| 摘要 |
PURPOSE:To make a device small in size and light in weight by integrating and providing an optical path separating element which transmits or reflects light with a diffraction grating type polarizing plate which polarizes and separates the reflected light from an optical information recording medium and has a diffraction grating formed so that the grating directions are orthogonally crossed with each other. CONSTITUTION:The optical path separating element 8 which transmits or reflects the light and the diffraction grating type polarizing plate 9 which polarizes and separates the reflected light from the optical information recording medium 10 and has the diffraction grating formed so that the grating directions are orthogonally crossed with each other are integrated to be provided on the optical path of the light emitted from a laser light source 7. Then, the light emitted from the laser light source 7 is reflected by the optical path separating element 8 and guided to the optical information recording medium 10. The light reflected on the medium 10 is guided to the optical path separating element 8 again and transmitted through there. Then, the light is polarized and separated by the diffraction grating type polarizing plate 9 having the diffraction grating and guided to a signal detection optical system. Therefore, the information is reproduced and a focusing error signal and a tracking error signal, etc., are detected. Thus, the number of parts in a signal detection optical system is reduced and the entire device is made small in size and light in weight. |
