| 摘要 |
PURPOSE: To unnecessitate the movement of an objective lens, to reduce the distance of such a moving stroke of the objective lens from an optical path in thickness and also to enter all of a beam light quantity sent from a light source into a converging system. CONSTITUTION: The converging system 4 having a rising mirror 2 and the objective lens 3 is fixed. Focusing and tracking are adjusted by driving an optical block 1. The focusing is adjusted by moving the optical block 1 along the direction of an optical axis of a laser beam in the direction of an arrow F in Figure. The tracking is adjusted by moving the optical block 1 to draw a circular arc around the center of the converging system 4 in the direction T in the Figure. |
