This PDF file contains the front matter associated with SPIE Proceedings Volume 8074, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Digital holographic microscope (DHM) allows for direct accessing to the quantitative phase contrast. In this way it becomes a completely non-invasive tool for a contrast living cells observation and the dry-mass density distribution of a cell measurement. Current DHMs use the off-axis holographic setup based on conventional interferometers, which properly work with the coherent illumination. However, this type of illumination is inconvenient for microscopy because of the coherence noise, unwanted interference and a worse lateral resolution. An uncompromising solution to this problem is a DHM based on the Leith achromatic interferometer. While in this setup an off-axis hologram is formed with an arbitrary degree of the illumination coherence, the resolution and the image quality typical for an incoherent-light widefield microscopy can be achieved. Moreover, coherence gating can be introduced which makes the DHM image similar to that of confocal microscope. Hence the character of the DHM image is controlled by the coherence between two extremes: fully coherent-light holography and confocal-microscope-like imaging. The above described possibilities were proved experimentally by the coherence-controlled holographic microscope, which is a DHM based on the achromaticinterferometer. Living cancer cells were observed and their motility was evaluated in the quantitative phase contrast. The presence of the coherence gate was demonstrated by imaging of model samples through a scattering layer.

The aim of this research is to calculate the refractive index of transparent atmospheric aerosols, which have biological origin, using a digital holographic microscopy technique (DHM). The samples are collected on filters, using miniature impactors for particles with dimensions smaller than 10μm (on even one axis), from a height of over 20 meters, in Magurele, a rural location near the urban and industrial agglomeration of the capital city, Bucharest. Due to their organic or inorganic origin, each atmospheric aerosol particle has different size, shape and optical properties which have a determinant role in LIDAR measurements. We record on a CCD camera hundreds of holograms which contain the diffraction pattern from every aerosol particle superposed with the reference wave. Digitally, we scan the entire volume of one particle with nanometric resolution (using an algorithm based on the Fresnel approximation). The calibration was done using an object with known dimensions fabricated by e-beam lithography and some complementary measurements were done in confocal microscopy. Our analysis separates four main classes of atmospheric aerosols particles (wires, columns, spherical fragments, and irregular). The predominant class in the investigated period is the first one, which has biological origin and the refractive index was calculated starting from the phase shift introduced by them in the optical path and models for their cylindrical shape. The influence of spatial filtering in the reconstructed object images was investigated.

We discuss some common sources of noise which affect the quality of reconstruction in digital holography. We show that by using holograms obtained with independent illumination patterns, we can suppress these noise sources in a unified manner and improve the image quality while reducing the memory usage.

Digital holography is used for a wide range of applications. A lot of techniques deal with holographic microscopy or the 3D shape measurement of objects. We present our approaches to these applications. To increase the resolution of a microscopic imaging system a method for aperture synthesis is applied, where the spatial frequency shift, the global phase differences and the amplitude ratios of the individual sections of the Fourier spectrum are measured by using an overlap between them. It is shown that this method can be performed out including sub-pixel accuracy. The experimental holographic setup uses tilted illumination beams realized by an LCoS SLM, which can be easily adapted to the numerical aperture of the microscope objective. For the 3D shape measurement of arbitrary diffuse-reflecting macroscopic objects a novel approach is demonstrated, which uses common digital holographic setup together with a second CCD and an LCoS to modulate the object wave. Our idea is to capture a series of holograms from multiple positions and to apply concepts of structured light photogrammetry, which deliver more accurate depth information. The method yields a dense 3D point cloud of a scene.

Computer generated holograms (CGH) are expected in holography 3D display for the reconstruction of realistic or artistic virtual 3D objects. We propose a CGH approach that combines computer graphics (CG) technology and wave propagation theory. Our approach is based on the following assumptions. Virtual 3D objects are described by the popular computer graphics format that uses a set of triangular surfaces, and CG technology can be used to render ray information on these surfaces. The hologram plane is flat. Each triangular surface is tilted (that is, not parallel) relative to the hologram plane. An advantage of our approach is that even though the surfaces are tilted, the sampling pitch on the tilted surfaces can be defined.

The use of theoretical models to represent the photochemical effects present during the formation of spatially and temporally varying index structures in photopolymers, is critical in order to maximise a material's potential. One such model is the Non-local Photo-Polymerization Driven Diffusion (NPDD) model. Upon application of appropriate physical constraints for a given photopolymer material, this model can accurately quantify all major photochemical processes. These include i) non-steady state kinetics, (ii) non-linearity iii) spatially non-local polymer chain growth, iv) time varying primary radical production, v) diffusion controlled effects, vi) multiple termination mechanisms, vii) inhibition, (viii) polymer diffusion and ix) post-exposure effects. In this paper, we examine a number of predictions made by the NPDD model. The model is then applied to an acrylamide/polyvinylalcohol based photopolymer under various recording conditions. The experimentally obtained results are then fit using the NPDD model and key material parameters describing the material's performance are estimated. The ability to obtain such parameters facilitates material optimisation for a given application.

We propose to record digital Fourier hologram of a 3D diffused object and to reconstruct numerically and optically by using phase-only information. This phase-only information is obtained by using 1D-Continuous Wavelet Transform (1DCWT) from the intensity of digital Fourier Hologram. 3D object image is obtained by numerical reconstruction on computer and optical reconstruction by using a phase-modulated liquid crystal spatial light modulator (SLM). Numerical and experimental results are presented.

Recording of periodic structures is employed, instead of printing techniques, for moiré pattern to be generated. Diffraction gratings are utilized not only as substitutes of printing inks here but also to employ variation of visual appearance for revealing information encoded in a data-carrier structure. Two designs are analysed - one relying on very precise alignment of a decoding overlay grid and the other one allowing the use of the decoding grid to be avoided. The latter design is found more suitable to serve as an authentication element at first-line inspection.

A hybrid system that allows a high quality (low distortion) imaging in strong off axis configuration (50°) is proposed and analyzed in this paper. This imaging system is composed of a Bragg volume hologram (BVH) operating in catadioptric conditions and a programmable transmission computer generated holographic optical element (PCG-HOE). The BVH is used to produce a point by point virtual image in a sequential way by varying the angle of incidence of the reading wave. The PCG-HOE provides sequential aberrations correction adapted to each point to improve the image quality. A method to calculate the phase transfer function (PTF) to be implemented into the PCG-HOE to compensate for the aberrations of each virtual image points is presented. By applying the proposed approach we first demonstrate that the compensation of the aberrations is theoretically possible to a certain extent. In the last part of the paper, we discuss the constraining experimental conditions which have to be met, as well as obstacles to be overcome in order to achieve the fabrication of the BVH.

Iterative Phase Retrieval (PR) techniques represent an alternative means to Digital Holography (DH) for estimating the complex amplitude of an optical wavefront. To achieve a high-resolution reconstruction from a digital hologram, one must use Phase-Shifting Interferometric (PSI) techniques to remove the DC and twin image terms that are a feature of holographic recordings. Unfortunately this approach is not suitable for imaging dynamic events, since a minimum of 3 sequential captures, are typically required and the scene cannot change during this recording process. PR algorithms may provide a solution to this dynamic imaging problem, however these algorithms provide solutions that are not unique and hence cannot ensure an accurate solution to the problem.

Silver halide materials have occupied an important place in the recording of images. The reason is mainly given by the high sensitivity of the recording medium, thus permitting the use of minimal levels light and hence easing the stability problems of apparatus and the need for high powered laser equipment. When the film is exposed in a holographic process a latent image of a diffraction grating is formed. The developing solution reduces exposed silver halide grains to silver at a higher rate than the unexposed grains. Among the commercial emulsions, recently good results have been reported in BB-640 photographic emulsions, since in this work we present the experimental results related to the response of this emulsion to the interference of pulsed Gaussian beams. For this, diffraction gratings were recorded by the interference of pulsed Gaussian beams with 120 fs of width, 76 MHz of frequency repetition and central wavelength of 790 nm, where the transmittance of this emulsion is higher than 99%. As a result, diffraction efficiencies up to 30% were obtained with low sensitivities due to the low absorption and grain size (18 - 20nm). The thickness of the photographic emulsions and the bleached process has been analyzed and the sensitivity has been optimized with D8 developer.

New glassy 1,3-dioxo-1H-inden-2(3H)-ylidene fragment und (3-(dicyanomethylene)-5,5-dimethylcyclohex-1-enyl)vinyl fragment containing push-pull type derivatives of azobenzene able to create thin layers have been synthesized. Thin films of synthesized glasses for holographic recording were prepared using spin coating technique from saturated chloroform solution. Holographic grating recording in films of 6a-b, 7 and 12 has been experimentally studied at 633 and 532 nm in both transmission and reflection modes with p-p recording beam polarizations. The film 12 was found to be the most efficient at both wavelengths in transmission mode exhibiting the maximum self-diffraction efficiency of 9.9% at 633 nm, and 15.3% at 532 nm. The film of 6a was the most efficient in reflection mode with the maximum selfdiffraction efficiency of about 3%.

We describe an experimental investigation of the photopolymerization kinetics and volume holographic recording characteristics of silica nanoparticle-polymer nanocomposites using thiol-ene monomers capable of step-growth polymerization. We characterize the visible light curing kinetics of a thiol-ene monomer system consisting of secondary dithiol with high self-life stability and low odor and triene with rigid structure and high electron density by using real-time Fourier transform spectroscopy and photocalorimetry. In plane-wave volume holographic recording at a wavelength of 532 nm it is shown that while volume holograms recorded in the nanocomposites exhibit high transparency, their saturated refractive index modulation (Δn_sat) and material sensitivity (S) are as large as 1x10^-2 and 1615 cm/J, respectively. The polymerization shrinkage is reduced as low as 0.4% as a result of the late gelation in conversion. These values meet the acceptable values for holographic data storage media (i.e., 5x10^-3, 500 cm/J and 0.5% for Δn_sat, S and shrinkage, respectively). The improved thermal stability of volume holograms recorded in the nanocomposites is also confirmed experimentally.

The Non-local Photo-Polymerization Driven Diffusion (NPDD) model indicates how a material's performance might be improved, and provides a tool for quantitive comparison of different material compositions and to predict their fundamental limits. In order to reduce the non-locality of polymer chain growth (i.e the non-local response parameter, σ) and to improve the spatial frequency response of a photopolymer material, we introduce the chain transfer agent (CTA). In the literature, extensive studies have been carried out on the improvements of the non-local response modifying by the CTA, sodium formate, in the polyvinyl alcohol-acrylamide (PVA/AA) material. In this article, i) based on the chemical reactions of CTA, we extended the CTA model in the literature; ii) we compare two different CTA materials, sodium formate and 1-mercapto-2-propanol without cross-linker in order to obtain the experimental confirmation of the reduction in the average polymer molecular weight is provided using a diffusion-based holographic technique; iii) we examine the non-local responses of several spatial frequencies with the two CTAs. Using the extended CTA model it is demonstrated that the CTA has the effect of decreasing the average length of the polyacrylamide (PA) chains formed, thus reducing the non-local response parameter, especially, in the high spatial frequency case.

Holographic recording at shorter wavelengths enables to capture holograms with a greater resolution. Photopolymer material sensitisation to a blue or violet wavelength might require replacement of photosensitive dye or whole photosensitiser system which leads to different photoinitiation kinetics. There are known photoinitiator systems which have high values of key photoinitiation parameters, e.g., molar absorption coefficient at a broad range of wavelengths, quantum yield etc. An example of such photosensitiser is an organometallic titanocene, Irgacure 784. However Irgacure 784 in an epoxy resin photopolymer undergoes a complex photo-kinetics which is neither fully understood nor quantified. This complex photo-kinetics results in different bleaching evolution when using green and blue exposing light. The aim of this paper is to identify relevant photo-kinetic reactions taking place during exposure and driving the bleaching process. For this purpose photopolymer layers of four material compositions containing Irgacure 784 were prepared and exposed for nine exposure times. Absorbance spectrum was measured before after each exposure. We report on our experimental results and draw conclusions identifying relevant reactions of the Irgacure 784 photo-kinetics in epoxy resin photopolymers.

The new modified holograms multiplexing method using normal to holographic recording medium reference beam incidence and off-normal signal beams incidence is offered for application in holographic memory having high information capacity and high data rate. Signal beams are located around reference beam concentrically. In this case quantity of multiplex holograms in the same area of recording media is equal to quantity of signal beams. Experimental model of holographic memory applying the offered method was tested. Possibility of multichannel optical head application for data recording and retrieving is shown. Wet photochemical processing is disadvantage of argentum halogenide recording media. Argentum halogenide "PFG-03M" produced by Slavich Company was considered for applying in holographic memory system. Photosensitive layer of "PFG-03M" has thickness ~7-12 μm. The optical scheme of the multiplex holograms record device using a multichannel writing head, where number of channels is equal to number of micro-holograms in the multiplex hologram, is developed. The central part collimated a bunch is used as the basic bunch falling on the photosensitive medium perpendicularly its surface. The peripheral ring part collimated a bunch is distributed by system of mirrors on channels of the multichannel writing head, symmetrized concerning an axis of the basic bunch.

We report an investigation of manipulation and trapping capabilities of polarization holographic tweezers. A polarization gradient connected with a modulation of the ellipticity shows an optical force related to the polarization of the light that can influence optically isotropic particles. While in the case of birefringent particles an unconventional trapping in circularly polarized fringes is observed. A liquid crystal emulsion has been adopted to investigate the capabilities of the holographic tweezers. The unusual trapping observed for rotating bipolar nematic droplets has suggested the involvement of the lift hydrodynamic force responsible of the Magnus effect, originating from the peculiar optical force field. We show that the Magnus force which is ignored in the common approach can contribute to unconventional optohydrodynamic trapping and manipulation.

Three-dimensional photonic crystals with face-centered cubic lattice structure, whose top plane is (111) plane, were fabricated by triple exposure of two-beam interference fringes. The transmittance of photonic crystals with face-centered cubic lattice structure fabricated by the holographic lithography mentioned above is analyzed by reducing the threedimensional structure into multilayer thin films employing the effective medium theory (EMT) and matrix method. The remarkable stop bands appeared at the Bragg wavelength calculated from the average of effective index. Relationships between stop bands and effective refractive index on the reduced film or filling factor of photonic atoms for a facecentered cubic lattice structure simulated by holographic lithography are shown. The validity of EMT result is also discussed in comparison with that of plane wave expansion method for a face-centered cubic lattice structure with sphere shape atoms. The stop bands were calculated by using the zero-th order, the second order and higher order EMT. The stop bands calculated using higher order and second order EMT fairly well agreed with that of plane wave expansion method, while the zero-th order result roughly agreed with that.

Two optical interference methods of surfaces characterization with subwavelength resolution are presented. One of the methods is based on recording of the interferograms of the near-field, which contains information about subwavelength structure of the surface. The concept of the other method consists in transformation of the near-field evanescent waves to propagating waves and measuring of their parameters far from the surface. Proposed methods have been tested numerically.

The method for estimation quality and adequacy of reconstructed holographic 3D images by means of stereogrammetry and digital image processing is proposed. The quality as a subjective parameter is considered and analyzed with the most often used criteria, which can be applied to reconstructed 3D scene or object. The method of stereogrammetry with its application for holographic images is considered and expressions for definition of method's accuracy are derived for ideal and non-ideal stereopairs. The measuring accuracy of surface of holographic image estimated to be less then 25 μm which is far below of the human eye resolution, and hence stereogrammetry method can be employed for quality estimation in 3D holographic simulators.

ptical interferometry techniques were used for the first time to measure the volume resistivity/conductivity of carbon steel samples in seawater with different concentrations of a corrosion inhibitor. In this investigation, the real-time holographic interferometric was carried out to measure the thickness of anodic dissolved layer or the total thickness , U_total , of formed oxide layer of carbon steel samples during the alternating current (AC) impedance of the samples in blank seawater and in 5-20 ppm TROS C-70 inhibited seawater, respectively. In addition, a mathematical model was derived in order to correlate between the AC impedance (resistance) and to the surface (orthogonal) displacement of the surface of the samples in solutions. In other words, a proportionality constant ( resistivity (ρ) or conductivity(σ)=1/[ resistivity (ρ)]) between the determined AC impedance (by EIS technique) and the orthogonal displacement (by the optical interferometry techniques) was obtained. The value of the resistivity of the carbon steel sample in the blank seawater was found similar to the value of the resistivity of the carbon steel sample air, around 1x10^-5 Ohms-cm. On the contrary, the measured values of the resistivity of the carbon steel samples were 1.85x10⁷ Ohms-cm , 3.35.x10⁷ Ohms-cm, and 1.7x10⁷ Ohmscm in 5ppm,10ppm, and 20ppm TROS C-70 inhibited seawater solutions, respectively. Furthermore, the determined value range of the ρ of the formed oxide layers, 1.7x10⁷ Ohms-cm to 3.35.x10⁷ Ohms-cm, is found in a reasonable agreement with the one found in literature for the Fe Oxide-hydroxides, i.e., Goethite(α-FeOOH) and for the Lepidocrocite (γ-FeOOH), 1x109 Ohms-cm. The ρ value of the Fe Oxide-hydroxides, 1x10⁹ Ohms-cm, was found slightly higher than the ρ value range of the formed oxide layer of the present study. This because the former value was determined by a DC method rather than by an electromagnetic method, i.e., holographic interferometry, with applications of EIS, i.e., AC method. As a result, erroneous measurements were recorded due to the introduction of heat to Fe oxidehydroxides.

The urgency of application of the optoelectronic analyzer for security holograms identification in real time for paper documents and plastic cards is obvious. The spatial-frequency spectrum analyzing method for security hologram is offered. The essence of the method consists in reception of the security holograms (SH) microstructure spatialfrequency spectrum (SFS), description SH SFS by means of integral, peak and combined parameters, and identification analyzed SH by the correlation recognition method by comparison of analyzed SH SFS parameters with reference SH SFS parameters. For this purpose it is enough to illuminate SH by laser or light-emitting diode (LED) radiation to construct by Fourier lens SH SFS, to register it with matrix receiver of radiation, and to process a signal in the electronic block. The mathematical model of a spatial-frequency spectrum of the SH is constructed and investigated. We will consider SH SFS in the limited sector of spatial frequencies. It is possible to describe SH SFS in terms of integral parameters, peak parameters, and their combinations. A series of such parameters is offered. Several SH identification algorithms is offered. The optical scheme of optoelectronic spectrum analyzer for identification SH is offered and experimentally investigated.

A method for fabrication of a microlens raster with full filling on photographic plates PFG-01 is proposed. A twodimensional holographic crossed grating (TDHG) with improved imaging properties is used as an image multiplying optical element. In order to create the improved TDHG, we have proposed a special technique for photographic emulsion layer treatment. The light intensity distribution from the display image was projected onto a light-sensitive material using the TDHG. After the development of the photographic plates, either hardening bleaching or short-wave ultra-violet illumination is used for relief creation.

Electron beam (EB) induced changes in thin films of the amorphous chalcogenide semiconductors As-S-Se have been studied. The experimental results on patterning of As-S-Se film surfaces by EB exposure and following chemical etching are presented. The possibilities of practical application of this material as resists for the production of relief holograms and diffractive optical elements (DOE) are discussed.

In this work, we present the analysis of a photopolymerizable system based on pyrromethene dye (PM567) acting as a photoinitiator and HEMA as monomer both of them dissolved in a dry polymeric matrix of PMMA. Previously, we reported the recording of diffraction gratings in this composition, resulting in diffraction efficiencies near 60 % with exposures of 1 J/cm² in materials with thicknesses around 500 microns. Although, the mentioned response (best) was observed at low intensities but at higher ones lower diffraction efficiencies were reached. Furthermore, in all the studied cases inhibition periods with asymmetrical angular selectivity curves were obtained. Since, in order to solve the mentioned drawbacks, the aim of this work is to analyze the effect of the addition of a crosslinking agent (PETA) in a photopolymerizable holographic material based on a pyrromethene dye (PM567) acting as a photoinitiator and HEMA as monomer both of them dissolved in a dry polymeric matrix of PMMA. For this, diffraction gratings were recorded at different intensities and the energetic evolution of the diffraction efficiency as well as the observed inhibition period were studied as a function of the concentration of crosslinking agent. Moreover, the experimental angular selectivity curves were theoretically analyzed by the model of Kubota and Uchida, and as a result information such as the effective thickness, fringe bending and non-uniform index modulation against the thickness of grating was obtained.

The aim of this work is to analyze the effect of the addition or substitution of several components (coinitiator and photoinitiator) in a photopolymerizable holographic material based on a pyrromethene dye (PM567) acting as a photoinitiator and HEMA as monomer both of them dissolved in a dry polymeric matrix of PMMA. For this, diffraction gratings were recorded at different intensities and the energetic evolution of the diffraction efficiency as well as the observed inhibition period were studied as a function of the component that has been modified (coinitiator (tert-butyl peroxybenzoate (tBPH)) or photoinitiator PM546 and PM556). Moreover, the experimental angular selectivity curves were theoretically analyzed by the model of Kubota and Uchida, and as a result information such as the effective thickness, fringe bending and non-uniform index modulation against the thickness of grating was obtained. It is observed that when PM546 is used instead of PM567, better responses for a wide range of intensities are obtained, in particular at high intensity where gratings with low fringe bending and a relative constant index modulation against thickness is reached. When a coinitiator such as tert-butyl peroxybenzoate (tBPH) is added to the reference composition, shorter inhibition periods are obtained with low fringe bending but with lower diffraction efficiencies.

The multiplexing of holographic reflection gratings with a spatial frequency higher than 5400 lines/mm in photopolymerizable sol-gel materials is experimentally demonstrated. The effect of the angular separation of the gratings and exposure time is characterized. Moreover, 9 reflection gratings are angularly multiplexed with diffraction efficiencies between 6 and 12% using an energy of 9 mJ/cm² in each exposure, resulting in a dynamic range M/# = 2.8.

The given work investigates a way of integrating Diffractive Optical Elements (DOE) in the structure of a protective image-matrix hologram. An important feature of the suggested method is simplicity of realization by some modification of the frames exposure software and full hardware compatibility with image-matrix technology. Unlike other methods, the suggested one does not require changing the optical scheme between transitions from recording holographic frames area to the DOE ones and vice versa. Any shape of DOE in the hologram approximated to the size of the frame is available. A DOE frame cannot contain any part of a holographic region due to the different method of exposure. The minimal size of one DOE pixel is about 3 micrometer. The method under discussion allows for recording both binary (two-phase) and multilevel (multi-phase) DOE at corresponding calibrations of the employed Spatial Light Modulator (SLM). The method has passed an experimental approbation and is now used for embedding DOE into an image-matrix hologram as an additional security element.

The DOE-HOE made by Dot-matrix technology, have found the application in various areas, such as protection of the various goods and securities, packing etc. These holograms contain set of pixels with various spatial frequency and orientation diffraction gratings. Process of manufacturing represents consecutive pixels exposure. The pixels quantity is great (about 10⁵-10⁶), that's why there is a problem of considerable time to master-shim manufacturing. Spatial frequency and orientation of gratings changes because of mechanical moving of elements. For acceleration of recording process it is necessary to replace slow mechanical devices with high-speed ones. One of variants of this problem solution, using spatial light modulator, is given in proposed article. This paper contains the techniques and results of optical components parameters calculations.

Necessity of devices and systems for identity verification and individualization of security holograms (SH) is growing together with the growth of SH production. The hidden coded micro image as a set of points (bits) was chosen as a new security element. This image is separately added into hologram by laser perforation on the final stage of SH production after replication. Such element is different for different SH, that allows not only controlling identity of SH, but also distinguishing one hologram from another. Designed optoelectronic system HOLOINID consists of two blocks: laser microperforator for SH individualization and optoelectronic device for micro-images readout and SH identification. Specialized software allow control the laser microperforator, process micro-images received by reading optoelectronic device using certain algorithm, and make a decision about SH identity. The block of laser microperforator for SH individualization works due to the high power density of the laser radiation in a focused spot forming at the SH metalized thermolacquered layer. Hidden coded image represents a set of optical bits (which form information field) and check objects for image capturing and processing. Optical point (bit) size is usually 30..50 μm while period between points is 70 μm. Advantage of laser miroperforator for SH individualization is ability to get hidden coded images in holograms without SH surface layer damage. It is possible to get by using high-aperture short-focus optical system. Know-how of the technology is an ability to use laser microperforation as in thermolacquered layer (which is lied between lavsan layers and metalized layer) and in metalized layer (for SH on hot stamping foil).

Off-axis holographic diffractive optics creates beams with an elliptic cross section. Focusing properties of that beams differ from beams having a circular aperture. Axial intensity distributions of converging spherical waves behind elliptic apertures are analyzed. Similarly to behaviour of circular cross section beams, main maxima move from the geometric focus to the location of the aperture with decreasing the Fresnel number. However, their displacements and values are higher than for the circumscribed circular aperture. Minima of curves do not achieve zero values as expected. All results can not be given in closed form; only numerical results for specific parameters can be computed.

A major barrier to the practical use of holographic memories is deterioration of reconstructed signals due to shrinkage of the medium. It is reported that a photopolymer medium shrinks mainly in the thickness direction during recording or as a result of variations in ambient temperature, and the optimal reconstruction angle shifts and deteriorates. To avoid the influence of medium shrinkage, we propose co-axial, dual-reference-beam recording and reconstruction. The recording and reconstruction characteristics of this method were examined through simulation and experiments, and the results confirmed that in holographic multiplex recording, the reference-beam angle is not affected by medium shrinkage, and stable recording and reconstruction are achieved.

Holographic data storage is a new optical technology which allows storing an important number of bits in a recording material. In this work, two different types of modulations, defocused binary intensity modulation and phase modulation, are compared to obtain which modulation could be the most suitable for holographic data storage. The best modulation would be the modulation with a homogeneous distribution of energy in the FT plane with no zero frequency peak.

A compact optical correlator applicable to the retrieval of colour and texture as well as shape information was developed. A new technique for retrieving colour and texture information by using a slot-in-type compact joint-transform correlator (JTC) with minimum size (140 (W) × 220 (L) × 40 mm (H)) was developed. The developed techniques were used to retrieve images of fruits and vegetables, taken by the digital camera. The developed technique can retrieve images of certain fruits, such as an apple, from images of many different fruits and vegetables. It will open up a new area of retrieval techniques for ambiguous images based on shape, colour and texture information.

Holographic screen (HS) is designed for using in 3D displays. HS is produced as a hologram of converging light wave and it presents an interference pattern of the reference and the object beams as a diffraction grating with variable pitch registered in the recording medium. While a color image is projected on such screen the problem of perception of the undistorted color image by the observer is appeared (due to the inherent angular dispersion of a grating with different values for different wavelengths) because the observation zones are displaced in space for each spectrum section. The problem is solved due to recording the HS by the object beam from the set of point sources, i.e. recording lengthy in the appropriate direction diffuser. With this type of HS, the observation zones, providing an undistorted perception of full-color images, are located in the imposition of lengthy images of projectors' pupils corresponding to different spectral components of projectors' radiation beams. To form an image, different projectors can be used in the display: slide projectors, video projectors based on LCD- or DMD-panels, etc. Three-dimensional images of both static and dynamic scenes can be viewed as video films at the appropriate information flows synchronization which are received by the projector from external sources.

We present a holographic system that can be used to manipulate the group velocity of light pulses. The proposed structure is based on the multiplexing of two sequential holographic volume gratings, one in transmission and the other in reflection geometry, where one of the recording beams must be the same for both structures. Analytical expressions were obtained for the transmittance induced at the forbidden band (spectral hole) and conditions where the group velocity was slowed down were analyzed. Moreover, the propagation of Gaussian pulses is analyzed in this system for a fixed reflection grating and three different transmission gratings.