| 摘要 |
PURPOSE:To reduce the necessity of complicate adjustment by arranging a beam splitter consisting of a single optical component having a couple of reflecting surfaces arranged almost in parallel so that incident light from a light source and reflected light guided to a photodetector are directed in parallel and in the opposite directions between a light source, and the photodetector and objective lens. CONSTITUTION:Laser light 11 emitted by a semiconductor laser 101 is diffracted by a diffraction grating 103 into plural light beams, which are reflected by a beam splitter 104 at right angles. Further, they are reflected by a mirror 106 in a Z direction to enter the objective lens 107, thereby forming light spots on a disk 108. Light reflected by the disk 108, on the other hand, travels in the direction opposite to that of the incident light. Thus, the beam splitter 104 directs the incident light from the light source 101 and the reflected light guided to the photodetector 110 in parallel and in the opposite directions, so the tolerance to the relative position relation between the beam splitter 104 and photodetector 110 is extremely large, and the assembly and adjustment of the device are extremely easy. |
