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We developed a standard credit card-shaped general-purpose data carrier, a reflective Holographic Memory Card (HMC), and the appropriate equipment for its handling. Data recording and retrieval are accomplished by polarisation Fourier holography using a thin layer of photo-anisotropic polymer as the storage material. The data density is about 1 bit/micrometers 2, the maximum storage capacity of the card is around 10 Mbytes assuming a 10 x 10 mm storage area. Data is stored in the form of microholograms, from which 40x40 pieces are recorded on the HMC. The optical system involved performs data writing/reading/erasing and also locates the position of the microholograms. Main components of the optical system are an SLM and CCD for opto-electronic conversion, a frequency-doubled solid-state laser source, a beam shaping system that provides homogeneous illumination of the SLM, an interferometer for hologram construction, special Fourier transforming objectives and a random-phase mask for optimised hologram recording. Our results include conceptual planning, design, fabrication and assembling of the optical system. In the present paper we describe principle of operation including layout of the elements, and explain the operation of the equipment in detail.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. |
