11 November 2004 Geometrical image distortion and aberration for long-range targets in a non-homogeneous atmosphere
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Abstract
When images are made of distant targets over long atmospheric paths, local variations of the refractive index of the air may lead to severe optical distortions and aberrations. An extreme example of such variations is the stream of hot exhaust gases on ships. The performance of infrared and optical sensors, mounted on elevated platforms on board, is strongly reduced when targets are observed through this highly inhomogeneous medium. By means of a high precision ray-tracing model, the effects are quantitatively predicted and compared with measured data. In another application the model is used to predict distortions such as caused by atmospheric layers of variable wind speed, pressure and temperature. In this kind of atmospheric conditions, aircrafts tend to make irregular motions, which can be dangerous in landing operations. The distortions provide information on the presence of this kind of dangerous conditions: the magnitude and the location of the so-called "air pockets". The installation of a suitable distortion measurement system together with an advanced meteorological station (including LIDAR) provides great opportunities to act as a warning device in the neighbourhood of airports. Sample calculations are presented as illustration of the prediction method.
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Arie N. de Jong, Arie N. de Jong, } "Geometrical image distortion and aberration for long-range targets in a non-homogeneous atmosphere", Proc. SPIE 5572, Optics in Atmospheric Propagation and Adaptive Systems VII, (11 November 2004); doi: 10.1117/12.565690; https://doi.org/10.1117/12.565690
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