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US 8,077,585 B2Granted
Condenser lens for an objective lens system
AssigneeKonica Minolta Opto, Inc.
InventorsTohru Kimura, Junji Hashimura, Yuichi Atarashi, Toshiyuki Kojima
Life of this patent
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Abstract
An objective lens system for an optical pickup apparatus, includes in order from an object side: a first lens group having negative paraxial power P1 (mm−1); and a second lens group having positive paraxial power P2 (mm−1) for converging a light flux emitted from the first lens group on an information recording surface of an optical information recording medium.
Claims4
A condenser lens used in an objective lens system for an optical pickup apparatus, the condenser lens comprising:
- one lens group for converging an incident light flux representing divergent light onto an information recording surface of an optical information recording medium,
- wherein a numerical aperture on an image side is 0.8 or more, and an effective diameter Dc (mm) on a plane of incidence, a focal length fc (mm) and on-axis thickness dc (mm) satisfy the following expressions,
- 0.7<Dc<3.0
- 0.75≦dc/fc≦1.4, and
- wherein a magnification mc satisfies the following expression,
- −0.15≦mc≦−0.03.
3 more elements
Dependencies are inferred from the claim text.