| 摘要 |
PURPOSE:To attain the reduction of the incident angle to a condenser lens despite the large eccentricity and a large inter-track shift, by performing the position control of a beam spot on a disk in the track direction and at the same time detecting the angle of a mirror by a 2-split optical sensor. CONSTITUTION:The light transmitted and separated through a half mirror 11 is made incident on a half mirror 15 to be separated into two beams. Then a focus error is detected by a lens 17, a knife edge 18 and a 2-split optical sensor 19. At the same time, a tracking error is detected by a 2-split optical sensor 16. In this case, the incident light of a half mirror 5 is reflected by a reflecting surface 51 and made incident on a 2-split optical sensor 20. When a mirror actuator 8 is turned toward an arrow head 10 around a shaft 9, the light beam on the sensor 20 moves in proportion to the turning position of the actuator 8. Then the different of output is calculated between elements 201 and 202 of the sensor 20 to detect the turning position of the actuator 8.
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