| 摘要 |
PURPOSE:To measure the projecting power correctly with removing the returning light of a semiconductor laser, and without breaking the semiconductor laser while the semiconductor laser is APC driven. CONSTITUTION:An adapter 4 is mounted to a head 1 which measures the optical output, and is provided above an objective lens 12 of a pickup. The luminous flux entering a polarizing beam splitter 6 reaches a photodetector 3 of the head 1 through a lambda/4 plate 7. The returning light due to the reflection at the surface of the photodetector 3 is, again passing the lambda/4 plate 7, incident upon the polarizing beam splitter 6. At this time, since the returning light enters as an S-polarized light, the returning light is projected from a surface opposed to the bonded surface of a lambda/4 plate 8, therefore not reaching the semiconductor laser. |
