| 摘要 |
PURPOSE:To make luminous flux incident on an information recording medium in a proper state. CONSTITUTION:A laser beam L emitted from a semiconductor laser 1 is made parallel luminous flux by a collimate lens 2 and after the parallel luminous flux is made to have a circular cross-section by a beam shaping prism 3, it is projected on an optical disk D through a objective lens 5 as a light spot. The collimate lens 2 is moved in the direction of the optical axis of the lens by an electromagnetic coil 13 being a lens actuator and the collimate lens is position-corrected and the light spot on the optical disk D is maintained in a prescribed setting state. |
