| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical pickup device capable of shaping a laser beam so that no optical axis tilt is caused when the wavelength of a laser beam fluctuates by temperature change, thereby obtaining stable reproducing performance, and facilitating preparation of a pinhole and positional adjustment. SOLUTION: The optical pickup device is such that a laser beam from a semiconductor laser 1 is emitted, through a beam splitter 3 and an objective lens 6, to an information recording medium 8 having plural recording layers 7 in the depth direction, that the reflected light is received by a photodetector 10 through the objective lens 6, beam splitter 3 and a pinhole 9, and that the information is thereby reproduced which is recorded in the desired recording layers 7 of the information recording medium 8. In such optical pickup device, a beam divergence angle converting element 2 is arranged in an optical path between the semiconductor laser 1 and the beam splitter 3, shaping a crosssectional 1y elliptical laser beam from the semiconductor laser 1 into a nearly cross-sectionally circular laser beam. |
