Patent ID: 6587420
Filing Date: 2003-07-01
Classification: G11B

Abstract:
A method for recording and reproducing information on an optical information recording medium, comprising the steps of:irradiating an optical information recording medium with a laser beam based on an information signal, the optical information recording medium comprising at least a recording thin film that effects a phase change between an amorphous state and a crystalline state by the irradiation of the laser beam, the recording thin film formed on a disk-shaped substrate including guide grooves; thereby recording a desired signal by forming a record mark on the recording thin film while applying a tracking servo mechanism with a tracking error signal obtained from the guide grooves of the substrate; and irradiating the optical information recording medium where the record mark is formed on the recording thin film with laser beam; thereby reproducing a signal while applying a tracking servo mechanism based on a tracking error signal obtained from the record mark; wherein a groove depth d (nm) of the guide groove, a wavelength &lgr;1 (nm) of the laser beam for recording and a refractive index n1 of the substrate at the wavelength &lgr;1 satisfy a relationship: 0.05Ã—&lgr;1/n1&lE;d; a groove depth d (nm) of the guide groove, a wavelength &lgr;2 (nm) of the laser beam for reproducing the record mark formed on the recording thin film and a refractive index n2 of the substrate at the wavelength &lgr;2 satisfy a relationship: d&lE;0.09Ã—&lgr;2/n2; andthe wavelength &lgr;2 and the wavelength &lgr;1 satisfy a relationship: &lgr;1&lE;&lgr;2.