Uncooled optical imaging device

• US 7,091,488 B2
• Filed: 06/19/2003
• Issued: 08/15/2006
• Est. Priority Date: 07/15/2002
• Status: Expired due to Term

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Maurel, Gilles
• Primary Examiner(s): Porta, David
• Assistant Examiner(s): BOOSALIS, FANI POLYZOS
• Application Number:
  US10/464,660
• Publication Number:
  US 20040155195A1
• Time in Patent Office: 1,153 Days
• Field of Search: 250/351, 250/352, 250/330, 250/331, 250/332, 250/338.3, 250/338.1
• US Class Current: 250/351
• CPC Class Codes: H04N 23/52 Elements optimising image sensor operation, e.g. for electromagnetic interference [EMI] protection or temperature control by heat transfer or cooling elements
• CPC Class Codes: H04N 25/63 applied to dark current
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

Optical sensors, more particularly infrared sensors, use an array of MEM micromirrors to chop a light beam impinging on an array of sensors of an imaging device to minimize the influence of thermal noise. The array of micromirrors preferably switches the beam impinging on the array of sensors between an image to be analyzed and an image of a reference black body at a clearly defined temperature. These sensors are not cooled and require no cryogenic devices.

Claims

1. An optical imaging device that is not cooled and in which an optical image is transported along an optical path onto an array of optical sensors and an array of MEM micromirrors is inserted into said transfer optical path outside and downstream of intermediate images to chop the light beam impinging on said array of sensors.

2. The device claimed in claim 1 wherein said array of micromirrors is disposed in the vicinity of a real pupil.

3. The device claimed in claim 1 wherein said array of micromirrors when in a first state directs onto said array of sensors an image to be analyzed and when in a second state directs onto said array of sensors an image of a black body at a clearly defined temperature.

4. The device claimed in claim 3 wherein said array of micromirrors when in a plurality of separate states directs onto said array of sensors images of a plurality of separate black bodies having different characteristics.

5. The device claimed in claim 1 including a plurality of arrays of micromirrors associated side by side.

6. An optical imaging device that is not cooled and in which an optical image is transported along an optical path onto an array of optical sensors and an array of MEM micromirrors is inserted into said optical path outside locations of intermediate images to chop the light beam impinging on said array of sensors;

and

wherein the imaging device further comprises an afocal optical system for associating an entry image, an array of micromirrors, and an array of analyzers with different dimensions.

7. The device claimed in claim 6 wherein said entry image and said array of sensors have substantially equal dimensions and said array of micromirrors has linear dimensions substantially twice those of said sensor and said entry image.

8. An optical imaging device, comprising:

an optical system that receives an image;

an array of micromirrors located on an optical path outside and downstream of intermediate images; and

an array of optical sensors located on the optical path downstream of the array of micromirrors and that receive radiation from the image;

wherein the optical system transports radiation from the image along a portion of the optical path through the optical system; and

wherein the array of micromirrors are controllable to chop the radiation.

9. The optical imaging device according to claim 8, wherein the optical system comprises infrared optics.

10. The optical imaging device according to claim 9, wherein the array of optical sensors comprises an array of bolometers.

11. The optical imaging device according to claim 10, wherein linear dimensions of the array of micromirrors are about twice linear dimensions of the array of bolometers.

12. The optical imaging device according to claim 9, wherein the device does not include a mechanism that actively cools the device.

13. The optical imaging device according to claim 9, further comprising an exit pupil and wherein the array of micromirrors are located in a vicinity of the exit pupil.

14. The optical imaging device according to claim 9, further comprising an exit pupil and wherein the array of micromirrors crosses a plane of the exit pupil.

15. The optical imaging device according to claim 9, wherein the device is a video camera that generates successive frames.

16. The optical imaging device according to claim 9, wherein the optics are of the afocal type that alters the size of a beam of radiation traveling through the optics.

17. An artificial satellite comprising a video earth sensor that includes the imaging device according to claim 9.

18. An optical imaging device, comprising:

an optical system that receives an image;

an array of micromirrors located on an optical path downstream of the optical system; and

an array of optical sensors located on the optical path downstream of the array of micromirrors and that receive radiation from the image;

wherein the optical system transports radiation from the image along a portion of the optical path through the optical system;

wherein the array of micromirrors are controllable to chop the radiation;

wherein the optical system comprises infrared optics;

wherein the array of optical sensors comprises an array of bolometers; and

wherein the array of micromirrors are located such that a majority of rays of the radiation focused on one bolometer of the array of bolometers are affected by a majority of the individual mirrors.