Wide-angle variable focal length lens system

• US 7,440,193 B2
• Filed: 01/14/2008
• Issued: 10/21/2008
• Est. Priority Date: 04/30/2004
• Status: Expired due to Fees

• Current Assignee: Louisiana Tech University Foundation (Louisiana Tech University)
• Original Assignee: Louisiana Tech University Foundation (Louisiana Tech University)
• Inventors: Fang, Ji, Wang, Weisong, Agarwal, Mangilal, Gunasekaran, R. Alfred, Varahramyan, Kody, Chen, Jackie
• Primary Examiner(s): SCHWARTZ, JORDAN MARC
• Application Number:
  US12/013,937
• Publication Number:
  US 20080144187A1
• Time in Patent Office: 281 Days
• Field of Search: 359/665, 359/666
• US Class Current: 359/666
• CPC Class Codes: G02B 1/06 made of fluids in transparent cells
• CPC Class Codes: G02B 15/00 Optical objectives with means for varying the magnification anamorphotic objectives G02B13/08
• CPC Class Codes: G02B 3/14 of variable focal length

Abstract

A variable focal length microlens system having a base section with a fluid chamber and a fluid pressurization mechanism. A flexible, substantially transparent polymer lens section is fixed above the fluid chamber and the lens section has a curvature providing an initial focal point when in an unstrained state. The fluid chamber is substantially sealed and the fluid pressurization mechanism includes a flexible wall in the base section. The flexible wall may be displaced by magnetic activation, PZT activation of another activating mechanism.

Claims

1. A variable focal length microlens apparatus comprising:

a. a lens frame comprising a first surface and a second surface, with a view aperture formed through said first and second surfaces;

b. a fluid chamber formed between said first and second surface;

c. a flexible, substantially transparent polymer lens section positioned over said view aperture on each of said first and second surfaces; and

d. a fluid pressurization mechanism capable of causing an increase or a decrease of fluid pressure in said fluid chamber, thereby adjustably forming a DCV lens or a DCX lens comprising a focal length range which can vary between about 1.5 mm and about 16 mm.

2. The variable focal length microlens apparatus of claim 1, wherein multiple lens frames are positioned adjacent to one another in order to form a series of DCV and/or DCX lens and said lens frames communicate with a common fluid transfer path.

3. The variable focal length microlens apparatus of claim 1, wherein said lens section has a curvature providing an initial focal point when in an unstrained state.

4. The variable focal length microlens apparatus of claim 3, wherein said lens section has a contact angle of at least ten degrees in an unstrained state.

5. The variable focal length microlens apparatus of claim 1, wherein said lens section is formed substantially of a PDMS material.

6. The variable focal length microlens apparatus of claim 1, wherein said lenses have a base diameter of between about 100 um and about 3000 um.

7. The variable focal length microlens apparatus of claim 4, wherein said lenses have a height of between about 15 um and 200 um in said unstrained state.

8. The variable focal length microlens apparatus of claim 1, wherein said fluid pressurization mechanism comprises a fluid channel connecting said fluid chamber to an exterior of a base section.

9. The variable focal length microlens apparatus of claim 8, wherein said fluid channel is connected to a fluid pump exterior to said base section.

10. The variable focal length microlens apparatus of claim 1, wherein said fluid chamber is substantially sealed and said fluid pressurization mechanism comprises a thermo-expansive liquid and a heating element positioned in contact with said thermo-expansive liquid.

11. The variable focal length microlens apparatus of claim 10, wherein said liquid has a thermal expansion coefficient of between about 0.0002 and about 0.002°

C.<sup>−

1</sup>.

12. The variable focal length microlens apparatus of claim 10, wherein a temperature sensor is positioned in contact with said liquid.

13. The variable focal length microlens apparatus of claim 12, wherein said temperature sensor comprises a conductive metal trace applied to a bottom wall of said fluid chamber.

14. The variable focal length microlens apparatus of claim 10, wherein said heating element is an electrically conducting strip applied to a bottom wall of said fluid chamber.

15. The variable focal length microlens apparatus of claim 1, wherein said polymer lens section is formed by a method comprising the steps of:

a. using a lithography process to form a lens base of a thermally reflowable first material;

b. heating said reflowable first material to formed a convex mother lens;

c. transferring the shape of said mother lens to a mold master of a second material;

d. coating a substantially transparent polymer lens material onto said mold master; and

e. releasing said transparent polymer lens material from said mold master.

16. The variable focal length microlens apparatus of claim 1, wherein said polymer lens section is formed by a method comprising the steps of spin coating and curing a polymer material to form said lens section and transferring the formed lens section to a frame structure.

17. A variable focal length microlens apparatus comprising:

a. at least two lens frames, each lens frame comprising a first surface, a second surface, with a spacer positioned therebetween and a view aperture formed through said first and second surfaces and said spacer;

b. a fluid chamber formed between said first and second surface;

c. a flexible, substantially transparent polymer lens section positioned over said view aperture on each of said first and second surfaces;

d. a fluid pressurization mechanism capable of causing an increase or a decrease of fluid pressure in said fluid chamber, thereby adjustably forming a DCV lens or a DCX lens; and

e. wherein said lens frames are positioned adjacent to one another in order to form a series of DCV and/or DCX lens and said lens frames communicate with a common fluid transfer path.

18. The variable focal length microlens apparatus of claim 17, wherein said lenses have a base diameter of between about 100 um and about 3000 um.

19. The variable focal length microlens apparatus of claim 17, wherein said polymer lens section is formed by a method comprising the steps of spin coating and curing a polymer material to form said lens section and transferring the formed lens section to a frame structure.

20. The variable focal length microlens apparatus of claim 17, wherein said lens section is formed substantially of a PDMS material.

21. The variable focal length microlens apparatus of claim 17, wherein said fluid path comprises a fluid channel connecting said fluid chamber to an exterior of a base section.

22. The variable focal length microlens apparatus of claim 21, wherein said fluid channel is connected to a fluid pump exterior to said base section.

23. The variable focal length microlens apparatus of claim 17, wherein said fluid chamber is substantially sealed and said fluid pressurization mechanism comprises a thermo-expansive liquid and a heating element positioned in contact with said thermo-expansive liquid.