Hokkaido University
Publishes on Semiconductor Lasers and Optical Devices, Iterative Learning Control Systems, Advanced Surface Polishing Techniques. 16 papers and 27 citations.
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光ディスク装置のトラッキング引込みを安定に行うための条件について検討した.5.25インチ追記型光ディスク (WO) において, ISOで規格となっている連続サーボ方式およびサンプルサーボ方式について, サーボ系の帯域, 位相余裕およびサーボ系をオンするタイミングをパラメータとして光ビームとトラックとの相対速度とオーバシュートの関係についてシミュレーションと実験を行い, 安定に引込むための条件を求めた.また, 引込み可能な相対速度を向上するため, トラッキング誤差検出特性を正弦波特性から位相周波数比較器特性とする方式について検討を行った.サンプルサーボ方式光ディスク装置に適用し, 相対速度12.5mm/sec以上においても安定に引込めることを確認した.
In order to realize high-speed access using a direct seeking system, new methods of tracking error signal transformation, relative velocity detection, and double window detection have been developed. These methods were applied to a 5.25” magnetooptical disk drive, and a direct seeking system whose counting error is less than one track was realized.
The chemistry of potassium–sodium ion exchange on hydrated molybdenum bronzes (ion-exchange isotherms and structural changes during the ion exchange,etc.) was investigated. Rather complex ion-exchange behaviour, including hysteresis phenomena, was observed. The behaviour was interpreted based on a discussion of structural changes of the materials and of the solvation and coordination behaviour of the investigated ions. A variety of techniques characterized the properties of the intercalated Na and K ions or their intercalation compounds.
The read/write performance at 4times-speed for BD drive system was investigated. The criteria of residual error and write strategy suitable for 4times recording were found. Then, a prototype drive proved 4times recording with sufficient low jitter value.
Charge damage considerations are prompting the development of neutral beam sources for etching applications. Anisotropic etching with hyperthermal Cl2 and SF6 beams has been demonstrated. We describe a two-dimensional plasma chemistry fluid model of laser ablation of frozen Cl2 in vacuum as a neutral beam source. In this scheme an externally applied electric field would be used to enhance the dissociation rate of Cl2 potentially providing an enhanced Cl content in the beam for a greater etch rate. Laser ablation generated neutral beams also may contain a desirable and controllable ion content which may be used to further enhance the etch rate. Limitations of the concept are discussed.