DEVICE AND METHOD FOR STORING PHASE CONJUGATION HOLOGRAPHIC INFORMATION USING MULTI-FOCAL LENS

摘要

PURPOSE: A device and a method for storing phase conjugation holographic information using a multi-focal lens are provided to reduce a DC(Direct Current) term, that is light intensity in a central Fourier plane, and to maintain information storage density high, when recording information on the holographic information storage device. CONSTITUTION: A focusing lens(41) focuses object beam(44) having information. An SLM(Spatial Light Modulator,42) located on an optical path of the object beam passing the focusing lens modulates the object beam. An information recording medium(43) records an interference fringe by the interference between reference beam and the object beam passing the SLM and is focused. The focusing lens is a multi-focal lens having more than 2 focuses, and is shaped with a spherical surface in one side or both sides. As the multi-focal lens, the focusing lens has focusing distances varying according to a normal distance of a lens central axis from a center of the lens.