Instrumental development of NanoCarb, a new spectro-imaging sensor

Estimating emissions of the main greenhouse gases (such as CO2 and CH4) is a challenge in studying climate change. The European project called SCARBO, which involves several partners, aims at evaluating the feasibility of a low-cost constellation of small satellites onboarding small instruments, which could be capable of quantifying greenhouse gases. In this context, we propose NanoCarb, a miniature snapshot Fourier-transform imaging spectrometer concept dedicated to the measurement of two greenhouse gases: CO2 and CH4. Its compact design makes it a good candidate for small satellites. It is based on a multi-channel architecture which provides a sparse interferometric sampling strategy. This multi-channel design only involves two specific optical components: a microlens array and an interferometric plate, which is a stepcase phase plate. We have developed and assembled two NanoCarb prototypes which have been experimentally validated through a dedicated airborne campaign. This paper focuses on the design and laboratory calibrations of the two prototypes. The tests include both imaging and spectral features of the instruments. An adequate laboratory calibration is essential to process the data acquired by the prototypes during the airborne campaign. Experimental results show the good quality of the prototypes.