Optical disc drive and objective lens for the same

Dynamic information storage or retrieval – Specific detail of information handling portion of system – Radiation beam modification of or by storage medium

Reexamination Certificate

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Details

C369S112230, C369S112260, C369S112010, C369S112080

Reexamination Certificate

active

07738345

ABSTRACT:
There is provided an objective lens used for three types of optical discs including by selectively using one of three types of light beams. At least one of surfaces of the objective lens is provided with a first region converging the third light beam on a recoding surface of the third optical disc. The first region has a step structure configured to have concentric refractive surface zones and to give an optical path length difference to an incident beam at each step formed between adjacent refractive surface zones. The step structure is configured such that the optical path length difference given by each step is substantially equal to an odd multiple of a wavelength of a first light beam, and a value of differentiation of an optical path difference function defining the step structure crosses zero in a height ranging from 30% to 70% of an effective diameter of the first region.

REFERENCES:
patent: 6900949 (2005-05-01), Takeuchi et al.
patent: 6982838 (2006-01-01), Maruyama et al.
patent: 7035193 (2006-04-01), Takeuchi et al.
patent: 7038862 (2006-05-01), Maruyama et al.
patent: 2001/0050894 (2001-12-01), Takeuchi
patent: 2004/0047269 (2004-03-01), Ikenaka et al.
patent: 2004/0136096 (2004-07-01), Takeuchi et al.
patent: 2004/0213131 (2004-10-01), Kimura et al.
patent: 2004/0257958 (2004-12-01), Kimura et al.
patent: 2005/0002118 (2005-01-01), Maruyama et al.
patent: 2005/0078593 (2005-04-01), Maruyama et al.
patent: 2005/0157624 (2005-07-01), Koreeda et al.
patent: 2005/0201250 (2005-09-01), Mimori et al.
patent: 2005/0270958 (2005-12-01), Ikenaka
patent: 2005/0281173 (2005-12-01), Koreeda et al.
patent: 2006/0114796 (2006-06-01), Maruyama et al.
patent: 2006/0176578 (2006-08-01), Kimura
patent: 2004-247025 (2004-09-01), None
U.S. Appl. No. 11/419,810 to Koreeda et al., filed May 23, 2006.

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