Compact Thermal Infrared Sensor for Weather and Land Remote Sensing

JHU/APL has developed a space-qualified microbolometer-based thermal infrared (TIR) camera with a large array format (1024 x 768) that is temperature controlled by thermoelectric heaters. Although a microbolometer is capable of operating at warm temperatures, the background temperature must be well characterized in order to avoid unacceptable noise levels. Measurements have demonstrated the NEdT for this camera to be 0.5 K at a signal level of 200 K. By operating the sensor as a line array in a push broom modality, time-delay integration (TDI) can be used to improve the NEdT, which results in acceptable noise levels at colder radiometric temperatures. The applications for a large format, compact, TIR imager in Earth Science are large and varied. As the sizes of the detector arrays for low-cost microbolometers approach those of optical imagers, the spatial resolution of thermal imagery can approach that of optical imagery (as limited by diffraction). This enhances its utility for multi-spectral algorithms such as those for cloud remote sensing. Airborne tests demonstrated the sensitivity of microbolometer-based TIR for estimating cloud phase and cloud-top altitude. Examples from an airborne collection in the continental US will be presented.