Recording holographic memory device based on computer synthesis of Fourier holograms

Roadmap on holography

“…To this end, a new method of manufacturing holographic memory is proposed-a combination of the computer-aided synthesis of Fourier holograms and their rewriting on a photosensitive medium using a projection method in incoherent light (figures 11 and 12) [131][132][133][134][135][136][137][138][139][140].…”

“…When illuminated by their reference radiation, diffraction of optical radiation occurs only in the direction corresponding to the orientation of 1D holograms. This feature allows multiplexing 1D Fourier holograms by their rotation about an axis perpendicular to the recording plane [131][132][133][135][136][137][138][139][140]. A method was developed for synthesizing 1D Fourier holograms with a count of the discretization parameters and a phase mask, the nonlinearity of the modulation characteristics of the SLM, the modulation transfer function of the incoherent projection optical system.…”

Transparency function presentation of computer generated Fourier holograms for complex data page restoration

“…Conventional holographic memory systems developers use physical multiplexing of holograms in order to achieve a high density of data record. [1][2][3][4][5][6][7] Another trend to increase the record density of data storage system is the use of advanced modulation formats, which utilize both amplitude and phase modulation to represent digital data as symbols of constellation diagram (bauds). Application of methods such as spatial quadrature amplitude modulation (SQAM) for digital data encoding onto data page and its implementation to increase the holographic memory capacity were demonstrated theoretically and experimentally.…”

“…Recently it was demonstrated that computer generated Fourier holograms (CGFH) are a perspective candidate for application in holographic data storage (HDS) system design for the recording and reconstruction of binary amplitude data pages. [4][5][6][7]19) In the case of CGFH, a data page with any type of two-dimensional numeric complex function can be digitally encoded into the non-negative real valued holographic structure which can be physically realized as a diffraction optical element using amplitude-only or phase-only spatial light modulator (SLM) or transmitted onto the photosensitive carrier using a simple optical projection scheme based on amplitude-only SLMs or OLEDs. 20) Depending on the photosensitive material and post-processing methods, micro-holograms of data pages obtained in the projection schemes can be amplitude-only, phase-only or mixed amplitude and phase-modulating.…”

Development of projection-type optical scheme for computer-generated Fourier hologram recorder

“…6(b)]. The recorded holograms were recovered with the classic system of optical Fourier cascade [2] . An example of a data page restored as a hologram and post-processed digitally on a PC is shown in Fig.…”