METHOD AND DEVICE FOR REPRODUCING OPTICAL INFORMATION MEDIUM

摘要

PURPOSE: A method and device for reproducing an optical information medium are provided to get high C/N(Carrier to Noise Ratio) in reproducing pits or recorded marks having the dimension of a resolution limit decided by diffraction. CONSTITUTION: A method for reproducing an optical information medium comprising an information-recording layer(10) having pits(21) or recorded marks includes a step of irradiating a laser beam to the information-recording layer through an objective lens for providing readings of the pits or recorded marks. A wavelength of the laser beam is 400 to 410nm in reproducing recorded information. When a minimum dimension of pits or recorded marks irradiated with the laser beam through the objective lens having a NA(Numerical Aperture) of 0.70 to 0.85 is below 0.36 wavelength/NA, recorded information is reproduced by making the power of the laser beam over 0.4mW. When the laser beam has a wavelength of 630 to 670nm and the minimum dimension is below 0.36 wavelength/NA with being irradiated with the laser beam through the objective lens having the NA of 0.60 to 0.65, recorded information is reproduced by making the power over 1.0mW.