Sergey S. Donchenko

Holographic memory system based on projection recording of computer-generated 1D Fourier holograms.

Utilization of computer generation of holographic structures significantly simplifies the optical scheme that is used to record the microholograms in a holographic memory record system. Also digital holographic synthesis allows to account the nonlinear errors of the record system to improve the microholograms quality. The multiplexed record of holograms is a widespread technique to increase the data record density. In this article we represent the holographic memory system based on digital synthesis of amplitude one-dimensional (1D) Fourier transform holograms and the multiplexed record of these holograms onto the holographic carrier using optical projection scheme. 1D Fourier transform holograms are very sensitive to orientation of the anamorphic optical element (cylindrical lens) that is required for encoded data object reconstruction. The multiplex record of several holograms with different orientation in an optical projection scheme allowed reconstruction of the data object from each hologram by rotating the cylindrical lens on the corresponding angle. Also, we discuss two optical schemes for the recorded holograms readout: a full-page readout system and line-by-line readout system. We consider the benefits of both systems and present the results of experimental modeling of 1D Fourier holograms nonmultiplex and multiplex record and reconstruction.

A combination of computer-generated Fourier holograms and light guide substrates with diffractive optical elements for optical display and sighting system

A combination of computer-generated Fourier holograms (CGFH) and light guide substrate with diffractive optical elements (DOE) is described. The experimental results show that this combination can be used in display and sighting systems.

Application of optoelectronic micro-displays for holographic binary data recorder based on computer generated fourier holograms

Present article highlights the researches provided during the development of holographic memory system based on application of computational methods to encode binary data pages as amplitude computer generated Fourier holograms (CGFH). Using electro-optical micro-display and projection optics CGFH can be recorded onto photosensitive medium. The type of display that is used in data recorder determines the specificities of optical scheme architecture with its own limitations and advantages. There are three projection schemes of binary data recorder discussed in the paper. A linear scheme based on transparency-type liquid crystal spatial light modulator (LC SLM), a scheme based on reflection-type liquid crystal on silicon spatial light modulator (LCoS SLM) which uses a beamsplitting cube, and the most compact and simple scheme based on self-emitting OLED-display. The results of experimental implementation of all the three projection schemes for CGFH of binary data pages record onto the holographic carrier and consequent optical reconstruction and analysis of the encoded data are presented.

Algorithms used for read-out optical system pointing to multiplexed computer generated 1D-Fourier holograms and decoding the encrypted information

The holographic disk reading device for recovery of CGFH is described. Principle of its work is shown. Analyzed approaches for developing algorithms, used in this device: guidance and decoding. Listed results of experimental researches.

Analysis of data recorder optical scheme impact on quality of computer generated Fourier holograms in holographic memory system

Holographic memory systems provide such advantages as long data storage term, high data density and do not need a power supply. Instead of recording interference pattern, it is proposed to record computer generated 1D Fourier holograms (CGFH). High information density is reached by multiplexing 1D Fourier Holograms. In this work factors, which impact the quality of recorded CGFH are analyzed in mathematical modelling and experimental researches.

Optical memory system based on incoherent recorder and coherent reader of multiplexed computer generated one-dimensional Fourier transform holograms

The present article highlights the development results of archive memory holographic system based on application of computer generated Fourier holograms. The proposed idea allows realization of holographic principles of digital data record using simple and compact optical devices. Special interest is paid to synthesis and multiplexed record of one-dimensional Fourier transform holograms. The principal schemes of constructed prototypes of incoherent data recorder and coherent data reader are described in the present paper. The results of experimental implementation of the constructed devices are presented.

Recording holographic memory device based on computer synthesis of Fourier holograms

Holographic memory systems provide such advantages as long data storage term, high data density and do not need a power supply. But traditional holographic systems require vibration isolation and are rather complicated. So computer generation of Fourier holograms (CGFH) is proposed. Instead of recording interference pattern, it is calculated on computer. High information density is reached in new method by multiplexing 1D Fourier Holograms. Optical equivalent of the 1D Fourier holograms computer synthesis is listed. Different spatial light modulators are analyzed for displaying CGFH. System for hologram recording is described. Results of recovering information CGFH are also listed.

Read-out optical schemes for holographic memory system based on multiplexed computer generated 1D Fourier holograms

Computer holographic synthesis allows to significantly simplify the recording scheme of microholograms in holographic memory system as the classic high precision holographic setup based on two-beam interference is removed by simple scale reduction projection scheme. Application of computer generated 1D-Fourier holograms provides the possibility of selective reconstruction of the multiplexed holograms with different orientation of data lines by corresponding rotation of anamorphic objective (cylindrical lens), used in the read-out systems. Two configurations of read-out optical scheme were investigated by our team: full-page scheme and line-by-line scheme. In the present article we report the specificities of these schemes and consider their advantages and disadvantages. The results of experimental modeling of both read-out configurations are also presented.

Computer Generated Fourier Holograms Application for Projection Type Holographic Memory System

The specificities of synthesis, record and reconstruction of computer generated Fourier-microholograms for application in projection type holographic memory optical system are discussed. Also we represent the computer generated 1D-Fourier holograms suitable for multiplexed record.