Advanced multispectral TIR remote sensing

Recent advances in thermal infrared (TIR) detection offer design options for space sensors requiring temperature sensitivity in the 0.1-0.5 K range. A cost vs. performance trade-off is illustrated with two “reference” sensor concepts. Both systems use all reflective front optics designed for low cost “bolt-together” assembly-alignment. Cooled HgCdTe detection is illustrated by a reference hyperspectral concept using a 320×210 element cooled focal-plane array (FPA), offering ~0.15 K noise-equivalent temperature difference (NEDT) at 50 K FPA temperature for 60 meter pixels from a 705 km Earth orbit. Less expensive uncooled 1 μm bandwidth multi-spectral imaging is illustrated by a reference concept using silicon microbolometers. Test data from a 320×240 element microbolometer array suggest 0.2-0.5 K system accuracy. NEDT improvements are expected over the next two years. Improvements in the design of radiative coolers are also expected to lower the cost of cooled TIR sensor systems. A Mars mission imager now under development illustrates application of the uncooled technology to planetary exploration