Uncooled infrared sensor

• US 7,495,220 B2
• Filed: 04/28/2006
• Issued: 02/24/2009
• Est. Priority Date: 10/24/1995
• Status: Expired due to Term

• Current Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: Blackwell, Richard, Mroczkowski, Jacek, Butler, Neal R.
• Primary Examiner(s): Hannaher, Constantine
• Application Number:
  US11/414,513
• Publication Number:
  US 20070120058A1
• Time in Patent Office: 1,033 Days
• Field of Search: 250/338.1
• US Class Current: 250/338.1
• CPC Class Codes: G01J 5/061 by controlling the temperature of the apparatus or parts thereof, e.g. using cooling means or thermostats
• CPC Class Codes: G01J 5/10 using electric radiation detectors
• CPC Class Codes: G01J 5/20 using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices
• CPC Class Codes: H01L 27/14603 Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
• CPC Class Codes: H01L 27/14649 Infrared imagers
• 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

An uncooled infrared sensor can be used for a plurality of applications such as fire fighting, surveilling a border or any desired area, and limb sounding. The uncooled infrared sensor includes manually or automatically adjustable optics that receive an electromagnetic signal, focus the electromagnetic signal and provide a focused electromagnetic signal to a focal plane array. The focal plane array includes a plurality of detector devices disposed in rows and columns to form the focal plane array. Each detector device is constructed so as to have a reduced pitch and provide a maximum number of detectors within a minimum square area of the focal plane array. Each detector device detects the focused electromagnetic signal incident upon it, converts the focused electromagnetic signal into a sensed signal and outputs the sensed signal so that the focal plane array provides a plurality of sensed signals. The sensor also includes a focal plane array processor that has a plurality of cells corresponding to the plurality of detector devices. The focal plane array processor receives the plurality of sensed signals, processes the plurality of sensed signals to correct for any gain and any offset errors between the plurality of sensed signals due to any inconsistencies between any of the detector devices of the focal plane array and any inconsistencies within the cells of the focal plane array processor itself, and outputs a plurality of processed signals. The sensor also includes a display processor that receives the plurality of processed signals and converts the plurality of processed signals into a video signal suitable for display. The focal plane array processor, the display processor and a controller also provide temperature stabilization of the sensor, manual or automatic calibration of the sensor, manual or automatic gain and level control of the sensor and automatic or manual calibration of the sensor.

Claims

1. A microbridge detector, comprising:

a semiconductor substrate;

a microbridge disposed above the semiconductor substrate, the microbridge comprising an active area and a pixel collection area, the pixel collection area being an area of the microbridge that receives energy that is conveyed to the active area, wherein the microbridge detector is constructed and arranged such that, for incident IR radiation normal to the microbridge, the active area is smaller than the pixel collection area;

downwardly extending leg portions which are a continuation of the microbridge and which support the microbridge above the semiconductor substrate so that a thermal isolation gap exists between the microbridge and the semiconductor substrate; and

electrically conductive paths included within said downwardly extending leg portions connecting the active area to the semiconductor substrate.

2. The microbridge detector of claim 1, wherein the active area further comprises an infrared (IR) absorbing layer.

3. The microbridge detector of claim 2, wherein the active area is configured to absorb incident IR radiation and convert the absorbed IR radiation into heat.

4. The microbridge detector of claim 1, wherein the active area does not comprise an IR absorbing layer.

5. The microbridge detector of claim 1, wherein the active area is configured to change resistance in response to a change in temperature.

6. The microbridge detector of claim 1, further comprising a reflector, disposed between the active area and the substrate, the reflector being configured to reflect radiation towards the active area to enhance an absorption efficiency of the detector.

7. The microbridge detector of claim 1, wherein the active area is patterned with alternating absorption regions and transmissive windows.

8. The microbridge detector of claim 1, wherein each of the pixel collecting area and active area has a length, and wherein the length of the pixel collecting area is greater than or equal to twice the length of the active area.

9. The microbridge detector of claim 1, wherein the electrically conductive paths have a length such that a thermal time constant of the microbridge detector is substantially the same as that of a microbridge detector having an active area substantially equal to the pixel collection area of the microbridge detector.

10. A microbridge detector, comprising:

a semiconductor substrate;

a microbridge disposed above the semiconductor substrate, the microbridge comprising an active area and a pixel collection area, the pixel collection area being an area of the microbridge that receives energy that is conveyed to the active area, and wherein the microbridge detector is constructed and arranged such that, for incident IR radiation normal to the microbridge, the active area is smaller than the pixel collection area;

downwardly extending leg portions which are a continuation of the microbridge and which support the microbridge above the semiconductor substrate so that a thermal isolation gap exists between the microbridge and the semiconductor substrate; and

electrically conductive paths connecting the active area to the semiconductor substrate.

11. The microbridge detector of claim 10, wherein the active area further comprises an IR absorbing layer.

12. The microbridge detector of claim 11, wherein the active area is configured to absorb incident IR radiation and convert the absorbed IR radiation into heat.

13. The microbridge detector of claim 10, wherein the active area does not comprise an IR absorbing layer.

14. The microbridge detector of claim 10, wherein the active area is configured to change resistance in response to a change in temperature.

15. A microbridge detector, comprising:

a semiconductor substrate;

a microbridge disposed above the semiconductor substrate, the microbridge comprising an active area and a pixel collection area, the pixel collection area being an area of the microbridge that receives energy that is conveyed to the active area, and wherein the microbridge detector is constructed and arranged such that, for incident IR radiation normal to the microbridge, the active area is smaller than the pixel collection area;

downwardly extending leg portions which are a continuation of the microbridge; and

electrically conductive paths included within said downwardly extending leg portions connecting the active area to the semiconductor substrate.

16. The microbridge detector of claim 15, wherein the active area further comprises an IR absorbing layer.

17. The microbridge detector of claim 16, wherein the active area is configured to absorb incident IR radiation and convert the absorbed IR radiation into heat.

18. The microbridge detector of claim 15, wherein the active area does not comprise an IR absorbing layer.

19. The microbridge detector of claim 15, wherein the active area is configured to change resistance in response to a change in temperature.