Recording Of Dynamic Holograms Research Articles

Correction of segmented mirror aberrations by phase conjugation and dynamic holography

A novel approach is proposed for using the phase conjugation phenomenon for dynamic correction of distortions in beam forming laser systems. The method is based on the well-known application of a special diffraction structure on the surface of corrected optical elements ensuring nonreciprocal beam propagation in a system including a phase conjugate mirror. The main feature of the proposed approach is that it uses the diffraction structure which is not static (as usually) but is written dynamically by a small auxiliary laser source irradiating the corrected element surface simultaneously with the working beam. This makes it possible to extend the capabilities of the known method with respect to scaling-up the size of compensated mirrors and allows replacement of a large solid mirror by a segmented one. The novel method of correction has been tested experimentally by the use of 1.06 μm radiation for recording the dynamic hologram and a 10.6 μm laser beam as the working beam, distorted by a two-segment mirror with a dynamic hologram on its surface and corrected by a phase conjugate mirror. The means of dynamic hologram recording in different spectral ranges are discussed.

Correction of segmented mirror aberrations by phase conjugation and dynamic holography

A novel approach is proposed for using the phase conjugation phenomenon for dynamic correction of distortions in beam forming laser systems. The method is based on the well-known application of a special diffraction structure on the surface of corrected optical elements ensuring nonreciprocal beam propagation in a system including a phase conjugate mirror. The main feature of the proposed approach is that it uses the diffraction structure which is not static (as usually) but is written dynamically by a small auxiliary laser source irradiating the corrected element surface simultaneously with the working beam. This makes it possible to extend the capabilities of the known method with respect to scaling-up the size of compensated mirrors and allows replacement of a large solid mirror by a segmented one. The novel method of correction has been tested experimentally by the use of 1.06 μm radiation for recording the dynamic hologram and a 10.6 μm laser beam as the working beam, distorted by a two-segment mirror with a dynamic hologram on its surface and corrected by a phase conjugate mirror. The means of dynamic hologram recording in different spectral ranges are discussed.

KINETICS OF DYNAMIC HOLOGRAM RECORDING IN POLYMER FILMS WITH IMMOBILIZED BACTERIORHODOPSIN

Abstract— Polymer films with immobilized photosensitive membrane protein, bacteriorhodopsin (BR), were prepared and investigated. A sensitive holographic interferometer with phase modulated optical beams was used for investigation of kinetics of dynamic hologram recording in BR polymer films. It was found that phase hologram formation consisted of two quasi-exponential stages demonstrating existence of a diffusive process in obtained films. It was shown that the kinetics of a phase hologram recording by high intensity beams do not correlate with the exponential law. The applicability of BR polymer films as reversible photorefractive materials for dynamic holography and real-time interferometry was discussed.

Two-Wave And Four-Wave Mixings In Photorefractive Crystals: An Overview of Numerical Modeling

This review paper contains three parts. The first part covers the photorefractive (PR) effect and the processes [e.g. two-wave mixing (TWM) and four-wave mixing (FWM)] which are associated with the recording of dynamic volume holograms. This part reviews the PR effect, popular PR crystals and their performances in dynamic holography, general aspects of hologram formation, coupled wave formulations of dynamic holograms through degenerate two wave mixing (DTWM) and degenerate four-wave mixings (DFWM), and performances in obtaining analytical or numerical solutions of DTWM and DFWM equations. The second part presents a brief summary of our recent investigations in this area. The third discusses some suggestions for future research activities and outlines the current status and progress.

Photorefractive barium sodium niobate

Abstract Recording of transmission and reflection dynamic holograms, beam coupling, phase conjugation due to backward-wave four-wave mixing, and coherent optical oscillation with frequency degenerate pump have been studied in nominally pure barium sodium niobate crystals.

Recording and readout of resonance dynamic holograms in the scanning regime

Recording and readout of resonance dynamic holograms in the scanning regime

Two-dimensional character of the self-diffraction in wedgelike α-SiC(6H)

Dynamic hologram recording (λ = 694 nm) in a wedgelike sample of α-SiC(6H) (Nd ≃ 1018 cm−3) was investigated. Two-beam (two-dimensional gratings) and one-beam (self-pumped phase conjugation) recordings of the dynamic gratings have been carried out.

KINETICS OF DYNAMIC HOLOGRAM RECORDING IN POLYMER FILMS WITH IMMOBILIZED BACTERIORHODOPSIN

AbstractPolymer films with immobilized photosensitive membrane protein, bacteriorhodopsin (BR), were prepared and investigated. A sensitive holographic interferometer with phase modulated optical beams was used for investigation of kinetics of dynamic hologram recording in BR polymer films. It was found that phase hologram formation consisted of two quasi‐exponential stages demonstrating existence of a diffusive process in obtained films. It was shown that the kinetics of a phase hologram recording by high intensity beams do not correlate with the exponential law. The applicability of BR polymer films as reversible photorefractive materials for dynamic holography and real‐time interferometry was discussed.

Holographic technique for photovoltaic constant determination

The technique of photovoltaic constant determination from transient characteristics of dynamic hologram recording is described. The temperature dependencies of the driving photovoltaic field and of the photoconductivity of nominally pure LiNbO3 crystals are measured.

Dynamic holography and optical image processing

Possible applications of dynamic holograms for image amplification and image processing are discussed. The principal physical processes of holographic amplification of coherent light are analysed. Amplification of grey scale images during recording of dynamic holograms in pure reduced and Fe-doped crystals of LiNbO 3 is demonstrated. One-exposure technique of image subtraction or addition is proposed and realised in Fe-doped crystals of LiNbO 3.

Recording of dynamic holograms in a lithium niobate crystal with a high iron impurity concentration

An investigation was made of the fast (~1 sec) self-erasure of holograms recorded in a lithium niobate crystal containing 0.3 wt.% iron. The holograms were recorded using the second harmonic of a neodymium laser in the form of 25 nsec pulses. The results indicated that these crystals could be used in optical high-speed memories.