| 摘要 |
PURPOSE:To reduce output fluctuation due to return light on driving a semiconductor laser at a low output by arranging a 1/4 wavelength board in an optical path from a beam splitter to an objective lens in the recording/reproducing of a postscript type optical disk and making a optical axis direction different on recording and on reproducing. CONSTITUTION:On recording, a 1/4 wavelength board 14 arranged between a beam splitter 3 and an objective lens 5 is inclined for 45 degrees to the polarizing direction of incident irradiating light by a rotational device. Thus, S polarization from a laser diode (LD) 1 is reflected by the beam splitter 3, becomes circularly polarized light to transmit through the wavelength board 14 and records information. On reproducing, the wavelength board 14 is set parallel or vertically to a polarizing face, and the LD 1 is driven at a low output. Then, when reflected light from a disk 6 is transmitted through the wavelength 14, it is converted into P polarization, is transmitted through the beam splitter completely, and is incident on a light detecting system 20. Consequently, it is not incident on the LD 1 as a return light, and the output fluctuation is reduced. |
