Title:
OBJECTIVE LENS AND OPTICAL PICKUP DEVICE
Document Type and Number:
Japanese Patent JP3932578
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To provide an objective lens capable of obtaining sufficiently high numerical aperture(NA), sufficiently correcting color aberration, making light in weight and facilitating manufacture by using low dispersion glass material whose Abbe number is spedified for glass material constituting two lenses as a color aberration countermeasure for two lenses of two groups.
SOLUTION: The objective lens possesses the constitution of two groups being two lenses formed of the glass material whose Adde number at a (b) line is ≥40, and at least one surface is made as an aspherical surface, and the numerical aperture is made as ≥7.0. Thus, the objective lens is constituted of a first lens 3 arranged on the side of an object (the side of a light source) and a second lens 4 arranged on the side of an image(the side of an optical recording medium). A plane parallel plate 5 equivalent to the transparent substrate of the optical recording medium is arranged on the side of the image of the objective lens. In this case, the low dispersion glass material is used for the glass material so as to suppress the color aberration.
Inventors:
Kenji Yamamoto
Isao Ichimura
Fumisada Maeda
Toshio Watanabe
Kiyoshi Osato
Isao Ichimura
Fumisada Maeda
Toshio Watanabe
Kiyoshi Osato
Application Number:
JP28275096A
Publication Date:
June 20, 2007
Filing Date:
October 24, 1996
Export Citation:
Assignee:
ソニー株式会社
International Classes:
G02B13/00; G02B3/02; G02B9/06; G02B13/18; G02B13/24; G11B7/1374; (IPC1-7): G02B13/00; G02B3/02; G02B13/18; G11B7/135
Domestic Patent References:
| JP10082951A | ||||
| JP61177408A |
Attorney, Agent or Firm:
Akira Koike
Eiichi Tamura
Seiji Iga
Eiichi Tamura
Seiji Iga
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