We can commemorate this year the 25th anniversary of the laser and the 20th anniversary of holographic interferometry.

The process of hologrammetry, whereby accurate holographic images are used for inspection purposes has considerable attraction where hostile environments are concerned. In particular the use of projected images has received attention where metrological data is required. This paper discusses investigations into the direct use of the television camera plate for the automatic analysis of a holographic image of an AGR final rod assembly.

The structure of the reconstructed image from an in-line hologram of a semi-transparent droplet has been studied. Fine, circular fringes occur in the image because of the refraction and reflection of the droplet.

Preliminary investigations of the resolution from holographic real images underline the potential of holography as a tool for underwater visual inspection.

We have developed an holographic interferometry set-up for the study of concrete shrinkage. The deformation of the upper face of a sample, placed in controlled conditions of temperature and humidity, is observed. Essential parameters for the building of a practical numerical model are deduced from these results.

This paper presents the interest of the use of holographic interferometry to verify and ajust tools and machine elements used in ultrasonic machining. First of all, it deals with a brief presentation of the principle of ultrasonic machining. The main shaft of the machine has a disk to be adjusted. The time average holographic interferometry permits to find out the best diameter of this disk. This machine uses tools called "sonotrodes". By this method, it is possible to show how this tool is working under load. Afterwards, this paper describes the holographic bench and the various tests. In the last part, we present the results we obtained during the various tests.

In this paper, we will analyze and compare the different results obtained by Holographic Interferometry and by Ultra-Sonic method in function of external fields applied to the object under test.

Fundamentals of time average hologram interferometry and procedures for quantitative interpretation of holograms of vibrating beams are presented. Unification of the holographic method with the finite element method (FEM) is discussed, with particular emphasi on estimation and control of errors inherent in the numerical methods. These discussions are illustrated by representative examples of holographic and FEM studies of vibrating beams.

Double exposurs holographic technique is used for mapping the surface temperature distributions of an integrated circuit chip. The same results are obtained from the solution of Poisson's equation in two-dimensions to simulate these thermal fields.

Conditions are determined at which rotation compensation is needed when pulsed holography is used to study the vibration of rotating structures. Conclusions are validated using interferograms of a rotating aero engine fan.

By the use of two different optical technics, we investigate the resonant response of a bladed disk (30 blades, 1.2 m diameter) under various industrial conditions of rotation and vibratory excitation. The two complementary technics we used to perform a modal analysis are : the double pulse image derotated holography and the laser vibrometry. By spectral analysis of the vibrometer's signal, we are able to construct an inverse Campbell diagram of the spinning disk. A six minutes movie shows the test facility, the optical systems and some holograms with nodal lines.

A circular, concave, imaging mirror of variable focus is described. The mirror is a very thin plastic membrane with a highly reflective metallised front surface. Mirror curvature is determined by the strength of a vacuum applied to the rear face of the film, increasing the vacuum will increase the curvature. High resolution reflected and focussed images have been observed from targets, using both white light and infra-red. Mirror curvatures from f/10 to f/0.4 have been examined, high resolution images were obtained at all curvatures. Such a wide range covers large f number astronomical telescopes, to the 'fast' small f number concave mirrors used in infra-red imaging. The contents of this paper will describe the application of holographic testing to such devices. The tests were undertaken in order to examine the symmetry of the mirror surface and to study the vibratory response of that surface.

Two-wavelength holographic contouring for fringe intervals between 5 and 20 microns is studied in detail. Particular attention is given to the fringe visibility and to the position of the reference plane. Dimensional limitations are considered. Measurement of the bending of a glass plate due to shrinkage of the epoxy coating is presented.

A new analysis system for computerbased fringe interpretation is decribed. The principle of the evaluation is based on intensity measurements in the image-plane and a combined phase shift technique. The evaluation technique offers some essential advantages. - suitable for CW- and Pulse-Laser - data evaluation by optical preprocessing and an image an-lyzing system - digitizing of the interferogram in up to 512 x 512 picture elements with 756 grey levels - calculation of the object-deformation or the vibration amplitude for the complete image with high accuracy - no sign ambiguity - help text supported user-software The data output is made in coordinates, in false colour graphics and in pseudo 31)-plots. The applications are demonstrated on vibration modes of automobile components, excited by running engines with the aim of noise reduction, on deformation analysis of static problems and on non destructive tested parts.

Sandwich holography has been just used in artwork conservation; its capability in detecting incipient faults or cracks in wooden panel paintings and statues has been tested successfully on models and ancient artifacts under restoration; a part from its ability to render significant services in non destructive inspection, sandwich hologram is expected to find application in other problems having considerable interest as displacement derivative measurement. The purpose of this paper is to extend this simple method of measurement to the study of lining canvas behaviour under a slight mechanical stress, in order to characterize the material employed to line painted canvases, both for improving the existing techniques and for selecting new materials. Some preliminary experimental results on models of lining canvases are presented.

Holographic flow visualisation has been successfully employed by Rolls-Royce to investigate three dimensional flows in rotating aero-engine fans and two dimensional flows in cascades of blades in wind tunnels. In a development of the latter technique, flow fields in life-size models of labyrinth seals have been investigated. These tiny components are used to block gas flow between rotating and stationary parts of the engine without physical contact. The models are typically 20mm across with gaps of less than 0.5mm. Careful design of the optical system and the use of broad-band reconstruction techniques minimise the deleterious effects of diffraction and laser speckle. High resolution interferograms of the complicated flow field can be achieved. The paper discusses the optical system and presents examples of the holographic reconstructions.

Development of the technique of great depth holography applied to the engineering measurement is introduced in this paper. In double-exposure holographic interferometry the object is illuminated by multi-beam of object waves with various path difference of even multiple of cavity length. This method is useful for the holographic interferometry applied to large engineering structure.

This paper describes a site test on the deformation of loaded track by white light speckle method. The results obtained from double-exposured speckle patterns by pointwise method show that the resultant displacement at every point within the test section along the loaded track is not vertically downward as some people usually consider it to be. Each displacement has a horizontal component opposite to the direction of motion of the locomotive. The vertical components are different in magnitude and direction.In front of the pressed point under the test wheel of the locomotive there exists a certain point such that the vertical components at places behind this point are downward and at places in front of this point are upward. This particular point is an inflexion point. The part of loaded track behind this inflexion point sinks downward while the part in front of this point bends upward. This Phenomenon shows that the running locomotive creates an "elastic-wave" along the track. The maximum displacement of the loaded track is about 5 - 7 mm,and the relative error is within the limit of 1-5 % .

A computer-aided holographic system which enables a complete analysis of holographic interferograms with high phase accuracy is presented and discussed in detail. The system is based on the two-reference-beam holography and uses the phase-shift-method for fringe analysis. Various examples are cited to illustrate industrial applications of this system, including the determination of two dimensional vector fields.

In general the automatic analysis of double exposure and live fringe holographic interferograms requires different and complementary approaches to the development of digital image processing software. In the former case, intensity pattern analysis must be performed, whereas in the latter, phase modulation techniques are applicable. Examples of both types of analysis will be presented, in the context of developing holographic measurement systems for use in the determination of surface deformation and strain fields in engineering components.

The determination of 3-D displacement and strain by holographic interferometry for industr'ial applications is a problem still not resolved satisfactorily. Important requirements are: 1) simple optical arrangement requiring only one hologram recording, 2) fully automated fringe evaluation and data processing. The proposed arrangement with quasi-heterodyne (phase shifting) fringe interpolation and video-electronic detection offers fast and automated phase measurement with high accuracy. The 3-D information about the deformation is obtained by moving the TV-camera behind the hologram plate to get different directions of observation. If the object shape is known, the effects of image distortion due to perspective can be corrected by appropriate interpolation of the measured interference phases. In this paper, the optical setup and the data acquisition system will be described. The calculation of vector displacement and strain, including correction of the distortion by perspective, are discussed in detail. Finally, experimental results with an estimation of the accuracy for displacement and strain will be reported.

A digital phase shifting technique capable of quantitatively determining the phase of holographic interferometric fringes is presented. This technique uses computer control to take data and to calculate phase. The phase value at each detector point can be calculated by taking four successive intensity data frames with the reference phase shifted between each frame. The amount of phase shift introduced by this technique is unimportant. Theoretical analysis and experimental systems are described. Experiments are made in beam deflection measurements, holographic nondestructive testing and surface contouring of diffuse object to show the versatile applications of this technique.

A system is presented that performs a quantitative computer analysis of interferograms. The system is modularly built around a VME-bus backbone, and uses an interpreter language as software structure, meeting the demands for flexibility in development and for external utilisation tailored to specific applications. The algorithms for the analysis of single-image interferograms are briefly discussed. Due to delay in the project, the exact performance of the system is still unknown.

Objective of this work was to realize and test a digitizer which locates precisely and rapidly, the fringe centers of an interferogram so as to perform their evaluation procedure automatically by means of a microcomputer. The adopted opto-electronic sensing device is a linear array of 1024 bar-shaped (15μmx26μm) silicon photodiodes with center-to-center spacing of 25μm. A stepping motor can move the array board in order to investigate the whole interferometric image. Scanning time is about 10ms/line. Application of the system to a Wollaston prism interferometer, in order to measure concentration profiles in a mass diffusion process of a binary gas mixture, proved the ability of the digitizer to accurately interpret interferograms. The performance and the potentiality of the system are analyzed and discussed.

In this paper a new technology for measuring the dynamic behaviour of structures using the stroboscopic laser speckle interferometry is introduced. A good quality of whole-field speckle fringe patterns and Young's fringe patterns can be obtained when this method is used. Moreover, the methods of identifying the phase information of the vibratory structure and choosing the width of He-Ne laser pulses are discussed. Lastly, it presents the experimental results of comparing the stroboscopic laser speckle interferometry with the time-average speckle interferometry.

The measurement of in-plane strain under service conditions on components that are rotating is an attractive proposition. Pulsed laser Electronic Speckle Pattern Interferometry (ESPI) which possesses the accuracy of holographic interferometry may be used for the measurement of small strains. The short pulse width of the pulsed laser "freezes" the component motion and overcomes the conventional holographic stability requirements showing this technique to have potential use in an industrial environment. Electronic processing of television speckle images provides an immediate display of interference pattern information for in-plane displacements. Good contrast interference fringes have already been achieved at The City University over a range of component tangential velocities up to 120 ms-1 for a component rotational speed of 10500 rpm. Use of the conventional optical system reveals a certain speed limitation to the technique. However, recent modifications to the optical system have removed this limitation and show potentiallanalysis of components whose tangential velocities are in excess of the present 120 ms-1.

Attempt has been made in this paper to depict, through the illustration of a few typical examples, how in the People's Republic of China today, scientific researchers and engineers have applied modern optical methods such as holographic interferometry, speckle image-shearing interferometry in non-destructive tests to solve some of the difficult problems they are to tackle.

The development of double pulsed Electronic Speckle Pattern Interferometry (E.S.P.I) to include a frequency doubled YAG laser is compared with the more conventional double pulsed Holographic Interferometry. The value of these techniques is examined for their engineering relevance and how they can be applied to problem solving within industry.

A method of optically contouring object surfaces for inspection purposes, based on electronic speckle pattern interferometry is described. The technique forms a "bolt-on" addition to existing ESPI systems. It is shown that the correlation fringe contours thus obtained are equivalent to those of projected, two-beam interference fringe contours. Attractive features are the possibility of identifying a stationary reference contour, economy of light usage, and the possibility of programmable control of sensitivity.

A new technique combining holographic and speckle-shearing interferometry is applied. Using the technique, the displacement and the slope of diaphragms of the silicon pressure sensor have been measured separately from a single holospeckle-shearinggram. The experimental results are in good agreement with theoretical analysis.

The analysis of vibration modes of engineering components is an important aspect of industrial testing. Holographic interferometry is one technique for studying whole areas of an object at the same time. Electronic speckle pattern interferometry (ESPI) uses a TV video system to perform a similar function by means of the speckle effect from an object that is illuminated with coherent laser light. While useful for converting light intensities into phase information relating to movement of the surface, speckles represent unwanted video noise in the final interferogram on the monitor screen. This paper presents a technique for reducing the speckle noise by sequentially averaging a large number of interferograms with de-correlated speckle patterns in a video frame store. A silicon-target storage tube or a digital frame store is used to produce high contrast ESPI fringes. This simplifies analysis by eye from the screen or by computer from the digital frame store. The combination of real time frequency scanning and contrast enhancement at a chosen frequency in only a few seconds makes ESPI a useful industrial test instrument.

When measuring in plane surface deformation using white light speckle photography, errors will arise if an out of plane displacement is present. Here it is shown that stereoscopic photography resolves this problem and makes the measurement of true in plane displacements possible. A rigid body translation is also introduced to determine unambiguously the direction of the displacement.

The experimental investigation is described of the reinforced concrete construction pro blems mentioned in the title, making use of the Laser-Speckle-Photography optical measurement method- Proceeding from the material-conditional particularities and the high demands on the accuracy of the measurement values, a semi-automatically working device. was developed for analysing the Laser-Speckle photographs. The method of working with this device, the statistical routines applied in the process and the attainable accuracy are reported on. Moreover, reference is also made to the strains in a reinforced concrete member and the crack. formation. In the last section, the results of measurements of the joint rotation on the inner support of a two-span beam of reinforced micro-concrete, as well as the shear bearing behavior observed in this context, are discribed.

The paper deals with direct measurement of residual stresses by means of multiple image-shearing interferometry in combination with stress release at drilling hole. In order to facilitate collection of information and to obtain three sets of clear fringe patterns simultaneously, experimental studies were made to testify the stress condition of thin rectangular plate clamped at four edges, subject to concentrated central loading, by means of a kind of unequal right-angled wedge, to probe into the reliability of the method. The experimental results agree closely with theoretical values. Preliminary findings of measurements of simulated residual stresses in specimens subject to uniaxial tension with multiple image-shearing cameras as well as surface displacement field formed as a result of release of residual stresses in weldment by means of sandwich holography prove that the aforesaid methods may find application in direct in-situ measurement of residual stresses for engineering project using modern optical method.

The elastic modulus of fresh human dentin and alveolar cortical bone have been measured in this present work by laser speckle photography which is a non-contact, non-destructive and visual method with a high sensitivity, simple optical system and easy calculation. So it is more suitable than the present strain gauges to measure in-plane displacement of tooth and bone whose specimens are so small and are anisotropic. A special loading apparatus and a technique of sharpening fringe have been tried to use in this study.

Amplitude and specific phase modulation techniques are used to reduce the complexity of ESPI fringes describing the deformation of a submerged elastomeric subject. This leads to a characterisation of the volume viscoelasticity of the elastomer.

An application of speckle velocimetry technique to Rayleigh-Benard convection (small boxes) is presented. A 5 mW He-Ne laser allows precise determination of the 2-D velocity flow field, up to several mm/sec. The digital techniques used to analyze automatically the multiexposed photographs and to generate velocity and vorticity fields are described. The obtained results are in good agreement with previously reported data. The ability of the technique to cover other experimental conditions is discussed.

The effect of object diffusivity on the MTF measured in a moire deflectometer is discussed and demonstrated. The diffusive MTF can be isolated and measured independently of diffraction effects. A propagator which expresses the change in MTF with the path is defined and demonstrated on a colloidal solution serving as the tested object. Good agreement is found between the formalism and experimental results.

An optical method for slope measurement based on the reflection grating method is presented. By integration of the slope the out-of-plane deformation of the considered object surface can be determined. Applying picture processing to the image of the reflected grating lines, the method is suitable for automatic testing in labs and production environments. Two examples, delamination of multilayer tension specimen and quality control of lacquered surfaces, are described in detail.

In this paper, first, the insufficient of the metheds used to determinate light source's size and grating gaps in linear grating sensors is refered. Then, according to the general model of grating measurement systems, the complete expressions of moire intensity distribution are derived by means of partially coherent light theory. The effects of spatial coherence of light sources and grating gaps are particalarly discussed, too. In this paper, not only the simple and correct formulas and rule of determinating the modulation depth of moire signal and grating gaps are derived, but also it is proved that coherent light illumination is only one special case of this paper. In the end, an experiment whose results are fundamental in agreement with the theoretical analysis is presented. The conclusions of this paper are very important to design linear grating sensors and its formulas are very practical.

Mass transfer measurements have a wide range of applications in science and industry. In some instances, the mass transfer is of prime importance - e.g. in wood and paper drying. In many cases, however, the mass transfer measurements are made to be used in the mass/heat transfer analogy. Here, the heat transfer can be calculated from the mass transfer results; an analytical solution for turbulent heat transfer is not generally possible as numerical solutions are limited by a lack of comprehensive model for the various physical properties required in the equations.

When a beam is focused into grating elements, it is diffracted and phase-shifted. These fundamental characteristics of gratings have been found very useful for converting conventional interferometers into real-time wavefront sensors for digital computer control and data analysis. The principle of phase-shifting interferometry has been combined with above characteristics of the gratings to produce instantaneous multichannel interferograms. Attempts have been made successfully to apply these principles to three well-known interferometers, (1) the point-diffraction interferometer, (2) the radial-shear interferometer, and (3) the double-frequency crossed-grating lateral-shear interferometer. The advantages of these new approaches are simplicity and versatility, in particular, these wavefront sensors can measure wavefronts from both continuous and pulsed sources. Optical principles and the laboratory results will be shown.

In this paper, the theoretical expressions of modulation depth of moire signal under the incoherent illumination are derived. It follows as a concequence that, the modulation depth of moire signal is in relation to the following factors: the geometric share and size of light source, the diffraction effect of grating,which relates to the line numbers of grating, the line and space ratio, the gap of grating pairs, the geometric shape and size of receiving window, etc. In addition, the influences of grating fair on the period and inclination of moire fringes under the noncollimated illumination are discussed, and the comparisons of the changes of modulation depth of moire signals and the noncollimated illumination with that under the collimated illumination are made. Finally, some exoeriment results are given to verify the theoretical expressions. This parer is useful to the actual design of grating sensors.

In an angle calibration instrument and a generating machine of radial grating, the opto-electronic signal is generated by a novel fiber optic whole-circum sensor. The construction of the sensor is introduced, the principle to i prove the accuracy under partially coherent illumination is derived, and the experimental results are presented. Because of its excellent characteristic, the residual phase error (peak to peak) of moire signal is less than 0.03 sec. of arc., the accuracy of machine is increased about 30 times.

This paper presents a novel method for evaluating the resolution and the wavefront of a plane diffraction grating. Essentially, it is an application of Fourier transformation to the grating. The results of experiments and computation are present, too. They are in good agreement with the results obtained by the method commonly used.

WYKO Corporation has developed a new instrument that is capable of measuring surface heights over an area from 0.5 mm square to 4.0 mm square. The instrument is based upon an interference microscope and uses direct phase measurement techniques to allow computer calculation and three-dimensional graphic display of the surface heights. The instrument uses a 256-by-256 grid of data points obtained from a photodiode array which provides a lateral resolution of 2 μm on the surface. Computer software has been written to perform statistical analysis of the surface under test, including surface roughness measurements and autocovariance. Results are shown for measurements of optical surfaces as well as magnetic media surfaces.

A review of optical techniques for the measurement of surface geometries of complex components will be presented. Factors limiting the performance of the techniques together with areas of difficulty in use are identified. The paper concludes with a general assessment of the potential of optical techniques as a tool for engineering metrology.

A series of equi-thickness interference fringes will be produced by the paired-optical testing plates in a Fizeau interferometer. The paired-plates are also formed a structural part of the interferometer. The variation of the light intensity distribution of these fringes will character the relative flatness of two plates in pairing, therefore, one can accurately measure the flatness of the above mentioned plates if a detector is used to scan the light intensity distribution on some certain points of these interference fringes. These points will display the error of the testing surface effectively and sensitively. That is the principle used to measure the ultra-precision plane in this paper. The authors had been developing this principle and suggested a corresponding device and its practicable operation, as well as the discussion about the theoretical accuracy and optimal measuring condition was done. According to the experimental divice, the obtainable relative flatness resolution of two plates in pairing is better than λ/1000. The absolute error of one plate from relative measurements also could be obtained after a special calculating if necessary.

In this paper, a dynamic optical matrix method about auto detecting kinds of surface is presented. A method of setting dynamic optical matrix, gists of image element intensity and logical feature, and using microcomputer to realize plan of detecting kinds are described

As the final goal of HIPPARCOS mission is to measure star positions with an extreme accuracy (2 milli-arc sec), severe requirements have been put on the performances of the optical telescope. One of the most stringent requirements applies to the wavelength dependence of the position of the diffraction image given by an all-reflective telescope. After a short introduction relative to this so called "chromaticity" effect and its relation with the wave-front error (WFE) of the telescope, this paper present briefly the various interferometric test methods used at component level to achieve WFE better than λ/60 RMS. Integration of the mirrors in the telescope structure, will be followed by 2 different tests under vacuum = - an interferometric evaluation of the WFE of the telescope followed by S/W derivation of residual chromaticity; - a direct measurement of the wavelength dependance of star position; Sensitivity of both methods are discussed. Possibility of calibration in-orbit is also mentioned.

A real-time photogrammetric system has been developed at the Technical Research Centre of Finland. The system consists of solid-state video cameras and a photogrammetric microprocessor. The processor is especially programmed for image processing and for photogrammetric operations. The system concept is versatile in regard to the measuring requirements: first, the cameras may be freely oriented in relation to the object; secondly, the use of video allows the utilization of different kind of imagery in respect of the spectral response; and thirdly, the spatial measuring accuracy may be adjusted according to the purpose. The first tentative applications of this non-contact and three-dimensional machine vision technique have been within the fields of surveillance and industrial quality assurance.

The paper reviews the techiques of photogrammetry available and highlights the methods used for a variety of measurements on nuclear plant. The methods of camera calibration are discussed and the practical solutions of measurement problems outlined.

The optical testing methods have gained a considerable upswing due to the development of the laser. Despite all the progress made, however, there are still problems which cannot be neglected concerning operation and application. The current development is either enlarging the spectrum of the application or facilitating the operation. An interferometer for industrial application purposes is shown. Developments in the field of holography and image processing in connection with optical testing techniques are to be seen. A new kind of laser measuring system for non-contactive measurement of distance and thickness will be introduced. The industrial applicability of the developments is discussed.

Measurements of coherent transients resulting from fine and hyperfine structure level splittings in alkaline atoms with frequencies up to 500 GHz have been performed with ultra-short light pulses in combination with a polarization sensitive detection scheme. Further the potentiality of high resolution level splitting measurements with a train of picosecond light pulses from a semiconductor laser is demonstrated.

Investigations of the torsional vibration characteristics of shaft systems which transmit pulsating torques are an important part of a machinery designer's responsibility. Satisfactory operation of such systems depends to a large extent on successful treatment of this vibration problem, since incorrectly or insufficiently controlled torsional oscillations can lead to fatigue failure, rapid bearing wear, gear hammer etc. The problem is particularly severe in engine crankshaft design where numerous failures have been traced to abnormal vibration at "critical" speeds. Traditionally, the monitoring of torsional oscillation has been performed using strain gauges, slip rings and a variety of mechanical and electrical "torsiographs". More recently systems employing slotted discs or toothed wheels together with proximity transducers have been preferred, but a disadvantage arises from all these methods in that they require contact with the rotating component which necessitates "downtime" for transducer attachment. Moreover, physical access to the rotating surface is often restricted thus making the use of such methods impractical. The "cross-beam" laser velocimeter provides a means of measuring torsional vibration by a non-contact method, thus effectively overcoming the disadvantages of previous measurement systems. This well established laser-based instrument provides a time-resolved voltage analogue of shaft tangential surface velocity and laboratory and field tests have shown it to be both accurate and reliable. The versatility of this instrument, however, is restricted by the need for accurate positioning, since the velocimeter must be arranged so that the rotating surface always traverses the beam intersection region, which is typically only a fraction of a millimetre in length. As a consequence use is restricted to components of circular cross section. This paper compares and contrasts the "cross-beam" system with a new laser instrument, the laser torsional vibrometer. The optical geometry employed in this new instrument offers a means of producing a hand held laser tool which the operator can simply "point" at the rotating surface of interest. Other important advantages include Insensitivity to operator or shaft radial movement and the ability to measure torsional oscillations of any rotating component of arbitrary cross-section.

A simple, portable device is described which is able to count the number of sheets of metal or plastic plates in a stack. The device, for which patents have been applied, is capable of counting plates which are only 0.1 mm thick. The limiting resolution of the device is limited only by the quality of the optical system used and the relative stability between the plates to be counted and the measuring device itself.

A new optical method for measuring the diameter of transparent filaments has been developed. It is based on determining the dimension of a sharp shadow image of the filament on a photo-detector. The influence of transmitted light is diminished by spatial filtering. The resolution is better than 1% for diameters down to 10 μm.

Even at the present time it is not always possible to obtain satisfactory results from plasma spraying in aerospace applications. This is because there is insufficient theoretical and experimental understanding of all the parameters which influence the deposition process. Among the important factors which must be further explored are the velocities and the flow characteristics of the plasma jet. In this paper we present new results from measurements utilizing a Laser Dual Focus Velocimeter. Velocity and turbulence intensity measurements of both the plasma and powder particles were taken at tank pressures of 50 and 1013 mbars.

A method of measuring the acceleration of unsteady fluid flows using standard L.D.A. Optics has been developed. This is expected to have applications in many areas. It is demonstrated to be reliable in flow fields of breaking wave crests where no other method of fluid velocity or acceleration measurement is applicable. Comparison is provided with other methods of flow measurement and with numerical predictions of the fluid velocity and acceleration fields under a breaking crest.

A simple fiber-optic interferometer was developed for testing black & white photographic materials. By means of the interferometer a sinusoidal fringe pattern is formed directly on a film under investigation, and the fringe spacing can be gradually varied. After developing and examining the film in coherent light it is possible to determine the absolute value of its resolving power. The resolving powers of several common negative films were measured to verify the usefulness of the method in photographic materials testing.

A laser Doppler vibrometer which measures noncontact vibration frequencies and amplitudes at distances up to 20 meters in the 10 Hz-10 KHz range is described. Sensitivities from .1 mm/s to 1 mm/s are well matched to the needs of power plant alternaltors maintenance programs.

The paper presents a method for the measurement of surface deformation using an incoherent optical fibre bundle to transmit ordinary illuminating light to the test surface with artificially generated speckle pattern and using a coherent fibre bundle to transmit the generated artificially speckle pattern to photographic film, for recording and analysis. The doubly-exposed speckle pattern is analysis using point-by-point method to measure the surface deformation. The white light speckle measurements have the advantage that there is no need requirement of constant phase difference in producing holograph and laser speckles. We have discovered the relation each other between the speckle dimension, single fibre diameter and the across section size of the coherent fibre bundle using the sinesoide grating frequency analysis. We have also found that the Young's fringes of considerably higher visibility can be obtained while point-by-point analysis of the recorded film is performed in the reflected light field.

Pseudo-color techniques involve the introduction of colors in a monochromatic image to increase the ability of the human viewer to analyze and memorize the information. Several quantities can be coded in pseudo-color, for example temperature gradient, index variations of transparent materials, spatial frequencies of periodic objects or densities.

The determination of position and orientation errors made by large-scale cartesian coordinate robots using latest 3D-measurement methods has proved to be difficult in practise. A method has been developed to determine the mechanical inaccuracies of linear motions, perpendiculars, deflections, rotations and bends of a robot, relative to the common reference coordinates of the robot and the work area. The measurement method is based on the use of a laser diode and a position sensitive detector (PSD). A PSD is an optoelectronic sensor capable of providing position data about a light spot incident on its surface. The dual-axis, non-discrete PSD provides continuous analog X- and Y-axis information as the light spot transverses its active area. It senses the centroid of the light spot so that the position daa is indpendent of the focus of the spot. The PSD typically has an active area of - 1 cm - 20 cm , a resolution of 1/5000, nonlinearity of + 1% - + 15% and a fast response enabling accurate detection even of a rapidly moving light spot. The system developed consists of a laser diode transmitter, two beam splitters, a retro-reflective mirror, a PSD based receiver and a microcomputer unit for controlling the system and analysing the measured information. The divergence of the laser diode transmitter is - 0.1 mrad, it is small in size and lightweight (about 100 g), the direction of the laser beam of a fastened transmitter can easily be adjusted and it can be modulated electronically. The direction of the laser beam is not so sensitive to temperature variations as is for example an He-Ne-laser. The effective size of the PSD is enlarged with the aid of optics to have a diameter of 10 cm. Using a modulated laser beam the background light can be compensated. The position data from the PSD receiver to the memory of the microcomputer is gathered continuously and information is produced by a graphic printer in the form of graphs or numbers. This enables the measurement of the straightness of moving paths of machines such as robots, displacement and vibration measurements, optical position and angle sensing and surface flatness measurements. The performance of the system will be reviewed by considering the results of the practical measurements for determining mechanical misalignments of linear motions of cartesian coordinate robots.

It is the purpose of this paper to describe an opto-electronic method which allows non-contacting and non-reactive measurements to be performed of the space position of a rod-shaped body in free-flight such as a projectile. The beam of light from a laser is wide-ned to form a thin lighting row oriented preferably normal to the direction of flight. As the subject under investigation passes through the plane of measurement, a light spot is observed on the surface of the test object, which drifts more or less strongly with the angle of attack and angle of precession. This motion is imaged on two uniaxial position-sensitive photodiodes. The photocurrent generated is recorded by means of a four-channel transient recorder which, in turn , is connected to an electronic computer. Here the data measured are analyzed, the velocity, angle of attack and angle of precession of the test object thereby being determined from the discrete absolute values of the photocurrents and their functions of time. The first measurements achieved show the angular resolution to be 0.1°.

A new type of range sensing method adopting a mirror tunnel optics and based on the principle of triangulation have been developped. A mirror tunnel is placed between an observation lens and an object to be measured; a bright spot or a shadow grating is projected on to the object through the observation lens; the bright spot or the shadow grating is observed through the observation lens after reflection with the mirror tunnel; range information can be determined based on the principle of trianguration. The width of an optical system can be reduced to remarkably smaller than the effective base line of the triangulation, and it may be suitable to miniaturize a range sensing system such as an optical stylus, a proximity sensor, a miniaturized moire topography system and so on.

Anew type of optical range sensing method suitable for surface tracing ( RORST : Riken Optical Range Sensing Method for Surface Tracing ) has been developped. An axial symmetrical cylindrical or circular conical ) light sheet is projected on to an object; a ring pattern is produced on the surface of an object; the ring pattern image is projected on to an observation plane by an objective lens; radii of the ring pattern image on the observation plane for different azimuths are detected; distances corresponding to the specified azimuths are determined by the principle of triangulation; thus the information of partial inclination can be obtained. Basic experiments have been perfomed and it has been proved that the proposed method can provide a compact optical range sensor which can detect not only the distance but also the partial inclination of a surface.

A description is given of how the technique of image derotation is applied to the study of low frequency noise generation of disk brakes. Infra-red imaging is combined with derotation to show the heat emission distribution on the rotor surface during a braking cycle. A series of regularly spaced hot spots are observed on the rotor's surface only when juddering-type, low frequency vibrations are present. This relationship will be discussed and future areas of research will be outlined including the use of laser doppler velocimetry and Electronic Speckle Pattern Interferometry (ESPI)/T.V. Holography techniques to study this phenomena.

Scanning Tunneling Microscopy (STM) gives information on the topography, chemical composition and electronic structure of metal and semiconductor surfaces down to the atomic scale. The experimental data can be filtered using a Wiener-type or least-square filter to eliminate blurring, to suppress noise, and, in addition, to correct spatial distortions by correlating typical picture elements. The three-dimensional profile of the processed surface picture can then be represented according to techniques developed by map-makers.

An experimental study was carried out to evaluate the optical performances of radial GRIN lenses. The GRIN materials were fabricated by the CGE Research Center through the vapour deposition process, which generally involves index profile perturbations. We purposed to test the feasability of making lenses from such materials. Specific evaluation means were developped for the lens characterization. The wavefront was obtained from phase interferometry, also leading to the refractive index profile. A set-up was realized for the assessment of chromatic variations of the index maximum slope. Dependence of birefringence as a function of index variation was investigated. Automated measurements of line spread functions and modulation transfer functions were also implemented. We particularly investigated, both experimentally and through computer raytracing, the effect of macroscopic and microscopic perturbations of the index profile on imaging. We showed up the quite different influences of low frequency and high frequency fluctuations. The ray trapping predicted in a previous paper was observed as a depression of the on-axis illumination. We evidenced the correlation between the amplitude of the high frequency fluctuations and the observed drop of illumination. These fluctuations could be cut down to a negligible level. In return, the low frequency fluctuations, due to a want of precision in the fabrication process, could not be easily eliminated, leading to a drop of the MTF.

The properties of interference formed by a spherical confocal Fabry-Perot interferometer (FPS) are studied in terms of laser Gaussian beam. The mathematical expression for the interference field of FPS has been initiated. Furthermore, the centering precision of incident rays with the axis of FPS has also been derived by both theoretical computation and experimental measurement. The results show that FPS could be used as a high precision centering device in the edging, cementing and mounting stages of various optical components and systems, especially suitable for the small aperture and high-power optical system centering such as microscope objectives.