| 摘要 |
PROBLEM TO BE SOLVED: To improve the fidelity in a reproducing pit image by inserting a pin hole so as to impart absorption to a periphery of an objective lens aperture onto a laser beam optical path generated from a single laser beam generation source. SOLUTION: The laser beam outgoing from a laser diode 6 is shaped to a circular beam by a collimate lens 5 and a wedge prism 4. Then, the circular beam is absorbed in its light intensity distribution of the periphery of the laser beam by passing through the pin hole 13 inserted into the optical path. Then, a disk recording medium 1 surface is irradiated by a point image with excellent light intensity contrast through a polarizing beam splitter 3 and an objective lens 2. Thus, a random noise component incorporated in reflected light is reduced remarkably to be differential detected by photodetectors 10, 12 through the splitters 3, 7. Thus, the random noise of a regenerative signal is suppressed, and the regenerative signal performance of the information is improved. |
