Signal calibration and stability in an uncooled integrated bolometer array

Operation of an uncooled bolometer array in the space environment imposes stringent calibration requirements. A calibration strategy is presented for a 256×40 element integrated microbolometer array fabricated by L´Institut National d´Optique for a Centre for Research in Earth and Space Technology satellite attitude sensor. Measurements are described for bolometer parameters that affect the calibration, such as electrical resistance, temperature coefficient of resistance and conductance as functions of temperature, time and pixel location on the chip. The prototype integrated chip has built in provisions for static gain and offset correction. The pixel gain and offset coefficients are strongly dependent on the chip temperature, but are otherwise able to be matched in pairwise fashion to a level of about ten parts per million. With a suitable combination of static and dynamic gain and offset coefficients, the above level of pixel matching is expected to be achievable on a continuing basis in space with the aid of occasional on-orbit recalibration