Optical information recording/reproducing device, optical...

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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Reexamination Certificate

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07872958

ABSTRACT:
In an optical information recording/reproducing device which executes information reading or writing on multiple types of optical discs having different data densities by selectively using first through third light beams having first through third wavelengths, respectively, at least one side of an optical element is provided with a step structure including a plurality of concentric refracting surfaces and steps between them. The steps include first steps each giving a first optical path length difference specified by a first optical path difference function, second steps each giving a second optical path length difference specified by a second optical path difference function, and special steps each giving an optical path length difference obtained by the sum or difference of/between the first and second optical path length differences. Annular zone widths between adjacent steps are set at 10 times the first wavelength or more.

REFERENCES:
patent: 6791764 (2004-09-01), Hosoe
patent: 2003/0185134 (2003-10-01), Kimura et al.
patent: 2005/0281173 (2005-12-01), Koreeda et al.
patent: 2006/0181978 (2006-08-01), Koreeda et al.
patent: 2006/0203692 (2006-09-01), Ota et al.
patent: 2006/0280061 (2006-12-01), Koreeda et al.
patent: 2001 195769 (2001-07-01), None
patent: 2005 203043 (2005-07-01), None
English language Abstract of JP 2001-195769, Jul. 19, 2001.
English language Abstract of JP 2005-203043, Jul. 28, 2005.
Komma et al, “Compatible Objective Lens for Blu-ray Disc and DVD using Diffractive Optical Element and Phase-step Element which Corrects both Chromatic and Spherical Aberration”, ISOM 2003 Proceedings, Matsushita Electric Co., Ltd.
U.S. Appl. No. 11/762,096 to Koizumi et al., which was filed Jun. 13, 2007.

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