| 摘要 |
PURPOSE:To unify the optical path system for detecting a signal and to miniaturize the titled device by using a Savart plate as a photodetector. CONSTITUTION:The Savart plate 10 converts the rotation of a polarizing face in an information signal light to the change of an intensity and separates it to the two light fluxes of a P polarizing component and an S polarizing component. Then, as the photodetector 10, the Savart plate is used, two outgoing light fluxed from the Savart plate are used for detecting a focal point dislocation and detecting a track dislocation and a reproduced signal can be obtained. In such a way, since as the photodetector, the Savart plate is used, the optical path system and the focal point dislocation, the track dislocation and the reproduced signal can be detected by one photodetector consisting of plural light receiving faces 14, 16. |
