The state of development of one-dimentional holograms storage systems technology is discribed. In the experimental holographic system the writing (and the reading) was carried out simultaneosly by 32 channels with the speed of 16 Mbits/s. The capacity exceeded 1 GB for 200 mm diameter disk. The increase of the recording densi-ty by means of superimposed one-dimentional holograms is discussed. The new principle of optical recoding, based on the self-organization effect in biochemical structures, is considered.

The holographic recorder on optical disc pack was designed for solving the problem of recording high-speed data stream. This paper describes the new methods of frequency synthesis of Fourier holograms and heterodyne readout and their applications to designing the recorder1,2.

The local hologram recording on an organic photosemiconductors with IRAleating is studied. Advantages of the simultaneous method for the local holograms recording in comparison with sequential one is shown.The documents with formats A2-A4 are recorded as frost-free holograms of 1-5 mm in diameter with diffraction efficiency about 4-5%. The possibility of the local recording of one-dimensional microholograms onto moving reversible disk is shown.Microhologram quality stabilization on the whole disk surface has been supplied by the constant linear velocity of the disk. Single-mode optical fibers are used in recording- reading schemes.

Shape memory alloys as a new material for optical processor elements are suggested and temperature, time and energy characteristics of alloy specimens are investigated. Optical shutter, spatial light modulators and deflector developed on the base of shape memory effect are presented and the use of spatial light modulator as an input device of holographic correlator is considered.

The capability of the spatial-time light modulators (STLM) with the photosensitive organic polymer - liquid crystal (POP-LC) type for reversible registration of the optical information is shown 1-3 In . At the continious writing the following characteristics have been obtained: maximal resolution - 300 1/mm - diffraction efficiency - 23 % - holografic sensitivity - 410-7J/cm210 - time of switching-on (Ton) - 15 ms - time of switching-off (Toff) - 300 ms

Modal division multiplexing (MDM) can increase the information capacity of a single optical fiber through the separation of modal groups with indential wavelength. How to design mode demultiplexer is its key. G.A.Gasparian,C.S.Ronald and et al present Fresnel lens assembly and graded index rod lens for both accomplishing mode demultiplexing and output coupling. But the fabrication of them is complicated and higher cost. A composite holographic lens (CHL) with three focal points is introduced in this paper.This CHL can separate the mode groups, and converge them upon detectors or intasub-channer. It has also advantages of higher efficieny, lower cost, easier fabrication and so on. Thus the CHL can be used a mode demultiplexer in MDM system. Holographic lens (HL) is one of holographic optical elements (HOE). Its action bases on interference and diffraction of optical wave. When a diverging spherical wave interferes with a in-line converging spherical wave, we record the formed fringes using thick recording material. The recorded fringes are a set of hyperboloid situated in the volume of the material. A volume HL is obtained through processing of developing, fixing . Analyzing diffraction law of volume hologram we can know that the Bragg'ef-fect occurs and there is only one-order diffraction light but two-order or higher-order light. The diffraction efficieny of its one-order light is 100 % theoretically. When the volume HL is illuminated by original diverging spherical wave, a converging spherical wave is only diffracted from the hyperboloidal fringes, and focused at a point. The kind of volume HL is also called in-line HL with two focuses. According to the mode coupling equation of multimode fiber the far field at output end of the fiber consists of a number of con-centric annular rings. When two modes are excited and transtmited in the fiber, they emanate from the output end of the fiber, and are limited respectively to a cone cup angular and a cone angular which are concentric. Using the two emanating waves we design two off-axis sub-HLs correspondingly. Then we correct the two sub-HLs' aberration caused by wavelength shift. We eliminate Frensel reflection effect for diffraction efficieny. The dichrometed gelatin (DCG) having high diffraction effect is used as recording material. The two sub-HL is made at indentical plate and is called CHL. We make a simulate experiment and measure the parameters of the CHL. Higher coupling efficiency and higher signal-to-noise are obtained. Measuring results demostrate that the CHL used as a mode demultiplexer is feasible. Finally some problems about fabricating practical CHL are also discussed in the paper.

An approach to estimation of information properties of optical scanning imaging systems at computer output is considered.

An energy model of the method of sequential reproduction of holographic records is developed from the point of view of a general mathematical description.

Comparison between 2-D and 3-D hologram properties is made. Light-sensitive materials used for recording holograms of several millimeters in depth are considered, including the polymer light-sensitive material Reoksan, whose action is based on the sensitized reaction of photooxidation, and light-sensitive materials obtained by introducing a light-sensitive compound into porous glass. The results from the studies on the creation of optical elements, based on deep 3-D holograms - a supernarrow spectral selector with a transmission band width of 1 A, and an element for expanding the image in an orthogonal Walsh function system - are given. The properties of deep holograms of Walsh function light models are considered in detail. It is shown that each of these light models reconstructs the object corresponding to it independently of one another, which allows to use these models as a reference source in the multiple hologram recording.

Since Gabor's first demonstration of reconstructed wavefronts, many holographic techniques provided interesting tools and applications. Presently the future of holography is strongly dependent upon new holographic recording thin films. Because of their excellent responses to high spatial frequency grating recordings (up to 6800 cycles/mm), photopolymers and photocrosslinking materials seem to be good candidates to overcome some limitations. Dichromated gelatin films demons-trated excellent properties for permanent recording grating applications like HOE construction but they are humidity sensitive and they need a chemical development. Today's holographic works need real-time like recording material and law cost organic materials as DYE/POLYMER systems offer some possibilities. We present a review of research works done in our holography laboratories of COPL at Universite Laval. Using an automated spatial frequency analyzer designed at COPL, DYE/POLYMER systems are characterized for transmission holography and also for applications involving real-time holography and four-wave mixing techniques. Also, most of our characterization studies consider volume polarization holograms. The second subject is devoted to polarization hologram recordings in thin colored polyvinyl alcohol films. Those AZO/WA solid films are erasable and can be used for many thousands duty cycles for polarization volume holograms. Holographic characterization studies are conducted in order to know best experimental conditions and applications that allow to use those films. Finally, sensitized PVA films will be discussed.

It has been shown that the most perspective media suitable for high density optical and holography recording with improved base pa-rameters and first of all sensitivity are materials with complicated surface shape, weak chemical bonds, essentially heterogeneous. Among those are, thin layer systems with textured surface, thin films of composed materials as well as amorphous semiconductor films with the content of hydrogen. Comparative analysis of the properties and peculiarities of such media and of optical recording in them has been undertaken and carried out. Possibilities of developing research in this field along the lines indicated have been discussed.

Laser recording at λ= 514 nm in dynamic conditions is realized using thin mirror-like films of silver-gold particles dispersed in gelatin. The recording medium is prepared on the basis of vacuum deposited layers of doped silver bromide. The values obtained for the writing energy (0.33 nJ), reflective contrast (up to 4:1), resolution (0.3pm) show that this medium can be used for digital optical recording.

Discussed are the conditions of sublimation and condensation of the films from Ge-Se-TI glasses and the composition of the obtained films. They are irradiated for 10 minutes with a mercury lamp after which, depending on the glass composition and irradiation intensity, a shift of the absorption edge towards the longer wavelengths is observed. The kinetic curve for dissolution with sodium hydroxide and sodium sulphide show a negative effect of the photoexcited dissolution. This effect is changed to positive after annealing.

A direct imaging method is proved by which the amorphous Se-Te-Ag thin films are illuminated through a test pattern by direct contact and an image of the test pattern is recorded without further etching or stabilization. Some related with the process properties are investigated.

The aim of the present work is to study experimentally the influence of the matrix and readout light on the characteristics of holagraphic recording in bacteriorhodopsin containing samples. The photoinduced anisotropy is also investigated. On the basis of a simpified model of the photoprocesses in bacteriorhodopsin, numerical results are obtained. Using this model the basic relations in the experiment can be modeled numerically.

Studies on the sensitivity of dichromated gelatin ( DCG) to blue and red light are reported. DCG sensitivity is improved when gelatin bias hardening is applied through the use of hardeners. Electron donors are found to increase the DCG light sensitivity. For hologram recording with a He-Ne laser, methylene green dye sensitizer is added and the role of dye concentration and pH of the solution is investigated.

Silver halide materials for holographic recording have relatively low light sensitivity. This is due mainly to the small size of their emulsion microcrystals. The process of chemical sensitization of fine-grain emulsions is hampered by the following factors: 1. Microcrystals sized under 50 nm feature very high dimensional instability1. That is why when such emulsions are heated, processes of physical ripening ( dissolution of the small crystals and growth of the big ones) take place after which the sensitivity specks remain under the grain surface. The crystal growth is favoured in polydisperse systems, and such are almost all ultrafine-grain silver halide emulsions2. 2. The size of the microcrystals in the emulsions for holographic recording, that we investigate, is 10 nm. Electron micrographs show that grains of this size are spherical and do not have a clearly pronounced crystal form. There is a lot of equivalent, but not sufficiently deep defects on the surface. That is why, there are substantial difficulties for carrying out chemical sensitization whose objective is the formation of one or more efficient sensitivity specks on the surface of the microcrystals.

The wide practical application of pulsed holography is conditioned by the feasibility of recording and studying fast processes ( surface displacements, relief changes, vibrations, etc. ).

The nonlinearity of silver holographic recording materials is studied quantitatively by means of an analytical approximation of the amplitude transmittance versus exposure characteristic curve. The influence of film nonlinearity on the optical transfer function of a diffraction limited optical system is examined. Optimisation of the modulation transfer function and holographic sensitivity in respect to average exposure (biasing point) and modulation depth are also considered.

The objective of this paper is to provide an overview of the art organic media for photofabrication of holographic optical elements. Perforce data are presented for a variety of relevant organic light-sensitive media manufactured by Soviet scientists.

A Lamda Physics EMG 102E excimer laser operating at wave-lengths of 248nm (KrF) and 193nm (ArF) was employed either to transfer structures by 1 : 1 shadow printing from a micromask onto a resist coated wafer using ablation technique or to develop ion exposed resists by blanket exposure at the ArF line.

The mechanism of self-enhancement effect of amplitude-phase ho-lographic gratinosin As₂S₃ films as well as possible applications of this effect are considered.

The present state of research in the field of the holographic cinematography in the USSR is reviewed. Theoretical foundations of the holographic cine-process are discussed. Research work carried out in the USSR is described. It proves that the use of the holographic cinematography is promising.

I present a model which describes the effects of bandwidth and peak replay wavelength shifts on the image color of color display holograms. The model applies to white light reflection holograms recorded with three component colors, but is also applicable to other types of color holography such as pseudocolor techniques. A computer program is used to transcribe the predicted spectral power distribution of the color hologram into coordinates plotted on a standard chromaticity diagram. The increase in bandwidth between recording in laser illumination and replay under white light causes a proportional shift of the replay color towards white, and is thus one of the causes of desaturation found experimentally in color holograms. The model is used to show the shifting of the image color when the peak replay wavelengths of the component holograms are changed as a result of shrinkage or swelling of the recording medium; this can have devastating effects on the image color reproduction, especially when the peak of the red or blue components moves to a longer wavelength.

The chemical processes involved at development and bleach stages of silver halide holograms sometimes show variations that are difficult to explain, but are related to procedures that are normally not considered in "classical" photography. This paper is a second of a series describing some work about those effects, and some efforts to minimize variations by the use of more or less controlled automatic development machinery. In this presentation, we will deal with the influence of the quality of prebleach rinse water, of developer temperature and of emulsion batch.

The development of holography as decoration for architectural glass is at an early stage. Some considerations pertaining to such an application and problems arising therefrom. Aspects of the author's own work which may indicate possible solutions.

The characteristics of conformational optical nonlinearity of nematic liquid crystals (NLC) were investigated. Expressions for NLC nonlinearity tensor as a function of order parameters are obtained for the small concentration of fototransforsed solecules.The dynamic holography procedure has shown that the contribution to the NLC refractive index change under optic nonlinearity lade by the order parameter change is dosinant.The effect of critical increasing of the parameter of nonlinearity near the nesatic-isotropic liquid phase transition was predicted and experimentaly revealed by dynamic holographic method. It was shown that the effect was caused by the increasing of correlation of the photoconformer concetration fluctuation and polarizability molecular fluctuation near phase transition.

The schemes of optical bistable systems employing the dynamic holographic gratings are analysed. A counter-propagating four-wave mixing in a medium with cubic nonlinesrity and local response is used for dynamic grating recording.

In this paper the problem is considered of essential increasing of fiber memory device informative capacity using optical solitons. It is shown that for optical signals regeneration both Raman scattering and nonstationary parametric amplification of soliton pulses can be applied. On the basis of Raman regeneration the two schemes of fiber memory devices are proposed. The operating of dynamic memory device using soliton information's carriers are estimated. The real-time transformation dynamics of ultrashort pulses is investigated for nonstationary parametric amplification The quantitative assessments of parametric. regeneration process are presented. The advantages of the soliton pulses parametric regeneration in comparison with Raman scattering regeneration are also discussed.

The influence of magnetic field on the wave-front conjugation at degenerate four-wave mixing in resonant-absorbing atomic iodine va-pors has been studied theoretically. It is shown that depending on the magnitude and direction of the magnetic field, interacting waves pola-rization, as well as on the interaction length and intensity of pump waves, the conjugation efficiency can both increase and decrease. The greatest increase in the wave-front conjugation efficiency of radia-tion with a frequency corresponding to the line centre F =4- r =3 is attained in a transverse magnetic field with the interacting waves polarization orthogonal to the field.

Recently it has been observed an effect of prolonged memory of holographic recording without applied electric field in photorefractive Bi12Ti020 (13T0) crystals at room temperatures. High frequency holographic diffraction gratings (with K = 2 71- / Λ - 3.104 mm-1 , where A is the grating period) are recorded in BTO with He-Ne laser. The homogeneous interfering beams are incident on two mutually perpendicular crystal surfaces. This is the orthogonal recording geometry².

Holographic subtraction of two images was first realized by Gabor et al-1 by using a successive recording of the two images with a 180 degree phase shift between them and subsequent readout of the composite hologram. Other techniques for image subtraction are proposed2-5 . In Ref. 2 the ,rr phase shift between the image complex fields is ensured by spatially modulation of the images by periodic waves that are themselves 180 deg out of phase. Phase conjugation and Stokes' relation are also used3'4 . In Ref. 5 subtraction is fulfilled by the help of two orthogonal lineary polarized waves.

The first ever dynamic recording of total internal reflection holograms is reported. Investigations are carried out on the diffraction efficiency dependence on the dye concentration, exposure time, spatial frequency of the recorded gratings, and on the polarization dependence of the reconstructed wave.

The use of photoanisotropic materials for holographic recording was first proposed by Kakichashvilil in order to registrate and reconstruct the light wave polarization (polarization holography). In this paper we have made a review of the original investigations on polarization holography carried out in our laboratory.

F.Weigert first described the effectoccording to which some media become anisotropic,if they are exposed to linearly polarized light! The new impulse to the study of Weigert-effect in different media contributed to the development of laser technique and polarization holography,for whose material realization it is necessary to use photoanisotropic media:3 Our interest to the basis of organic dyes is explained by their granularitiless,by the possibility of achieving high values of diffraction efficiency by comparatively high sensitivity and by the relative simplicity of receiving layers.

The properties of reflection unslanted gratings recorded in materials with anisotropic response are considered. The state of polarization of the diffracted wave is analyzed in a simple model by the help of Jones matrix method.

Disazobenzols are dyes of the type: Y X-cc:-N=N a N=N 0 Z Like in monoazobenzols, their molecules exist both in trans- and cis-forms, irradiation with light in the transabsorption band causing transcisisomerization. This changes the absorption spectrum (hence, the refractive index) of the samples, and therefore, such systems can be used for optical recording. Normally, the transabsorption band of these dyes is in the longer wavelengths than that of monoazodyes. The aim of our investigation was to produce a rigid solution of a dye in a polymer, suitable for optical recording in the red region. Most suitable among the great number of investigated dyes proved to be:

Experimental results on the decay of photoinduced birefringence in methylred / polymer after cut-off of the exciting light are presented. Optical anisotropy is induced by an Ar laser beam ( λ = 488 nm), and the induced birefringence is detected by a He-Ne laser. The decay in the photoinduced anisotropy is investigated at different temperatures and intensities of the exciting light.

The aim of this work was to produce a new type of diffraction grating, having two diffraction orders only ( ±..1), whose intensities are proportional to the intensities of the left-hand and right-hand circularly polarized components of the light wave, incident on the grating. According to the existing theoretical considerations [1], such a grating can be recorded holographically by irradiating a recording material, possessing linear photoanisotropy, with an interference pattern, resulting from the interaction of two coherent wavefronts with orthogonal circular polarizations.

An instrumental device for complete, accurate, fast and simultaneous measurement of all parameters of quasi-mono-chromatic light: wavelenth, intensity, degree and state of polarization is presented. The performance of the device is based on a new principle which makes use of a polarization holographic grating. The measured light is split into four beams of intensities I , 12 , 13 and 14 . To determine the four Stokes parameters, these intensities are measured simultaneously by four photocietectors and the electric signals are processed by a microcomputer. At the output of the device all the four Stokes parameters are given as well as the ratio of the polarization ellipse axes and its azimouth. The use of linear ray detector for measurement of 13 and 14 intensities makes it possible the evaluation of light wavelenth through analysis of light beams angle of diffraction.

Investigations on silver halide emulsion layers with a pronounced Weigert effect are carried out in order to demonstrate the possibilities for using them as a real operating model of an optical disk for digital information recording. Quite interesting is the production of a reversible thin-film photodichroic medium with a thickness below 1µm.

The holographic method was created by D.Gabor in 1948.1 Gabor proposed to divide the process of image formation in two stages. At the first stage the complex amplitude of the field scattered by an object is imaged on a material carrier - on a hologram. At the second stage the material carrier organized in a such way is used for reconstruction of the repeated formation of the original object field. For imaging characteristics of the object field on the material carrier Kabor proposed to use a two-dimensional photographic recording of interference pattern with a reference wave which reconstructs the object field when it illuminates the received recording.

The diffration efficiency of a grating photoinduced in an FA(I1)KCili crystal by two perpendicularly polarized light vibrations, may be amplified by coupling the directly transmitted and diffracted beams. The best results are obtained for the reading wavelength λD corresponding to the isobestic point of the crystal.

Optically addressed spatial light PRIZ modulators are used as input devices in coherent optical information processing systems. These modulators have a high information recording density (ZIO' bit/cm2) and provide low intrinsic noises of coherent optical spectrum analyzers and correlators. In our experiments we used the BIM spatial light modulator in coqinatiqn with image intensifier to increase sensitivity up to =10-5 J/am' and to get a broader wavelength range for the recording light. The transfer function and speed of operation of the PRIZ/image intensifier device have been studied. The use of the new device for recording real-time holograms of diffusely scattering objects is discussed.

A theory of polarization holographic recording and image reconstruction has been worked out for three-dimensional photoanisotropic medium in kinematical approximation. The expression of wave fields formed by a hologram have been received at arbitrary coefficients of vector and scalar reactions and at a reference wave of elliptical polarization. The possibility of adequate image reconstruction in the particular case of a reference wave of linear and circular polarizations has been proved which is realized at a definite relation of connection of vector and scalar reactions with the original characteristics of the medium and the intensity of a reference wave. Under these conditions a conjugate image has been transformed according to polarization.

Difference holographic interferometry (DHI) is a useful method for direct optical comparison of the dynamic be-haviour of two nominally identical objects (master and test object). A simplified technique of DHI was recently developed by the authors. This method, the single reference beam DHI (SRB DHI), has an inherent drawback. Due to the complexity of the difference interference fringes, the difference interferograms are of relatively low visibility in comparison with those obtained by the dual reference beam DHI (DRB DHI). The present paper reports the evaluation and measurement of the difference interference patterns obtained by SRB DHI for unstructured object beams and for actual phase objects (filament lamps), too. In the first case the reconstructed holographic interferograms were directly scanned. In the latter case the holographic interferograms were photographed. It was shown, that, albeit with a reduced visibility, usable difference holographic interferograms can be obtained by this method.

Difference holographic interferometry makes the direct interferometric comparison of two objects possible by using holographic illuminations. In the present paper the case of phase objects is investigated at direct transillumination.

Theoretical analysis and experimental results on holographic moire contouring (HMC) of difussely reflecting objects are presented. The sensitivity and application constraints of the method are discussed. A high signal-to-noise ratio and contrast of the fringes is achieved through the use of high quality silver halide holographic plates HP-650. A good agreement between theoretical and experimental results is observed.

Results from investigations on non-destructive testing of machine parts, using comparative holographic moire interferometry, are reported. The specimens are metal castings for bearing bushings before their precise mechanical machining. The results obtained experimentally are compared to those from X-ray defectoscopy and from a numerical model

Results from theoretical and experimental investigations on coherent-optical and digital processing of holographic moiregrams are presented. The cases of holographic moire contouring, comparative holographic moire interferometry, and in-plane displacement measurement in sample bodies with mechanical stress concentrator, subjected to pure tensile loading, are considered.

For quite a number of years Electronic Specklepattern Interferometry (ESPI) has been an attractive alternative to Holographic Interferometry in industrial surroundings. As for conventional holographic interferometry, the information which is primarily obtained, is an image of the object superposed by a fringe pattern related to object motion. For harmonic loading integration over many periods leads to Besselfringes whereas subtraction mode used for deformation analysis leads to cosinefringes. In both cases a qualitative evaluation can be performed by visual inspection of the fringe pattern whereas quantitative analysis requires digital image processing, the latter becomning increasingly attractive with the access to more efficient PC's. A very prominent feature of ESPI is the possibility of aquiring one "hologram" per 1/25 sec. This makes it possible to obtain information of both vibrational amplitudes and phases within reasonable timeframes. This paper presents results of qualitative ESPI measurements on two transducers (an electretmicrophone and an accelerometer) identifying critical resonances. In both cases the measurements resulted in improved transducerdesign. Further presented are results of quantitative deformation analysis by phaseshifted ESPI followed by digital imageprocessing using a very simple phaseshift algorithm.

1. Presentation In 1988 the "Optics Group" was formally established as a part of the Physics Laboratories I and III at The Technical University of Denmark. The Group consists at present of 12 persons: 1 Professor 6 Lecturers 3 Ph.D. Students 1 Post Graduate Researcher 1 Laboratory Tecnician

Two fully automated and essentially different methods for Young's fringes analysis are applied to thermal expansion coefficient determination of engineering ceramics by double-exposure speckle-photography. The first one creates fringe structures and fits them to the experimental images. The cross-correlation functions between the given image and the generated fringe structure are calculated and serve as a measure of coincidence. In order to reduce the computational demands,the second method analyses the fringe intensity profile along four selected directions.

The aim of this work is to analyse the bulk and local mechanical features of specially light concrete under load. Observation of yield zone, microcracks appearance and crack development is followed at the tip of incision made in advance. Tfte various techniques of holographic interferometry were used for optimal observation sensitivity to the persumed displacement and for coherent speckle noise elimination. The actual fringe patterns are interpreted on the basis of finit-element model analysis of the rectangular beam under imposed boundary conditions.

A method for measuring the change of the refractive index of a loaded body is proposed. The change of the tickness is measured holographicaly, by two double exposure holograms on each side of the body, after delivering an opaque coating onto specimen. On such a way errors, which make occurs during the loading, because of some slope of the specimen, are avoid. A simple plane parallel state of stresses is used for quantitative measurement of the change of the refractive index. Evaluation of the error is made and some results of experiments carried out to approve the method.The possibilities and the future of the method are discused.

In this work, a holographic interferometric method and device for determining the refractive index change in transparent samples is proposed that can find application in measurements and nondestructive testing of non-homogeneities, cracks and other hidden defects.