US 6,982,412 B2
Infra red camera calibration
Norman Frederick Watson, Edinburgh (United Kingdom); and Michael Grant McGuigan, Edinburgh (United Kingdom)
Assigned to BAE Systems plc, London (United Kingdom)
Appl. No. 10/506,081
PCT Filed Mar. 04, 2003, PCT No. PCT/GB03/00923
§ 371(c)(1), (2), (4) Date Aug. 31, 2004,
PCT Pub. No. WO03/077539, PCT Pub. Date Sep. 18, 2003.
Claims priority of application No. 0205482 (GB), filed on Mar. 08, 2002.
Prior Publication US 2005/0103989 A1, May 19, 2005
Int. Cl. G01D 18/00 (2006.01)
U.S. Cl. 250—252.1 8 Claims
OG exemplary drawing
 
1. A method of calibrating an infrared detector using a temperature-adjustable reference surface within its field of view, the method being characterized by the steps of:
a) controlling the temperature of the reference surface to a first surface temperature and measuring the output of the detector over a first stare time, the first temperature and stare time being selected so as to achieve a predetermined first well-fill (Wactual) of the detector pixels at the lowest possible temperature of the reference surface;
b) processing the output measurements of the detector to obtain a first calibration coefficient (coeffcal1);
c) adjusting the temperature of the reference surface to a second surface temperature and measuring the output of the detector over a second stare time period (Sactual), the second temperature and stare time (Sactual) being selected so as to achieve a second predetermined well-fill of the detector pixels
d) processing the output measurements of the detector to obtain a second calibration coefficient (coeffcal2);
e) re-adjusting the temperature of the reference surface to a third surface temperature and measuring the output of the detector over the first stare time period, the third temperature being selected so as to achieve the second predetermined well-fill of the detector pixels over the first stare time period;
f) processing the output measurements of the detector to obtain a third calibration coefficient (coeffcal3); and
g) adjusting the first calibration coefficient (coeffcal1) on the basis of the second and third calibration coefficients (coeffcal2, coeffcal3) obtained.