Optical disk apparatus and accessing methods, and disk cartridges for housing optical disks

摘要

An optical disk unit (10) and cartridge are capable of reading/recording desired data by thermomagnetic recording, local heating or other techniques via an optical system (11) with a large numerical aperture and a small working distance. Magnetic field generating coils are arranged on the laser beam irradiating side and generate the magnetic field for thermomagnetic recording. The type of optical disk (12), i.e. whether it is a thermomagnetic disk, a local heating disk, etc., is identified by a disk discriminator (50) on the basis of disk identification indicia, and the laser beam in the optical system (11) is switched accordingly.