Apparatus and methods for recording and/or reproducing data on to and/or from optical disks, and disks cartridges for such disks

摘要

An optical disk apparatus for recording and/or reproducing user data on to and/or from an optical disk (12) includes an optical head (11) with a semiconductor laser (13) for irradiating a laser beam having a wavelength of approximately 680 nm or less to the optical disk (12) and having a lens (17) with a numerical aperture (NA) of approximately 0.7 or more and a working distance of approximately 560 µm or less. By utilizing such apparatus, a relatively large amount of data may be recorded onto the optical disk (12).