| 摘要 |
PURPOSE:To reduce the number of parts and to miniaturize a device, by forming a stable and simplified optical system by providing a hologram device having a composite function in an optical pickup device. CONSTITUTION:An optical beam from a semiconductor laser 1 is diffracted by a diffraction element 30, and a part of it is reflected and returned to the laser 1 as a feedback beam. A non-feedback beam passes through the optical system, and performs the recording and the reproduction of a recording medium by a micro spot, and also, performs focusing and tracking control. At this time, on one side of the diffraction element 30, a diffraction grating and a polarization selection reflecting film are provided, and it functions as an optical device having the composite function. Also, on the end face on one side of the laser 1, a reflection preventing film 100 for an oscillation wavelength is provided. In such way, it is possible to suppress noise by simplifying the optical system by attaching the composite function on the optical device, and stabilizing the oscillation mode of the laser. Thereby, the number of the parts can be reduced, and the optical system can be miniaturized. |
