A miniature scanning radiometer for vertical profiles

Abstract:

I have developed a miniature radiometer for use on balloons, small unmanned vehicles, or other lightweight platforms. It performs a subset of the AERONET measurements in a 360-gram package about 12x10x10 cm. A small telescope with a narrow field of view continuously scans the sky at the elevation angle of the sun, nominally one revolution every 30 seconds. Measurements are made through four 10 nm wide filters in the visible and near infrared. The radiometer has the dynamic range and signal to noise to measure both the sun and sky radiance in the same scans. An onboard processor can compensate for a tilting platform in real time as the telescope rotates. With enough altitude range the radiometer can be calibrated from the top of the profile. Preliminary data show a sensitivity of about 0.02 or better in optical depth.