Compact Infrared Camera (CIRC) for earth observation adapting athermal optics

We have developed the compact infrared camera (CIRC) with an uncooled infrared array detector (microbolometer) for space application. The main mission of the CIRC is the technology demonstration of the wildfire detection using a large format (640x480) microbolometer. Wildfires are major and chronic disasters affecting numerous countries, especially in the Asia-Pacific region, and may get worse with global warming and climate change. Microbolometers have an advantage of not requiring cooling systems such an a mechanical cooler, and is suitable for resource-limited sensor systems or small satellites. Main characteristic of the CIRC is also an athermal optics. The thermal optics compensates the defocus due to the temperature change by using Germanium and Chalcogenide glass which have different coefficient of thermal expansion and temperature dependence of refractive index. The CIRC achieves a small size, light weight, and low electrical power by employing the athermal optics and a shutter-less system. Two CIRCs will be carried as a technology demonstration payload of ALOS-2 and JEM-CALET, which will be launched in JFY 2013 and 2014, respectively. We have finished the ground calibration test of the CIRC Proto Flight Model (PFM). Athermal optical performance of the CIRC have been confirmed by measuring modulation transfer function (MTF) in a vacuum environment and at environmental temperature from -15 to 50 degrees C. As a result, MTF was found to be effective at capturing clear images across the entire range of operating temperatures. We also provide an overview of the CIRC and radiometric test results in this presentation.