Apparatus and method for performing optical signal intensity correction in electro-optical sensor arrays

• US 6,288,387 B1
• Filed: 04/21/1999
• Issued: 09/11/2001
• Est. Priority Date: 04/21/1999
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation), FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Woolaway, James T. II, Black, Stephen H.
• Primary Examiner(s): Evans, F. L.
• Assistant Examiner(s): Smith, Zandra V.
• Application Number:
  US09/296,044
• Time in Patent Office: 874 Days
• Field of Search: 250/252.1, 250/332, 250/334, 250/214.A, 250/214.AG, 250/208.2, 250/208.1, 348/241, 348/300-302, 348/308
• US Class Current: 250/214.00A
• CPC Class Codes: H04N 25/68 applied to defects
• 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

A method and related system provides an array of sensing elements located in rows and columns, and each column of sensing elements has a connected circuit chain which processes the signals from the sensing elements in that column. Each circuit chain produces a signal with a corrective gain value calculated for it relative to the datum of the array which is selected for the point where signal strength would be strongest. The method and device is capable of being used in a starring or scanning type array mode.

Claims

1. A device for enhancing signal detection comprising:

a sensory array of sensing elements extending in rows and in columns in first and second orthogonally disposed directions, respectively;

a datum selected on said array for reference relative to said rows and columns;

a plurality of circuit chains each associated with a given column of said sensing elements for processing a signal into recognizable form; and

wherein each of said circuit chains taken relative to said datum has a means for producing a gain different from that of a circuit chain associated with a column of said sensing means located coincidentally with said datum.

2. A device as defined in claim 1 further characterized by said array being defined by a planar image surface made up of said plurality of said sensing elements and said datum is a point on said array referenced to the optical central axis.

3. A device as defined in claim 1 characterized by each of said circuits associated with a column of said sensing elements having a capacitive transimpedance amplifier portion.

4. A device as defined in claim 3 wherein the capacitive transimpedance amplifier portion of each of said circuit chains associated with a given column of said sensing elements has a capacitance which differs from the circuit chain associated with the column of sensing elements located coincidentally with said datum.

5. A device as defined in claim 1 characterized by each of said circuits associated with a column of said sensing elements having a skimmer circuit portion.

6. A device as defined in claim 5 further wherein the skimmer circuit portion of said circuit chain associated with a given column of sensing elements other than that located coincidentally with said datum has a capacitance which differs from the capacitance of the skimmer circuit portion of a circuit chain associated with said circuit chain associated with said sensing elements coincident with said datum.

7. A device as defined in claim 1 further characterized by each of said circuits associated with a column of said sensing elements having a circuit portion defined by a capacitive transimpedance amplifier and skimmer circuit portion.

8. A device as defined in claim 7 wherein the capacitive transimpedance amplifier portion and skimmer circuit portion of each of said circuit chains associated with a given column of said sensing elements not coincident with said datum has a capacitance which differs from the corresponding capacitive transimpedance amplifier portion and skimmer circuit portion of the circuit chain associated with a column located coincidentally with said datum.

9. A device as defined in claim 3 further characterized in that each of said circuit chains associated with a column of said sensing elements has for each sensing element in said column a capacitance associated with the capacitive transimpedance amplifier portion which is dependent on the row of the sensing element.

10. A device as defined in claim 5 further characterized in that each of said circuit chains associated with a column of said sensing elements has for each sensing element in said column a capacitance associated with the skimmer circuit portion which is dependent on the row of the sensing element.

11. A device as defined in claim 7 further characterized in that each of said circuit chains associated with a column of said sensing elements has for each sensing element in said column a capacitance associated with the skimmer circuit portion which is dependent on the row of the sensing element and a capacitance associated with the capacitive transimpedance amplifier portion which is dependent on the row of the sensing element.

12. A device as defined in claim 1 further characterized by each column of said sensing elements extending in said first given direction and each of said circuit chains associated with said columns of sensing elements being connected to one another to effect communication therebetween in said second orthogonally disposed direction.

13. A device as defined in claim 12 further characterized by said circuit chains being multiplexed to an output amplifier to effect function in said second given orthogonally disposed direction.

14. A device as defined in claim 12 further characterized by said array of said sensing elements being row addressed and column addressed by a plurality of multiplexers.

15. A method of enhancing a signal comprising the steps of:

providing a sensory array comprised of a plurality of sensory elements arranged in rows and columns;

selecting a datum on said array and referencing said rows and columns of said sensing elements relative to said datum;

determining a prescribed gain for signals generated from a given column of said sensing element taken relative to the strength of a signal from sensory elements at said datum;

and processing signals generated by a given row of said sensing elements in a dedicated circuit chain having an preassigned gain value capable of compensating for signal strength which is less than that of a signal detected at the datum.

16. A method as defined in claim 15 further characterized by interconnecting circuit chains in each column of sensing elements with one another.

17. A method as defined in claim 15 further characterized by configuring each circuit chain associated with a given column of sensing element to an established prescribed gain by altering the capacitance of that circuit chain relative to the capacitance of the circuit chain associated with the column of sensing elements located coincidentally at said datum.

18. A method as defined in claim 17 further characterized by sampling the signals produced in a given column of sensing element to establish a prescribed gain.