Title:
OBJECTIVE LENS FOR OPTICAL PICKUP DEVICE, OPTICAL PICKUP DEVICE, AND OPTICAL INFORMATION RECORDING/REPRODUCTION DEVICE
Document Type and Number:
WIPO Patent Application WO/2011/132691
Kind Code:
A1
Abstract:
Disclosed are an optical pickup device, an optical information recording/reproduction device, and an objective lens favorable thereto that are compact and secure a working distance even for CDs having thick substrates, while enabling compatibility of three types of optical disc, i.e. BDs, DVDs, and CDs, using a common objective lens. The objective lens is provided with a first optical path difference imparting structure wherein the fundamental structures are superimposed in a manner such that the direction of the step of the fundamental structure of which the order of diffraction of a blue-violet laser beam is an odd order is directed in the opposite direction from the optical axis, and the direction of the step of the fundamental structure of which the order of diffraction of the blue-violet laser beam is an even order is directed in the direction of the optical axis. Also, the effective diameter of the objective lens is at least 2.0 mm and no more than 3.0 mm.
Inventors:
NAKAMURA KENTAROU (JP)
Application Number:
PCT/JP2011/059680
Publication Date:
October 27, 2011
Filing Date:
April 20, 2011
Export Citation:
Assignee:
KONICA MINOLTA OPTO INC (JP)
NAKAMURA KENTAROU (JP)
NAKAMURA KENTAROU (JP)
International Classes:
G02B13/00; G02B13/18; G11B7/1353; G11B7/1367; G11B7/1374; G11B7/1392
Domestic Patent References:
| WO2010013616A1 | 2010-02-04 | |||
| WO2008044475A1 | 2008-04-17 | |||
| WO2007145202A1 | 2007-12-21 |
Attorney, Agent or Firm:
TAMURA Keijiro et al. (JP)
Keijichiro Tamura (JP)
Keijichiro Tamura (JP)
Download PDF:
Claims: