V. E. Mandel

Drift model of photoinduced processes in alkali-halide crystals during volume hologram recording

Investigations of photoinduced processes, which occur in alkali-halide crystals during volume hologram recording, are performed with the help of new holographic method. New diffusion-drift model of the charge carriers and defects migration in high gradient interference light field during hologram recording is offered.

Optimization of the Recording Conditions for Holograms Recorded in Additively Colored KCl Crystals

The dependences of the characteristics of volume holograms recorded in additively colored crystals of potassium chloride on the spatial frequency and the recording temperature are studied. It is found that these dependences are nonmonotonic, which indicates the presence of nonlocal mechanisms of holographic recording in the crystals. These mechanisms involve diffusion and drift processes of redistribution of color centers between the nodes and antinodes of a recorded interference pattern. The results obtained are used to determine the recording conditions providing the maximum possible diffraction efficiency of the holograms.

Space-periodic laser irradiation action on cell structures

A new model of low intensity laser irradiation action (LILI) on biological objects on cell level was suggested. Up to this model the effect of LILI action is a result of that fact that laser light irradiation due to it coherence can obtain periodical character (interference picture or speckle-structure) with small enough periods of dark and light parts changing comparable with cell or cell organelles sizes. In this conditions inhomogeneous light absorption can lead to electrical field appearance (Dember effect), which can change the character of photostimulated reactions and change membrane charge condition either of cell itself or of its organelles, that is lead to cell life cycle shifts.

Stabilization of the interference pattern when recording volume transmission holograms

This paper describes a method of stabilizing the interference pattern when recording threedimensional transmission holograms in photochromic and photorefractive media. The method is based on using the dynamic interaction of the interference field with the recorded hologram.

Noncontact holographic method of measuring linear displacements

A noncontact optical method has been developed for measuring the linear displacements of an object to within several angstroms by measuring how the intensity of a light beam coming from a three-dimensional transmissive holographic diffraction grating (a hologram) depends on the phase mismatch between the beams incident on the hologram. The phase mismatch between the beams is caused by the displacement of the object, from which one of the beams incident on the grating is reflected. It is shown that, when a He?Ne laser (Lambda=633nm) and a photodetector whose relative error DI/Imax is 0.5X10-3 is used, the error in measuring the displacement of the object can be brought to about 0.1 nm.

Method of determining small linear displacement

A method of small linear displacement determination with subnanometer accuracy, which is based on interaction of the interference field of two laser beams with a 3D holographic diffraction grating fastened on the moveable object, was suggested.

Method for determining changes of 3D hologram parameters during recording

In this work for the first time the light induced phase transitions in amorphous As-S compositions in periodic interference field have been studied with the help of holographic method, offered by us earlier, which permits us to carry out independent measuring of absorptivity ((Delta) (alpha) ) and refractivity ((Delta) n) changes in studied materials in bulges and nodes of interference pattern. It is shown that stable high-temperature (T approximately 100 degrees Celsius) transitions happen due to a D degree(s)-centers diffusion from bulges of interference pattern to nodes. The disturbance of thermodynamic equilibrium distribution of defects (D-centers) resulted in a diffusion of D degree(s)-centers in the case of As2S3.

Volume diffraction gratings for optical measuring devices

Investigations of fast processes in transparent media are being successfully performed by means of coherent optics methods such as interference, correlation, laser Doppler anemometry (LDA), etc. All these methods require splitting and further bringing together laser beams and following the processing of a useful signal. It is very difficult to fulfill these requirements with the help of traditional optical means, especially for many beams with complex wave fronts. In these cases one has to use optical schemes with a great number of elements, which results in great losses at reflection, in depolarization of the beams, in worsening of the device vibration stability, and in climatic changes. It is possible to get rid of all these disadvantages by using holographic optical elements in such devices.