Remote fluorescence measurements of vegetation spectrally resolved and by multi-colour fluorescence imaging

A remote sensing system for combined fluorescence spectral recordings and multi-colour fluorescence imaging of vegetation will be presented. The system configuration will be explained and data from several field campaigns will be shown. The excitation light pulses for remote fluorescence detection are produced by a frequency tripled Nd:YAG laser emitting at 355 nm and shifted to 397 nm in a deuterium containing Raman cell. The receiving optics includes a Newtonian telescope and is shared by an optical fibre bundle connected to an OMA system and by a secondary Cassegrainian split-mirror telescope for fluorescence imaging at four wavelength bands simultaneously. The multi colour fluorescence images are computer processed to form images of a ratio at two wavelengths or if necessary a more complex mathematical function including the four wavelength bands is used. Examples of remote multi-colour imaging of vegetation from the past field campaigns will be given. Remote fluorescence spectra from several plant species were recorded at an excitation wavelength of 397 nm. Furthermore, the system was found capable of producing high-quality single-shot spectra at a range of 125 m. Lastly, a recently developed push-broom scanning technique for fluorescence imaging will be discussed and some preliminary data will be shown