Noboru Mamiya

Video Disk Recorder System Using Magneto-Optical Disk

We have developed a video disk recorder system using a magnetically induced super resolution (MSR) magneto-optical (MO) disk 120 mm in diameter and achieved a user data capacity of 4.1 Gbytes per disk using land/groove recording technology, a laser wavelength of 685 nm, and (1, 7) run-length limited (RLL) code. In this case, track pitch is 0.7 µm and minimum mark length is 0.4 µm. The system can record 125 minutes of moving images encoded using the MPEG2 method. In this paper we describe our high-density magneto-optical recording technology and the video disk recorder system which incorporates magnetic field modulation.

Zero-Field Magnetic Amplifying Magnetooptical System Applied to Next Generation “iD PHOTO” System

We investigated very high-density recording performance of the zero-field magnetic amplifying magnetooptical system (MAMMOS) with a 635 nm laser diode and a 0.60 N.A. objective lens. It was shown that the linear bit length of 0.13 µm was successfully reproduced with sufficient readout margins. The recording density up to 7.1 Gbit/in2 was demonstrated by combining the zero-field (ZF)-MAMMOS with an in-groove disk structure.

Examination of the read/write characteristics of an mo signal with a wobbled groove clock

We manufactured a high-frequency wobbled groove disk, and examined reading/writing a magneto-optical signal by using a clock generated from the wobbled groove. We also measured clock jitter and bit error rate. The results of this were clock jitter of under 2.5 ns, and a bit error rate almost equal to that of a self-clock. This wobbled groove clock method is therefore effective for higher density recording.