High-density spatial light modulator

• US 7,027,204 B2
• Filed: 09/17/2004
• Issued: 04/11/2006
• Est. Priority Date: 09/26/2003
• Status: Active Grant

• Current Assignee: Silicon Light Machines Corporation (SCREEN Holdings Co., Ltd.)
• Original Assignee: Silicon Light Machines Corporation (SCREEN Holdings Co., Ltd.)
• Inventors: Carlisle, Clinton B., Trisnadi, Jahja I.
• Primary Examiner(s): Mack, Ricky L.
• Assistant Examiner(s): Dinh, Jack
• Application Number:
  US10/944,059
• Publication Number:
  US 20050068609A1
• Time in Patent Office: 571 Days
• Field of Search: 359/290, 359/291, 359/295, 359/298, 359/197, 359/224, 359/231, 359/572, 359/247
• US Class Current: 359/291
• CPC Class Codes: G02B 26/0808 by means of one or more diffracting elements

Abstract

In one embodiment, a high-density spatial light modulator includes a substrate having a reflective surface and a reflective ribbon over the reflective surface. The ribbon may have one or more openings, such as rectangular slots. The openings allow light to pass through the ribbon and impinge on the reflective surface. Deflecting the ribbon towards the substrate thus allows for dynamically-controllable diffraction of incident light. The spatial light modulator pixel requires less space than a conventional light modulator, thus allowing for relatively large pixel count within a manufacturable device size. Other embodiments are also disclosed.

Claims

1. A MEMS spatial light modulator comprising:

a substrate having a reflective surface; and

a ribbon, having end supports but no side supports, configured over the reflective surface of the substrate, the ribbon comprising an elongated flat member with a reflective surface, the member spanning a length over a cavity of the substrate and having one or more openings in a middle portion, the opening(s) allowing light to pass through and impinge on the reflective surface of the substrate,

wherein the ribbon is deflectable towards the substrate to diffract incident light in a controllable manner.

2. The light modulator of claim 1, wherein the ribbon is deflectable using electrostatic force.

3. The light modulator of claim 1, wherein the light modulator is configured to controllably deflect the ribbon by approximately one quarter wavelength of the light.

4. The light modulator of claim 1, further comprising a second ribbon that is deflectable towards the reflective surface of the substrate.

5. The light modulator of claim 4, wherein a gap between the two ribbons has a same distance as a width of an opening in the ribbon.

6. The light modulator of claim 1, wherein each opening comprises a slot.

7. The light modulator of claim 6, wherein the slot is substantially rectangular in shape.

8. The light modulator of claim 1, wherein a width of each opening is equal to a distance between two adjacent openings.

9. The light modulator of claim 1, wherein a single ribbon is controlled so as to represent a single pixel.

10. The light modulator of claim 1, wherein an undeflected height of the ribbon is approximately equal to one fourth a wavelength of the light multiplied by an integer.

11. The light modulator of claim 10, wherein the integer is at least a minimum number to avoid a snap down condition of the ribbon when the ribbon is deflected.

12. The light modulator of claim 11, wherein the minimum number is four.

13. The light modulator of claim 10, wherein the integer is odd, and wherein the light is diffracted when the ribbon is undeflected.

14. The light modulator of claim 10, wherein the integer is even, and wherein the light is specularly reflected when the ribbon is undeflected.

15. A high-density spatial light modulator comprising:

a substrate;

an array of deflectable ribbon devices, having end supports but not side supports, configured above the substrate and spanning a length across a cavity on the substrate;

one or more openings within each ribbon device;

an opening between adjacent ribbon devices;

a reflective layer on each ribbon device,

a reflective layer on the substrate configured at least beneath said openings; and

wherein the spatial light modulator is configured such that area-reflectivity products of a) the reflective layer on the ribbons and b) the openings within and between the ribbons to the reflective layer on the substrate, are approximately equal.

16. The spatial light modulator of claim 15, wherein the array comprises a linear array.

17. The spatial light modulator of claim 16, wherein a periodicity of ribbon devices in the linear array is one ribbon device per three micrometers or less.

18. The spatial light modulator of claim 16, wherein the array includes 10,000 ribbon devices or more within a single die, wherein each ribbon device corresponds to a controllable pixel.

19. The spatial light modulator of claim 15, wherein the array comprises a two-dimensional array.

20. A method of spatially modulating light, the method comprising:

impinging light of a wavelength upon an array of ribbon devices, having end supports but no side supports, over a substrate; and

controllably deflecting the ribbon devices,

wherein the substrate comprises a reflective surface, and

wherein each ribbon device comprises a reflective surface and further comprises one or more openings in a middle portion to allow light to pass through to the reflective surface of the substrate.

21. The method of claim 20, wherein at least a single ribbon device corresponds to an individually controllable pixel.