| 摘要 |
PROBLEM TO BE SOLVED: To read out information from optical disks having different thicknesses by using one piece of an objective lens. SOLUTION: This optical pickup has first and second hologram laser units 1, 4 emitting laser beams whose wavelengths are different with each other. Then, in the case a substrate 5 is a thick optical disk, the first hologram laser unit 1 is selected and in the case the substrate 5 is thin optical disk, the second hologram laser unit 4 is selected. The laser beams emitted from the first and second hologram laser units 1, 4 are condensed on recording surfaces of optical disks by respectively being passed through a polarizing beam splitter 2 and an objective lens 3. |
