| 摘要 |
PROBLEM TO BE SOLVED: To have high speed access to information recorded on an optical disk. SOLUTION: The device 10 is equipped with a semiconductor laser 52 as a laser light source, a photodetector 54 and an optical system 12 for converging emitted light from the semiconductor laser 52 onto the optical disk 58 by an objective lens 56, etc., and guiding this reflected light to the photodetector 54. Then, a conical lens 14 is provided in the optical system 12 to give a special feature. A beam diameter on a luminous flux A made incident upon the objective lens 56 from the semiconductor laser 52 is enlarged by the conical lens 14. |
