Mr. Hans Günter Dahn Profile

Hans Günter Dahn

Lead Scientist

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Publications (4)

Proceedings Article | 2 July 1997 Paper

Laser-induced leaf fluorescence: a tool for vegetation status and stress monitoring and optical-aided agriculture

Wilhelm Luedeker, Kurt Guenther, Hans-Guenter Dahn

Proceedings Volume 3059, (1997) https://doi.org/10.1117/12.277619

KEYWORDS: Luminescence, Vegetation, Ultraviolet radiation, Remote sensing, LIDAR, Picosecond phenomena, Laser induced fluorescence, Agriculture, Sun, Photosynthesis

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Since the second half of the 1980s several efforts started to establish the laser induced vegetation fluorescence as remote sensing tool to detect the growth and/or stress status of plants. The most extended European project, the EUREKA project LASFLEUR (1989 - 1994), demonstrated the technical feasibility and the significance of the sensed data. Exciting leaves with strong light pulses anywhere in the UV-A region of the electromagnetic spectrum stimulates a broad fluorescence emission from 400 to 750 nm. This emission is separated in two main components, the 'blue-green' (400 - 600 nm) and the red fluorescence region (680 - 750 nm). The blue-green band is originated by polyphenolic compounds of the cell walls, NADPH of the photosynthetic apparatus and possibly by several other plant pigments, except chlorophyll, which is the only emitter of the fluorescence at two bands in the red and in the NIR respectively. On the basis of the photon flux in these channels and with additional information, derived from e.g. the elastic back scattered signal, the time duration of back scatter and fluorescence signal, environmental light conditions, etc. a large set of vegetation parameters could be determined. During several demonstration campaigns status parameters as e.g. the chlorophyll concentration, photosynthetical activity and canopy structure were investigated. Additionally stress conditions as e.g. drought-, UV-stress and infection with different kinds of fungi were examined as well as the differentiation of plant types as e.g. mono-and dicotyledons. Extrapolating the knowledge of the EUREKA project leads to two different main applications. First with an advanced airborne remote sensing system monitoring of the vegetation status and stress conditions may be possible independently of other remote sensing techniques or the data may be used as input parameter for e.g. passive radiometer images. The second application will be a miniaturized sensor for agricultural machines giving direct access to plant parameter and hence the possibility for individual plant treatment as e.g. determining the growth state, fertilization or weed protection.

Proceedings Article | 9 October 1995 Paper

Detection and mapping of oil-contaminated soils by remote sensing of laser-induced fluorescence

Wilhelm Luedeker, Kurt Guenther, Hans-Guenter Dahn

Proceedings Volume 2504, (1995) https://doi.org/10.1117/12.224129

KEYWORDS: Luminescence, Contamination, Vegetation, Signal detection, LIDAR, Laser induced fluorescence, Soil contamination, Remote sensing, Distance measurement, Spatial resolution

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SPIE Journal Paper | 1 August 1992

Multiple-scattering lidar experiments

Christian Werner, Juergen Streicher, H. Herrmann, Hans-Guenter Dahn

OE, Vol. 31, Issue 08, (August 1992) https://doi.org/10.1117/12.10.1117/12.58707

KEYWORDS: LIDAR, Multiple scattering, Clouds, Fiber optic gyroscopes, Receivers, Scattering, Visibility, Visibility through fog, Laser scattering, Backscatter

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Proceedings Article | 1 September 1990 Paper

Lidar measurements of multiple scattering in dispersing plumes

Christian Werner, Juergen Streicher, Hans-Guenter Dahn

Proceedings Volume 1312, (1990) https://doi.org/10.1117/12.21881

KEYWORDS: LIDAR, Multiple scattering, Scattering, Clouds, Fiber optic gyroscopes, Polarization, Scatter measurement, Receivers, Laser scattering, Backscatter

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