Optical disc player with molded diffractive optical elements

• US 5,825,741 A
• Filed: 07/10/1996
• Issued: 10/20/1998
• Est. Priority Date: 01/31/1995
• Status: Expired due to Term

• Current Assignee: DigitalOptics Corporation East (Adeia Inc.)
• Original Assignee: Digital Optics Corp. (Adeia Inc.)
• Inventors: Feldman, Michael R., Welch, William H., Te Kolste, Robert D.
• Primary Examiner(s): Huber, Paul W.
• Application Number:
  US08/677,521
• Time in Patent Office: 832 Days
• Field of Search: 369/110, 369/109, 369/112, 369/94, 264/1.33, 264/1.1, 264/2.5, 264/1.32, 425/808, 425/810
• US Class Current: 369/112.08
• CPC Class Codes: B29C 33/303 centering mould parts or halves, e.g. during mounting
• CPC Class Codes: B29C 45/00 Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor injection blow-moulding B29C49/06
• CPC Class Codes: B29C 45/372 provided with means for marking or patterning, e.g. numbering articles
• CPC Class Codes: B29D 11/00 Producing optical elements, e.g. lenses or prisms grinding or polishing of optical elements B24B; constructional form of optical elements G02B; optical parts of spectacles G02C7/00
• CPC Class Codes: B29D 11/00269 Fresnel lenses
• CPC Class Codes: B29D 11/00432 Auxiliary operations, e.g. machines for filling the moulds B29D11/00125 takes precedence
• CPC Class Codes: B29D 11/00769 Producing diffraction gratings
• CPC Class Codes: B29L 2011/005 Fresnel lenses
• CPC Class Codes: B29L 2031/7224 Holograms
• CPC Class Codes: G02B 5/1852 using mechanical means, e.g. ruling with diamond tool, moulding

Abstract

A method of fabricating a diffractive optical element includes the steps of: etching a negative of a desired multi-level diffraction pattern onto a molding surface of a quartz master element using photolithography, assembling the master element as a portion of a mold,and injecting a plastic molding composition into the mold and against the molding surface of the master element to injection mold a diffractive optical element whereby the optical element has the desired diffraction pattern on its surface. The diffraction pattern is preferably formed on the quartz master using VLSI photolithography.

Claims

1. An optical disc player comprising:

a laser;

a lens receiving emissions from said laser, said lens including an injection molded item having a surface and a diffraction pattern having multiple discrete levels molded on said surface, said diffraction pattern being molded using a non-metallic, photolithographically generated master element;

an optical disc support to position an optical disc to reflect laser emissions output from said lens; and

a sensor to receive the reflected emissions.

2. The optical disc player of claim 1 wherein said lens is a plastic material.

3. The optical disc player of claim 1 wherein the multi-level diffraction pattern is a computer generated hologram.

4. The optical disc player of claim 1, wherein said molding of said diffractive pattern includes compensating for thermal mismatch between the master element and adjacent portions of an injection molding machine.

5. An optical disc player as claimed in claim 1 wherein said lens has been made by:

fabricating a negative of a desired diffraction pattern on a molding surface of a master element using photolithography,

assembling the master element with the molding surface as a portion of a mold, and

injecting a molding composition into the mold and against the molding surface of the master element to injection mold a diffractive optical element as said lens, whereby the optical element has the desired diffraction pattern on its surface.

6. The optical disc player of claim 5 wherein the diffraction pattern on the negative is a multi-level diffractive.

7. The optical disc player of claim 5 wherein the master element is quartz.

8. The optical disc player of claim 5 wherein said fabricating step comprises etching the negative of the desired diffraction pattern onto the master element using photolithography.

9. The optical disc player of claim 5 wherein said lens is a plastic material.

10. The optical disc player of claim 5 wherein the multi-level diffraction pattern is a computer generated hologram.

11. An optical disc player comprising:

a laser;

a lens receiving emissions from said laser, said lens being formed by injection molding having a first surface and a second surface wherein the first surface and the second surface each have a diffraction pattern having multiple discrete levels molded thereon using a non-metallic, photolithographically generated master element;

an optical disc support to position an optical disc to reflect laser emissions from said lens; and

a sensor to receive the reflected emissions.

12. The optical disc player of claim 11 wherein said lens is a plastic material.

13. The optical disc player of claim 11 wherein the multi-level diffraction patterns are computer generated holograms.

14. The optical disc player of claim 11, wherein said molding of said diffractive pattern includes compensating for thermal mismatch between the master element and adjacent portions of an injection molding machine.

15. An optical disc player comprising:

a laser;

a lens receiving emissions from said laser, said lens being formed by injection molding having a first surface and a second surface wherein the first surface has a diffraction pattern having multiple discrete levels molded thereon using a non-metallic, photolithographically generated master element and the second surface is shaped to refract light,

an optical disc support to position an optical disc to reflect laser emissions from said lens; and

a sensor to receive the reflected emissions.

16. The optical disc player of claim 15 wherein said lens is a plastic material.

17. The optical disc player of claim 15 wherein the multi-level diffraction pattern is a computer generated hologram.

18. The optical disc player of claim 15, wherein said molding of said diffractive pattern includes compensating for thermal mismatch between the master element and adjacent portions of an injection molding machine.