Yoshihiro Muto

10 Gb/in. 2 MO disk using blue laser

We studied a high areal density recording using a conventional disk on a blue MO system. To increase the areal density, we used mainly three techniques. First, we reduced a disk noise by UV irradiation. Second, we made CNR higher by adjusting the thickness of a metal layer to control the thermal conductivity. Third, we adopted an optical phase shift method for land and groove recording to increase the track density. Using these techniques on an optical pick-up with a 407 nm-Kr laser and a 0.6-NA objective lens, practical system margins were obtained at a 10 Gbit/inch2 areal density.

50-mm CAD-MSR disk system with blue laser

A mobile magneto-optical disk system with 2 Gbytes user- capacity is proposed. The disk consists of a center aperture detection type of magnetically induced super-resolution medium, a 0.5 mm thickness substrate with 50 mm in diameter, and a newly developed UV curing resin film to keep the disk tilt small even if its surrounding environmental condition changes. The optics contains a blue laser diode of a 406 nm wavelength and an objective lens with a numerical aperture of 0.6. A laser pulsed magnetic field modulation method is employed and it realizes land and groove recording with an effective track pitch of 0.40 micrometers . Practicable system margin values are confirmed at 0.146 micrometers bit density.