US 2002/0057632 A1 · MULTI-BEAM OPTICAL PICKUP

Abstract

An optical pickup for simultaneously reading a plurality of data tracks of an optical storage medium is provided. The optical pickup uses a diffractive element to split an illumination beam into a plurality of reading beams which are projected onto a plurality of tracks of the optical storage medium. Apparatus and methods are shown for improving the optical characteristics of the optical pickup by reducing vignetting, optical aberrations, and field curvature. These improvements are achieved by relocating the diffractive element at a greater distance from the laser source, so that a diffractive element having a larger period, and a smaller angle between diffractive orders may be used. The apparatus and methods shown also reduce the number of components and the manufacturing cost of the optical pickup.

Claims20

Dependent claims

An optical pickup for simultaneously reading multiple tracks of an optical disk, the optical pickup comprising:

a laser source emitting an illumination beam along a path;
a diffractive element disposed in the path of the illumination beam, the diffractive element splitting the illumination beam into a plurality of reading beams;
a collimator interposed between the laser source and the diffractive element and in the path of the illumination beam;
an objective lens that focusses the plurality of reading beams onto a plurality of tracks on a surface of the optical disk;
a plurality of photodetector elements, each one of the plurality of photodetector elements generating a signal corresponding to the data stored in a respective one of the plurality of tracks;
and
means for directing reading beams reflected from the surface of the optical disk to the plurality of photodetector elements.

4 more elements

Dependencies are inferred from the claim text.

Multi-beam optical pickup

Life of this patent

Multi-beam optical pickup

Life of this patent

Abstract

Claims20