RedEye-1: A New Short-Wavelength Infrared Hyperspectral Imager for Atmospheric Observation

Abstract

Efficient monitoring of atmospheric constituents, particularly methane (CH4) and carbon dioxide (CO2), is paramount for addressing global warming and its climate change repercussions. Hyperspectral imaging in atmospheric measurement is dominated by large-scale, high-resolution systems and their smaller, lower-resolution counterparts. However, developing such systems, especially in the short-wavelength infrared (SWIR), often incurs substantial costs due to specialized optics and detectors. To mitigate these challenges, RedEye-1, a compact and cost-effective SWIR hyperspectral imager, was developed. Operating within the 1588-1673 nm spectral range with a resolution of about 0.5 nm, RedEye-1 fills the gap between existing paradigms. With a Ground Sampling Distance (GSD) of approximately 2.4 meters from an altitude of 3 kilometers, it proves to be a suitable tool for quantifying CH4 and CO2 within Earth's atmosphere. The development stages of RedEye-1 included design, construction, assembly, spectral and radiometric calibration, and both ground and airborne tests. During its initial airborne reconnaissance mission on a light aircraft, RedEye-1 successfully operated and provided invaluable insights into airborne operations' challenges. Utilizing an inversion model and a Line-by-Line radiative transfer algorithm, groundbased single path measurement near 1645 nm estimated the CH4 concentration to be around 1912 ppb, indicating a reduction of approximately 5 ppb compared to the standard atmospheric CH4 level. Conversely, airborne double-path measurement at the same wavelength revealed a higher concentration of approximately 5229 ppb, signifying substantial CH4 emissions from the coal mine it flew over.