Field calibration of a broadband compact thermal infrared spectrometer for earth science

We present field results showing excellent performance for a compact earth observing thermal infrared (EOTIR) hyperspectral grating spectrometer using a combination of a Quantum Well Infrared Photodetector (QWIP) and grating based Dyson spectrometer. The Dyson design allows for a very compact and optically fast system (F/1.6). Cooling requirements are minimized due to the single monolithic prism-like grating design. The configuration has the potential to be the optimal sciencegrade imaging spectroscopy solution for lighter-than-air (LTA) vehicles and unmanned aerial vehicles (UAV) due to its small form factor and relatively low power requirements. The QWIP allows for optimum spatial and spectral uniformity and provides adequate responsivity to allow for near 100 mK noise equivalent temperature difference (NEDT) operation across the EOTIR passband. These tests are in preparation for the deployment of the Hypserspectral Thermal Infrared Spectrometer (HyTES) which is currently being funded under NASA´s instrument incubator program (IIP). Test results show NEDT, linearity as well as applicable earth science emissivity target results (silicates, water) measured in direct sunlight. A calibration is also performed to derive direct water temperature using a well calibrated transfer radiometer operating simultaneously.