The holographic method for investigation of a static triplet - triplet (T-T) annihilation kinetics in rigid mediums and diffusion-controlled annihilation kinetics is proposed. The annihilation stage of the reaction T plus T yields 0 is visualized by measuring of the diffraction picture dynamics. It has been found theoretically that the second range diffraction maximum is appearing in consequence of the nonsinusoidal grating form. The analytical expressions for the intensity of first and second range diffraction maximum are obtained. The time dependence of the second range diffraction maximum shows some features. The light intensity increases with time in the initial stage of the kinetics. Values of effects are estimated and calculation results of the kinetics are represented.

Photopolymers usually present lower energetic sensitivity, and to narrower wavelength range, than other more conventional recording materials for holography such as dichromated gelatins. We have previously overcome some of these disadvantages using a mixture of visible light photoinitiators. In present communication we describe a new aqueous photopolymer containing the monomers, methylenbisacrylamide and zinc acrylate, the initiators 4,5- diiodosuccinyfluoroscein (2ISF) and methylene blue (MB), and the coinitiator sodium p-toluensulfinate. This formulation exhibits a dramatic enhancement of the energetic sensitivity upon radiation with 514 or 633 nm light (Ar or He-Ne laser respectively), with regard to the same mixture but with only one dye, reaching maximum diffraction efficiencies of 15 - 20% with 15 - 60 mJ cm^-2. This enhancement is explained through a more efficient photogeneration of initiator radicals by the ground-state formation of on ion- pair complex between cationic (MB) and anionic (2ISF) chromophores, the proximity of which must favor electron transfer between groups. This must compensate the observed absorbance decrease at 514 nm, with regard to the absorbance of 2ISF alone in the same medium (maximum absorption at 490 nm). A clear absorbance increase at 633 nm, with regard to the absorbance of MB alone (maximum absorption at 660 nm), must also favor the photopolymerization.

Photopolymers have been analyzed as holographic recording materials by measuring their diffraction efficiency in relation to the index modulation that is obtained with these materials, their spatial response and their energetic and spectral sensitivities. However, even though they are considered good recording materials for the storage of information and for the production of holographic optical elements, little information has been offered on the image quality that these recording materials produce. Among the different sources of noise in holography, noise gratings have been analyzed extensively in photographic emulsion due to the granular nature of these recording materials. However, information about photopolymers is quite scare. For material that work in real time, it is the transmittance function which measures the appearance of noise gratings given that the presence of this noise source manifests itself when transmitted light decreases due to diffraction. We present a theoretical model that relates the photopolymer transmittance function response with the noise grating structure. In keeping with the experiments we can say that noise gratings also appear in photopolymers which proves the presence of a certain granular structure in these materials. Their appearance and storage in these materials can be used as a methodology for the optimization of these recording materials.

We studied energy coupling between gratings and angularly multiplexed 20 gratings with a uniform diffraction efficiency within 25 micrometer layer thickness of dichromated gelatin. The dependence of diffraction efficiency on beam ratio is given. We recorded a matrix form memory of nxmxp elements, where n and m are the rows and columns and p the number of multiplexes. For indication only, n equals m equals 10, p equals 20, the surface area of the matrix is 1 cm². Color diffractive images and digital data are illustrated as well as video, cartography and medical applications.

The birefringent property of the mylar sheet which is used as a substrate for DuPont photopolymer film is measured experimentally and its effect on the hologram recorded on the film is investigated. The fringes produced when a diverging laser beam is passed through the sheet forms symmetric patterns of hyperbolas and parabolas which are similar to that when the diverging laser beams are passed through an anisotropic crystal sheet which has its optic axis aligned near or parallel to it. To determine the influence of the mylar sheet on the quality of hologram, a hologram with the property of a lens, i.e., holographic lens is recorded on DuPont photopolymer film HRF-600-20 by directing the recording beams, green line of Ar laser, to the mylar sheet side. When the hologram is illuminated a halogen lamp covered a red filter, many parasitic fringes appeared along with the image of the lamp, which resemble to the fringe patterns formed by the mylar sheet. The parasitic fringes indicates the locations of low diffraction efficiency along the surface of the holographic lens. When the holographic lens is recorded by directing the beams to the glass side, no visible parasitic fringes are appeared. During the recording process of the holographic lens, its diffraction efficiency changes are monitored with a He-Ne laser to obtain the maximum efficiency. The efficiency is continuously increased until it is saturated.

A model of holographic recording in thermoplastic materials has been developed. The effects of the nonlinear characteristic and the MTF of the material were included in a double Fresnel-Kirchhoff integral to evaluate the reconstructed image. The model was applied to calculate the reconstructed images of microline objects (3 and 5-element Ronchi rulings). The results suggest that it is possible to reconstruct high resolution images from such holograms by optimizing the recording conditions.

Holography and holographic interferometry in spite of their attractive features are rather rarely used for industrial inspections of products and components or in medical practice due to relative complexity, costs, lengthy multi- stage procedures, need of dark rooms and vibration insulation. But the most of these drawbacks might be avoided if momental holography on silver halide (SH) media is involved. Momental technique simplifies drastically the holographic process and ensures quasi real time or real time (in situ) bright reconstructions from holograms, real time or double exposure holographic interferograms. This technique permits the user to avoid dark rooms and to work with standard office or industrial illumination of 0.5 klx or even much more. Moreover, very bright holograms and holographic interferograms might be obtained also in the street in a diffused daylight or even under strong direct sunlight illumination. High quality off-axis and reflection holograms, interferograms, HOE were obtained utilizing ruby, semiconductor, He-Ne and Ar laser sources. Agfa-Gevaert 8 E 75 HD films and plates, Russian PFG-03 and PFG-03 C (color) plates were used as recording media. Different levels of external polychromatic illumination were applied to holograms and holographic interferograms during production. Extremely high levels (more than 50 klx) were also tested. Bright holographic reconstructions were obtained even in such unpromising environment. Photographic images from such holograms are presented. One of the holograms was momentally photoprocessed in the light of projector (a few klx) during presentation of this paper at the conference 'Holographic and Diffractive Techniques' in Berlin. Another unique feature of the technique: extremely long-term storage of holographic data on SH media in latent form is shown. It relates both to holograms recorded with cw lasers and to those recorded with pulsed laser sources. The latter case is the most interesting because it was not possible previously to avoid rapid fading of latent images in pulsed holography on SH media. Finally, quite novel results and photographic images from the first SH holograms obtained with no liquid baths are presented.

Holographic microscopy with conjugate reconstruction for the interferometric determination of three-dimensional displacement is described. Two different experimental setups for the exposure of the holographic interferograms were used, one for the application of the spatial heterodyne technique, the other for the application of phase shifting. Three holograms for different illumination directions recorded on one holographic plate are reconstructed conjugately, and spatial heterodyne technique as well as phase shift technique were used to evaluate the interferograms. Only by conjugated reconstruction it is possible to obtain a perfectly optimized interferometer for the static evaluation method. The evaluation of interferograms which are strongly disturbed by speckle noise can be performed successfully. A comparison of the results of the application of both techniques is given.

In this paper we present the results in the development of large format (20 cm by 50 cm) cylindrical holographic mirrors (CHMs) recorded in dichromated gelatin, for use in solar chemistry applications. The realized spectral reflectivity of 400 - 440 nm is adapted to the sensitizer zinctetra-phenylporphine. Effective efficiency of the mirror (i.e. referred to the incident radiation at the desired wavelength of 420 nm) is 75% with excellent homogeneity across the aperture.

Large scale holograms of the reflective type are applied on concentrating devices for photovoltaics and solar chemistry as well as in building applications. Especially in window applications holograms with best homogeneity in large scale are demanded by the house owners and architects. To meet this demand, we have used a scanning laser beam and internal total reflections in a moving prism for recording. This technique is usually applied to record holograms for the near infrared (NIR), but due to controlled mixture of gelatine and water-soluble polymer in addition with a matched thermo-chemical treatment the central wavelength can be adjusted in a wide range to special requirements. For application in solar chemistry we manufactured parabolic concentrators with holographic foils of size 50 cm by 10 cm in dichromated gelatine (DCG). The central wavelengths can be chosen between 400 nm and 600 nm with bandwidths of 50 nm as well as up to 200 nm. The comparison of the transmitted and reflected spectrum shows good agreement and consequently minimal scattering losses of the layer. A photovoltaic concentrator concept uses a silicon solar cell and a spectrally matched broad band spectral characteristic is required. A bandwidth of 600 nm can be achieved with a stack of two foil or even a single foil. Large scale e investigations (up to 100 cm by 10 cm)² show best results of diffraction efficiency and large scale homogeneity.

An iterative method in this paper reports the design of a phase diffractive optical element (DOE) that has a transmission function in the form of a linear combination of a finite number of Hadamard functions with different carrier spatial frequencies. If such a DOE is coupled with a spherical lens and illuminated by the light wave, the light intensities in desired points will be proportional to the squared modules of the expansion coefficients of that light field in terms of the Hadamard basis. It is found that 80% of the incident light energy is accounted for by the formation of the desired coefficients.

A scattering light pipe has been designed for a non- conventional illumination system. The spatial distribution of the light is controlled by diffusers which are deposited on top of the pipe faces. The first realized samples have used a scattering paint as diffuser which has good optical properties but is unsuited to fabrication. Diffusers based on micro-optics have the potential to replace favorably classical Lambertian diffusers. Micro-optical diffusers (MODs) allow the generation of perfectly defined scattering distributions which are well adapted for the design of an optimized light pipe. A further advantage of such surface relief elements is their potential for cheap mass production. The strengths and limits of micro-prisms, micro- lenses, and gratings are evaluated in view of their use as diffusers. Finally a proposition for an optimized design of the illumination light pipe is presented.

Cuneiform inscription signs are three-dimensional objects composed of wedge-shaped imprints that vary in number, size, and orientation of wedges from sign to sign. The properties such as features in object and Fourier space, or similarity measures between different samples of signs have been investigated. The main optimization steps describing the development of experimental systems and techniques for the characterization of the signs are given here.

The complex transmittance and selected physical parameters (molecular director, twist angle, optical flatness, static intensity contrast ratio) of liquid-crystal displays removed from a commercially available Sanyo video projector are studied. The phase modulating behavior and phase and amplitude coupling are determined as function of the video drive signal and the polarizer/analyzer configuration. The suitability of the LC displays as input modulator in a joint transform correlator (JTC) setup is shown. Correlation experiments with input signals taken from an original Babylonian cuneiform inscription are carried out. The influence of small rotations of the target sign as well as small changes in size of the target on the correlation spot height is studied.

An evanescent wave can be converted into a propagating wave by means of gratings. In particular, it is possible to couple an evanescent wave into a diffractive optical element in order to fulfill a specified optical function.

The main drawback of a transmission type holographic screen is the color separation when the color images are projected on it due to its high dispersion. This drawback can be overcome by recording the screen with use of a long narrow slit type diffuser as an object. With the diffuser, a holographic screen of size 30 by 40 cm² has been recorded to display a full color stereoscopic image. The images displayed on the screen show a good resolution and are naturally colored, except near the edges of the screen. The color distortions in the edges of the screen are reduced by a lenticular sheet attached to the screen. The lenticular sheet enlarges the viewing zone. The image that appears on the screen is bright enough to watch even in a normally illuminated room

In a recent publication (Ostromoukhov95), a new image reproduction technique, artistic screening, was presented. It incorporates freely created artistic screen elements for generating halftones. Fixed predefined dot contours associated with given intensity levels determine the screen dot shape's growing behavior. Screen dot contours associated with each intensity level are obtained by interpolation between the fixed predefined dot contours. A user-defined mapping transforms screen elements from screen element definition space to screen element rendition space. This mapping can be tuned to produce various effects such as dilatations, contractions and non-linear deformations of the screen element grid. Although artistic screening has been designed mainly for performing the creation of graphic designs of high artistic quality, it also incorporates several important anti-counterfeiting features. For example, bank notes or other valuable printed matters produced with artistic screening may incorporate both full size and microscopic letters of varying shape into the image halftoning process. Furthermore, artistic screening can be used for generating screen dots at varying frequencies and orientations, which are well known for inducing strong moire effects when scanned by a digital color copier or a desktop scanner. However, it is less known that frequency-modulated screen dots have at each screen element size a different reproduction behavior (dot gain). When trying to reproduce an original by analog means, such as a photocopier, the variations in dot gain induce strong intensity variations at the same original intensity levels. In this paper, we present a method for compensating such variations for the target printer, on which the original security document is to be printed. Potential counterfeiters who would like to reproduce the original with a photocopying device may only be able to adjust the dot gain for the whole image and will therefore be unable to eliminate the undesired intensity variations produced by variable frequency screen elements.

As a part of a project for using short laser pulses and holographic techniques to measure three-dimensional shapes, measurements have been carried out of the pulse shapes of laser pulses from a mode-locked argon-ion pumped dye laser with autocorrelator, light-in-flight recording by holography and nonscanning white-light interferometer. The aim of the study is to find a reliable, inexpensive and fast method for measuring the pulse length of laser pulses in the picosecond region, when exposing and reconstructing the light-in-flight hologram, in respect to pulse width, symmetry and signal-to- noise ratio. Experimental results, along with the theoretical background, from these tests are accounted for in this presentation.

Speckle photography for small displacements can be carried out rather easily. It is a well established method. Unfortunately problems arise when specklegrams must be obtained in real time. Silver halide media infer lengthy multi-stage photoprocessing of specklegrams. Real time speckle photography utilizing non-silver media can be implemented but the techniques involved are rather complicated. Extremely simple and inexpensive approaches to speckle photography are introduced here. They combine positive features of speckle photography and momental holography. This permits the user to produce quasi real time specklegrams within a few seconds. High quality speckle photographs were obtained with different laser sources on high resolution silver halide media: Russian PFG-03, PFG-03 C (color), Agfa-Gevaert 8E 75 HD films and plates. Very good specklegrams were obtained also in lighted environment. Hybrid holospecklegrams i.e. holograms and speckle photographs of the same object were obtained simultaneously on the same media. Such holospecklegrams were also produced within fa few seconds. Quite unexpectedly good specklegrams were recorded even in water. Photographs of momentally produced specklegrams are given.

The paper describes a simple interferometer which has been used to visualize the airborne noise induced, low frequency, very small amplitude, vibrations on thin plastic membrane mirrors. Plastic membrane concave imaging mirrors are the patented invention of the first named author and have been the subject of papers since 1983. The mirrors have already been used for inexpensive large aperture flow visualization systems and the transfer of images in holography. The mirrors are being used currently for high definition, natural color large aperture stereoscopy and self focused real imaging with no spectator glasses, i.e., 3D imaging systems. As the mirror diameter increases for the same type and thickness of membrane material then the fundamental resonant frequency decreases. For very large diameters the mirrors become susceptible to aerial noise of a few Hertz, this being equal to the fundamental resonant frequency. For the small mirror tested for this paper, the fundamental resonance was approximately 600 Hz. The mirror was, however, continually vibrating due to aerial room noise frequencies of between 1 Hz and 20 Hz. No proper nodal patterns can be seen, these only occur at frequencies above the fundamental. The vibrations are extremely small, requiring an interferometer to visualize and record amplitude and frequency. The vibration energy can be destroyed by several techniques. The mirrors have already been used for long exposure white light reflection holograms, effectively no vibrations at all on the mirror surface, achieved by destroying the vibration energy.

Few conditions are absolutely necessary to improve the accuracy of quantitative measurements of displacements in an interferometer: the accurate calibration of the phase- shifter, the control and the suppression of the interferometers drift. Calibration consists in measuring phase shifts generated by piezoelectric transducers (PZT). We have developed an original in-line PZT calibration based on speckles intensity modulation. A new method to measure the phase drift versus time in the whole interferometer (reference and object arm) is presented. Two innovative methods to compensate phase drift in real time allow accurate displacements measurements. Both compensation methods do not use a feedback loop active control during DSPI measurements. So it allows us to avoid overshoot or oscillation problems linked to the feedback loop. All presented methods allow inexpensive data processing and were successfully applied to an out-of-plane sensitive interferometer. PZT calibration, drift measurements and real time compensation are automated.