Title:
OPTICAL PICKUP DEVICE AND COUPLING LENS FOR THE OPTICAL PICKUP DEVICE
Document Type and Number:
WIPO Patent Application WO/2011/122275
Kind Code:
A1
Abstract:
Provided are a compact and low-cost optical pickup device which can read and write information on an optical disc having multi-layered information storage surfaces, and a coupling lens therefor. To this end, the coupling lens is made up of a positive lens having positive refractive power and a negative lens having negative refractive power, and only one of the positive lens and the negative lens can be displaced along the optical axis. The difference in thickness ΔT(mm) between the information storage surfaces that have the smallest and the greatest protecting-substrate thickness between the incidence surface of the optical disc and the information storage surface satisfies that 0.04 ≤ ΔT ≤ 0.05. The amount of displacement L(mm) of the one lens along the optical axis for focusing light beams of wavelength λ1 on the information storage surfaces with the smallest and the greatest protecting-substrate thickness satisfies that 0.5 ≤ L ≤ 2.0. The focal distance f(mm) of the coupling lens achieved when the one lens is displaced to the position at which the coupling lens emits a collimated light beam satisfies that 9 ≤ f ≤ 15.
Inventors:
TATEYAMA Kiyono (Inc. 2970, Ishikawa-machi, Hachioji-sh, Tokyo 05, 〒1928505, JP)
Application Number:
JP2011/055477
Publication Date:
October 06, 2011
Filing Date:
March 09, 2011
Export Citation:
Assignee:
Konica Minolta Opto, Inc. (2970, Ishikawa-machi Hachioji-sh, Tokyo 05, 〒1928505, JP)
コニカミノルタオプト株式会社 (〒05 東京都八王子市石川町２９７０番地 Tokyo, 〒1928505, JP)
コニカミノルタオプト株式会社 (〒05 東京都八王子市石川町２９７０番地 Tokyo, 〒1928505, JP)
International Classes:
G11B7/125; G02B13/00; G11B7/09; G11B7/135
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Claims: