US 6,285,646 B1 · Optical pickup using objective lens compatible with a plurality of optical disks

Abstract

An optical pickup device including an objective lens which is compatible with a plurality of optical disks of respectively different specifications, such as a digital versatile disk (DVD), a compact disk-recordable (CD-R) medium, a compact disk (CD) and a laser disk (LD). The optical pickup device includes a laser source to emit light, an objective lens to focus the light emitted from the laser source on respective information recording surfaces of a plurality of optical recording media as an optimal optical spot, and an optical detector to detect light reflected from the information recording surface of the optical recording medium on which the optical spot has been focused and transmitted through the objective lens. The objective lens includes a first lens area, a second lens area, and a third lens area to focus the light emitted from the laser source. The first lens area has an aspherical surface corresponding to a first optical recording medium and a second optical recording medium, the second lens area has an aspherical surface corresponding to the second optical recording medium, and the third lens area has an aspherical surface corresponding to the first optical recording medium. As a result, the optical pickup can be compatible with a plurality of the optical disks of a respectively different specification irrespective of the thickness of the disk.

Claims24

Dependent claims

An objective lens to selectively focus light emitted from a laser source onto a first optical recording medium and a second optical recording medium having different thicknesses, the objective lens comprising:

a first lens area having an aspherical surface to focus light emitted by the laser source onto the first optical recording medium and the second optical recording medium;
a second lens area having an aspherical surface to focus light emitted by the laser source onto the second optical recording medium;
and
a third lens area having an aspherical surface to focus light emitted by the laser source onto the first optical recording medium, wherein
said first lens area reduces optical aberration with respect to the first optical recording medium and the second optical recording medium,
said second lens area reduces optical aberration with respect to the second optical recording medium, and
said third lens area reduces optical aberration with respect to the first optical recording medium.

4 more elements

An optical pickup device for recording and reproduction of a first optical recording medium and a second optical recording medium having different thickness, the optical pickup device comprising:

a laser source to emit light having a first wavelength and a second wavelength, the first wavelength not equal to the second wavelength;
an objective lens that includes a first lens area, a second lens area, and a third lens area to focus the light emitted by said laser source, wherein
the first lens area comprises a first step difference from the third lens area and a second step difference from the second lens area and having an aspherical surface corresponding to the first optical recording medium and the second optical recording medium,
the second lens area comprises an aspherical surface corresponding to the second optical recording medium, and
the third lens area comprises an aspherical surface corresponding to the first optical recording medium;
and
an optical detector to detect light reflected from the first optical recording medium and the second optical recording medium,
wherein the first step difference generates an optical aberration which is an integer multiple of the first wavelengths, and the second step difference generates an optical aberration which is an integer multiple of the second wavelength.

5 more elements

Dependencies are inferred from the claim text.

Optical pickup using objective lens compatible with a plurality of optical disks

Life of this patent

Optical pickup using objective lens compatible with a plurality of optical disks

Life of this patent

Abstract

Claims24