Tatsuhiro Otsuka

Wobble Addressing Method for Land and Groove Structured Optical Storage

In this paper, two wobble addressing methods for land and groove structured optical discs are proposed. These methods use only modulated wobble signals for addressing, while excluding the need for an embossed prepit. As a consequence, the overhead associated with the proposed methods is less than that of the conventional addressing method for rewritable digital versatile discs. In addition, the proposed methods enable the use of a one-beam mastering machine for making discs. This is possible because a signal from a land track is optically added to two signals from adjacent groove tracks, which are produced by a single laser beam for each signal, while maintaining its phase relationship for signal decoding. The advantages of the proposed methods have been demonstrated through computer simulation as well as through evaluation of test discs.

Three-Element Objective Lens with Numerical Aperture of 0.85

We have developed a three-element objective lens with a numerical aperture of 0.85 at 405 nm, which can correct chromatic aberration caused by mode hopping and wavelength change of the laser diode.

QPSK wobble addressing method for rewritable land/groove optical disks

An experimental result of QPSK wobble addressing method is presented. The wobble address signal which is formed on groove track in BPSK method can be read back on land track as well. The performance of wobble addressing method is explained by its CNR characteristics and corresponding BER