JPS6459650A - Optical head - Google Patents

Abstract

PURPOSE:To simplify the constitution of an optical system by controlling the converging point of a reflecting light from a recording medium through a converging means based on a light irradiation having a different astigmatic difference. CONSTITUTION:A recording reproducing laser beam 4 and an erasing laser beam light 5 having a different astigmatic difference from respective recording reproducing light emitting part 2 and erasing light generating part 3 of a semiconductor laser array 1 form the circular and elliptical light spot through a polarization beam splitter 7 and a 1/4 wavelength plate 8 at the different position on an optical disk 10. The convergence of a reflecting light reflected by a half prism 11 having the astigmatic difference from the disk 10 is controlled by a shading plate 13 for separation, only the reflecting light corresponding to a beam light 4 is converged and made incident on a light detector 14 for detecting a track and a tracking control is executed. On the other hand, the convergence is controlled by a focusing shading plate 17, the light-receiving signal of the reflecting light corresponding to the beam light 5 is obtained through an erasing light correcting signal generator 20, a focusing control is executed, and the constitution of the optical system of an optical head to use the beam light with the different astigmatic difference becomes simpler.