| 摘要 |
PURPOSE:To enhance signal detecting accuracy by disposing a monitoring photodetector to be inclined to an incident light axis on an optical path of an optical system constituting the pickup and preventing stray light of a part of a light beam due to its reflection on the surface of the monitoring photodetector. CONSTITUTION:A light beam emitted from a laser light source 11 is passed through a grating 13 and splitted into two by a beam splitter (BS) 14, and a part of each beam incident upon a front photodetector 15 (25), so as to monitor the beam output, etc., of the light source 11. Now, since the detector 25 is disposed to be inclined to the incident light axis on the optical path, the stray light due to the reflection on the surface of the detector 25 to be entered into an optical element is evaded. Other light is passed through a collimator lens 17, and is bent at 90 degrees by a reflecting surface of a prism mirror 18 and converged on the surface of an optical disk 21 via an objective lens 19. This reflected light is returned backward to be reflected by a reflecting surface 14a of the BS 14 and splitted via a Wollaston prism into three, which are then inputted via a multilens assembly 22a to a photodetector 23. |
