Solar-induced chlorophyll fluorescence imaging spectrometer: design, manufacture, and evaluation

A scientific imaging spectrometer has been presented for the observation of solar-induced chlorophyll fluorescence of vegetation in NIR waveband, which may provide a new method to scale SIF application from leaf to canopy for the research of terrestrial vegetation photosynthesis. The SIF imaging spectrometer accommodates a telescope with a medium spatial resolution (1 mrad) over a field of view of 20°, a high spectral resolution (0.3nm) to measure the fluorescence spectrum within two oxygen absorption bands (O_2A and O_2B), and a high numerical aperture (0.25) for high SNR. Both of transmission optical systems, with high etendue and dispersive prism-VPH grating (P-G) with high diffraction efficiency, have been utilized for the optical design of imaging spectrometer. The design and prototype present excellent optical performances as demonstrated by the latest simulation and calibration. The in-situ observation proves that the advanced SIF imaging spectrometer could provide precise fluorescence data. The instrument will highlight SIF signal retrieval strategies, techniques for field and airborne and satellite sensing, and applications of these capabilities in evaluation of photosynthesis and stress effects for fluorescence science.