| 摘要 |
PURPOSE:To detect a moving position of a movable optical section with a high precision in an optical pickup of a separation optical system in which an optical system is separated into a fixed optical section and a movable optical section. CONSTITUTION:A fixed optical section 20 emits a moving position detecting light beam to a movable optical section 21. The light beam is reflected by a reflection prism mounted on the section 21 and is returned to the section 20. The reflection prism separates the incident light into two light beams which are tilted in different directions with respect to the moving axis of the section 21. The two beams are received by two semiconductor position sensors 10a and 10b mounted on the section 20, respectively. When the moving position of the section 21 is chagned, the light receiving positions at the sensors 10a and 10b are moved in the different directions. When a section 21 makes a rotational deviation, the light receiving positions at the sensors 10a and 10b move in a same direction, the output change caused by the motion is cancelled and the effect caused by the rotational deviation of the section 21 is eliminated. |
