| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical head device capable of executing stable recording, reproducing and erasing by reducing the return light of the reflected light of an optical beam of large power to light sources, when two light sources of different wavelengths are used. <P>SOLUTION: The optical head device applies an optical beam to a high-density medium or a low-density medium. This device includes a first light source, a second light source, an objective lens for converging a first or second optical beam as a first or second optical spot on the high-density medium or low-density medium, an optical system for guiding both of first and second reflected light beams from the high-density medium and low-density medium to one optical detecting means, an optical detecting means having first and second detection surfaces; and a diffraction-type element disposed in the optical system, which receives the first and second reflected light beams from the objective lens, has diffraction angles different between those of the respective reflected light beams, and diffracts the respective reflected light beams, to irradiate them on the first and second detection surfaces. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
