Recent progress in a real-time three-dimensional display

A concept for a holographic display system that can accept data in coordinate form and synthesize a three-dimensional scene in real time has been reported. Recent progress on this system centers around the recording medium and compensation of the frequency shift introduced by the deflection system. The need for a holographic recording medium that can be exposed, developed, and viewed in about 1 s is being met by a thermoplastic-photoconductor (TP-PC) film. The reusable TP-PC film has photographic characteristics comparable to standard holographic films. Improved TP-PC films having greater spatial frequency bandwidths, higher sensitivities, less background noise, and increased sequential recording capacity have been developed. The use of acousto-optic beam deflectors in the object and reference beams causes these beams to have different frequencies. In order to record holographic fringes of sufficient visibility, some frequency compensation scheme is therefore required. Several methods for achieving this compensation are discussed.