| 摘要 |
PURPOSE:To reduce power consumption and to prolong the life of a semiconductor laser by increasing the recording density of an optical disk utilizing a super resolution phenomenon and improving availability in a laser beam. CONSTITUTION:A laser beam LB outgoing from a semiconductor laser 2 is converted to parallel rays of light 3, and split 4. Then the beam LB is reflected toward an optical disk 5, and is condensed 7 on the disk 5, and the return beam LB split by a beam splitter 4 is detected by a detector 8. Further, a phase plate 10 lies between the beam splitter 4 and a reflection prism 6, and the plate 10 is provided with a first and a second wavelength plates 11, 12 arranged concentrically around an optical axis C. The first wavelength plate 11 is formed in a disk shape around the optical axis C, and the second wavelength plate 12 is arranged in doughnut-like around the optical axis C as a polarizing surface orthogonal intersection means. The crystal axis of the wavelength plate 12 is arranged at 45 degrees to that of the wavelength 11 and the beams LB passes through the wavelength plates 11, 12 whose polarizing surfaces are intersected orthogonally each other and no both beams interfer with each other, and both beams are set so that prescribed laser beam intensity is obtained on the optical disk 5. |
