Tetsuo Hosokawa

2 GB/130 mm Capacity Direct-Overwrite Magneto-Optical Disk

Precise mark-edge recording on a high signal-to-noise ratio (S/N) exchange-coupled direct overwrite magneto-optical (MO) disk provides 2 GB capacity on a 130 mm disk with a sufficient edge jitter margin. Write compensation technology was proven to be effective for both non- and direct-overwrite MO disks.

LIMDOW-MSR MO disk memory

Summary form only given. Light intensity modulation direct overwrite (LIMDOW) magneto optical disc memory with magnetically induced superresolution (MSR) is studied. LIMDOW-MSR added only one layer in a conventional LIMDOW and deposited by a production-machine is enough to support a linear density of 0.34 /spl mu/m/bit.

Optimization of Pit Depth for Concurrent Read Only Memory?Random Access Memory Optical Disk

We have studied a concurrent read only memory?random access memory (ROM?RAM) optical disk system without laser feedback by optimizing pit depth. When the pit depth was 47 nm (optical depth about 1/11 ?) and the pit width 0.45 ?m, about 8% jitter in both pit and magneto-optical (MO) signals was obtained with a 785 nm wavelength laser diode and 0.55 NA objective lens by employing magnetic-field-modulation (MFM) MO recording. Both pit data and MO data were recorded with eight to fourteen modulation (EFM) code with a minimum mark length of 0.83 ?m and a track pitch of 1.6 ?m and thus the areal density is comparable to 1.3 GB for ?120 mm single sided disk. By the optimization of the pit depth, sufficient system margins for practical use were obtained without laser feed back for the simultaneous reproduction of both pit and MO signals.