| 摘要 |
PROBLEM TO BE SOLVED: To interchangeably reproduce optical disks having different thicknesses of substrates by one optical pickup. SOLUTION: At the time of reproducing an optical disk 7 of a standard thickness, an aspherical aberration compensating means 50 for thin type is removed and an aperture 4 and an aspherical aberration compensating means 5 for standard thickness are inserted. At this time, a half of a laser beam of short wavelength emitted from a semiconductor laser 1 is reflected by a half mirror 2, made to be a parallel beam by a collimator lens 3, its outer peripheral side is shielded by the aperture 4, it is made incident on an objective lens 6 and converged on a signal recording surface 7a. At the time of reproducing a thin type optical disk, the aperture 4 and the aspherical aberration compensating means 5 for standard thickness are removed and the aspherical aberration compensating means 50 for thin type is inserted. |
