Shutterless calibration

Abstract

An imaging system includes a focal plane array including an array of pixels. An isothermal diaphragm covers a first portion of the pixels along a periphery of the array and exposing an imaging portion of the pixels. A controller is operatively connected to the focal plane array to read sensor data from the focal plane array, wherein the sensor data includes image data from the imaging portion of the pixels and non-uniformity data from the first portion of the pixels. The controller is operatively connected to the focal plane array to enhance the image data based on the non-uniformity data.

1 . (canceled) 
     
     
         2 . An imaging system comprising:
 a focal plane array comprising an array of pixels configured to detect long wavelength infrared radiation;   a diaphragm covering a first portion of the pixels along at least two edges of a periphery of the array and exposing an imaging portion of the pixels, the diaphragm configured to have a uniform temperature across a surface of the diaphragm, and   a controller operatively connected to the focal plane array and configured to correct for at least one of column-correlated or row-correlated non-uniformity.   
     
     
         3 . The system of  claim 2 , wherein the diaphragm covers a portion of the pixels along at least two perpendicular edges of the array. 
     
     
         4 . The system of  claim 2 , wherein the array of pixels forms a rectangle, and wherein the diaphragm covers the portion of the pixels along at least a portion of four edges of the periphery of the array. 
     
     
         5 . The system of  claim 2 , wherein the focal plane array is a first focal plane array that is sensitive to wavelengths in a first band and wherein the system further comprises a second focal plane array operatively connected to the first focal plane array for multi-band imagery, wherein the imaging portion of the pixels define an imaging array with an aspect ratio matched to that of the at least one additional focal plane array. 
     
     
         6 . The system of  claim 2 , wherein the focal plane array is uncooled. 
     
     
         7 . The system of  claim 2 , wherein the diaphragm permanently covers the portion of the pixels along the periphery of the array. 
     
     
         8 . The system of  claim 2 , wherein the controller is configured to perform a non-uniformity correction on the imaging portion of the pixels based at least in part on the row-correlated non-uniformity, the column-correlated non-uniformity, or both. 
     
     
         9 . The system of  claim 7 , wherein the non-uniformity correction on the imaging portion of the pixels comprises compensating for a non-uniformity comprising a 1/f type drift. 
     
     
         10 . The system of  claim 2 , wherein the controller is configured to correct for the at least one of column-correlated or row-correlated non-uniformity using a spatial estimation technique. 
     
     
         11 . The system of  claim 2 , wherein the diaphragm is configured to permanently cover the first portion of the pixels. 
     
     
         12 . The system of  claim 2 , wherein the controller is configured to correct for the at least one of column-correlated or row-correlated non-uniformity without interrupting an acquisition of a stream of video data. 
     
     
         13 . A method for correcting for non-uniformities in an image sensor, the method comprising:
 detecting long wavelength infrared radiation at a focal plane array comprising an array of pixels;   covering a first portion of the pixels along at least two edges of a periphery of the array using a diaphragm, the diaphragm configured to have a uniform temperature across a surface of the diaphragm; and   correcting for column-correlated and row-correlated non-uniformity in the focal plane array.   
     
     
         14 . The method of  claim 13 , wherein covering the first portion of the pixels along the at least two edges of a periphery of the array comprises covering the first portion of the pixels along at least two perpendicular edges of the array. 
     
     
         15 . The method of  claim 13 , wherein covering the first portion of the pixels along the at least two edges of a periphery of the array comprises covering the portion of the pixels along at least a portion of four edges of the periphery of the array. 
     
     
         16 . The method of  claim 13 , further comprising operatively coupling a second focal plane array to the focal plane array, wherein the imaging portion of the second focal plane array defines an imaging array with an aspect ratio corresponding to that of the focal plane array. 
     
     
         17 . The method of  claim 13 , wherein the focal plane array is uncooled. 
     
     
         18 . The method of  claim 13 , wherein covering the first portion of the pixels along the at least two edges of a periphery of the array using a diaphragm comprises permanently covering the portion of the pixels along the periphery of the array. 
     
     
         19 . The method of  claim 13 , further comprising performing a non-uniformity correction on the imaging portion of the pixels based at least in part on the row-correlated non-uniformity, the column-correlated non-uniformity, or both. 
     
     
         20 . The method of  claim 19 , wherein performing a non-uniformity correction on the imaging portion of the pixels comprises compensating for a non-uniformity of a 1/f type drift. 
     
     
         21 . The method of  claim 13 , wherein performing a non-uniformity correction on the imaging portion of the pixels comprises estimating a spatial relationship.