Infrared image scintillation:: comparison of modeling and measurement -: art. no. 016001

Atmospheric scintillation effects on point targets and small targets are studied in the middle-wave infrared (MWIR) band over a 2.5-km horizontal path. Expressions are presented for both exact numerical calculations and for a Gaussian-aperture approximation of scintillation that has an accurate analytic solution. Experimental results show that measurements of C-n(2) using a commercial NIR scintillometer allow the prediction of average scintillation levels in the MWIR when corrections are made for wavelength and dimensions of the source and receiver. The measured log-irradiance values are approximately lognormal, and are about a factor of 2 higher than would have been expected from theory. Our results are relevant for analysis of detection and false-alarm probabilities over long horizontal paths in the MWIR. (c) 2006 Society of Photo-Optical Instrumentation Engineers.