| 摘要 |
PURPOSE:To reproduce information with a high quality and a high S/N ratio simplify the adjustment by making a beam, whose polarization direction is rotated with a frequency twice or more as high as a maximum frequency of a reproducing signal, incident to an optical magnetic memory and detecting the phase of a change in the polarization direction of a reflected light or a transmitted light on a basis of the rotation frequency of the incident light to reproduce information. CONSTITUTION:A frequency twice or more as high as a maximum frequency of the reproducing signal is selected as the frequency, with which the polarization direction is rotated, in accordance with the sampling theorem. The parallel luminous flux from a laser light source 26 becomes a linearly polarized light by a polarizer 28 and is divided to diffracted lights 30 and 31 in an acoustooptic modulator 29, and they are made incident to lambda/4 plates 33A and 33B to become clockwise and counterclockwise circularly polarized lights. Two circularly polarized lights become rotating linear polarized lights by mirrors 34 and 35 and are divided to a phase detection reference signal, which is made incident to a photodetector 38, and a light, which is condensed on an optical magnetic memory medium 40 and passes the mirror 36 again and passes an analyzer 41 and a photodetector 42, by a half mirror 36, and phase comparison is performed in a phase detector 43B to reproduce information recorded on the memory 40. |
