OPTICAL PICKUP DEVICE, AND RECORDING AND/OR REPRODUCING DEVICE OF OPTICAL INFORMATION RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To provide an objective lens for an optical pickup device having a large numerical aperture and a superior image height characteristic; to provide an objective lens suitable for a recording/reproducing device, hence the thickness of a protection layer of an information recording medium is thin, substantially 0.1 mm, the objective lens being favorable despite a small working distance; and to provide an optical pickup device using the objective lens.

SOLUTION: The objective lens is a recording/reproducing objective lens of an information recording medium and satisfies the following expression. 1.1≤d1/f≤3 (where d1 represents an on-axis lens thickness and f represents a focal length). Alternatively, it is preferable to satisfy the following respective expressions. 1.2≤d1/f≤2.3, f/νd≤0.060 (where νd represents Abbe number), 1.40≤n (where n represents a refractive index in use wavelength), 1.40≤n<1.85, and 0.40≤r1/(n*f)≤0.70 (where r1 represents a paraxial radius of curvature of a light source side).

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