| 摘要 |
PURPOSE:To discriminate the abnormality of the whole optical system of an optical pickup irrespectively of a recording medium by detecting the quantity of the light of the optical pickup through the emitting side optical system of the pickup without passing through the recording medium. CONSTITUTION:A laser beam from the laser diode 5 of the optical pickup 3 is reflected by means of a totally-reflecting mirror 20 through a collimate lens 6, deflection beam splitter 7, 1/4-wave plate 8, mirror 9, and object lens 10. The reflected light is made incident on a photodetector 12 through the lens 10, the mirror 9, the wave plate 8, the beam splitter 7, and the emitting-side optical system of a collimate lens 11 and the detecting output of the photodetector 12 is stored in a memory 22 through an A/D converter 21 after it becomes abnormality discriminating signals containing the transmissivity information of the whole optical system of the optical pickup irrespectively of the a recording medium. |
