| 摘要 |
PURPOSE:To extremely increase the frequency band of an optical pickup and to improve the designing flexibility of an optical pickup device by preventing the incidence of the laser beam in the areas except the effective light receiving area of a light receiving element and therefore suppressing the gain ripple. CONSTITUTION:When the data are recorded on an optical disk 7, the laser beam of high output is emitted from a semiconductor laser 2 to form a data pit on the surface of the disk 7. The laser beam is partly detected by an emitted beam quantity monitoring beam receiving element 5 and converted into the electric signals. These electric signals are sent to a control system. The size d2 of a single side of the effective light receiving area of the element 5 is set larger than the size d1. As a result, no carrier is produced at the outside of a depletion layer and therefore the gain ripple cam be excluded out of a desired frequency band. Thus the designing flexibility is improved for selection of the semiconductor laser, the setting of the emitted beam quantity, etc. |
