Search

Results of investigations of acoustic signals induced in a copper plate irradiated with a microsecond lowenergy high-current electron beam (LEHCEB) are presented. The characteristic acoustic signal waveforms, their amplitudes, phases, and frequencies are experimentally measured. It has been established that the acoustic signals induced by LEHCEB irradiation have groups of characteristic spectral components with fundamental frequencies of 6, 11, 22–24, 80, and 100–120 kHz whose amplitudes increased with charging voltage. It has been established that from the change of the 80 kHz harmonic with the charging voltage, the beginning of LEHCEB generation, its stable or unstable phase, and the beginning of target melting can be traced. It has been found that for a fixed charging voltage of each pulse in a series, the amplitude and phase-frequency structure of acoustic signals are almost the same.

The paper presents the results of numerical simulation of the distribution of thermal fields during the formation of Cr-Zr surface alloy using a pulsed low-energy high-current electron beam (LEHCEB). The melting thresholds of the Cr-Zr system for different thicknesses of Cr films were calculated. The melting threshold of the Cr-Zr system increases linearly with increasing Cr film thickness. A linear regression dependency model of the melting threshold on the film thickness is proposed. Evaporation thresholds of the Cr-Zr system for different thicknesses of Cr films were calculated. The evaporation threshold of the Cr-Zr system increases linearly with increasing Cr film thickness. A linear regression dependency model of the evaporation threshold on the film thickness is proposed. The value of the LEHCEB energy density at which the lifetime of the film and substrate are equal is calculated. This value is a maximum value for the effective formation of Cr-Zr. A model of the LEHCEB energy density, at which the lifetime of the film and the substrate are equal, in the form of a third-degree polynomial is proposed.

The description and the main performance specifications are presented for a device in which a high-current electron gun and a magnetron sputtering system are integrated in a common casing. This device is efficient for surface alloying on metallic materials. It is shown that the magnetic system of the magnetron does not degrade the characteristics of an electron beam that is formed in the gun and passed through a hole in the magnetron sputtering system.

Effective performance of laser systems intended for power delivery on a distant object requires an adaptive optics system to correct the laser beam distortions caused by atmospheric perturbations along the propagation path. The turbulence-induced effects are responsible for beam wobbling, wandering, and intensity scintillation, resulting in degradation of the beam quality and decline of the power density on the target. Adaptive optics methods are used to compensate these negative effects. In its turn, operation of the Adaptive Optics System (AOS) requires a reference wave that can be generated by the beacon on the target. This report discusses the requirements to the beacon that can support optimal correction of the wavefront. Post-processing of the beacon-generated light field enables retrieval and detailed characterization of the turbulence-perturbed wavefront — data essential to control the adaptive optics module of a high-power laser system.

In this paper we discuss the background and principles of an optical non-contact sensor fusion concept, the Interferometric Correlator for Acoustic Radiation and Underlying Structural Vibration (ICARUSV) and give practical example of its capabilities, focusing on its ability to simultaneously capture, visualize and quantitatively characterize full-field non-stationary structural dynamics and unsteady radiated sound fields or transient flow fields around the structure of interest. The ICARUSV’s multi-sensor design is based on a parallel architecture and therefore the data capture is fast and inherently support a wide variety of spatio-temporal or spatio-spectral analysis methods which characterize the structural or acoustic/flow field dynamics as it occurs in real time, including short-lived transient events. No other technology available today offers this level of multi-parameter multi-dimensional data1.

Effects accompanying the propagation of an electromagnetic pulse with a nanosecond edge length in a finite-length dielectric gradient circular cylinder are studied within a three-dimensional model based on Maxwell’s equations. The pulse-edge length is commensurate with the dimensions of the dielectric body being considered. The effect of the direction of electric-vector polarization on the distribution of regions of electric-field enhancement is explored. The effect of the dielectric-cylinder length on special features of the formation of electric fields both within the body and in the surrounding medium is considered.

A kinetic equation for low-energy electrons induced in gas by ionizing radiation is studied. The kinetic equation takes into account elastic, inelastic, and ionization collisions between electrons and gas molecules, as well as the interaction with an external electric field. The process of the conduction current generation is considered. A small parameter is calculated as a ratio of the energy accumulated by an electron between collisions to the thermal energy. An approximate solution is constructed of the kinetic equation for electron concentration and flow. The study resulted in obtaining quadrature formulas for the calculation of electron conduction of an ionized gas in the model of a radiation-induced electromagnetic field.

The design of a multiperspective, ‘look around’ time-multiplexed autostereoscopic display featuring eight independent viewing zones is described. In order to achieve full-motion colour imagery, a novel high-framerate image projector, based on a digital micromirror display (DMD) with an interface capable of directly linking to commercial graphical processing units (GPUs), is utilised. A high-speed synchronised liquid-crystal display (LED)-based light engine is employed to allow for high-framerate sequential colour imagery. Real-time interactive rendering of multiperspective imagery with standard GPUs has been demonstrated.

This paper discusses some aspects of holographic display techniques pertinent for museum applications. In particular, it revises the features and requirements for three-dimensional (3D) holographic displays, examines the practical use of holographic interferometry as an effective tool for non-destructive inspection of museum items, discusses holographic methods for high-density data storage and outlines how 3D images can be integrated into a large coverage area.

This paper discusses an advanced target in the loop (ATIL) system with its performance based on a nonlinear phase conjugation scheme that performs rapid adjustment of the laser beam wavefront to mitigate effects associated with atmospheric turbulence along the propagation path. The ATIL method allows positional control of the laser spot (the beacon) on a remote imaged-resolved target. The size of this beacon is governed by the reciprocity of two counterpropagating beams (one towards the target and another scattered by the target) and the fidelity of the phase conjugation scheme. In this presentation we will present the results of the thorough analysis of ATIL operation, factors that affect its performance, its focusing efficiency and the comparison of laboratory experimental validation and computer simulation results.

Based on the results of numerical simulation of temperature fields, the reasons for the growth of the layer thickness of the zone of thermal effect in a target of 45 steel during pulse-periodic stimulation by a low-energy high-current electron beam in the mode of initial melting are analyzed. It is concluded that the growth of thickness of these layers is primarily caused by the spread of the beam energy density from pulse to pulse and by the presence of individual pulses with a higher-than-average value of energy density. It is shown that the variation of the thermal properties of steel, which occurs during irradiation due to the carbon saturation of the surface region of the target, results in the increase of the thickness of only those layers of the zone of thermal effect which are formed in the region of former melt. The dependence of the target temperature on the number of irradiation pulses is measured and calculated numerically. It is demonstrated that the increase of the target temperature has no noticeable effect on the growth of the thickness of the zone of thermal effect

This paper discusses a new conformal imaging fiber-optic heterodyne vibrometer developed for in-vacuum measurement of MEMS micro-resonator spatial dynamics in real time. The all-fiber optic probe design incorporates many standard fiber-optic telecommunications components, configured to enable light delivery directly to the MEMS device under test in vacuum. The CIV measures the equatorial dynamics of micro-shells currently being developed as microscale hemispherical resonant gyroscopes (HRG). The modular fiber optic design lends itself readily to other conformal configurations (e.g planar, multi-faceted) or to simultaneous measurement of shell, stem and substrate dynamics.

Some experimental results are presented, related to practical applications of a holographic nondestructive technique for inspection of museum item conditions, especially in the detection of deformation, stress concentration and defect localization. These results are obtained using the basic principles of traditional double-exposure holographic interferometry, as well as its electronic variant with computer image processing. In the latter case the accuracy in displacement measurements was studied on a test object. Two museum items have been selected for their condition inspection: a XVIIIth century icon on wooden panel and a precolumbian terracotta anthropomorphic. The technique described can give quite accurate metrological information, and is also rather promising for rapid qualitative analysis of the object condition before and after restoration, as well as during its storage.

Possible applications of holography for cultural heritage study, demonstration and restoration, particularly in practical museum applications, are discussed. In this respect two main applications of holography are of interest: display holography and technical holography. The latter includes holographic NDT methods, three-dimensional measurements of objects, memory systems, and so on.

A method for preliminary treatment of electrodes by a microsecond low-energy intense electron beam is proposed. It has been demonstrated that such a beam melts off the electrode surface and cleans the surface layers from impurities and dissolved gases. In combination with subsequent conditioning of the vacuum gap with low-current pulsed discharges, high breakdown electric fields can be attained. >

Achieving a minimal size laser spot (beacon) on a remote object is a major objective of the adaptive optics-based phase conjugations methods used in laser communications and directed energy systems. Achieving this goal not only requires a high quality conjugation of the laser beam wave front relative to the object-returned beacon beam, but also fulfillment of the reciprocity condition. The latter can be defined as precise matching of the intensities and wave fonts of two contrapropagating beams in each cross section along the propagation path. This condition is central for effectively focusing a laser beam on a remote object. Violation of the conditions of reciprocal propagation occurs, for example, when the receiving aperture is of limited size compared to the size of the object-returned beacon beam. Such size disparity between the receiving aperture and beacon returned beam results in decreased power density on the focused spot and reduced intensity of the target-returned beam. When the beacon wave is formed on a rough-surface object there is an additional decrease in the efficiency of the beam focusing. The paper provides a detailed discussion of these phenomena.

In this paper we report the results of the analysis and experimental modeling of the target-in-the-loop (TIL) approach that is used to form a localized beacon for a laser beam propagating through turbulent atmosphere. The analogy between the TIL system and the laser cavity has been used here to simulate the process shaping the laser beacon on a remote image-resolved target with rough surface. The TIL breadboard was integrated and used for laboratory modeling of the proposed approach. This breadboard allowed to simulate the TIL arrangement with a rough-surface target and laser beam propagation through the turbulent atmospheric layer. Here we present the initial results of the performed studies.

We describe a hybrid system for real-time, full-field vibrometry, incorporating features of high-speed electronic speckle pattern interferometry (ESPI) and laser Doppler vibrometry (LDV). Based on a 2D interferometric sensor array, comprising 16 × 16 parallel illumination and detection channels, the matrix laser vibrometer (MLV), captures full-field data instantaneously, without beam scanning. The instrument design draws on the advantages of scale offered by modern telecommunications fiber optic and digital electronics. The resulting architecture, comprising a compact measurement probe linked by fiber optic umbilical to a remote electronics unit, facilitates practical application of the system in fullfield measurement of transient vibrations and rapid non destructive testing of composite materials.

This paper reports studies of the performance of a phase-conjugate mirror (PCM) with its operation based on the stimulated Brillouin scattering (SBS) of the focused laser beam in ultra-pure fluorocarbon FC-75 (C8F18). A pulsed laser with 15-ns pulse width from a home-made injection seeded single frequency MOPA configuration Nd:YAG laser with variable output energy (from several mJ to 300 mJ) was used as a coherent light source in these experiments. The PCM reflectivity better than 90% has been achieved at optimized focusing conditions of an incoming beam, and the output energy of the phase conjugate pulse linearly followed the input pulse energy after reaching the threshold level of about 3.3 mJ. The slope efficiency was estimated to be approximately 95% without taking into account of losses in some optical components, including the thin film polarizer. We believe that a higher level of PCM efficiency can be achieved with more careful selection of the critical optical components, including the thin film polarizer, quarter-wave plate and focusing lens.

This paper discusses the realization of an injection-seeded single frequency Q-switched Nd:YAG ring laser with pulse width adjustability from several nanoseconds to 20 ns and an output energy in excess of 100 mJ from a ring cavity slave oscillator. In the cavity configuration under study, the slave ring oscillator was injected by a pulse formed from a CW single frequency non-planar ring oscillator (NPRO) Nd:YAG laser with a Pockels cell modulator. The injected pulse duration is slightly shorter than the emission round trip time inside the slave laser cavity. The use of this injection seeding results in unidirectional Q-switched laser oscillation with suppression of bidirectional Q-switched oscillation that otherwise may be initiated from spontaneous emission. The advantage of these regime is in stable laser operation with no need in adjustment of the seeded light wavelength and the mode of the cavity because there are never two waves of the same polarization existing inside the cavity at the same location and the same time. The cavity contains two Pockels-cells, in which the first cell serves to open the oscillator cavity and the second one performs cavity dumping, generating a pulse with optimized characteristics and enables variation of the duration of the Q-switched output pulse. Proper selection of the pump parameters and Pockels-cell gating enables further operation of the system in a mode when the Q-switched pulse can be formed only under the seeding conditions. It is found that the wavelength of the Q-switched laser radiation matches well to the injected seed NPRO laser longitudinal mode. By using two-stage amplifiers, an output energy better than 300 mJ has been achieved in a MOPA configuration without active control of the cavity.

This article describes the development and application of a 16x16 array (matrix) laser vibrometer based on a parallel architecture which supports fast 2D measurement of arbitrary (steady state, non-steady state, transient) solid body vibrations without beam scanning. The small size and low weight of the measurement probe, which is linked to a remote detector/processor unit via a flexible armoured fibre-optic umbilical, enables deployment in areas with restricted access. Incorporating aspects of high-speed electronic speckle pattern interferometry (ESPI) and laser Doppler vibrometry (LDV), the design is based on a hybrid fiber-optic/bulk optic interferometer which operates at a wavelength of 1550 nm. Test data illustrate high-speed capture of transient vibrations, showing the full 2D temporal evolution of surface deformation, including multiple resonant modes, of a center-pinned metal plate excited by a 1-50 kHz frequency chirp of 109 ms duration. We discuss preliminary data showing detection of sub-surface defects in composite materials, based on non-contact (frequency chirped) acoustic resonance of the locally damaged structure. For large area NDT the probe can be mounted on a lightweight XY gantry for automated multi-frame measurements.

The wave-function of a laser beam can be measured with a phase-shifting interferometer. Its direct detection enables deriving the correlation function of various orders - the parameters that cannot be measured directly by existing methods.

The possibility of information storage using the angular speckle-selectivity of volume holograms is analyzed. It is demonstrated that such holograms can be used to construct high-capacity memory elements.

Digital holography has been around for over thirty years; however only in recent years has necessary and affordable recording and computing hardware become widely available. Some of the first works in digital holography are described as far back as 1966, with others following shortly after that. Today many researchers are working in this area for both application and further development of the technique. Indeed, digital holography may represent the best hope for holography as a thriving area of optics, and science. In this paper we discuss of the many applications, advantages, challenges, and opportunities that exist in the field of digital holography.

This paper describes a method for real-time 'mapping' of atmospheric turbulence. This can be achieved through excitation of a Rayleigh laser-guide star and coherent detection of the wave-function in the back-scattered light. Detailed information about this function is essential for establishing efficient performance of an adaptive optics system and estimation of atmospheric turbulence parameters such as Fried radius, Rytov parameter, and isoplanatic angle. Amplification of low intensity back scattered light can be achieved by coherent detection based on multi-beam interaction in a non-linear medium. The wave-function of the scattered light can then be recorded and reconstructed with phase-shifting interferometry. The proposed method offers a new tool for wavefront assessment in beam control systems for high energy lasers and other applications.

High-finesse Fabry-Perot interferometers are useful tools when it comes to high-resolution spectroscopy and narrow-band filtering. Rugged, reliable, narrow-band tunable filters are of special interest for remote sensing from ground, airborne and space-based platforms. This report discusses the results of a numerical analysis and experimental study of such a filter with its design based on the unique features of the photonic crystal interferometer (PCI). An optimal choice of the PCI components and their parameters allows achieving a sub-angstrom bandpass combined with a broad tunability range (< 10 nm) in the visible spectral regions. The prototype PCI system has the tunability over a 1 nm with a bandpass near 0.02 nm and an acceptance angle about 1 angular degree. Detailed consideration is given to the imaging characteristics of such an interferometer, and their dependence upon the quality of the individual components (i.e. the mirror substrates, dielectric layers, etc.). In summary, we present the results of the theoretical analysis and experimental study of the spectral and imaging characteristics of a high-finesse PCI, and their impairments due to deviations from the required parameters of the optical elements.

Optical detection of material damage, especially fatigue, has obvious importance in many aspects of engineering. Recent work in the area has shown that scanning light scattering is capable of detecting signs of fatigue and foreign-object damage on many types of surfaces; however, the persistent problem with practical implementation of this technique is the presence of background noise signals, false defect counts. Several new approaches to discriminating fatigue damage signals from non-fatigue-related signals have been developed, including filtering of 2-dimensional scattered intensity maps, peak detection and correlation among multiple channels, and exploitation of surface reflectance and scattering properties to control the information received by the sensor. Similar techniques are also shown to enable highly robust detection of foreign object damage (FOD) on turbine blade edges

During the last decade Proskurovsky and Ozur [1] ; [2] ; [3] at the Institute of High Current Electronics (Tomsk) have developed and built sources of wide-aperture (≥50 cm 2 ) low-energy (up to ∼40 keV), high-current (up to ∼50kA) electron beams (LEHCEBs) of microsecond duration, intended for surface treatment of materials. At the present time, these sources are superior in performance to other known sources of pulsed electron beams, pulsed lasers, sources of high-power ion beams, and pulsed plasma generators used for surface treatment. Important advantages of the LEHCEB sources are their reliability, high electrical efficiency, X-ray safety, and low cost. The promise of LEHCEBs as candidates for surface modification of materials is due to the following circumstances. The electron energy is absorbed within a thin (∼1 μm) surface layer, and this, in combination with the short pulse duration, allows one to realize pulsed melting and smoothing of the surface at rather low energy densities (2–5 J cm −2 ). As a result of the heat transfer into underlying layers of the material, the resolidification of the molten layer occurs at a cooling rate of ∼10 9 Ks −1 , which is high enough for nonequilibrium microstructures, including amorphous and nanocrystalline ones, to form. One can easily realize controlable evaporation of the near-surface layers by varying the energy density and the number of pulses, and this, in particular, makes it possible to efficiently clean the surface of oxides and other contaminants. Finally, pulsed melting of film-substrate systems allows one to produce nonequilibrium surface alloys. Thus, LEHCEB sources offer a unique tool for investigations in materials science and for developing new vacuum technologies for surface treatment of materials.

This paper presents the results of the analysis and experimental characterization of a narrow bandpass optical filter based on the Fabry-Perot interferometer configuration with a variable spacing between the mirrors allowing for a relatively wide spectral tunability. Such a filter with a high-throughput bandpass and sufficiently large aperture and acceptance angle is of practical interest for a high-resolution spectral measurements and remote sensing in the visible and infrared spectral regions. The Fabry-Perot filter (FPF) can be designed in a compact single-assembly architecture that can be accommodated within existing instruments and should provide a stable performance under variable thermal and mechanical conditions, including space and airborne platforms. Possible applications of the filter include high-resolution multi-spectral imaging, terrain mapping, atmosphere and surface parameters measurements, and detection of chemical and biological agents.

We performed architecture and design analyses of coupled-cavity laser systems to arrive at a concept for tracking distant objects. We also conducted an experimental study of such a system using a pulsed ruby laser as a prototype for the laboratory tests. Both laser cavities were coupled through the dynamic holographic grating. Special attention was paid to characterization of the coupled-cavity laser system and its operation. In particular, we studied the formation of holographic grating that serves to couple the cavity; the slope efficiency of the master and slave arms and their dependence upon cavity parameters. The resulted experimental data and analyses verified the tracking principle and proved the feasibility of the proposed phase-conjugate double cavity laser system for tracking moving object at distance with high accuracy.

Number of applications require technology that allows storing, retrieving, and processing a large volume of information. Holographic memory offers high-density data storage with parallel access and high throughput. Several methods exist for data multiplexing based on the fundamental principles of volume hologram selectivity. We recently demonstrated that a spatial (amplitude-phase) encoding of the reference wave (SERW) looks promising as a way to increase the storage density. The SERW hologram offers a method other than traditional methods of selectivity, such as spatial de-correlation between recorded and reconstruction fields. In this report we present the experimental results of the SERW-hologram memory module with solid-state architecture, which is of particular interest for space operations.

A method is presented to store biometric and/or other important information on an ID card in the form of a Card Hologram that cannot be read or duplicated without the use of a special Key Hologram that is secured inside of an automated reader. The Key Hologram produces the unique wavefront required to release the information contained in a complex, 3- D diffraction pattern recorded in a volume hologram attached to the card. Experimental results are presented in which the image of an Air Force resolution target are recorded and reconstructed in a volume material using a random speckle wavefront and that cannot be viewed using a simple wavefront such as a collimated or diverging laser beam.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A method is presented to store biometric and/or other important information on an ID card in the form of a Card Hologram that cannot be read or duplicated without the use of a special Key Hologram that is secured inside of an automated reader. The Key Hologram produces the unique wavefront required to release the information contained in a complex, 3D diffraction pattern recorded in a volume hologram attached to the card. Experimental results are presented in which the image of an Air Force resolution target are recorded and reconstructed in a volume material using a random speckle wavefront and that cannot be viewed using a simple wavefront such as a collimated or diverging laser beam.

Important advances of holographic memory. such as parallel input-output, high data transfer rate and ultimate density for optics storage have attracted a lot of interest. The principal feature of volume holography (known as very high selectivity of the diffracted beam intensity to reference beam deviation) is typically used for data multiplexing. Thus, most common techniques for data sampling are based on angular' and spectral2 selectivity resulting from the momentum conservation law (Bra law) for volume holograms3. Angular selectivity has been used more often as it is simpler to implement in practice. It was demonstrated4.5 that data multiplexing with up to 10.000 pages of information can be stored in one crystal as write-read/erase or read-fix. Refextnce bean arbitrary phase encoding also was demonstrated as a useful technique for this purpose, although the detailed analysis of the method was limited only by the conditions where the profile modulation across the reference beam was altered by arbitrary encoding. The first demonstration of shift selectivity of thick holograms with a speckle encoded reference beam was reported7, and later a theoretical explanation of the observed peculiarities8 was given suesting this type of selectivity for high density data storage9. A similar approach was suested for volume holograms with a spherical reference wave;10 however the existing methods do not explore the possibility of the effective use of an entire volume of the hologram as suested in the development for optical disc memory systems11. In this report we present the results of volume hologram recording with high density data obtained through a real volumetric encoding method that allows an increase in the data storage density.

We have shown the vortex structure of the dislocation appearing in a laser beam passing through a Gaussian lens induced in a cubical, non-linear media during self-action. We make such studies using focusing and defocusing Gaussian lenses both theoretically and experimentally.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Here a method for data storage by means of multiplexing 3D holograms is considered. The method consists in shifting the recording material with respect to a reference speckle wave. The experimental data on the dependence of the diffraction efficiency of the hologram with respect to the shift is presented. The general scheme of data storage in 3D-speckle shift hologram is considered and presented. It's shown that this kind of hologram substantially outperforms all other types for the number of cells (pixels) in which information can be stored. At the same time, the noises that are inherent in a 3D-speckle shift hologram restrict the density of the information storage.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this paper we demonstrate the scheme for volume holographic data multiplexing by using the features of shift selectivity of a random encoded speckle reference wave. The proposed recording method results in a more efficient use of the recording medium volume and increases the storage density in comparison with spherical or plane-wave reference beams. The mechanism of lateral and longitudinal shift selectivity are described theoretically and shown to agree with experimental measurements for holographic data multiplexing in the volume of the Fe:LiNbO 3 crystal.

Bacteriorhodopsin (BR) has been proven to be an effective non-linear media for a variety of applications, such as optically addressable spatial light modulators, volumetric memories, optical image processing systems, optical sensors, and optical correlators. However, practical realization of such systems with BR depends upon the specific characteristics of this material. In this report we present experimental results of the time evolution and intensity dependent characteristics of a BR gelatin film. In particular we studied the spectral dependence of the optical density/refraction index modulation. A holographic technique was used to investigate the exposure characteristics of photorefraction, recording versus storage time, as well as the connection between the diffraction efficiency of the recorded grating and light induced scattering (noise)--the parameters that are of primary importance for such applications as high density memory systems and optical correlators.

In this paper we present the results of analytical study and experimental examination of long pipe oscillations. Two different approaches have been used for theoretical study, which are the Global Modal Analysis and direct solution of the wave equation for oscillating modes revealing and analysis of the displacement. The obtained results are compared with experimental data from pulse-laser holographic non-destructive testing of pipe vibration.

This paper deals with characteristics of volume hologram recorded and reconstructed with random amplitude-phase encoded reference wave. The speckle-encoded reference wave was proposed as the method to modify selective properties of the hologram. In particular, it is demonstrated that volume holograms recorded with this type of reference beam are taking new selective features, such as the sensitivity of the diffracted beam intensity to spatial mismatch between the hologram and reconstructing beam in transversal and longitudinal direction. Moreover, the conditions can be set, when the hologram's angular selectivity is not due to violation of the Bragg conditions, but is a result of spatial angular de-correlation between recorded and reconstructing structures. The analysis is made on the applicability of these features of volume hologram for high density information storage.

The effects connected with the laser modes' variations at volume hologram recording and reconstruction are studied. Theresults of the theoretical analysis for the reconstructing wave are compared with experimentally obtained data. PhotorefractiveFe doped LiNbO3 crystals are used as the recording media for volume holographic storage. Laser modes of different indiceswere applied at hologram reconstruction, and methods of the diffracted beam intensity enhancement are discussed.Keywords: volume hologram, laser modes, speckle-pattern. 1. INTRODUCTION Holographic optical elements can be used to transform (or correct) the structure the laser beam'. Earlier experiments withthin hologram recording/reconstruction proved such possibility2 . The "universal" corrector was suggested3 for phase andpolarization correction of the light beam transmitted by optical fiber. Volume hologram recording with spatially encodedreference wave allows to increase the efficiency of this type of the laser beam corrector45. Theoretical analysis made in frameof hologram mode theory6 justified that diffracted beam amplitude is proportional to the scalar product of the reference andreconstructing wave functions. Similar inference on the reconstructed beam structure transformation can be obtained from thesuperimposed hologram analysis7. 1n89 the kinematics approximation was practiced to study the light models of the discreetfunctions recording by volume hologram, and it was suggested to use such hologram as an element for arbitrary optical fielddecomposition.This paper deals with the analysis of the characteristics of volume hologram that is recorded and reconstructed withorthogonal wave functions. The factors that allow to improve the diffraction properties of such holograms are studied.

Processing of color silver halide holographic materials is still the subject of laboratory studies rather then established technology. Therefore any new approaches to the problem would extend the understanding of the process. the article describes the chemical processing of color holograms recorded on PFG-03C plates that is supposed to be more adequate compared to formerly known ones. The processing employs the experience accumulated during years of work with Russian PE-2, PFG-03 and -03M emulsions and is the application of well known solution physical development to the case of color hologram recording. Once such color hologram is recorded, its optimal reconstruction conditions should be determined for proper color revision. This can be done through the analysis of the angular-spectral selectivity of the hologram.

THe hologram multiplexing method for the 3D data storage with speckle reference wave is considered. It permits to multiplex holograms by shifting of the speckle wave on the value equal to the its correlation radius. The limit of the number of information units presented by this type of holographics storage exceeds the same value for the spectral or angular multiplexed holograms. However, the system noises reduce it to the regular value. Two different experimental set-ups were tested for the holograms recording: with incident beams and with included beams. It occurred that the number of information units that can be stored in unit volume is larger in the case when both beams possess speckle structures, however the signal-to-noise ratio is also larger in this case, so the spatial modulation of the object beam does not improve the information capacity. Holograms recording was carried out using volume photosensitive medium: newly developed self processing dichromated gelatin of 0.5 mm thickness, and it was compared with the recording in DuPont photopolymer of 100 micron thickness and Fe:LiNbO3 crystal of 2 mm thickness. The method seems to be very suitable for the laser-disk-memory devices.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A new method of 3-D image projection is considered. The recording of the image includes two steps and is performed with the help of conventional photographic methods. At the first stage of the recording the set of aspects of a 3-D scene is registered. At the second stage the set of aspects is transformed into a set of so-called subaspects. At the stage of projection the subaspects are transilluminated by a laser beam that is focused in spot. The beam scans the screen and as a result the matrix of luminous spots is formed. It is shown that when viewing such a matrix, the spectator sees on the screen a two-dimensional image of the scene. When the point of observation is changed, the configuration of the image represented on the screen is changed, too, simulating the changes of the aspects of the scene which take place when viewing a real 3-D object. As a result, the spectator has got the illusion of the 3-D character of the projected image. It is mentioned that the process of scanning the screen by the set of aspects focused in spots is equivalent to simultaneous scanning of the screen by a set of independent thin beams of light, a special 'own' aspect being projected on the screen by each beam of light. The version of the display that reproduces the horizontal parallax only is considered. It is shown that the viewing zone should be stretched in this case in the vertical direction with a help of a one-dimensional diffusing screen. The case when the scanning beam is controlled by a conventional TV signal is analyzed. It is shown that the display is compatible with existing TV systems. An experiment on modeling the display that reproduces the horizontal parallaxes of a 3-D scene only was carried out. A photograph of a speckle pattern which was formed by a diffusing luminous line was used as a one-dimensional diffusing screen. Some data on the chemical treatment of this photograph are presented. The experiment has shown that while stretching the viewing zone in the vertical direction, such a screen practically does not impair the quality of the image of the aspect projected through the screen. The experiment has also confirmed the possibility of the complete elimination of the speckle structure of the projected image by giving small circular movements to the screen.

In this paper some experimental results related to practical applications of holographic non-destructive techniques for the inspection of the condition of museum items are presented, especially those used in the detection of deformation, stress concentration and defect localization. These results are obtained using the basic principles of traditional double-exposure holographic interferometry, as well as with its electronic variant with image processing. In the latter case, the accuracy in displacement measurements was studied on a specific test-object. Two museum items were selected for their condition inspection: a XVIIIth century icon on wooden panel and a precolumbian terracotta anthropomorphic. The described technique can give quite accurate metrological information, but is also rather promising for rapid qualitative analysis of the object condition before and after restoration, as well as during its storage.

Early treatment for anemia with epoietin (EPO) and intravenous iron after replacement of the large lower extremity joints permits an 8 g/l increment in hemoglobin concentration to be achieved by postoperative day 10 versus day 2. Objective: to evaluate the efficiency of medical stimulation of erythropoiesis in the treatment of anemia after large joint replacement. Materials and methods. The medical records of patients who had undergone hip or knee joint replacement in January 2010 to August 2011 were retrospectively analyzed. Group 1 (EPO group) included 32 patients who postoperatively received iron saccharate 600 mg and subcutaneous epoietin alfa 40,000 IU. In Group 2 (IRON group), 27 patients took iron saccha-rate 600 mg without epoietin. In Group 3 (CON group) 62 patients had no parenteral erythropoietic stimulants. Blood hemoglobin levels on postoperative days 1, 2, and 10 were a main control indicator. Blood transfusion therapy was not performed in the identified groups. Results. In the first two days, hemoglobin levels were statistically significantly higher in the CON group than those in the EPO group and on day 10 intergroup differences were absent. By day 10 versus day 2, a statistically significant increase in hemoglobin concentrations was found in the EPO and IRON groups. In the EPO group, the hemoglobin concentration increment was significantly higher than that in the CON group. There were no clinical signs of thrombosis and thromboembolic events in the patients of the study groups. Conclusion. The co-administration of intravenous iron and epoietin enables an 8 g/l increase to be achieved on postoperative day 10 versus day 2. Key words: joint replacement, anemia, epoietin, iron saccharate, intravenous iron.

We report some results of theoretical analysis and experimental study of selective properties of 3D holographic grating. In particular, the case of strong deviation of the propagation vector of the reconstructing wave from Bragg conditions by tuning the wavelength and/or the angle of the incident illuminating beam is considered. In this case, it is more convenient, to operate with joint function of angular-spectral selectivity. The character of this joint function should be taken into consideration, if true color holographic images are of interest. Key words: angular and spectral selectivity, 3D reflection grating, diffraction efficiency.

In this paper we present the results of analytical examination of long pipe oscillations. The study performed the characteristics of the oscillations, based on solution of a system of the wave equations for surface displacement. The pipe under the consideration is an elastic cylindrical shell. The oscillations are initiated by an externally applied loading force, that has a form of short-acting pulse. The results obtained are compared with experimental data from interferometric analysis of a 6m long polymer pipe. Keywords: holographic non-destructive testing, oscillation analysis.