| 摘要 |
An optical head device includes a light source for emitting a light beam and a focusing device for focusing the light beam onto a recording medium. An optical path directs the light beam from the light source toward the recording medium. The optical path directs a first portion of the light beam to fall upon the focusing device. A second portion of the light beam does not fall upon the focusing device. A light detector is positioned such that a light receiving face of the light detector is approximately perpendicular to an advancing direction of the second portion of the light beam and detects an amount of light in the second portion of the light beam for control of the power of the light beam emitted from the light source. Thus, APC processing is performed without reducing utilization efficiency of the laser beam of a trunk system.
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