NGST long-wave hyperspectral imaging spectrometer system characterization and calibration

Northrop Grumman Space Technology (NGST) has developed and tested a Long-wave Hyperspectral Imaging Spectrometer (LWHIS) that operates in the 8 to 12.5 micron band. An overview of the system design has been described elsewhere.(1) This paper describes the system characterization and radiometric calibration of this instrument using NGST's Long-wave Hyperspectral Test Facility which uses a 1375K globar source assembly, a monochromator, a collimator and a fine pointing mirror to provide image quality and FPA alignment data. Image quality characterization results presented here include measurement of the instrument's Modulation Transfer Function (MTF), spatial co-registration of spectral channels (spectral smile), cross-track spectral error (spatial smile), and spectral calibration. Radiometric calibration results for laboratory targets are also presented.