Exploring laser-induced fluorescence: An experimental approach towards the remote application of laser-induced fluorescence in vegetation monitoring

By Annemieke Verhoek

Abstract
Vegetation fluorescence is nowadays widely used for phenotyping vegetation and detecting biotic of abiotic stress. Vegetation fluorescence induced by sunlight is emerging as an approach for early stress detection in the remote sensing domain. However, laser induced fluorescence (LIF) of vegetation in remote sensing is underexplored. This study takes an experimental approach in exploring the remote applicability of LIF sensing of vegetation. Based on a literature review, a low-cost set-up and various experiments were designed to explore the chlorophyll fluorescence signal of vegetation. Here, fluorescence signals were obtained from different species, at different distances and power density, and from vegetation subjected to water stress. Using the designed set-up, results show that the chlorophyll ratio derived from the maximum fluorescence signal is comparable to the ratio derived from the steady state fluorescence. Next to that, the set-up showed the ability to derive information about photosynthesis activity and efficiency. Furthermore, drought stress was detected while relative greenness showed no significant change. Lastly, the effect of distance and power density on measuring the fluorescence signal were assessed. While more research is needed to evaluate the applicability of the LIF set-up in real-word scenarios and validate its results, this study took the first steps and showed the possibility of using a cost-efficient set-up for remote LIF applications.