| 摘要 |
PURPOSE:To suppress the lowering of modulation factor low and to improve reading accuracy even at the time of making the recording pit of a disk high density. CONSTITUTION:An optical head device 21 is constituted of a light source 22 consisting of a laser diode, etc., a beam splitter 23, a condenser lens 24, a cylindrical lens 25, a photodetector 26 consisiting of a pin photodiode, etc., and an attenuation filter 27 and a light shielding belt 28 prolonging to a tracking direction in the center part of a linear velocity direction is formed on the attenuation filter 27. The beam of an area containing the center part is shielded for a reflected beam from the disk D by the light shielding belt 28 and the beam of other peripheral part passes through. Thus, the ratio of an AC component to a DC component is increased for the modulation of a high space frequency and the modulation factor is increased. |
