| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical pickup device which employs a front monitoring system APC(auto-power control), that is hardly affected by the fluctuation in production and environmental variations and has high reliability, and controls the output power of optical beams. SOLUTION: The light beams emitted from a semiconductor laser 20 are made incident on an orthoscopic prism 24 through a collimetor lens 21 and a grating 22. At that time, a portion of the beams is reflected by a reflection surface 24a, which is not AR coated, led to a front monitoring detector 23 and controlled by an APC circuit 31 so as to maintain the output power of the laser 20 constant. On the other hand, the light beams passed through the surface 24a, go through a reflection film 24b and irradiate an optical disk with a stable light quantity through a 1/4 wavelength plate 25, a reflection prism 26 and an objective lens 27. The reflected light beams are finally received by a detector 30. |
