Masakuni Yamamoto

Edge Shift Characteristics Of A Magneto-optical Edge Detection Signal

INTRODUCTION With the recent mark edge mrding method, various methods have been proposed for reducing the intersymbol interference which occurs on making the capacity bc in high density in the magneto-optical(M0) disk. But few proposals have been made on the optical edge detection system of the MO disks!)* 2, We have studied a MO edge readout system. The system optically processes diffraction wavefronts from the MO edges within a diffraction limited spot, and detects edges from their intensity distributions. We estimated the readout edge signal experimentally by measuring frequency response of a carrier to noise ratio and a edge shift characteristics.

Diffraction Pattern From Magneto-optical Edges

Mark edge recording and short wavelength sources have been examined as a technique of higher density capacity in magneto-optical (MO) disks. Although various methods for reducing the intersymbol interference in the high density MO disks have been proposed, few schemes have been made on the optical edge detection system of the MO We have studied a MO edge readout system which optically processes diffraction wavefronts from the phase edges within a diffraction limited spot, and detects edges from their intensity distributions. The edge detection utilizes characteristics of the MO edges that behave as the phase edges with phase shift of 0 and r radians to the Ken components of the reflected light.

A New Data Detection Method for 35 Gbit/inch2 Multilevel Recording Using a Blue Laser and 0.85 Numerical Aperture Optics

In this study, a commercial Blu-ray disc was used for multilevel recording. The goal is to make its present capacity 2 times larger and data transfer rate 2 times faster. This technology is a promising candidate for improving extending the standard of the Blu-ray disc. To achieve this specification corresponding to an areal density of 36 Gbit/in.2, the bit length is reduced to 56 nm. The features of technology for 36 Gbit/in.2 are as follows: First, eight-level recording is adopted. Second, a new detection method named cell boundary data detection (CBDD) is developed to overcome severe intersymbol interference (ISI) from outer cells at a small cell length. Finally, we use the same optical pickup as that of the Blu-ray disc for doubling areal density. CBDD utilizes data sampled at the cell boundary, which is almost free of the influence of ISI without an equalizer. In addition, the popular error correction code of Bose–Chaudhuri–Hocquenghem (BCH) is applied to the part of the least-significant bit (LSB). As a result, CBDD with the BCH code achieved a bER of 1 ×10-5 at the effective bit length of 57.6 nm, which indicates an areal density of 35 Gbit/in.2 by computer simulation. Moreover, we experimentally obtained a bER of less than 1 ×10-5 using CBDD with the BCH code at a cell length of 200 nm.

An Advanced Data Detection Method for 34.6-Gbit/in2 Multilevel Recording using a Blue Laser and NA0.85 Optics

In this study, a commercial BD (Blu-ray disc) and BD optics (blue laser and NA0.85) were used for multilevel recording. The goal is to double both the present capacity and data transfer rate. To achieve this, it is necessary to overcome severe inter-symbol interference (ISI) from outer cells at a small cell length. In order to suppress ISI, we have developed an advanced data detection method that uses CBDD (Cell Boundary Data Detection) and TCM (Trellis-Coded-Modulation), and have achieved an areal density of 34.6-Gbit/in2 multilevel recording.