Objective lens system and optical disk apparatus using the same
AssigneeFujitsu Limited
InventorsKazushi Uno, Tsuyoshi Matsumoto
Life of this patent
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Abstract
An objective lens system includes a first lens and a second lens. The first lens has a first surface for allowing entry of light and a second surface opposite to the first surface. The second lens has a spherical third surface and a flat fourth surface opposite to the third surface. The third surface faces the second surface and has a radius of curvature r0. The second lens has a thickness d0 and a refractive index n0. The thickness n0, the radius of curvature r0 and the refractive index n0 satisfy a relation: d0>r0>n0d0.
Claims8
An objective lens system comprising:
- a first lens that includes a first surface for allowing entry of light and a second surface opposite to the first surface;
- and
- a second lens that includes a spherical third surface and a flat fourth surface opposite to the third surface, the third surface facing the second surface and having a radius of curvature r0, the second lens having a thickness d0 and a refractive index n0;
- wherein the thickness d0, the radius of curvature r0 and the refractive index n0 satisfy a following relation:
- d0>r0>n0d0.
An optical disk apparatus comprising:
- a light source;
- and
- an objective lens system including at least one lens which is provided with a spherical surface having a radius of curvature r0, the lens having a thickness d0 and a refractive index n0;
- wherein the thickness d0, the radius of curvature r0 and the refractive index n0 satisfy a following relation:
- d0>r0>n0d0.
An optical disk apparatus comprising:
- a light source;
- an aspherical first lens which light emitted from the light source enters;
- a second lens that includes a spherical surface and a flat surface opposite to the spherical surface, the spherical surface facing the first lens and having a radius of curvature r0;
- and
- a storage disk facing the flat surface;
- wherein the second lens comprises both a spherical lens element including the spherical surface and a transparent base including the flat surface, the lens element having a thickness d1 and a refractive index n1, the base having a thickness d2 and a refractive index n2;
- and
- wherein the radius of curvature r0, the thicknesses d1 and d2, and the refractive indexes n1 and n2 satisfy a following relation:
- d1+d2>r>{n1/(n1+1)}d1+{n2/(n2+1)}d2.
Dependencies are inferred from the claim text.