Calibration campaign of SPEXone Second Generation: early results and instrument performance

SPEXone is a compact multi-angle spectropolarimeter that measures both spectral intensity and the state of linear polarization of light scattered by aerosols in the Earth’s atmosphere at five different viewing angles simultaneously. This enables a very accurate quantification and characterization of atmospheric aerosols, helping us to better understand their effects on global climate and air quality. Building upon the success of its predecessor SPEXone, which has been launched in 2024 as part of the NASA PACE observatory, a second and improved instrument, SPEXone Second Generation, has been built within the ESA PRODEX program. Most recently, the integrated instrument underwent full on-ground characterization and calibration in ambient conditions at SRON. This contribution gives an overview of the measurements and presents preliminary results from the characterization and calibration campaign, focusing on the instrument performance. A few key performance aspects such as straylight, spatial and spectral resolution are discussed, with data from SPEXone for PACE serving as a comparison. The result of the analysis shows excellent image quality and indicates an improvement in the amount of diffuse straylight.