High Spectral Resolution Imager for Solar Induced Fluorescence Observation

The use of high-resolution imagers for determination of solar-induced fluorescence of natural bodies by observing the infilling
of Fraunhofer lines has been frequently adopted as a tool for vegetation characterization. The option to perform
those measurements from airborne platforms was addressed in the past. In-field observations gave evidence of the main
requirements for an imaging spectrometer to be used for Sun-induced fluorescence measurements such as high spectral
resolution and fine radiometric accuracy needed to resolve the shape of observed Fraunhofer lines with a high level of
accuracy. In this paper, some solutions for the design of a high spectral resolution push-broom imaging spectrometer for
Sun-induced fluorescence measurements are analysed. The main constraints for the optical design are a spectral
resolution better than 0.01 nm and a wide field of view. Due to the fine instrumental spectral resolution, bidimensional
focal plane arrays characterized by high quantum efficiency, low read-out noise, and high sensitivity are requested. The
development of a lightweight instrument is a benefit for aerospace implementations of this technology. First results
coming from laboratory measurements and optical simulations are presented and discussed taking into account their
feasibility.