Atmospheric scintillation effects on point targets and small targets are studied in the middle-wave infrared ͑MWIR͒ 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

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... 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 falsealarm probabilities over long horizontal paths in the MWIR.