Dynamic information storage or retrieval – Specific detail of information handling portion of system – Radiation beam modification of or by storage medium
Patent
1997-05-27
1998-08-04
Chan, Eddie P.
Dynamic information storage or retrieval
Specific detail of information handling portion of system
Radiation beam modification of or by storage medium
369 4424, 369 94, 369112, G11B 7125, G02B 110
Patent
active
057905061
ABSTRACT:
In an optical recording and reproducing device, an aperture member is provided in a region between an objective lens and a reflection mirror so as to be freely pushed into and pulled out of a light flux, and a masking member is provided on the objective lens. The masking member has an inside diameter smaller than an aperture diameter of the aperture member, and has an outside diameter greater than the aperture diameter of the aperture member. The aperture member has an outline size greater than a size of an aperture of an objective lens holding member. Therefore, an effective numerical aperture of the objective lens is determined in accordance with the inside diameter of the masking member in the case where the aperture member is placed in the light flux, whereas the effective numerical aperture is determined by the aperture of the objective lens holding member in the case where the aperture member is not placed in the light flux. With this arrangement, stable reproduction of a compact disk without being affected by a shift of the objective lens is enabled, while reproduction of a high-density disk is also enabled.
REFERENCES:
patent: 5281797 (1994-01-01), Tatsuno et al.
patent: 5665957 (1997-09-01), Lee et al.
Morita Hideji
Seike Yasusi
Chan Eddie P.
Chu Kim-Kwok
Sharp Kabushiki Kaisha
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