| 摘要 |
PURPOSE:To obtain a compact and light-weight optical head and to increase the information processing speed by using three sheets of holograms to form an optical system. CONSTITUTION:The coherent light is projected from a semiconductor laser LD to the holograms H1 and H2 which are put on each other at the opening part 14 of a metallic casing 13. The casing 1 is kept at a fixed temperature by a Peltier element 16 having a discharging fin 15. The laser light passed through the hologram H1 as it is and if focused by the hologram H2 to be made incident on a magneto-optical disk 4. The reflected light is diffracted by the H1 and made incident on a hologram H3. The hologram H3 has a polarizing/separating function and separates a P component from an S component to focus them onto photodetectors D1 and D2. Then the information on the disk 4 is read by the difference between outputs of both detectors D1 and D2. In such a constitution, a compact and light-weight optical pickup is obtained and the access time is shortened. |
