Hideaki Okano

Temperature Compensation Servo Algorithm for Holographic Data Storage

Photopolymers are widely used as media for holographic data storage because of their high dynamic range, high photosensitivity and availability. However, the most photopolymers have a large coefficient of linear thermal expansion. Therefore, it is known that the temperature changes cause deterioration of readout image under the Bragg-mismatch conditions. This paper proposes a new servo algorithm which includes both the servo error signals detection method and the automatic compensation procedures with feedback servo for the holographic data storage system. Experimental results for the proposed technique are demonstrated for temperature changes of up to +25 K successfully.

New Wobble-Address Format for an Optical Disc with a Separated Guide Layer

We propose a physical address format suitable for the separated guide layer of a multilayered optical disc. Since the track format of the guide layer is different from that of conventional multilayered discs, a novel address format is required. The proposed format adopts a land-and-groove-track structure to generate a stable tracking signal. The address information for land and groove tracks is physically premastered by the wobbling and width-modulating of grooves. We fabricated a replicated disc sample with the proposed format and demonstrated a sufficiently low bit error rate by an experiment. Consequently, we considered that the format is a promising solution for the physical format for multilayered discs with a separated guide layer.

Construction of holographic data storage system with dual-reference beam

A novel holographic data storage (HDS) system with dual-reference beam is proposed. Several servo techniques that construct a read and write procedure of the HDS system are introduced and experimentally confirmed.