice versa, how the obstructed propagation of thermal waves can be explained by thermal contact resistances when delaminations or disbondings are located between a coating and its substrate. For this purpose, we mainly analyze very accurately the frequency dependence of the photothermal phase signal. Theoretical calculations and some experimental verifications on painted and on galvanically plated metal substrates will be presented. In summary, the photothermal measurement techniques allow to characterize subsurface adhesion defects possibly leading to a failure of a used component. Therefore we suggest that the photothermal instruments are usable for production control.

We report quantitative evidence of the slight anisotropic behavior of several Ta₂O₅ dielectric thin films. Refractive indices and thickness have been determined by using the prism-film coupler setup. In order to obtain dispersion values for the refractive indices, the measurements have been realized at four different wavelengths, 632.8, 514.5, 488.0 and 457.9 nm. We have checked the results by measuring the layers with two different prisms. A new numerical approach to the problem has been useful to determine the parameters of the layers.

A fringe projection method (contouring) is applied for the mechanical characterization of thin films by bulging tests. This method is then coupled with the technique of phase modulation (phase shifting interferometry) thus allowing the phase image of the membrane, hence the displacements at all points, to be determined. We discuss the precision and the sensitivity of the method. This technique is then applied to membrane bulging tests performed on single silicon crystals, on thin Si-SiO₂ films and on electro-deposited nickel. For these materials, the Young's moduli and the internal stresses resulting from the fabrication process are determined and compared with the values obtained by other methods. The examples presented allow the principle of the bulging test and the apparatus to be validated.

To our best knowledge, longitudinal magneto-optic effects in ferrofluids are generally measured under a steady magnetic field. We present an original polarimetric method to measure the circular birefringence (CB) and the circular dichroism (CD) of magnetic liquid materials placed in low sinusoidal magnetic field H_M cos(Omega) t. A lot of results obtained with ferrofluids synthesized by the coprecipitation method. CoFe₂O₄, MnFe₂O₄ and (gamma) -Fe₂O₃, in dibutyl phthalate, diethylene glycol, glycerol or water are given. Measurements of CB and CD versus magnetic field, wavelength (500 nm to 1600 nm), frequency (1 Hz to 50 kHz) and temperature (253 K to 373 K) are reported. A clue for the interpretation of the magnetically induced circular anisotropy is given, which reinforced the hypothesis of the field induced aggregation of single particles into strings.

For the purpose of investigation and optimizing of micro- mechanical and harmonic vibrating devices a measuring setup was developed. The goal was to determine vibrational mode structures as well as the magnitude of the amplitudes in dependence on the surface position at the observed object. Frequencies up to 100 kHz cause typical low amplitudes in the order of microns. To prevent any influence of the measurement on the vibration an interferometric system with a rough, speckled object wave seemed to be appropriate. A number of phase-shifted and -modulated speckle- interferograms are detected with a CCD-camera, digitized and transferred to a computer. A suitable algorithm compensates phase fluctuations partially occurring between the image snaps and calculates the amplitudes. To assess the errors investigations of the setup and algorithm used were carried out. It was found that a part from speckle noise mainly the low dynamics and noise of the CCD-camera limit the accuracy to about 0.5 percent of peak-amplitude. The setup was used to analyze the electronic ultrasonic bonding. The measured amplitude distributions of the bond-tool showed a high sensitivity in the clamp-in-conditions and were the base for a statement of an optimized clamp-in-length and a new developed tool.

Self-pumped phase-conjugate mirrors (SPPCM) on the base of photorefractive crystals are able to produce the phase- conjugate replica of an incoming wave. That is within certain limits independent of the incoming wave front. One conclusion of that is the possibility of aberration compensation in interferometers. Hence the application of SPPCM offers new possibilities for interferometric tests, especially in fields where classical methods reach their limits. We have built up an phase-shifting interferometer for testing cylindrical and aspherical surfaces incorporating a SPPCM. The optics for generating the wave front adapted to the surface under test is placed in the entrance arm of the interferometer. For testing aspherical surfaces we used a computer-generated hologram. The SPPCM is located in the reference arm. We will discuss the advantages and disadvantages of this new approach and present the results of testing such surfaces.

Reflection polarization properties of a given target, evolve according to its state's surface and to the illumination angle. We have studied the evolution of the polarization given by an iron target the surface of which is progressively debased, the initial surface is polished up to one micron. The polarization is described with the Stokes- Mueller's formalism, from which the matrix exploitation gives us the degree of polarization. We take the measurement of each sample for different angles of incidence. In order to optimize the matrix elements, we reduce the noise by a statistical method. First, the results are presented in a global matrix form, then we present an analysis of the depolarization phenomenon, and we apply some techniques of classification. We also analyze the statistical effect of the polarization transformation on the Poincare sphere.

In our report we compare different ways of realizing an optical novelty filter with photorefractive barium titanate crystals. We present experiments on the basis of beam fanning, two-wave mixing and self-pumped phase conjugate geometries. The application of photorefractive novelty filters not only for phase visualization but also for the measurement of transient phase changes in a laser beam is demonstrated. The phase calculation from an interferogram is supplied or replaced by the novelty filter's phase transfer function. The use of such techniques instead of conventional interferometry for transient phase evaluation results in a simplified measuring procedure.

For the application of self-pumped phase-conjugate mirrors in interferometric arrangements, the properties of such devices have to be characterized. In this paper, we define figures of merit on the basis of experimental investigations and show, how the field of possible interferometric applications is limited in the case of a non-ideal phase conjugation process under stationary and transient conditions.

Novel optical sensors for the detection of weak radiation flux transients and mechanical micro-vibrations have been developed. The sensors are based on the modulation of an interference pattern created during the optical interrogation of a thin air cavity similar to a low finesse Fabry-Perot or Fizeau interferometer, formed between two parallel glass holographic plates. In the detection of radiation flux the sensor demonstrates high sensitivity, good stability and a fast response. When adapted to the measurement of mechanical micro-vibrations, high sensitivity at low frequencies can be achieved. In order to understand and optimize sensor performance, the mechanical, thermal and optical characteristics of the devices have been modelled theoretically and with finite element analysis. A principal feature of the devices is their low cost and potential for miniaturization thus making them suitable for a wide range of industrial applications.

A new contactless method is presented to measure the variations in the outer diameter of an optical fiber. The fiber is illuminated by a cw He-Ne laser beam that is perpendicular to its axis. The technique is based on an analysis of the light scattered by the fiber in a direction nearly perpendicular to the incident beam. This part of the pattern is very sensitive to a variation in the fiber outer diameter. A method to monitor the outer diameter during the drawing of the fiber has been deduced from the computation of the scattering pattern.

Second harmonic generation can be used to probe the microstructure of materials. This non-destructive all- optical method is applied to quantify the orientation of the micro-columns constituting aluminium nitride thin films. Very small tilt angles of the columns are easily detectable. This technique is applicable to the control of material structure during deposition.

The present work demonstrates the use of a general purpose interferometer to measure the deformations of a scattering surface by processing speckle patterns instead of smooth wavefronts. The operation of the interferometer are re- programmed to include algorithms adapted to handling speckle patterns. Details of the measuring operation are described, limits of applicability are discussed, and experimental results are presented.

The experimental model of laser interference refractometer and thicknessmeter (IRT) for simultaneous measurement of absolute refractive index and thickness of the plane parallel samples has been developed, manufactured and investigated. This IRT allows to test solid, liquid and gaseous media, including optical crystals, plastics and other sheet materials, over a wide spectral range. IRT accuracy of refractive index measurement is not worse than from the best modern goniometers and accuracy of thickness measurement corresponds to the interference accuracy.

This paper presents a method of displacement measurement that is based on Young's experiment. In the method, the displacement is determined according to the fringe spacing equation from Young's experiment. The method is examined in a fiber-optic interferometer system and a subpixel resolution of measurement is achieved from 100 X 152 pixel image patches using fringe pattern matching together with the polynomial curve fitting method. The effect of the number of discrete grey levels of an image on the accuracy of displacement measurement is also discussed. The computer simulation and experiment have shown that it is possible to measure displacement in a machine vision system in some cases using this method.

A non perturbative Rayleigh method is used to calculate the electromagnetic field in the vicinity of an interface between metal and air. The metallic surface is enlightened by a thin coated nano-source localized a few nanometers above the interface. We study the influence of the size of the tip apparatus and of the distance between the tip end and the sample on the confinements of the spot in the metallic sample. The knowledge of the electromagnetic field in metal could enable to calculate temperature and dilatation of the surface of the metal.

The paper describes the devices for measuring the normal- reflection birefringence with using of the photometric, balanced, compensation and interferometric methods. The suggested scheme may be used for research of optical anisotropy in optical recording disks, inner stress in transparent solid body, birefringence of crystals and for the measuring of temperature, pressure, electrical and magnetic field strength.

The devices transforming one frequency coherent radiation into two frequency ones for laser AC interferometers with polarization dived channels are examined. The relative analysis of their characteristics is given. The demands for them are determined. The ways of development and the results of elaboration and utilization of new electrooptic two frequency oscillators are represented.

The opportunities of spatial-resolvable atmosphere monitoring and atmospheric pollutions' remote chemical analysis based on the CW-laser radiants are investigated. A frequency-responsive processing peculiarities of atmosphere remote sensing signals are described. Application of the mentioned approach for the limited hydrocarbons remote detection and sensing is discussed. The requirements to the CW-LIDAR receiving and radiating systems parameters are formulated. The evaluations of the system sensitivity limit, measurement accuracy and accuracy increase ways are presented.

The photon scanning tunneling microscope (PSTM) yields topographical images of samples which are thin or which are transparent at the wavelength used. A wide range of samples sizes may be imaged extending to well below the diffraction limit, but samples on the order of several to many micrometers in size can be analyzed if total internal reflection occur in the sample. We have used the PSTM to examine the topography of mouse and human cells and of mouse chromosomes that are unstained. Our objectives were to compare the images as an improved resolution alternative to phase contrast microscopy, and to provide a sample preparation methodology that will permit localized simultaneous fluorescence or absorption spectroscopy with the signal collected by the probe tip of the PSTM. Further, the PSTM's ability to produce topographical profiles was tested in order to establish the basis for future investigation of possible structural abnormalities in the chromosomes. That is, we had both physical and biological objectives to consider. To this end we utilized the 442 nm line of a HeCd laser, the resulting image quality being tested partly on order to ascertain the increase effects of Rayleigh scattering relative to results at longer wavelengths. It is shown that adequate resolution and signal-to-noise ration can be obtained with the shorter wavelength even in the presence of intensity fluctuations from the laser, thus showing that fluorescence and absorption can be expected to be practicable.

We present a real-time holographic interferometer using sillenite crystals for measurement of deformations of large diffusive objects. Two kinds of optical heads have been investigated: a first system with a frontal crystal followed by a CCD camera with a short focal length objective, and a second system with imaging objective in front of the crystal, collecting light and imaging the object in its vicinity, the final image being observed with a second relay imagery. Both systems are compared with respect to their temporal behavior and quality of interferograms. This interferometer is connected with quantitative phase- measurement systems. First, phase-shifting (PS) can be performed by translating a mirror in the reference beam, enabling acquisition of several interferograms subsequently processed leading to the object phase deformation. Nevertheless this requires stability of the object during the shifting process. Second, Fourier transform (FT) processing can be used on a single interferogram. This interferometer has been successively used in different applications: detection of defects in weakly disturbed structures using PS and monitoring of thermal deformation of an object with FT.

The purpose of this work is to determine whether yes or no, there is a difference between the physico-chemical properties of the nanocrystalline and the microcrystalline materials. This paper deals with the acoustical behavior of nanocrystalline materials which were prepared by ball- milling and mechanical alloying. Based on two specific techniques (acoustic microinterferometry and acoustic microechography), some of the mechanical properties (elastic ones) may be determined, related to a materials volume of about a few micrometers ³ (for the high frequency 600 MHz apparatus). Thus the mechanically alloyed powders (typically 200 micrometers in diameter), behave as massive materials in this range of frequency. The measurements are directly obtained on the grains and do not take into account the voids induced by further sinthering process. The result of such a micromechanical approach will be given for pure ball-milled elements (Fe) and for the supersaturated solid phase Fe(Si) obtained by mechanical alloying.