Lidar Monitoring of Moisture in Biological Objects

We performed for the first time experiments on laser remote sensing of the moisture content of biological objects essential for the agricultural industry. Probing was carried out using a fluorescence lidar based on a pulsed solid-state laser (527 nm, 5 ns, 1 kHz, 200 μJ/pulse), developed at the Prokhorov General Physics Institute, Russian Academy of Sciences, and a gated intensified charge coupled device camera. The spectra of laser fluorescence of various biological objects of plant origin were recorded at different humidity values. The loss of water was accompanied by the degradation of biological pigments, causing an uneven increase in the intensity of bands in the fluorescence spectrum for different spectral ranges. The ratio of the spectral bands of chlorophyll a (680 nm) and protochlorophyllide (630 nm) has the best correlation with residual moisture, which opens up a promising direction for lidar measurement and monitoring of moisture/dry matter in silage or perennial grasses.