Method for reproducing holograms, kinoforms, diffractive optical elements and microstructures

• US 5,538,674 A
• Filed: 11/19/1993
• Issued: 07/23/1996
• Est. Priority Date: 11/19/1993
• Status: Expired due to Fees

• Current Assignee: Donnelly Corporation (Magna International Incorporated)
• Original Assignee: Donnelly Corporation (Magna International Incorporated)
• Inventors: Nisper, Jon, Kritchevsky, Gina
• Primary Examiner(s): Vargot, Mathieu D.
• Application Number:
  US08/154,558
• Time in Patent Office: 977 Days
• Field of Search: 264/1.31, 264/1.32, 264/1.36, 264/1.37, 264/219, 264/220, 264/22, 264/106, 264/107, 264/2.5, 264/485, 264/162, 264/328.1, 425/174.4, 425/808
• US Class Current: 264/1.31
• CPC Class Codes: B29C 33/3842 Manufacturing moulds, e.g. shaping the mould surface by machining
• CPC Class Codes: B29C 33/3857 by making impressions of one or more parts of models, e.g. shaped articles and including possible subsequent assembly of the parts
• CPC Class Codes: B29C 33/424 Moulding surfaces provided with means for marking or patterning for injection moulding B29C45/372
• CPC Class Codes: B29C 39/026 characterised by the shape of the surface
• 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 11/00769 Producing diffraction gratings
• CPC Class Codes: B29D 11/00971 using CNC machining to make mould surfaces
• CPC Class Codes: B29L 2011/00 Optical elements, e.g. lenses, prisms
• CPC Class Codes: B29L 2011/005 Fresnel lenses
• CPC Class Codes: B29L 2031/7224 Holograms
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing
• CPC Class Codes: G02B 5/1876 Diffractive Fresnel lenses; Zone plates; Kinoforms G02B5/1842, G02B5/1847 take precedence; optical systems having diffractive correction means G02B27/0037; Fresnel lenses operating by refraction G02B3/08
• CPC Class Codes: G03H 1/0276 Replicating a master hologram without interference recording surface relief holograms G03H1/0244
• CPC Class Codes: G03H 1/0891 Processes or apparatus adapted to convert digital holographic data into a hologram G03H1/2294 takes precedence
• CPC Class Codes: G03H 2001/0284 by moulding
• CPC Class Codes: G03H 2001/0296 Formation of the master hologram
• CPC Class Codes: Y10T 428/22 Nonparticulate element embedded or inlaid in substrate and visible

Abstract

A method of molding a plastic element having a microstructure embedded therein includes the steps of providing a master having a microstructure therein; casting a liquid surface coating over said master; solidifying the liquid surface coating to form a rigid molding tool containing said microstructure; placing the molding tool into a molding machine; introducing a plastic element into the molding machine; transferring the microstructure from the molding tool to the plastic element; and removing the molded plastic element from the molding machine. The molding tool may also be produced by machining directly into a molding base element a predetermined microstructure without machining through a transfer interlayer. An injection-molded binary optical element produced according to the method of the present invention provides an injection molded optical element which diffracts light.

Claims

1. A method of molding a plastic element having a microstructure embedded therein, comprising the steps of:

defining a microstructure for performing a predetermined function;

converting the defined microstructure into at least one pattern corresponding to a negative of the defined microstructure;

machining directly into a molding base element a negative microstructure corresponding to said pattern without machining material other than the molding base element;

placing the machined base element into a molding machine;

introducing a plastic element into the molding machine;

transferring the negative microstructure from the molding base element into a positive microstructure in the plastic element; and

removing the molded plastic element having the positive microstructure from the molding machine.

2. A method according to claim 1 wherein said machining step comprises the step of ion-milling a molding base element.

3. A method according to claim 1 wherein said machining step comprises the step of reactive ion etching the molding base element.

4. A method according to claim 1 wherein said machining step comprises the step of machining the molding base element using a numerical control milling machine to machine the molding base element.

5. A method according to claim 1 wherein said machining step comprises the step of machining the molding base element a plurality of times.

6. A method according to claim 1 wherein the molding base element is selected from a group consisting of hardened tool steel, aircraft aluminum, nickel, nickel plated aluminum, nickel plated steel, epoxy, metal matrix composites, metal filled epoxies, engineering polymers, ceramics, nickel alumanide, and gamma prime nickel alumanide.

7. A method according to claim 1 wherein said machining step comprises the step of electrical discharge machining a conductive molding base element.

8. A method according to claim 7 further comprising the step of forming a microstructure on a conductive electrode using one or more of the following methods:

diamond-machining, ion milling, reactive-ion etching, lithographic techniques.

15. A method according to claim 1, wherein the step of transferring the microstructure includes the step of transferring the microstructure from the molding base element to the plastic element to cause the plastic element to correct chromatic and/or thermal aberrations in light passing through said element.

16. A method according to claim 1, wherein said step of transferring the microstructure includes the step of transferring the microstructure from the molding base element to the plastic element to cause the plastic element to refract and diffract light passing therethrough.

17. A method according to claim 1, wherein said step of transferring the microstructure includes the step of transferring a fanout grating structure.

18. A method according to claim 1, wherein the step of transferring the microstructure includes the step of transferring a microstructure to the plastic element which causes a light beam incident on the plastic element to be split into a plurality of light beams.

19. A method according to claim 1, wherein the step of transferring the microstructure includes the step of transferring a binary microstructure.

20. A method according to claim 1, wherein the step of transferring the microstructure includes the step of transferring analog surfaces to the plastic element.

21. A method according to claim 1, wherein the step of transferring the microstructure includes the step of transferring a grating structure.

22. A method according to claim 1, wherein the step of transferring the microstructure includes the step of transferring a blazed diffraction grating.

23. A method according to claim 1, wherein the step of machining includes the step of diamond turning the molding base element.

24. A method according to claim 1, wherein said machining step comprises the step of machining into a metal molding base element the predetermined microstructure.

25. A method according to claim 1, wherein said machining step comprises the step of ion etching the molding base element.

26. A method according to claim 1, wherein said machining step comprises the step of electron beam etching the molding base element.

9. A method of forming a molding tool having a negative microstructure embedded therein, the molding tool for use in molding a plastic element having a positive microstructure corresponding to the negative microstructure, comprising the steps of:

defining a positive microstructure for performing a predetermined function;

converting the defined positive microstructure into at least one pattern corresponding to a negative of the defined positive microstructure; and

machining directly into a molding base element a negative microstructure corresponding to said pattern without machining material other than the molding base element.

10. A method according to claim 9 wherein said converting step comprises the step of producing at least one mask which defines said microstructure.

11. A method according to claim 10 wherein said machining step comprises the step of ion-milling the molding base element.

12. A method according to claim 10 wherein said machining step comprises the step of reactive ion-etching the molding base element.

13. A method according to claim 9 wherein said converting step comprises the step of producing at least one conductive electrode having said microstructure embedded therein.

14. A method according to claim 13, wherein said machining step includes the step of electrical discharge machining a conductive molding base element.

30. A method according to claim 9, wherein said machining step comprises the step of machining the molding base element using a numerical control milling machine to machine the molding base element.

31. A method according to claim 9, wherein the step of machining includes the step of diamond turning the molding base element.

27. A method of molding a plastic element having a microstructure embedded therein, comprising the steps of:

defining a microstructure for performing a predetermined function;

converting the defined microstructure into at least one pattern corresponding to a negative of the defined microstructure;

machining directly into a molding base element a negative microstructure corresponding to said pattern without machining material other than the molding base element;

placing the machine base element into a molding machine;

introducing a plastic element into the molding machine;

transferring the negative microstructure from the molding base element into a positive microstructure in the plastic element, the plastic element with microstructure refracting and diffracting light beams passing therethrough; and

removing the molded plastic element having the positive microstructure from the molding machine.

28. A method of molding a plastic element having a microstructure, comprising the steps of:

defining a microstructure for performing a predetermined function;

converting the defined microstructure into at least one pattern corresponding to a negative of the defined microstructure;

machining directly into a molding base element a negative microstructure corresponding to said pattern without machining material other than the molding base element;

placing the machined base element into a molding machine;

introducing a plastic element into the molding machine;

transferring the negative microstructure from the molding base element into a positive microstructure in the plastic element, the plastic element and microstructure correcting thermal and/or chromatic aberrations in light passing therethrough;

removing the molded plastic element having the positive microstructure from the molding machine.

29. A method of molding a plastic element having a microstructure embedded therein, comprising the steps of:

defining a microstructure for performing a predetermined function;

creating at least one primitive from the defined microstructure, the primitive corresponding to a negative of the defined microstructure;

converting the at least one primitive into at least one mask, said mask having at least one opening therein;

machining the predetermined microstructure into a molding base element directly through the openings in the mask without machining material other than the molding base element;

placing the machined base element into a molding machine;

introducing a plastic element into the molding machine;

transferring the microstructure from the molding base element to the plastic element; and

removing the molded plastic element from the molding machine.