Method and system for sensing light using interferometric elements

• US 20060066876A1
• Filed: 02/24/2005
• Published: 03/30/2006
• Est. Priority Date: 09/27/2004
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: IDC, LLC
• Inventors: Kothari, Manish
• Granted Patent: US 7,460,246 B2
• Time in Patent Office: Days
• US Class Current: 356/519
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3466 based on interferometric effect

Abstract

Certain embodiments of the invention provide a light sensor comprising at least one interferometric element that absorbs light in at least one wavelength. The interferometric element comprises a first surface and a second surface substantially parallel to the first surface. The second surface is spaced a gap distance from the first surface in a direction substantially perpendicular to the first surface. The light wavelength absorbed is dependent on the gap distance. The interferometric element further comprises a temperature sensor. The temperature sensor is responsive to changes in temperature of at least a portion of the interferometric element due to absorption of light by the interferometric element.

Claims

1. A light sensor having at least one interferometric element, the interferometric element comprising:

a first surface being partially transmissive and partially reflective to at least one wavelength of light;

a second surface substantially parallel to the first surface and spaced a first distance from the first surface in a direction substantially perpendicular to the first surface for reflecting at least a portion of the at least one wavelength of light; and

a temperature sensor responsive to changes of temperature of at least a portion of the first surface caused at least in part by absorption of the at least one wavelength of light.

2. The light sensor of claim 1, wherein the temperature sensor comprises a binary device.

3. The light sensor of claim 2, wherein the binary device is in a first state when the temperature is below a predetermined level and is in a second state when the temperature is above a predetermined level.

4. The light sensor of claim 3, wherein the binary device is formed using micro-electro-mechanical system (MEMS) fabrication techniques.

5. The light sensor of claim 1, wherein the temperature sensor comprises an analog device.

6. The light sensor of claim 5, wherein the analog device comprises a bimetallic thermocouple.

7. The light sensor of claim 5, wherein the analog device generates a voltage difference as a function of the temperature.

8. The light sensor of claim 1, further comprising a second interferometric modulator comprising:

a third surface being partially transmissive and partially reflective to at least one second wavelength of light;

a fourth surface substantially parallel to the third surface and spaced a second distance from the third surface in a direction substantially perpendicular to the third surface for reflecting at least a portion of the at least one wavelength of light; and

a second temperature sensor responsive to changes of temperature of at least a portion of the third surface from absorption of the at least one second wavelength of light.

9. The light sensor of claim 8, wherein the second temperature sensor comprises a second binary device.

10. The light sensor of claim 9, wherein the second binary device is in a first state when the temperature is below a predetermined level and is in a second state when the temperature is above a predetermined level.

11. The light sensor of claim 10, wherein the second binary device is formed using micro-electro-mechanical system (MEMS) fabrication techniques.

12. The light sensor of claim 8, wherein the second temperature sensor comprises a second analog device.

13. The light sensor of claim 12, wherein the second analog device comprises a bimetallic thermocouple.

14. The light sensor of claim 12, wherein the second analog device generates a voltage difference as a function of the temperature.

15. The light sensor of claim 1, further comprising a second interferometric modulator comprising,

a third surface being partially transmissive and partially reflective to the at least one wavelength of light;

a fourth surface substantially parallel to the third surface and spaced a first distance from the third surface in a direction substantially perpendicular to the third surface for reflecting at least a portion of the at least one wavelength of light; and

a second temperature sensor responsive to changes of temperature of at least a portion of the third surface from absorption of the at least one wavelength of light, wherein an activation temperature of the second temperature sensor is different than an activation temperature of the temperature sensor.

16. The light sensor of claim 1 further comprising a substrate.

17. A method for sensing light comprising:

providing a first surface being partially transmissive and partially reflective to at least one wavelength of light;

providing a second surface substantially parallel to the first surface and spaced a gap distance from the first surface in a direction substantially perpendicular to the first surface for reflecting at least a portion of the at least one wavelength of light;

absorbing the at least one wavelength of light on the first surface; and

sensing a change of temperature of at least a portion of the first surface.

18. A camera having a light sensor, the camera comprising:

a housing; and

an interferometric element within the housing, the interferometric element comprising;

a first surface being partially transmissive and partially reflective to at least one wavelength of light,

a second surface substantially parallel to the first surface and spaced a first distance from the first surface in a direction substantially perpendicular to the first surface for reflecting at least a portion of the at least one wavelength of light, and

a temperature sensor responsive to changes of temperature of at least a portion of the first surface caused at least in part by absorption of the at least one wavelength of light.

19. The camera of claim 18, wherein the temperature sensor comprises a binary device.

20. The camera of claim 18, wherein the temperature sensor comprises an analog device.

21. The camera of claim 18, wherein the changes of temperature is at least in part indicative of a wavelength of the at least one wavelength light.

22. The camera of claim 18, wherein the changes of temperature is at least in part indicative of an intensity associated with the at least one wavelength light.

23. A display device having a light sensor, the display device comprising:

a housing; and

an interferometric element within the housing, the interferometric element comprising;

a first surface being partially transmissive and partially reflective to at least one wavelength of light,

a second surface substantially parallel to the first surface and spaced a first distance from the first surface in a direction substantially perpendicular to the first surface for reflecting at least a portion of the at least one wavelength of light, and

a temperature sensor responsive to a change of temperature of at least a portion of the first surface caused at least in part by absorption of the at least one wavelength of light.

24. The display device of claim 23, wherein the change of temperature is at least in part indicative of a wavelength of the at least one wavelength light.

25. The display device of claim 23, wherein the change of temperature is at least in part indicative of an intensity associated with the at least one wavelength light.