Spherical Aberration Detection in the Optical Pickups for High-Density Digital Versatile Discs
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概要
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A new method of detecting the spherical aberration of a ray is described. In a high-density digital-versatile disc system achieved by means of a high-numerical-aperture objective lens system or a multilayer disc system, it is important to reduce the aberrations caused by substrate thickness error and layer distance, respectively. When rays with spherical aberration converge, the focus of the far-axis ray deviates from that of the near-axis ray, and gradually moves towards the optical axis. Based on this phenomenon, we demonstrated that spherical aberration can be detected by subtracting the focus-error signal of the far-axis ray from that of the near-axis ray. The resulting spherical aberration signal can be used in a phase-control device, such as an expander lens actuator or a liquid-crystal phase shifter, to produce a dynamic servo controller that can compensate for spherical aberration.
- 2001-04-15
著者
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Umeda Mariko
Hitachi Ltd Central Research Laboratory
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SHIMANO Takeshi
Hitachi Ltd, Central Research Laboratory
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Ariyoshi Tetsuo
Hitachi Ltd. Central Research Laboratory
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Umeda Mariko
Hitachi Ltd., Central Research Laboratory, 1-280 Higashi-Koigakubo, Kokubunji, Tokyo 185-8601, Japan
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Ariyoshi Tetsuo
Hitachi Ltd., Central Research Laboratory, 1-280 Higashi-Koigakubo, Kokubunji, Tokyo 185-8601, Japan
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- Spherical Aberration Detection in the Optical Pickups for High-Density Digital Versatile Discs
- Spherical Aberration Detection in the Optical Pickups for High-Density Digital Versatile Discs
- Aberration-Compensation Methods for 0.85-Numerical-Aperture (NA) Single-Element Objective Lens