Integrated optical unit for use with miniature optical discs
AssigneeSTMicroelectronics S.r.l.
InventorsAnthony M. Chiu, Danielle A. Thomas
Life of this patent
Estimating the term…
Abstract
Light from a laser diode is directed by mirrors on angled surfaces of an optical unit through a first lens at an optical disc. Light returns from the disc on a parallel path through a second lens and is directed at a photodetector. A semiconductor device controls the operation of the laser diode and receives signals form the photodetector for processing. The optical unit is formed from one or two glass elements cut from a larger glass wafer or wafers using photolithographic techniques. The mirrors are formed by thin films deposited on angled glass surfaces formed by selective plasma etching of the wafers. At least one mirror is partially reflective and is formed by depositing a thin film of titanium nitride.
Claims20
An electro-optical device for communicating with an optical disc, comprising:
- a semiconductor chip having analog-to-digital conversion circuitry and logic circuitry contained therein;
- first and second photodetectors on the semiconductor chip in electrical communication with the analog-to-digital conversion circuitry;
- a laser diode supported by the semiconductor chip oriented to emit a laser beam in a first direction;
- an optical unit supported above the semiconductor chip, the optical unit having a first mirror aligned to reflect the laser beam from the first direction to a second direction, a first lens for directing the laser beam outward to strike the surface of an optical disc, glass members for directing the laser beam from the second direction to the first lens, a second lens for receiving an information-containing beam from the optical disc, a second mirror for splitting the information-containing beam into first and second component beams, and a third mirror for directing the first component beam at the first photodetector, the second component beam passing through the second mirror in a direction at the second photodetector.
An optical unit for directing light from a laser at an optical disc and directing light reflected from the optical disc at at least one photodetector, comprising:
- a base element including a first mirror thereon for reflecting light from a first direction from the laser to a second direction;
- and
- a lens element including second and third mirrors, the second mirror being positioned relative to the base element to reflect laser light from the second direction to a third direction, the third mirror being positioned relative to the second mirror to reflect laser light from the third direction to a fourth direction, the lens element further including first and second lenses at one end thereof, the first lens being disposed to direct laser light from the fourth direction at the optical disc, the second lens being disposed to receive light reflected from the optical disc and direct it at the third mirror, the third mirror being partially reflective to permit light to pass therethrough at a first photodetector, the third mirror comprising an oxide, nitride, sulfide, or fluoride of a transition metal.
A method of making optical elements for an optical disc system, comprising:
- providing a glass wafer of a diameter sufficiently large to form a plurality of lens elements side-by-side therein;
- selectively etching a lens in each lens element;
- selectively etching angled surfaces in each lens element;
- depositing a reflective material on the angled surfaces;
- selectively etching the outline of each lens element leaving rods connecting the lens elements to the wafer;
- and
- cutting through the rods to separate the lens elements from the wafer.
An integrated optical unit for use with an optical disc, comprising:
- a laser diode for generating a laser light beam;
- a photodetector for detecting laser light returning from the optical disc;
- and
- an optical unit having an elongated glass element for carrying light beams along its length, the elongated glass element having angled surfaces with mirrors formed thereon, the mirrors being positioned to direct a laser light beam from the laser diode along a first path through the elongated glass element and out at an optical disc, the mirrors reflecting a light beam returning from the optical disc along a second path through the elongated glass element parallel and adjacent to the first path for detection by the photodetector, wherein at least one of the mirrors comprises an oxide, nitride, sulfide, or fluoride of a transition metal.
Dependencies are inferred from the claim text.