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US 11,430,479 B2Granted
Objective lens, optical head device, optical information device, and optical disk system
AssigneePanasonic Intellectual Property Management Co., Ltd.
InventorsYoshiaki Komma, Yasushi Kobayashi, Kazuhiro Minami
Life of this patent
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Abstract
Provided is an objective lens which is used so that more information can be accumulated in a large-capacity optical disk and which has a further enhanced numerical aperture NA. The objective lens is a single lens having the numerical aperture NA and a refractive index n, and is configured so as to satisfy: NA≥0.91 and 1.61≤n<1.72.
Claims15
An objective lens configured to receive a light beam having a wavelength λ and to focus the light beam into a small spot on a recording surface of an optical disk to record and reproduce information,
- wherein a range of the wavelength λ is from 390 nm to 415 nm;
- wherein the objective lens is a single lens having a numerical aperture NA and a refractive index n with respect to the focused light beam;
- wherein the numerical aperture NA satisfies NA≥0.91 and the refractive index n satisfies 1.61≤n<1.72;
- and
- wherein the objective lens is a biconvex lens, a sag amount of each surface of which always varies in a same direction from an optical axis toward a lens outer circumference of the biconvex lens.
2 more elements
Dependencies are inferred from the claim text.