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Proceedings Paper

Laser beam propagation through a full scale aircraft turboprop engine exhaust
Author(s): Markus Henriksson; Ove Gustafsson; Lars Sjöqvist; Dirk Seiffer; Norbert Wendelstein
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Paper Abstract

The exhaust from engines introduces zones of extreme turbulence levels in local environments around aircraft. This may disturb the performance of aircraft mounted optical and laser systems. The turbulence distortion will be especially devastating for optical missile warning and laser based DIRCM systems used to protect manoeuvring aircraft against missile attacks, situations where the optical propagation path may come close to the engine exhaust. To study the extent of the turbulence zones caused by the engine exhaust and the strength of the effects on optical propagation through these zones a joint trial between Germany, the Netherlands, Sweden and the United Kingdom was performed using a medium sized military turboprop transport aircraft tethered to the ground at an airfield. This follows on earlier trials performed on a down-scaled jet-engine test rig. Laser beams were propagated along the axis of the aircraft at different distances relative to the engine exhaust and the spatial beam profiles and intensity scintillations were recorded with cameras and photodiodes. A second laser beam path was directed from underneath the loading ramp diagonally past one of the engines. The laser wavelengths used were 1.5 and 3.6 μm. In addition to spatial beam profile distortions temporal effects were investigated. Measurements were performed at different propeller speeds and at different distances from exhaust nozzle to the laser path. Significant increases in laser beam wander and long term beam radius were observed with the engine running. Corresponding increases were also registered in the scintillation index and the temporal fluctuations of the instantaneous power collected by the detector.

Paper Details

Date Published: 12 October 2010
PDF: 9 pages
Proc. SPIE 7836, Technologies for Optical Countermeasures VII, 78360L (12 October 2010); doi: 10.1117/12.864679
Show Author Affiliations
Markus Henriksson, Swedish Defence Research Agency (Sweden)
Ove Gustafsson, Swedish Defence Research Agency (Sweden)
Lars Sjöqvist, Swedish Defence Research Agency (Sweden)
Dirk Seiffer, Fraunhofer-Institut für Optronik, Systemtechnik und Bildauswertung (Germany)
Norbert Wendelstein, Fraunhofer-Institut für Optronik, Systemtechnik und Bildauswertung (Germany)


Published in SPIE Proceedings Vol. 7836:
Technologies for Optical Countermeasures VII
David H. Titterton; Mark A. Richardson, Editor(s)

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