Patent ID: 6982412

Claim:
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 (coeff cal1 ); 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 (coeff cal2 ); 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 (coeff cal3 ); and g) adjusting the first calibration coefficient (coeff cal1 ) on the basis of the second and third calibration coefficients (coeff cal2 , coeff cal3 ) obtained.