| 摘要 |
PURPOSE:To stablize the output of a light source and to improve the performance of the optical disk device by specifying a ratio between a longest distance including the movable range of a full optical path length from the light source to the optical disk medium and a shortest distance. CONSTITUTION:A fixed part 13 including a light source 4 and a photodetector 10 is separated from a movable part 14 to position a light spot through an objective lens 9 in the radial direction of an optical disk medium 1. Then, the ratio between the longest distance of the entire optical path including a movable range (l) of an optical path 15 from the light source 4 to the medium 1 and the shortest distance is set less than 2. Therefore, the output of the light source is stablized by turning a resonator, which is formed corresponding to the distance from the reflection face of the medium 1 to the light emission end face of a semiconductor laser, to a non-resonance state regardless of movement in the movable range. Thus, the performance of the optical disk device can be improved. |
