Title
Investigation of optical turbulence from an unmanned aerial system
Author
Sucher, E.
Sprung, D.
Kremer, M.
Kociok, T.
Van Eijk, A.M.J.
Stein, K.
Contributor
Gladysz, S. (editor)
Stein, K.U. (editor)
Publication year
2018
Abstract
Wave propagation of electro-optical systems, lasers or imaging depends on the state of the atmosphere their beams are passing through. Fluctuations in the refractive index of air are responsible for signal attenuation and image degradation. This atmospheric effect is called optical turbulence and its strength is quantified by the structure function parameter of the refractive index Cn 2. In the atmospheric surface layer it is highly variable. Usually Cn 2 decreases with height. In non-uniform terrain, big horizontal variations can arise. We developed a mobile airborne system for monitoring Cn 2 to investigate the three-dimensional character of optical turbulence. Therefore the dodecacopter system HORUS ) was chosen as mobile platform. An ultrasonic anemometer was mounted on a boom for high-resolution measurements of temperature and wind speed. Analyzing the time series of temperature, Cn 2 values were derived from time averages of several minutes. The measurements took place in the surface layer over land in the vicinity of an 80 m high tower, equipped with ultrasonic anemometers at four discrete heights. Comparison measurements were performed. The minimum length of the boom outside the turbulent influence of the rotors was investigated. The comparison of the Cn 2 values shows a good agreement. A second, smaller quadrocopter system in combination with a new very small and light-weight ultrasonic anemometer was also tested for turbulence measurements. The system is introduced and the applicability shown. Results from first field trials are presented and discussed. © 2018 SPIE.
Subject
heterogeneous landscape
mobile platforms
optical turbulence
surface layer
ultrasonic anemometer
Adaptive systems
Anemometers
Antennas
Atmospheric structure
Atmospheric thermodynamics
Drilling platforms
Mobile phones
Refractive index
Remote control
Turbulence
Ultrasonic testing
Wind
Heterogeneous landscapes
Mobile platform
Optical turbulence
Surface layers
Ultrasonic anemometer
Light propagation
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http://resolver.tudelft.nl/uuid:72f3e6ed-7571-4a1a-9d31-509a1eb07e98
TNO identifier
844215
Publisher
SPIE
ISBN
9781510621572
ISSN
0277-786X
Source
Proceedings of SPIE - The International Society for Optical Engineering, 10787
Article number
1078706
Bibliographical note
The Society of Photo-Optical Instrumentation Engineers
Document type
conference paper