Gakuji Hashimoto

Miniature Two-Axis Actuator for High-Data-Transfer-Rate Optical Data Storage System

A miniature actuator for optical pickups is desirable not only for downsizing optical data storage systems, but also for increasing the data transfer rate. Since the size of an actuator is essentially determined by the size of the objective lens, recent developments in techniques for fabricating a small high-numerical-aperture (NA) objective lens enable us to develop a miniature actuator. In this paper, we report the successful development of a two-axis actuator using a 1.5 mm effective aperture objective lens (half the size of the lens we used in our last report on the optical data storage system using a high-numerical-aperture). We evaluated the dynamic characteristics of the actuator by the read/write test using a 23.3 Gbyte phase-change disk. We also confirmed that the actuator satisfies the specifications required for a high-data-transfer-rate system up to 140 Mbps, due to its broad servo bandwidth.

Dual-layer-compatible optical head: integration with a liquid-crystal panel

We have developed a dual-layer-compatible optical head integrated with a liquid-crystal panel. We conclude that our optical head possesses sufficient ability for recording and reading a dual-layer disc whose layer separation is 20 /spl mu/m or more. We have also confirmed the efficiency of a new method to drive a liquid-crystal panel, which is to mix the controlling signals of a liquid-crystal panel into the driving signals of a two-axis actuator. By using this integrated optical head instead of a beam expander, a compact optical pickup for dual-layer discs can be realized.