Molding diffractive optical elements

• US 6,021,106 A
• Filed: 06/10/1998
• Issued: 02/01/2000
• Est. Priority Date: 01/31/1995
• Status: Expired due to Term

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Digital Optics Corp. (Adeia Inc.)
• Inventors: Feldman, Michael R., Te Kolste, Robert D., Welch, William H
• Primary Examiner(s): Neyzari, Ali
• Assistant Examiner(s): CHU, KIM KWOK
• Application Number:
  US09/095,135
• Time in Patent Office: 601 Days
• Field of Search: 369/112, 369/109, 369/103, 264/2.5, 264/1.31, 264/1.36, 264/1.3, 264/1.4, 264/226, 156/379.8, 156/379.6, 359/565, 359/569
• US Class Current: 264/1.31
• 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 element formed by

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, wherein said molding of said diffraction pattern includes compensation for thermal mismatch between the master element and adjacent portions of an injection molding machine.

2. The element of claim 1 wherein the element is composed of a plastic material.

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

4. The element of claim 1, wherein the injection molded element has another surface opposite the surface having another diffraction pattern with multiple discrete levels molded thereon, said another diffraction pattern being molded using a non-metallic, photolithographically generated master element, wherein said molding of said another diffraction pattern includes compensation for thermal mismatch between the master element and adjacent portions of an injection molding machine.

5. An optical element formed by injection molding having a first surface and a second surface opposite the first surface, wherein the first surface and the second surface each have a diffraction pattern having multiple discrete levels, at least one of said diffraction patterns being molded using a non-metallic, photolithographically generated master element, wherein said molding of said diffraction pattern includes compensation for thermal mismatch between the master element and adjacent portions of an injection molding machine.

6. The element of claim 5 wherein the element is composed of a plastic material.

7. The element of claim 5 wherein the multi-level diffraction patterns are computer generated holograms.

8. The element of claim 5, wherein both diffraction patterns are molded using a non-metallic, photolithographically generated master element, wherein said molding of said both diffraction patterns includes compensation for thermal mismatch between the master element and adjacent portions of an injection molding machine.

9. An optical element formed by injection molding having a first surface and a second surface opposite the first surface, wherein the first surface contains a diffraction pattern having multiple discrete levels, and the second surface is shaped to refract light, said diffraction pattern being molded using a non-metallic, photolithographically generated master element, wherein said molding of said diffraction pattern includes compensation for thermal mismatch between the master element and adjacent portions of an injection molding machine.

10. The element of claim 9 wherein said element is composed of a plastic material.

11. The element of claim 9 wherein said multi-level diffraction pattern is a computer generated hologram.

12. The element of claim 9, wherein the element is composed of a plastic material.

13. The element of claim 9, wherein the second surface contains another diffraction pattern having multiple discrete levels, said another diffraction pattern being molded using a non-metallic, photolithographically generated master element, wherein said molding of said another diffraction pattern includes compensation for thermal mismatch between the master element and adjacent portions of an injection molding machine.