Abstract:
PURPOSE: A servo control technology for a hologram information storage device is provided to rotate a flat glass in a hologram information storage device which converges a reference beam into a local area by using a lens, and to control a horizontal displacement of the reference beam for a disk. CONSTITUTION: When recording a hologram, a signal beam(2) is converted through 4-f relay lens systems(11) after passing through an SLM(Spatial Light Modulator)(31) where a data image to be recorded is displayed, and a reference beam(1) is converged into a local area by using a lens(22) to store data. When reproducing the hologram, the signal beam(2) is cut off while the reference beam(1) only is illuminated, to read information from a detector array(13).