US 2002/0054558 A1 · Diffractive stack pickup head for optical disk drives and method to fabricate the pickup head

Abstract

The invention provides a pickup head used in an optical data storage system. The pickup head contains a diffractive optical element (DOE) stack on a semiconductor substrate. The DOE stack includes multiple diffractive lenses for providing several diffractive surfaces and a middle layer serving as a beamsplitter and servo-generating element for a light reflected from an optical storage medium. The middle layer is sandwiched by the diffractive lenses that are located on both outer parts of the DOE stack. The semiconductor substrate includes at least a laser source and several photodetectors. The middle layer serving its function preferably includes a polarization-selective DOE and a quarter-wave retarder oriented to rotate a polarization state of the laser source, so that only the light reflected from the optical storage medium is diffracted by the polarization-selective DOE.

Claims17

Dependent claims

A pickup head suitable for uses in an optical data storage system, the pickup head comprising:

a diffractive optical element (DOE) stack on a semiconductor substrate, wherein the semiconductor substrate comprises a light source to emit a light beam toward an optical storage medium of the optical data storage system, and a plurality of photodetectors for receiving the light beam reflected from the optical storage medium, wherein the DOE stack comprises:
a plurality of diffractive lens surfaces located on a top side and a bottom side of the DOE stack, wherein the bottom side is located on the semiconductor substrate, and the top side is directed to the optical storage medium of the optical data storage system;
and
a middle DOE layer sandwiched between the diffractive lenses, comprising a beamsplitter/servo-generating DOE for serving functions of beamsplitter and servo-generating for the light beam reflected from the optical storage medium of the optical data storage system.

1 more element

A method for fabricating a stacked optical pickup head, the method comprising:

providing a substrate, which comprises a plurality of photo-detecting systems arranged in a cell array, and each of the photo-detecting systems comprises a light source and a multi-element photodetector formed thereon, wherein the light source and the multi-element photodetector are used in the stacked optical pickup head to allow accessing data stored in an optical data storage medium at a desired position;
performing a semiconductor-like fabrication process to form a preliminary diffractive-stack-element (DOE) stack, which comprise a plurality of functional layers used for performing a desired function of a DOE stack, wherein the preliminary DOE stack comprises a plurality of DOE cells arranged in an regular array associating in space with the cell array of the photo-detecting systems;
slicing the array of the DOE cells into a plurality of I-dimensional arrays;
precisely locating the 1-dimesional arrays on the substrate so that the DOE cells are aligned to the cells of the cell array of the photo-detecting systems;
dicing the substrate and the preliminary DOE stack into a plurality of individual stacked pickup heads with respect to the DOE cells.

2 more elements

Dependencies are inferred from the claim text.

Diffractive stack pickup head for optical disk drives and method to fabricate the pickup head

Life of this patent

Diffractive stack pickup head for optical disk drives and method to fabricate the pickup head

Life of this patent

Abstract

Claims17