Turbulence effects in a horizontal propagation path close to ground: implications for optics detection

Lars Sjöqvist; Lars Allard; Ove Gustafsson; Markus Henriksson; Magnus Pettersson

doi:10.1117/12.898171

6 October 2011 Turbulence effects in a horizontal propagation path close to ground: implications for optics detection

Lars Sjöqvist, Lars Allard, Ove Gustafsson, Markus Henriksson, Magnus Pettersson

Proceedings Volume 8187, Technologies for Optical Countermeasures VIII; 81870M (2011) https://doi.org/10.1117/12.898171
Event: SPIE Security + Defence, 2011, Prague, Czech Republic

Abstract

Atmospheric turbulence effects close to ground may affect the performance of laser based systems severely. The variations in the refractive index along the propagation path cause effects such as beam wander, intensity fluctuations (scintillations) and beam broadening. Typical geometries of interest for optics detection include nearly horizontal propagation paths close to the ground and up to kilometre distance to the target. The scintillations and beam wander affect the performance in terms of detection probability and false alarm rate. Of interest is to study the influence of turbulence in optics detection applications. In a field trial atmospheric turbulence effects along a 1 kilometre horizontal propagation path were studied using a diode laser with a rectangular beam profile operating at 0.8 micrometer wavelength. Single-path beam characteristics were registered and analysed using photodetectors arranged in horizontal and vertical directions. The turbulence strength along the path was determined using a scintillometer and single-point ultrasonic anemometers. Strong scintillation effects were observed as a function of the turbulence strength and amplitude characteristics were fitted to model distributions. In addition to the single-path analysis double-path measurements were carried out on different targets. Experimental results are compared with existing theoretical turbulence laser beam propagation models. The results show that influence from scintillations needs to be considered when predicting performance in optics detection applications.

Citation Download Citation

Lars Sjöqvist, Lars Allard, Ove Gustafsson, Markus Henriksson, and Magnus Pettersson "Turbulence effects in a horizontal propagation path close to ground: implications for optics detection", Proc. SPIE 8187, Technologies for Optical Countermeasures VIII, 81870M (6 October 2011); https://doi.org/10.1117/12.898171

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