| 摘要 |
PROBLEM TO BE SOLVED: To improve the recording density of optical disk by offsetting the aberrations of an optical system and converging the spot size of a light beam down to the theoretical threshold by using a phase conjugation optical system. SOLUTION: In the optical pickup device for recording and reproducing information on and from an optical disk 8 by condensing the light beam to the beam spot on an optical disk plate 8, a light beam emitted from the laser diode 1 is shaped down to the spot size of the light beam required on the optical disk plate 8 by a pinhole. The optical path is bent at a prescribed angle by reflection with a polarization beam splitter 5 and thereafter, the light beam is polarized to be a circularly polarized light by a first quarter-wave plate. This light is made incident on the phase conjugation optical medium 13 excited by the light of the wavelength equal to the wavelength of a laser diode beam. The phase conjugation light emitted from the phase conjugation optical medium 13 is converged onto the optical disk plate 8 through the polarization beam splitter 5 and two pieces of the quarter-wave plates 6, 12. |
