Laser-Induced Chlorophyll Fluorescence Spatial Variation Distribution and Model Establishment Based on Multi-Angle Spectroscopy and Polarization Spectroscopy

According to the current research status, chlorophyll fluorescence is one of the important means of plant physiology research and plant remote sensing research. Previous studies on laser-induced fluorescence (LIF) have mostly used vertical directions, and less consideration has been given to the effects of multi-angle and fluorescence polarization. In this paper, Chlorophytum, Green radish, and Phnom Penh Tiger Piran were used as research objects, and multi-angle and polarization observation methods were used to analyze the laser-induced chlorophyll fluorescence spectra, and the models were established. At the same time, the spatial distribution of laser-induced chlorophyll fluorescence intensity and degree of polarization was plotted in polar coordinates. The results show that the shapes of fluorescence spectra of the three plants were different, and the changes in the Viewing Zenith Angles and Relative Azimuth Angles affect the fluorescence intensity and fluorescence parameters. The mathematical regression models of Viewing Zenith Angles and fluorescence parameter F-685/F-740 were established at Relative Azimuth Angles. According to the comparison of R-2 and RMSE of different models, the Relative Azimuth Angle of 225 degrees is the best angle to study the relationship between F-685/F-740 and Viewing Zenith Angles for these three plants at the same time. The regression coefficient is significant, which can accurately reflect that F-685/F-740 has a significant correlation with Viewing Zenith Angles. In addition, we also performed polarization observations on the laser-induced chlorophyll fluorescence of the three plants and calculated the corresponding fluorescence polarization in the 2 pi space. The studies have shown that the laser-induced chlorophyll fluorescence spectrum has significant polarization, and the Viewing Zenith Angles, Relative Azimuth Angles, and band information have different effects on laser-induced chlorophyll fluorescence polarization spectra. The mathematical regression models were established for the relationship between the fluorescence polarization at 685 and 740 nm for different plants. The regression coefficient is significant, which could accurately reflect the significant correlation between the fluorescence polarization at 685 and 740 nm.