Title:
CONDENSING OPTICAL SYSTEM
Document Type and Number:
WIPO Patent Application WO/2004/088648
Kind Code:
A1
Abstract:
A condensing optical system used for an optical pickup device that condenses a light flux having a wavelength &lgr 1 (350 nm≤&lgr 1≤450 nm) and a light flux having a wavelength &lgr 2 (650 nm≤&lgr 2≤ 700 nm) to first and second optical information recording media respectively having protection substrate thicknesses t1 (0.5 mm≤t1≤0.7 mm) and t2 (0.5 mm≤t2≤0.7 mm). The condensing optical system comprises a single-lens objective optical element and a single-lens first optical element disposed immediately ahead of and opposite to the incident plane of this objective optical element, a phase difference affording structure being formed in at least one of these optical elements. The phase difference affording structure has a color correction function for correcting, to up to 0.03 &lgr rms, aberration variations before and after wavelength changes at the same position in the optical axis direction when a wavelength changes 1 nm from &lgr 1.
Inventors:
IKENAKA KIYONO (JP)
Application Number:
PCT/JP2004/004032
Publication Date:
October 14, 2004
Filing Date:
March 24, 2004
Export Citation:
Assignee:
KONICA MINOLTA HOLDINGS INC (JP)
IKENAKA KIYONO (JP)
IKENAKA KIYONO (JP)
International Classes:
G11B7/135; G11B7/00; G11B7/125; (IPC1-7): G11B7/135; G02B5/18; G02B13/18
Foreign References:
| JP2001093179A | 2001-04-06 | |||
| JP2000348376A | 2000-12-15 | |||
| JPH10255305A | 1998-09-25 |
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