Odinokov

The authors present the results of their study of multilayer optical memory with a two-photon mechanism for recording and collinear heterodyne readout. The choice of materials for multilayer recording with a nonlinear two-photon absorption mechanism is justified. The authors give a description of the experimental setup for multilayer recording in the form of microholograms with relative phase modulation. They present the main characteristics of an experimentally validated installation. The authors consider the main sources of additive noise and their impact on the speed of reading and recording density. They empirically obtained a preliminary assessment of the impact on reliability of inter-symbol interference registration information.

The article considers problems of increasing density of information stored on optical-holographic discs and playback of data bits using a hybrid method of data page modulation. The authors carry out a theoretical and experimental analysis of liquid crystal display (LCD) panels used as space-time light modulators (STLM).

The authors consider capabilities of manufacturing diffraction and hologram optical elements (DOE and HOE) with the use of the “Caroline 15 PE” machine. The purpose of the work was to increase the quality of binary DOE-HOE which is defined mainly by depth of the regular profile on the functional surface. It is shown that the maximum of this depth corresponds to the maximum of the etching selectivity of glass concerning a mask material. It is established that at thickness of chromic mask of 100 nanometers the PE method reaches depth of surface to 1,4 microns. It allows to increase the diffraction efficiency of DOE-HOE. Relative intensity of light in the second order of diffraction is 30 %; it allows to create new products of micro-optics.

The article considers quality assessment criteria for recording/reading process of magnetic signalograms with correct information read-out. The authors analyzed the distortions arising during magnetic signalogram visualization. The article describes boundary conditions allowing to determine boundary values of spatial periods of recorded magnetic signalograms to which undistorted information corresponds. Recommendations on selection of double-layer magnetic materials parameters are given. The degree of the optical efficiency for reading process, image contrast and range of the reproducing of spatial periods is determined with the usage of these parameters.

Micro-hologram multiplexing method was proposed and researched; it allowed to increase data writing and reading speed. This method was implemented in the developed and tested system. The ability to multiplex holograms, with the usage of multichannel write head, and simultaneous reading of those holograms with the usage of multichannel read head, was shown. The advantages and the perspective of this method and developed optical system usage for creating multiplex holograms in the systems of archival optical-holographic memory are listed below. The first is the elimination of need for mechanical motion of system elements both when multiplexing on the stage of writing and when restoring of multiplex holograms. The second is the absence of crisscross interference in the beams, restored from multiplex holograms. And last, but not least, it is the ability to use relatively thin recording environment for the writing.