Patent ID: 7760407

Claim:
A multilayer holographic recording and reproducing method for holographically recording information on a multilayer holographic recording medium including a number of deposited holographic recording layers in each of which interference fringes can be formed by projecting an object beam and a reference beam that are split from a laser beam and for reproducing the recorded information by projecting a single laser beam for reproduction, the method comprising: a process of recording the information by fixing a projection condition of the reference beam and modulating the object beam for each of the holographic recording layers so that the holographic recording layers each have a different Bragg's condition; and a process of projecting the single laser beam for reproduction having the same projection condition as that of the reference beam is projected onto the deposited holographic recording layers so as to generate a diffraction beam in an upper holographic recording layer and to make a transmitted 0-th order diffraction beam be projected onto a lower holographic layer one by one, the diffraction beams generated in the respective holographic recording layers emitted to different directions from each other at the same time by the single projected beam are detected by two-dimensional photodetectors a number of which is equal to that of the holographic recording layers, thereby simultaneously reproducing pieces of information from light-detecting signals of the two-dimensional photodetectors.