Removing Sunlight Damage Patterns in Shatter-Less Bolometer Images by Utilizing Deepspace Observations

UNIFORM-1 is a small satellite that helps in the prevention of severe fire hazards by detecting the wildfire at an early stage. UNIFORM-l is equipped with an un-cooled bolometer imager (BOL), which observes temperature distributions of the earth surface. Uniquely, BOL is not equipped with any shutter mechanism to reduce the risk associated with the shutter that impacts the ability to conduct any observation in space. As a trade-off of shutter exclusion, BOL saw the Sun in its field of view (FOV) many times and the sunlight damage caused large brightness temperature error (60 K) in BOL images. To reduce the error, we have proposed a new calibration procedure utilizing deepspace observations, which enables the measurement of the increase in digital count offset due to the sunlight in a BOL image. After the correction, we successfully reduced the damage, and the relative accuracy of brightness temperature improved to more than 2 K, which is enough to detect a wildfire with a size smaller than one-pixel scale.