Light beam steering with deformable membrane device

• US 5,223,971 A
• Filed: 12/31/1991
• Issued: 06/29/1993
• Est. Priority Date: 12/31/1991
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Magel, Gregory A.
• Primary Examiner(s): Arnold, Bruce Y.
• Assistant Examiner(s): Lester, Evelyn A.
• Application Number:
  US07/816,434
• Time in Patent Office: 546 Days
• Field of Search: 359/290, 359/291, 359/295, 359/298, 359/319, 359/318, 359/847, 359/224
• US Class Current: 359/295
• CPC Class Codes: G02B 26/0825 the reflecting element being a flexible sheet or membrane, e.g. for varying the focus flexible mirrors for cosmetic use A45D42/24
• CPC Class Codes: G03H 2001/0434 In situ recording when the hologram is recorded within the device used for reconstruction
• CPC Class Codes: G03H 2001/0439 for recording Holographic Optical Element [HOE] HOE per se G02B5/32

Abstract

A deformable membrane type of spatial light modulator may be modified and used with a lens for beam steering applications. A reflective membrane is deformed by one or more of a multiplicity of underlying address electrodes, such that it has a different center of curvature depending on which electrode is being energized. An incoming beam is incident on the membrane and reflected from it. A lens collimates light reflected from the membrane so that a beam is reflected in a desired direction relative to the incoming beam.

Claims

1. A light beam steering device, comprising:

a membrane having a reflective upper surface, wherein said membrane is flexible and made from an electrically conductive material, and said membrane has a pattern of tiny holes in said upper surface;

an electrode circuit on a substrate underlying said membrane, wherein said electrode circuit is spaced under said membrane such that said membrane may deform toward such electrode circuit;

spacers on said substrate for supporting said membrane above said electrode circuit and said substrate; and

a lens spaced adjacent said membrane, having a power appropriate for collimating a beam of light reflected from said membrane.

2. The device of claim 1, wherein said membrane deforms to a concave shape with respect to said lens and wherein said lens is a negative lens.

3. The device of claim 1, wherein said lens is a refractive lens.

4. The device of claim 1, wherein said lens is a diffractive lens.

5. The device of claim 1, wherein said electrode circuit is between said membrane and said lens, rather than under said membrane.

6. The device of claim 1, wherein said electrode circuit is comprised of elongated electrode strips.

7. The device of claim 1, wherein said electrode circuit is an area array of point electrodes.

8. The device of claim 1, wherein said membrane, said electrode circuit, and said lens are duplicated as an array of such elements.

9. The device of claim 1, wherein said lens is cylindrical for enhancing a desired beam steering directionality.

10. A method of using a reflective deformable membrane for steering a light beam, comprising the steps of:

selecting an electrode on a substrate near said membrane to be energized;

energizing said electrode such that said membrane deforms to a curved shape on spacers above said substrate;

directing a beam of light toward said membrane such that it is reflected from the reflective surface of said membrane at a predetermined angle as determined by said selection step; and

collimating the reflected light beam after reflection.

11. The method of claim 10, and further comprising the step of repeating said steps for directing said light beam in a predetermined pattern.

12. The method of claim 11, wherein said energizing step is performed with an area array of electrodes to approximate a shifted center of curvature of said membrane.

13. The method of claim 11, wherein said energizing step is performed with strip electrodes to approximate a shifted line of curvature of said membrane.

14. A method of fabricating a beam steering device, comprising the steps of:

forming an array of electrode circuits on a substrate, each electrode circuit having a predetermined pattern such that they may be used to selectively deform a membrane in a predetermined shape when said membrane is electrostatically attracted to one or more of said electrodes;

forming spacers above said electrode circuit for supporting membranes of said beam steering device;

forming an array of reflective, flexible, membranes between said spacers, spaced above said electrodes such that it may deform toward them; and

placing a negative lens over each of said membranes, spaced a small distance apart from said membranes, designed for collimating a light beam reflected from the surface of said membranes.

15. The method of claim 14, and further comprising the step of compensating for aberrations in the deformation of said membranes that affect a desired directionality of said light beam.

16. A method of monolithically fabricating a beam steering device, comprising the steps of:

forming an array of transparent electrode circuits on a first side of a substrate, each electrode circuit having a predetermined pattern such that they may be used to selectively deform a membrane in a predetermined shape when said membrane is electrostatically attracted to one or more of said electrodes;

forming spacers under said electrode circuit for supporting membranes of the steering device;

forming an array of reflective, flexible, membranes between said spacers, spaced apart from said electrodes such that said membranes may deform toward said electrodes; and

forming positive lenses from said substrate on an opposing side of said substrate, wherein the distance of said lens from said membranes and the power of said lenses is such that light reflected from said membranes is collimated.