| 摘要 |
PROBLEM TO BE SOLVED: To secure a margin for a semiconductor laser rating output even when a scanning speed is raised and to perform stable recording/reproducing with less noise by equipping a 1st light source for recording information and a 2nd light source for reproducing information as light sources for an optical head. SOLUTION: The optical head consists of a fixed part 101 and a movable part 102. The fixed part 101 is composed of a semiconductor laser 22a for recording information, a semiconductor laser 22b for reproducing information, collimator lenses 23a and 23b, a diffraction grating 25, polarizing beam splitter 26, detecting optical system 30 and a photodetector 34. Then, the movable optical system 102 is composed of a dichroic prism(DP) 103, a deflection prism 27, 1/4-wavelength plate 28 and an objective lens 29. Then, the recording semiconductor laser 22a has its wavelength 830nm, while the reproducing semiconductor laser 22b has its wavelength 790nm. Only a beam of the wavelength 790nm is transmitted by the DP 103 having, on the other hand, a film characteristic for reflecting a beam of the wavelength 830nm. |
