Characteristics of multiplex recording in photorefractive disk-type memory

摘要

In this paper, we propose the disk-type memory with the photorefractive crystal. In the photorefractive memory, holograms can be multiplexed in a same spot of the crystal. Among various multiplexing method, we employ the shift multiplexing for our memory. In this method, we can angularly multiplex holograms by means of the shift of the recording position induced by the rotation of the disk. We analyze the amount of shift required for multiplexing differentiable holograms and carry out an experiment to measure the amount of shift. On the other hand, there is a problem that stored data is erased by the subsequent recordings when holograms are multiplexed. To store a grate deal of data, it is essential to balance the subsequent erasure against the initial exposure by means of recording schedule. We suggest two kinds of recording schedule for this multiplexing method, and estimate the optimum recording conditions and the generation efficiency of the output.