| 摘要 |
PROBLEM TO BE SOLVED: To perform servo control in accordance with the measured result by measuring whether signal light reproduced using a diffraction grating having a land and a groove is made incident accurately on a center of a pinhole of a pinhole plate or not. SOLUTION: A holographic ROM reproducing device includes an objective lens irradiated from a power source and converging light reflected from a storage medium, a pinhole plate having the pinhole having size in which one part of light converged by the objective lens is passed through, a light transmission type diffraction grating generating 0-order diffracted light, +1st order diffracted light, and -1st order diffracted light by diffracting light converged by the objective lens, a photodetector for detecting the amounts of the 0-order diffracted light, the +1st order diffracted light, and the -1st order diffracted light, and a servo controller for comparing an amount of light of an overlapped area of the 0-order diffracted light and the +1st order diffracted light with an amount of light of an overlapped area of the 0-order diffracted light and the -1st order diffracted light to control the objective lens to pass the light through a center of the diffraction grating if the amounts of light are not identical to each other. COPYRIGHT: (C)2006,JPO&NCIPI
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