Recent work at the Rome Air Development Center (RADC)1 and elsewhere' has indicated that the performance of sensors based on staring focal plane arrays ultimately may be limited by their nonuniformity of response. It has been shown that simple addition and multiplication operations alone are not sufficient to remove all detector-to-detector response variations. Post-correction error remains, arising from the fact that the individual detector sensitivities do not necessarily differ by a simple constant, but rather can differ in a spectrally dependent fashion across the entire waveband of interest. Using the RADC linear model for a general focal plane array, the theoretical MWIR response of a 256x256 PtSi device is calculated, and the effects of uncompensated imaging are demonstrated. Initial lab testing of this device will employ a single-point (additive) compensation method. Mathematical analysis is presented that predicts the contrast signal-to-noise ratio (CSNR) one might expect with such a scheme. It is demonstrated that even modest amounts of spectral nonuniformity can seriously degrade the ability to resolve small temperature differences in a thermal scene. It is anticipated that actual device testing will begin soon, with the hope of being able to quantify the individual magnitudes of the additive, multiplicative, and spectral nonuniformities of the device.
D L Perry,
E L Dereniak,
"Proposed Testing Of Spectral Nonuniformity In PtSi Area Arrays", Proc. SPIE 1071, Optical Sensors and Electronic Photography, (23 May 1989); doi: 10.1117/12.952502; https://doi.org/10.1117/12.952502