Collimator lens for optical pickup
AssigneeFujinon Sano Corporation
InventorsHideyuki Matsushita, Keiji Komiya
Life of this patent
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Abstract
A collimator lens located in a light path from a laser light source to an optical information recording medium. The collimator lens is constituted by a cemented lens which is composed of a biconvex lens and a meniscus lens, and an aspheric plastic lens in the form of a transparent thin synthetic resin film which is laminated on a lens surface of the biconvex lens on the side of or facing toward an optical recording medium. When calculated on the basis of a composite focal length f=10 mm, the collimator lens has an epaxial chromatic aberration correction rate (a) and a numerical aperture NA in the ranges of (1) (a) <2.2 μm/nm and (2) 0.4>NA≧0.12, respectively.
Claims10
A collimator lens for an optical pickup, said collimator lens being located in a light path from a laser light source to an optical information recording medium to collimate a laser beam from said lasor light source, and comprising:
- a cemented glass lens formed by bonding together two glass lens elements, i.e., a biconvex lens and a meniscus lens;
- and
- an aspheric plastic lens in the form of a thin transparent synthetic resin film laminated on a surface of said biconvex lens located on the side of said optical information recording medium;
- when calculated on the basis of a composite focal length f=10 mm, said collimator lens having an axial aberration correction rate (a) and a numerical aperture NA as expressed by following formulas (1) and (2),
- (1) (a)<2.2 μm/nm, (2) 0.4>NA 0.12.
Dependencies are inferred from the claim text.