| 摘要 |
PURPOSE:To enable a large grid period to be taken and to relax allowable accuracy for the generation of a grid, by forming a holographic device in an in-line type, and forming a laser light passage in the central position of an optical detector. CONSTITUTION:A semiconductor laser 1, a condenser lens 3, the holographic device 10, and the optical detector 8 are provided, and the holographic device 10 is formed in the in-line type. The in-line type holographic device 10 is the one in which the optical axis of a reflected beam of light is fitted to that of emitted light, and simultaneously, the laser light passage is formed in the central position of the optical detector 8. Therefore, the in-line type holographic device 10 only supplies aberration to the reflected beam of light, and the advancing direction of the beam of light remains unchanged. In such a way, since the diffracted light of the holographic device 10 is not provided with a large angle of diffraction, the grid period can be increased, and the generation of the holographic device 10 can be facilitated. |
