| 摘要 |
PURPOSE:To perform the formation of a stable ultra resolution spot with the small off-set of a focus signal and a track signal and to make constant the power of a semiconductor laser diode even when the optical axis dislocation exists. CONSTITUTION:Out of the light fluxes emitted from a semiconductor laser diode 4 to a moving optical system 2, the light flux near the optical axis of an objective lens 9 is reflected by a reflection mirror 20. The reflection light quantity is light-received by two-divided light-receiving elements 21A and 21B, an optical axis dislocation signal S3 or a sum signal S4 is obtained, and the optical axis dislocation off-set of the focus signal and the track signal is corrected. |
