| 摘要 |
PURPOSE:To facilitate miniaturization of the device and also to simplify adjustment of the optical parts. CONSTITUTION:The optical head device is composed of a semiconductor laser 3, a prism 5 and an objective lens 2. The prism 5 is installed with its one surface 5a facing the semiconductor laser 3 side and with the other surface 5b facing the objective lens 2 side, and the one surface 5a is provided with a reflecting coating layers 7c and 7d as reflecting films for reflecting +1st-order diffracted light 11 and -1st-order diffracted light 12 respectively, while the other surface 5b is provided with photodetectors 8 and 9 and a hologram element 4. In addition, the one surface 5a of the prism 5 is provided with a phase film 6 for changing the phase of a center part of a light beam emitted from the semiconductor laser 3 by pirad. |
