OPTICAL INFORMATION RECORDING MEDIUM

摘要

PURPOSE:To solve such problems for a phase transition type optical disk as an insufficient erasing rate and insufficient erasing power margin when information is recorded and erased by irradiation of laser beam of <500nm wavelength with using an objective lens having 0.55-0.70 numerical aperture. CONSTITUTION:This optical recording medium is used to record and erase information by irradiating the recording layer on the substrate with laser beam of <500nm wavelength with using an objective lens having 0.55-0.70 numerical aperture. As for the recording layer, such a material that the optical constants reversibly change with irradiation of the laser beam above described is used. The width w of the land or the groove for recording satisfies 0.20lambda/ NA<=w<=0.41lambda/NA, wherein lambda is wavelength of the laser beam and NA is the numerical aperture of the objective lens.