| 摘要 |
PURPOSE:To make an optical system simple and small by providing two objective lenses for the distance in which the actuator is coincident to a dividing area pitch of the band dividing type optical memory disk to an objective lens actuator, and detecting easily the tracking error. CONSTITUTION:Since the second objective lens, separating two objective lenses for the distance in which the actuator coincident to the dividing area pitch of an optical memory disk from an objective lens 7a, is fitted at a lens holder 30, the tracking control for the lens 7a is executed, and then, the tracking for the lens 7b is also completed. In such a case, a laser beam LB1 passing through the lens 7a is in charge of the area with a groove where the groove for the recording track is provided, and therefore, the tracking error can be easily detected. |
