New page-composer for holographic data storage.
CdS in the form of a single crystal is a material exhibiting a steep band edge at the green argon wavelength of 0.515 microm. The thermal shift of this band edge is used to modulate the transmittance of a matrix addressed page-composer for binary data presentation. Short switching pulses in the range of 20 / 50 V applied to evaporated transparent heating elements produce within 100 microsec a 70 degrees C temperature shift in a thin CdS-crystal, being the key element of the page-composer. Contrast ratios of the transmittance of better than 800 and optical efficiencies of 50% are easily obtained in 10 / 20-microm thick samples. Fast parallel switching of twenty-five elements using time multiplex heating has been demonstrated with a 5x5 CdS-page-composer. A 16x18 matrix is being fabricated, and the implementation of larger arrays accessible in 1 msec appears feasible.
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