Title:
OBJECTIVE LENS, OPTICAL HEAD, AND OPTICAL PICKUP DEVICE
Document Type and Number:
WIPO Patent Application WO/2005/098838
Kind Code:
A1
Abstract:
In an objective lens (2), a first lens (21) is meniscus lens having a negative refractive power and having a concave surface facing a semiconductor laser (3) as a light source. Thus, it is possible to reduce the Petzval sum and reduce the image plane curvature. A second lens (22) is a biconvex lens. A third lens (23) is a meniscus lens having a positive refractive power and having a concave surface facing an optical disc (6). Thus, it is possible to obtain a long working distance. With the objective lens (2) having the aforementioned configuration, it is possible to obtain a high NA while effectively suppressing generation of aberrations, thereby performing a highly accurate optical recording and/or reproduction with a high density.
Inventors:
SAKAMOTO KATSUYA (JP)
Application Number:
PCT/JP2005/005316
Publication Date:
October 20, 2005
Filing Date:
March 24, 2005
Export Citation:
Assignee:
KONICA MINOLTA OPTO INC (JP)
SAKAMOTO KATSUYA (JP)
SAKAMOTO KATSUYA (JP)
International Classes:
G02B9/12; G02B13/00; G02B13/18; G02B13/24; G11B7/135; G11B7/1374; G11B7/1392; G11B7/1372; (IPC1-7): G11B7/135; G02B13/00; G02B13/18
Foreign References:
| JPH06138384A | 1994-05-20 | |||
| JPS63106713A | 1988-05-11 | |||
| JPS6091317A | 1985-05-22 | |||
| JPS59176715A | 1984-10-06 | |||
| JP2003084196A | 2003-03-19 |
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