| 摘要 |
PURPOSE:To obtain the tracking error information, by locating the spot image of point light source to track direction and combining the condition change information with self coupling effect of semiconductor laser, in the optical system disc player. CONSTITUTION:The light from the semiconductor laser light source 2 is reflected on the video disc surface 4 via the lenses 3, 3', the light including the recording information returns to the light source 2, and the light including the self coupling effect of the light source 2 is incident to the information reading photo detector 1. In this case, when the light spot 5 from the light source 2 is located on the track, the light sources 2a, 2b are located so that the light spots 5a, 5b from the semiconductor laser light sources 2a, 2b are positioned by clipping the track and the light emitting plane of each light source is on the plane almost orthogonal to the light axis. Accordingly, the light output from the light sources 2a and 2b is changed on the position change of the spot 5, and the tracking error signal can be obtained with the operation 8 of the output of the photo detectors 1a and 1b corresponded. |
