US Patent 7254106 Method and equipment for storing holographic data

A method for storing holographic data in a medium having a reflection layer and a recording layer comprises: recording, rotating and repeating. An interference pattern is recorded at a recording position of the recording layer of the medium in a stationary state. The interference pattern is formed by an interference between an object beam and a reference beam which are irradiated into the recording layer from an opposite side of the reflection layer. The medium is rotated so as to shift the recording position by a distance of n×Sh where n is a positive integer and Sh is a predetermined recording shift amount. The recording and the rotating are repeated alternately.