Hitoshi Terasaki

High density digital videodisc using 635 nm laser diode

By developing a high resolution pick-up using a red laser diode with a wavelength of 635 nm and by examining the disc parameters, we have developed a CD-ROM which has a recording density four times that of existing CDs. The track pitch of this CD-ROM is 0.85 /spl mu/m and the recording linear velocity is 0.7 m/s. With these disc parameters, a storage capacity of 2.2 GB was obtained. We recorded digital motion pictures with a data transfer rate of 4 Mbps onto the disc and succeeded in the realization of a high quality digital videodisc with one hour of playback time. >

High Density Muse Videodisc

A MUSE (multiple sub-Nyquist sampling encoding) video disc with 60 min. of playback time per side of CLV disk has been developed. The recording density of the disc is double that of the NTSC video disc. A visible-laser diode with a wavelength of 670 nm and an objective lens with a numerical aperture of 0.6 are used for playing the disc. A fine played-back image with a signal-to-noise ratio of 44 dB was obtained. Two kinds of audio signals are recorded, frequency-division multiplexed PCM (pulse code modulation) and time-division multiplexed PCM. In both systems, a low error rate which presents no practical problems was obtained. >

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.

Fabrication of Laser Beam Axis Compensator by Photonic Crystal Technique for Optical Pickup Units

A laser beam axis compensator was fabricated for an optical pickup unit with blue and red lasers. The device consisted of multiwavelength wave plates and a double-refractive-index material. The wave plates were realized by a photonic crystal technique. By measuring the beam profiles of the blue and red lasers, the device was confirmed to function as a laser axis compensator. Under 110 µm laser beam axis shift setting conditions, readout signal patterns from an optical disc were measured.

Media design of iD PHOTO disk with the CAD structure

We have developed a new MO(Magneto-Optical) disk, which is named iD(image/intelligent disk) PHOTO, as a promising candidate for a digital still camera memory. The iD PHOTO disk achieves 730MB/disk in a 50.8mm diameter by adopting some techniques mainly as follows, CAD (center aperture detection) type Magnetic Super Resolution reading, recording both on land and in groove, magnetic field modulation writing with irradiation of a pulsed laser beam, and PR(1,1) code. The iD PHOTO disk is required high performance in various environments, for it is used in a portable drive. As one of the most important factors, we have previously reported a reduction of electric power consumption by reducing the recording magnetic field. Here, we introduce thermal structure design of iD PHOTO disk to be suit for a drive in a digital still camera.

Advanced MO disk and its application to a digital camera

A Magneto-Optical disk system, named iD (intelligent, image) photo disk has been developed as a next generation media for digital still cameras. It has a large recording capacity, 730 MB with a 50.8 mm diameter. It employs the magnetic field modulation method for recording and Center Aperture Detection (CAD) type magnetic super resolution for reproducing. The media is designed to decrease the recording field so as to reduce electric power consumption for mobile use.

High capacity MO media for digital still cameras "iD photo"

A magneto-optical disk system, named iD (intelligent, image) photo disk has been developed as a next generation media for digital still cameras. It has a large recording capacity, 730 MB with a 50.8 mm diameter. It employs the field modulation method for recording and center aperture detection (CAD) type magnetic super resolution for reproducing. The media is designed to decrease the recording field so as to reduce electric power consumption for mobile use.

2.5-inch quadruple-density CD-ROM using visible laser diode

We have achieved a 2.5 inch (64 mm) quadruple density CD-ROM by developing a high resolution pick-up with our newly-developed visible laser diode whose wavelength is 635 nm, and also developing a disk cutting machine using a Kr ion laser with a wavelength of 407 nm.

Baseband Hi-Vision Video Disc.

ディスクの両面を同時に, 2個のピックアップで読取る両面同時再生方式を開発し, CLV (Constant Linear Velocity) ディスク1枚で, 連続再生時間30分のべースバンドハイビジョンビデオディスクおよびプレーヤを実現することができた.

High-density HDVD system using visible laser diode

We have presented a high density MUSE videodisc with 60 minutes of playback time per side. It has been developed by doubling the disc recording density. We have continued examining the system mainly the optical pickup and the signal parameters and we determined the newly specifications. To reduce the influence of uneven thickness and tilt of disc we changed an N. A. of the objective lens to 0. 55 and to make the optical pickup smaller we employed a small packaged (