Holography has now become an established technique. While some of its early applications failed to fulfil their initial promise, others have opened up major commercial possibilities. This paper will briefly review the growth of holography and attempt an objective assessment of some of its current applications.

This paper briefly reviews the recent developments on holography in China,such as the application of holography to interferometry, optical information processing, information storage, 3-1) display, optical elements and nondestructive testing etc.

A holographic method for storing two or more logitudinally arranged journal page transparencies at a quasi-Fourier spot is developed. Adequate redundancy and high storage density can be expected. Theoretical analysis and experimental demonstration are given.

Phase analysis technique for reconstructed images of an electron holographic microscope is described. The fringe scanning method is applied to gain high sensitivity in phase detection. An example of measuring a magnetic field of a fine particle is presented. The measurement accuracy in the case of median filtering is about 1/70 fringe.

Important progresses were achieved for the first time: 1) recording of single-exposure cineholograms of living bodies on 126-mm films, at a repetition rate of 25 holograms per second with the help of a frequency-doubled pulse YAG-laser; 2) recording of double-exposure cineholograms of reflecting moving objects for medical and industrial applications. Limitations of 3-D movies are described.

In this paper several new methods for making holographic stereograms are presented. Wide angle, white light viewable flat stereograms with higher quality images, i.e, higher resolution, free of distortions and aberrations within a considerable viewing range, could be created.

A system that can be applied to high speed phenomena, especially with solid diffusely scattering objects is proposed, with which an automatic measurement of high precision can be realized.

The mechanism of the self-enhancement effect of dynamic amplitude-phase, amplitude and phase holograms in different materials is considered as well as its applications to the photorefraction investigation in electrooptic crystals and to the modification of holographic recording and readout.

A new coding method for a CGH with pure phase based on the decomposition of any complex vector into two symmetrically situated conponent vectors with equal amplitude is proposed. In this method only two cells are needed for each sampling point as compared with the conventional types with three or four cells of Burckhardt's and Lee's configurations. Theoretical analysis of this proposal is given and some preliminary experimental results are presented.

The results of the development of IR holography at 10.6μm wavelength and its application to inspection of nontransparent metal object and transparent Si-wafer are presented. Polyvinyl alcohol film and oil film have been used as recording media.

In this paper, the concept of holographic storage and reproduction of optical signals is generalized for the case of a spectrally highly selective recording medium, which in addition to fixing the spatial intensity distribution of the incident light is also able to memorize its intensity spectrum. We demonstrate persistent storage, recall and conjugation of picosecond light signals from various model objects by making use of coherent optical responses in photochemically active media. A simple linear theory of holographic storage and playback of both the spatial and the temporal behaviour of the signal is shown to well describe the experimental results obtained by utilizing octaethylporphin-doped polystyrene at 1.8 K as a spectrally selective recording material. The proposed method of time- and space-domain holographic recording provides the storage and reproduction of time-dependent optical signals with a duration of 10^-8 to 10^-13 sec. This presents unique possibilities for ultrahigh-speed data-storage and optical signal-processing.

This is a recent technical report of the optical holographic technique applied to the supersonic cascade wind-tunnel. The experimental methods, techniques and results are presented.

An interesting spacial moire hologram and its reconstruction were recommended. Some properties of reconstruction moire and its prospect of application were also discussed. A spacial moire hologram is given in this paper. The object of the hologram is two groups of transparant and opaque per or quasi-periodical grating, grid, Fresnal zone plate and so on. In order to form different kinds of spacial moire patterns, a certain spacing between two gratings is needed. Besides, they would be parallel, tilted or twist to form different structures of spacial moire. When reconstruction of the hologram, in the modulated optical field, there are not only the original per or quasi-periodical structure, but also the spacial bit frequency pattern --- the spacial moire fringe can be obtained.

A new method of producing multicolour holograms is proposed. The method is based on the technique of dispersion compensation, and exploits the wavelength selectivity of volume holograms. The colour saturation of the resultant image increases with increasing wavelength selectivity of the hologram.

In this paper, the authors derived general formulas for computation of in-plane displacements and stresses resulted from which, measurements being carried out by sandwich holographic interferometry. Computation of stresses due to in-plane deformations by means of derivatives of second order of contours of equal displacements, or second-order derivatives of the fringes, are also presented.

The influence of the third-order nonlinearity of a medium containing a steady-state holographic grating on the grating properties is nvestigated theoretically. It is shown that the angular position and the value of diffraction efficiency maximum can be radically changed. When utilizing the grating in optical scheme, its characterisrics appeare to behave in a jump-like way.¹ Nowadays holographic volume phase gratings (HVPG) are widely used as selective elements in laser systems, where they are irradiated by intense laser radiation.^l It is of particular interest to have a clear understanding of HIWG characteristics changes caused by the nonlinear optical properties of the HVPG storage medium. Thus the purpose of our analysis is to investigate the influence of the third-order nonlinearity in a HVPG storage medium with a local response on the HVPG diffraction characteristics.

In the field of medical diagnosis, many X-ray tomograms are taken at the different slice planes of affected parts and organs so as to grasp their three dimensional structures. Multiple recording hologram in which all slices are recorded on single holographic material is used for this purpose. To avoid the faults of usual incoherent superposition and to make possible white light reconstruction, we present a new recording method for making a multiple recording hologram. The hologram is made by two step process and can be reconstructed by white light illumination. Some example of hologram is also shown.

Based on the holographic theory,the optical properties and characteristics of aberrations for reflective holographic lens have been described in detail in this paper. The aberration distribution of holographic lens is confirmed by experiments. According to the aberration characteristics of reflective holographic lens, calculation and analysis on asymmetrical spheric system have been performed to compensate aberrations of holographic lens. The for-mulae of ray tracing and calculated aberrations of asymmetrical spheric system are deduced. The imaging properties of asymmetrical optical system are studied.

In this paper a practical method for making large rainbow holograms by using a common glass rod is introduced. It is able to make white-light transmission holograms as large as 1000 X 1000 mm².

The principle of recording the modulated optical signals in the holographic scheme used a nonstationary reference wave with linear change of frequency along the coordinate and in time in the detection plane is considered. The analysis of the signal spectrum reproduction is presented. The description of the experimentally realized scheme to form the nonstationary reference wave, of the holographic registration and reconstruction scheme is given. The expression of the instrumental function for recieving the signal spectrum pattern is presented. The results of measuring the spectrum components intensity distribution are presented. The examples of oscillating chemical reaction and of two liquids diffusion illustrate the scheme operation.

The conventional CGH is made by a graph plotter, in this paper a new way to make CGH by dot Matrix printer has been introducted. The CGHs of 16X16 samples of character 'F' 32X32 samples of Chinese word ' )0t; and 64X64 samples of Chinese word 'if' and their reconstructed images are given. The method is useful in industry science and instruction.

The Electron-beam Lithography is a newly developed microfabrication technique. The principle and technology of making CGH by E-beam were discussed. The influences of error on the E-beam Generated Holograms have been analysed. The experimental results of the differential filters and a CGH scatter-plate have also been presented.

By using holographic interferometry and speckle techniques we can measure deformation of diffusely reflecting surfaces with sensitivities related to laser wavelengths. Although these techniques use interference of diffusely reflected laser light and are similar to each other in optical arrangements, they are mutually complementary in various points. In this paper these relationships are discussed in view of fringe formations and recent advances using optoelectronic tools for practical applications.

Propotional exposure piled-plate holography, a new experimental technique to separate principal stresses for both static and dynamic photoelastic holography is described, solves the problem of principal stress separation in multi-frame recording dynamic photoelastic holography. Applying the new technique to the multi-frame recording dynamic photoelastic holography, the authors recorded eight separated dynamic stress patterns for four different transients of a plan plate subjected to an impacting load. The dynamic stresses of the plate are analysed.

The performance characteristics of an In-line Object Beam Hologram Interferometer working with a diffuse object are analyzed. This analysis considers two criteria optical path difference and the correlation of homologous points at the image plane.

A method using single-wavelength holographic interferometry for measurements of density and temperature distributions of an axial symmetric argon arc plasma flow field is presented. Calculating formulae and experimental results are given.

We present here a new technique of holographic interferometry for profile inspection of integrated circuit (IC) wafers. With this technique the lateral resolution of the profilometer will not be affected by the limitations on optical aperture. In addition, there are no stringent requirements on the spot size of the laser irradiation. A principal advantage of this system is that it needs no magnifying elements to give reasonable resolution for lateral measurements. Also the system will work even if multiple reflections exist.

A method of HFR combined with double exposure holography, sandwich holography and strobo scope holography respectively, and its applications of the quantitative analysis of 3-D displacement of human skull; of the change of dentomaxilla and vibration of violin are presented in this paper.

Employing a tuff rock cave as the vibration isolation system, made possible the measurement of the vibration mode of large-sized structure such as a fully equipped automotive bodies and producing 2m by 1m hologram for display.

A new method of holographic interferometry and an accurate data processing for determination of refractive index profiles of optical fibers are presented in this paper.

In this paper application of holographic time-average method to research the reason of spurting water of the antique "Water Spurting Basin" is presented.

The design and performance of a holographic interferometer for the assessment of thin film deposits made on dielectric substrates is presented. Thickness and uniformity of film deposits thicker than 1 micron can be evaluated with this device. This interferometer can also be used in a reflection mode to test non-dielectric deposits made on opaque substrates.

A set up for real-time and double-exposure microholographic interferometry has been assembled to determine temperature distribution in very small volumes of transparent mediums traversed by a laser beam. The axisymmetric refractive index distribution was evaluated from experimental data by means of a suitable mathematical model for the interpretation of the microinterferograms. Computer model calculations for the temperature distributions were also developed and compared with the experimental data.

The principle of inspecting solder joints by holographic interferometric technique is introduced. The criterion of discriminating the flaws is suggested. The results are given and testified by metallographical sectioning.

A method for automatic measurement of the small tilt angle variation of an object surface by using a digital holographic moire interferometryI based on computer processing is described. The test surface is placed in the middle of a set of two gratings. A monochromatic plane wave illuminates the first grating and undergoes diffraction. After being reflected by the test surface, the first grating produces the magnified Talbot image. The moire fringe is generated by superimposing this Talbot image on the second grating. The inclination angle of the moire fringe is a measure of the tilt angle of the test surface. Fast and automatic measurement has been achieved with improved accuracy and sensitivity. In the experiment, the small tilt angle variation of the plane mirror is measured.

A new holographic-moire is presented. The object is illuminated by double beams separately so that two different carriers are introduced. Pure strain patterns are obtained by filtering twice and shearing the plate.

Phase-only Fourier hologram is recorded optically and applied as matched phase-only spatial filter to the discrimination of characters. The comparison between this filter and the overexposed classical matched spatial filter is presented.

Holographic interferometry combined with the digital image processing technique was firstly used in whole field thermometry. Some discussions on the theoretical basis and operational steps of image processing were given in detail. Using M-75 image system, we easily obtained the 3-D temperature distribution of an alcohol flame within a few minutes.

The research work on moire evaluation techniques both in classical and electronic holography, and its practical consequences are reviewed. Advantages of the technique and examples of application are presented.

Field vector of laser light with sufficient approximation can be circumscribed by scalar function of the form: E(r,t) = E_r(r,t) + iE_i(r,t) (1) If the function (1) satisfies Gabor postulates, its real and imaginary parts makes the pair of Hilbert transformations - than the real part Er(r,t) can be circumscribed with the help of analytic signal of the form: Er(r,t) = A(t)exp[i Wt + i LV(r,t)] (2) In equation (2) the function exp [ig(r,t)] represents informative signal which modulates car-rier wave- laser light - expressed with the function A(t)exp (iWt). Measuring information included in the signal (2) can not be identified in a simple way be-cause of the laser light frequency band lies nearby 1014 Hz frequency. Informative signal detection is realized by photodetectors, which in the frequency band of the light have square -law characteristic and as low-pass filter satisfies dependences:

In this paper a new demodulating procedure for monowavelength holometry of arc plasma is advanced. The method of measuring arc plasma by monowavelength pulsed laser holometry has been investigated and realized. The temperature field and the density fields of electron, ion and atom of an argon arc plasma have been measured out by this method. It can be, in principle, extended to measuring other arc plasma. It has many advantages and wide prospects for application.

Computer aided methods for quantitative fringe analysis are presented. In these presentations, special emphasis is placed on automated data reduction from holographic interferograms.

Fatigue induced damage and crack initiation is certainly one of the most important problems in solid mechanics. Safety consideration for structures ranging from aircraft to nuclear reactor all hinge upon , to a large extent ,the early detection of fatigue induced damages. Thus, it is paramount that effective means be developed that can detect ,or better yet, predict the onset of a fatigue crack. Optical techniques being non-contact methods are ideally suited for such a tast. Indeed a number of techniques aiready exist, e.g. the methods of holographic correlation, speckle pattern correlation, speckle spectrum pattern correlation, speckle spectrum core energy variation, etc . In this paper a new method is given to detect fatigue damage and crack initiation and judge the shape , position and damage level of the damage zone, based on the change of laser-produced diffraction pattern.

A new method for edge enhancement of image using polychromatic speckle is presented. By using the polychromatic speckle pattern as the carrier of an object function,the edge enhancemept of image has been realized. This technique is similar to that proposed by M.Francon. The generalization of polychromatic speckle has been discussed by many authors. In this article, we just want to point out that when a rough object is illuminated by broad band-limited light or even white light, a field of coloured speckle will exist near the surface of the object, or if an optical system is used, the coloured speckle will appear on the image plane.

In this paper a new interferometric method for measuring errors of optical surfaces and their radii using a holographic phase conjugate compensation is proposed. It has the advantages such as good contrast of the fringes, low quality requirement of the main lens of the system and self-examination. It can be used to test a large size of convex spherical surfaces. The fundamental principle of the method is discribed in detail and the experimental results are given followed by the discussion of the features of this method.

Vibration modes from 30 Hz to 1 kHz were measured in full equipped automotive body, door, roof and windshield in a rock cave laboratory using continuous wave laser holographic interferometry and analyzed to reduce noise and vibration.

Two holographic gratings are used as beam splitting elements to form a special shearing interferometer through which time changing profiles of liquid drops evaporating on transparent flat plates are visualized and measured in real time. Binary liquids with various mixture ratios have been tested. Characteristics of thermal stability in binary droplet vaporization are revealed from the sequential changes of interference patterns. An interfacial flow map for binary drops is constructed that defines the domains of stable and unstable type evaporations.

Reflected light with a grazing angle from a gear tooth surface is put into a hologram recording a standard surface. Deviation of reconstructed wavefront from the standard one gives a surface error, and is detected by a simple photodetector with a small pinhole and by the fringe scanning technique.

A new interferometer, the Point Diffraction Holographic Interferometer (PDHI), is described in this paper, which covers its principle, structure, applications and error analysis. It is shown that this interferometer has some advantages over the conventional Point Diffraction Interferometer (PDI) such as easy alignment and adjustable visibility. It can be used for routine optical testing in optical shops or laboratories.

A laser beam impings on a small region of object surface to be measured and objective speckles are recorded by a photoplate. Strains at measured point on object surface determined from a double-exposure specklegram. The equations were derived and two experiments were done.

Holographic scanners with advanced features are described. Novel and synergetic scannings that can be created by holographic scanners and in particular those with an aspherical reflector are presented.

Holographic test methods have gained to become a valuable tool for the engineer in research and development. But also in the field of non-destructive quality control holographic test equipment is now accepted for tests within the production line. The producer of aircraft tyres e. g. are using holographic tests to prove the guarantee of their tyres. Together with image processing the whole test cycle is automatisized. The defects within the tyre are found automatically and are listed on an outprint. The power engine industry is using holographic vibration tests for the optimization of their constructions. In the plastics industry tanks, wheels, seats and fans are tested holographically to find the optimum of shape. The automotive industry makes holography a tool for noise reduction. Instant holography and image processing techniques for quantitative analysis have led to an economic application of holographic test methods. New developments of holographic units in combination with image processing are presented.

Fundamental properties of reconstructed images from a multiplex hologram are studied, and conditions for compensating distortions and for designing a reconstructing source are proposed. Applications of multiplex hologram to medical objects are reviewed, and a computer-aided hologram synthesizing system is proposed for obtaining better images and wider applications. An example of multiplex holograms synthesized from a series of CT images is also presented.

A method for determining ametropia of the eye by using dynamic laser speckles is described in this paper, including its theoretical basis,optical system and results of clinical applications.

Holographic interferometry was used to study the mechanical properties of human calvaria samples taken from macerated skulls. Deformations caused by static loading as well as their derivative functions are calculated from the recorded holographic interferograms. Elliptically shaped interference fringe patterns indicate the.generation of a shallow funnel around the point of force introduction. The lowest point of this impression is shifted sagittally in anterior direction with increased load. The load deformation curve is nonlinear before entering a linear range, demonstrating that in this experiment the calvaria can be regarded as a so called Kelvin body.

Today not only physicists and engineers but also biological and medical scientists are exploring the potentials of holographic methods in their special field of work. Most of the underlying physical principles such as coherence, interference, diffraction and polarization as well as general features of holography e.g. storage and retrieval of amplitude and phase of a wavefront, 3-d-imaging, large field of depth, redundant storage of information, spatial filtering, high-resolving, non-contactive, 3-d form and motion analysis are explained in detail in other contributions to this book. Therefore, this article is confined to the applications of holography in biomedical sciences. Because of the great number of contributions and the variety of applications [1,2,3,4,5,6,7,8] in this review the investigations can only be mentioned briefly and the survey has to be confined to some examples. As in all fields of optics and laser metrology, a review of biomedical applications of holography would be incomplete if military developments and their utilization are not mentioned. As will be demonstrated by selected examples the increasing interlacing of science with the military does not stop at domains that traditionally are regarded as exclusively oriented to human welfare like biomedical research [9]. This fact is actually characterized and stressed by the expression "Star Wars Medicine", which becomes increasingly common as popular description for laser applications (including holography) in medicine [10]. Thus, the consequence - even in such highly specialized fields like biomedical applications of holography - have to be discussed.

It was a great honour for me to assist in preparing this International Conference on Holographic Applications for that part of the world where the idea of holography was created by Dennis Gabor in the fourties - that is Europe. Although my function as a chairman of the regional European program committee was combined with some additional work, it was always a pleasure for me to contribute to an effort to bring us "holographers" together in a country most of us, who are foreign here, have not yet been before, and in this way spreading the exchange of experience and knowledge to our mutual advantage also in this part of the world. As scientists we have the great chance to overcome borders and restrictions of ideology and other constraints, and to meet openly and with friendship. The name of the place in Beijing where ICHA-86 was hold - Friendship Hotel - may act as a symbol in this sense. But on the other hand this puts a burden on our shoulders, that is to work on keeping this independance and freedom of science. If we look on our scientific child or - for the younger ones among us - already our scientific mother - I mean holography, we cannot avoid recognizing that we did not only always use ways to keep this independance and freedom. I mean the deep envolvement of holographic technolgies in the - to my feelings - darkest point of human thinking - that is the development of mutual military deterrence, which threatens mankind and separates people, including ourselves. We have to confess that this is true from the very beginning of practical applications of holography. Who takes the time to read not only the scientific text of publications in our field but also pays attention to where and what for these investigations were undertaken and by whom they were paid, can easily see that this is still an increasingly growing development. Also in this meeting, if we want to or not, we have to realize that the ambiguity of applications of the most modern developments in our field is demonstrated. Thus, I feel we are approaching a cross road, where we have to decide what the future way of our science will be. I hope, we will demonstrate with this conference clearly, what great potentials our work can offer to the benefit and social development of mankind. Thus, I also hope, that our decision for the future of holographic applications will go clearly in a non-destructive direction. In this sense I wish - not only the organizers of this conference - but all of us success.

Based on the regularity of laser speckles movement the method of exam the uncorrected eyes is determined. The apparatus with micro-computer and optical transformation is made. Its practical function is excellent.

The mechanical properties of normal lumbar vertebra and one with the interarticular part cut off to simulate hemi-spondylolysis were measured by the double exposure holographic interferometry. In the normal lumbar vertebra, displacement due to the load applied to the inferior articular process was greater than that of superior articular process under the same load. The interarticular part was subjected to the high stress. From these points, one of the valuable data to consider the cause of spondylolysis was obtained.

The basic principles of electronic speckle pattern interferometry (ESPI) are described, stressing its close similarity to hologram interferometry. The technique's applications for vibration and deformation testing within industrial and medical research are outlined. Future developments are discussed.

The method put forward in the paper can be used to measure not only the large dynamic deformation, but the small dynamic deformation as well. If the photoelastic material is taken as the test specimen, the isocromate and displacement patterns are obtained at the same time under the same load. So the principal stresses are separated.

This paper describes the application of particle image velocimetry to wake flows. As an example the vortex shedding from a circular cylinder is considered and a 'captured' instantaneous flow field presented. The current technique of analysis is described and alternative methods for the presentation of vortex wakes demonstrated.

In this paper a new technique for measuring 3-D displacements using oblique-optical-axis speckle photography (OSP) is introduced. The accuracy of seperating the out-of-plane displacement can be improved, and the visual field of the photographic lens can be utilized sufficiently when the OSP method is used. The experimental results of 3-D deformation of both the sample and the machine tool head stock are exemplified. Moreover, the Apple II microcomputer image processing system for fully auto-analysing the Young's fringe patterns is described principally. Lastly, by comparing the theoretical results with the experimental results, the OSP method and the image auto-processing system are satisfactory.

A non-contact method of experimental stress analysis which does not suffer from many of the restrictions of conventional methods and may be used under service environmental conditions is doubly attractive. Pulsed laser holographic techniques display considerable potential for use in this way. One of these methods, Electronic Speckle Pattern Interferometry, is being developed for measuring rotating component strains, at The City University. Results achieved so far display interference fringe information for component tangential velocities over the whole range 0-150 m s-1

In this paper, an expression which relates the normalized ensemble average of central peak intensity in the far field speckle pattern to the variance and correlation length of a rough surface under measurement is derived theoretically. On this basis, a new method of measuring surface roughness is suggested, and computer simulation experiment is conducted. The results obtained are in good agreement with the theoretical analysis.

Formation of phase diffusers by means of nonlinear record of speckle pattern in the phase photosensitive material is proposed. The essential parameters of diffusers for Fourier transform hologram recording are calculated for analytically approximated tipical nonlinearities.

Digital image processing technique for investigating the statistical properties of speckle pattern and measuring surface roughness is described firstly. With the aid of Model-75 Image Processing System, a speckle pattern can be processed within a minute.

This paper presents a method of measuring 3D minute displacement field of craniofacial bone by speckle photography. Multiple specklegrams are used in this method. Real spatial displacement is computed by the measurement of in-plane translations perpendicular to some viewing directions and the use of the projective transformation relation of the displacement vector. As a calculating example, the initial reaction of craniofacial bone produced by orthodontic forces is measured. Experimental results are in agreement with the results obtained by holographic interferometry.

Based on Gabor's holographic principle a generalized, qualitative model of the interaction of any signal carrier with the living material is presented. The model is applied to describe various physiological and psychophysical events, including brain functioning.

Visual perception has been investigated by holographic methods. The comparison between human sense of similarity and measurements made in optical correiator system leads to the conclusion of delineating procedure in human vision tract.

Based on speckle multiple-shearing interferometry advanced by Prof. Y.Y.Hung, the paper deals with further study of its principles and proposes several kinds of new wedges, as well as analyzes the frequency spectra of double-exposure specklegrams. Discussions are also made on second order statistical characteristics of speckles when non-coherent superposition is effected for two speckle fields with no correlation at all. In order to raise the cut-off frequency of Fourier's filtering system, it is recommended in the paper that non-coaxial system be employed in place of coaxial system commonly used. Formulas for computation of changes in phase difference in speckle shearing interferometry have also been derived, and results of computations are compared with those of Prof.Hung.

A design of disk-type holographic diode laser beam scanner exhibiting the bow-free and aberration-reduced properties is described, which is based on ray tracing and least-squares optimization technique. Scanning with a small bow deviation of less than ±130 μm on a 30-cm scan length has experimentally demonstrated for a holographic disk scanner recorded with the aid of a computer-generated hologram.

Recent development of hologram filters for optical image processing is reviewed. Designing and fabricating techniques of the hologram filters are discussed, and the applications of the filters to optical image processings are shown, which include image operation, image restoration, matched filtering, image transformation and wavefront conversion.

This paper after recalling the advantages and shortcommings of dichromated gelatin explains the process of holographic image formation in the medium with the quantitative results we obtained. As an example we apply the technique of Holographic Optical Elements to the realisation of laser scanners.

Optical elements made by holographic technology are called Holographic Optical Elements (HOEs). HOEs have some advantages as conventional optical elements are not equipped and have been applied in various optical devices. We have applied HOEs, a pair of holographic gratings and a holographic lens, in an oblique incidence interferometer. In following lines we call it OII as Oblique Incidence Interferometer.

The intensity-dependent absorption was discovered through experiments in photorefractive crystal BSO. The nonlinear coupled-wave equation describing the dynamic mixed volume gratings was derived, in which self-diffraction and the intensity-dependent absorption was considered. The calculated results are in agreement with the experiment.

High frequency blazed holographic grating (1800 and 3600 lines/mm) were used to design low detection limit emission spectrometer (sub pph for several elements) and high resolution Raman spectrometer (oxygen line at 2 cm well resolved on the air spectrum).

The purpose of development and the processing steps to fabricate high resolution zone plates, especially holographic exposure and ion-etching, are described. Also the experimental results and some prospects are presented.

This paper deals with the research works in constructing a kind of narrow band holographic reflection filters based on the coupled wave, theory. The methods of construction were discribed, and properties of the filters were analyzed. A few points relevant to the coupled wave theory were discussed, and suggestions for future practical use of the filters were given. Data proved that the holographic filters have narrow band-width, high efficiency, tunability, and large area filters can readily be constructed with very low cost.

We present a 3-D holographic inspection device for laboratory and industrial use. The photosensitive recording medium is a thermoplastic film with an effective aperture size of 70 x 50 mm. The physics of holographic recording on a thermoplastic film is well-known. This medium has numerous advantages over traditionnaly used holographic recording media : it is efficient, cheap and allows for dry, in-situ processing. However many technical problems had to be solved in order to develop an easy-to-use thermoplastic holographic camera. We will describe this camera and give some examples of its use for non destructive testing in laboratory and industrial environment. We will also point out the future possible developments of this device and the specific improvements we are expecting, in particular in the processing of the interference fringe pattern.

Proposed is an exploratory study to verify the feasibility of an inexpensive micro-climate control system for both marine and freshwater pond and tank aquaculture, offering good control over water temperature, incident light flux, and bandwidth, combined with good energy efficiency. The proposed control system utilizes some familiar components of passive solar design, together with a new holographic glazing system which is currently being developed by, and proprietary to Advanced Environmental Research Group (AERG). The use of solar algae ponds and tanks to warm and purify water for fish and attached macroscopic marine algae culture is an ancient and effective technique, but limited seasonally and geographically by the availability of sunlight. Holographic Diffracting Structures (HDSs) can be made which passively track, accept and/or reject sunlight from a wide range of altitude and azimuth angles, and redirect and distribute light energy as desired (either directly or indirectly over water surface in an enclosed, insulated structure), effectively increasing insolation values by accepting sunlight which would not otherwise enter the structure.

The storage of volume phase holograms yields extremely large recording densities. The physical processes involved and the most important storage properties (sensitivity, density, storage time and hologram stabilization) are discussed for various electrooptic crystals.

Microscopic properties of holographic emulsions are studied using electron microscopy. Absorption spectra, diffraction efficiency and signal to noise ratio are measured on plane wave holograms. Good qualitative agreement is observed between microscopic and macroscopic measurements. From these measurements the main feature of holographic emulsions for solution physical development are obtained.

The performance of a liquid crystal light valve (LCLV) is studied experimentally. The effects of applied voltage across the LCLV, its driven frequencies and the input polarization of the reading light are investigated for both the liquicLtrystal (LC) being in the 45° and in the 90° twisted modes.

Major environmental problems all over the world require immediate efforts. Often, it is necessary to obtain quantitative data on pollution-induced effects on natural or man-made systems exposed to a variety of environmental parameters. Useful information about the object may be acquired in the speckle-fields produced by illumination with coherent light. Changes in the object require a corresponding correlation of the speckle fields, a task for which optical methods are employed. Examples of such applications are shown which demonstrate the usefulness of optical metrology in a field challenging scientific engagement.

A new technique of image encoding with a computer-generated oriented speckle screen as the encoding element is presented. The high contrast and high diffraction efficiency of this kind of screen. enable the degree of modulation. of encoded transparency and the ratio of signal to noise (SNR) of the decoded image to be improved.

A digital-optical hybrid system composed of a computer and a coherent optical filtering system is successfully applied to perform a real-time correlation of aerial stereo photographs. A LOLV (Liquid Crystal Light Valve) as an incoherent-to-coherent convertor and a thermoplastic photoconductor material for holographic recording of MSF (Matched Spatial Filter) are used, and a sharp correlation peak with a good SNR is obtained.

Without spatial modulator real-time optical logical operations are scarcely reported. However, in this paper a new method to realize 16 different real-time optical logical operations of two variables is proposed and experimentally demomstrated. It employs two cascaded grating filtering of 4f systems as well as auxiliary coherent beams.

By using a coherent optical information processing system with two orthogonal polarization channels we have measured the Fourier phase experimentally for several two dimensional real objects. One is a shifted square. Its Fourier phase values measured by experiment are in agreement with the calculated phase values quite well. Another object is a binary alphabet, the real part and the imaginary part of its Fourier spectrum has been investigated.

A method of high resolution image processing, based upon the theory of projections, is presented. By using photonical devices including holographic filters and an original technique for coding image information from the scanning apparatus, we have shown that the process allows a fast parallel reconstruction with high resolution.

This paper presents the application of data processing technique to the spray analysis of a diesel nozzle. Faced with a large number of oil droplets, we have used several techniques to improve the image quality and to make the processing more rapid and reliable.

A modified Stroke filtering technique is applied to high resolution micrographs of a conventional transmission electron microscope (CTEM). In a coherent optical processor synthetic holograms are used. They are produced by an analog electron-optical device. A micro-processor-controlled electron beam writes the amplitude component on a fluorescent screen. This image is photographed through an alternately shifted grating. The defects of defocus, spherical aberration and axial astigmatism can be reduced.

A new type of holographic encoding filter for correlation is presented. This lensless system is especially simple and easy to operate. The low requirements of adjustment of the filter convinience the real-time correlation of opto-electronic hybrid system.

The application of the advanced holographic inverse filtering technique to the three dimensional X-ray imaging greatly simplifies the decoding process and makes the size of the imaged object twenty times larger than the coded aperture, This might be considered as a stride forward toward the practisal use of flashing tomography.

From physical analysis, we explained that the phase matching is more important than the amplitute in match filtering. Thus the amplitute of Fourier transform of object can be modified to reduce the dynamic range, while the phase information keeps unchanging. The holographic match filter was made by dichromatic gelatin. High efficiency correlation can be obtained by this method.

Combining phase-only filtering with the idea of multiple exposure hologram, we propose a method to make a phase-only synthetic filter for multiobject recognition. When the filter is used in an optical correlation, several correlation responses appear on the output plane. According to the height of the correlation peak, we can easily recognize each of the multiobjects. The results of computer simulation are presented. The characteristic and application prospects of this correlation recognition method are discussed.

According to the optical general transformation theory, the phase mask distribution of optical sine transformation has been calculated. In order to avoid the diffraction loss of phase mask, optical waveguide method is used. Computation shows that the optical sine transformation can be realized by one phase mask, i.e. one half of cylindrical lens in 1D case and one quarter of spherical lens in 2D case. Experimental results coincide with the theoretical prediction.

Generalized Laplace operator is defined as Δr'r" = ∂r'/∂xr' + ∂r"/∂yr", where r', r" are numbers. The operation is realized in coherent optical system by means of spatial filters. The transmittance of the filter T r'r" (u,v) has been computed by the Lohmann method.Plotted drawing after suitable deminishing is inserted in the back focal plane in the imaging system. In the image plane of the system we obtain searched derivative of the input function g. Generally the derivatives could be various in different directions with any order. The images of Δr'R" for r',r" = 1/2, 3/4; 1, 3/2; 4/3, 7/4 are realized.

An improved holographic technique, the filter-holographic technique for imaging through fog is presented to increase the diffraction efficiency of the hologram and the SNR of the corresponding holographic replica. And also considered is a situation when both the object wave and the reference wave are scattered by fog. The corresponding experimental results are given.

A new density pseudocolor encoding of black-white photograph by Bragg effect of the reflective grating is presented. The method and process are given. A initial research of the mechanism is dealed with.

Using synthetic holograms made by optical and digital method deconvolutions for high resolution electron micrographs of spatial rotational variant system have been developed. This makes possible the restoration of the limited diffraction resolution of the electron microscope.

A system of the holographic fingerprint lock to which the optical correlative technique is applied is presented in this paper. The reliability of the system has been hproved by adopting unbleached phase hologram.