| 摘要 |
PURPOSE:To carry out verification with equivalent performance in both forward and reverse directions by splitting a reproducing light beam into Oth-order and fist-order light, irradiating forward and backward areas of a data pit image on a recording medium in the moving direction with the light and reproducing it with a photodetector in a corresponding position. CONSTITUTION:A data pit 72 is made on an optical card 7 by a semiconductor laser 1, and the laser beam is split into Oth-order and 1st-order diffraction light by a diffraction grating 15, and then the verification is performed by using reflected light of the 1st-order diffraction light. The forward and backward areas of a beam light point 73 on the optical card 7 are irradiated with + or -1st- order diffraction light of the beam, whereas photodetectors 84 and 85 are arranged at this light point image forming position. By this constitution, data immediately after recording can be reproduced, and the verification can be carried out with the equivalent reproducing performance in any direction of forward or reverse moving of the recording medium. |
