| 摘要 |
PURPOSE: To perform recording and reproducing in real time and also to attain the reduction of the number of optical parts and miniaturization with low cost. CONSTITUTION: A 1st laser beam of a 1st wavelength is emitted to irradiate an optical disk 10 through a collimator lens 3, a 1/4-wavelength plate 5, a wavelength filter 7 and an objective lens 9 by a module 1. A 2nd laser beam of a 2nd wavelength is emitted and transmitted through a collimator lens 4 and a 1/4-wavelength plate 6 to irradiate the optical disk 10, and is then reflected by a mirror 8 and the wavelength filter 7 and transmitted through the objective lens 9 to irradiate the optical disk 10 by a module 2. Reflecting beams of the 1st and 2nd laser beams by the optical disk 10 are reversely advanced in an incident optical path and are incident upon the modules 1 and 2. Information is recorded by the 1st laser beam, while information is reproduced by a reflecting beam of the 2nd laser beam given to the module 2. The modules 1 and 2 possess a semiconductor laser, a photodetector and a polarization hologram respectively. |
