Push-broom scanning system for remote fluorescence monitoring of vegetation

摘要

A system for remote detection of vegetation fluorescence has been constructed. The light source was a frequency tripled Nd:YAG-laser in connection with a D(sub 2)-Raman cell. The wavelength used was 397 nm. For the collection of fluorescence light a 40 cm Newtonian telescope together with a combination of Fresnel lenses was utilized. The detector was an image-intensified CCD. During measurement a streak of laser light was directed onto the object. By a scanning procedure a complete image could be formed. Two different measuring modes were examined. First, a single scanning method recording only in one wavelength band and secondly, a double scanning method capable of simultaneous recording in two different wavelength intervals was investigated. The push-broom experiments were also combined with a series of point measurements, determining the spectral fluorescence behaviour of the plant specimen being used. The light source in this case was an N(sub 2)-laser in combination with a dye-laser emitting light at 400 nm. The excitation light was directed onto the sample and the fluorescence light collected with the same optical fibre. For the detection an OMA-system based on an image-intensified CCD was utilized. The results of the study is that a system of this kind might provide a powerful tool for airborne detection and monitoring of early damage on vegetation. 44 refs, 63 figs