Atmospheric turbulence effects on 3 ^rd generation FLIR performance

Previous analysis of ground-to-ground 3rd Generation FLIR performance (Driggers. et al ¹) showed two main performance characteristics of the 3 ^rd Gen sensor's MWIR and LWIR bands: first, that no major differences in detection range were observed between the two bands, and second, that a significant 1D range advantage for the MWIR band over the LWIR band resulted from the smaller diffraction spot of the shorter wavelength MWIR. That analysis predicted performance for a variety of atmospheric transmiltances but only al a single, relatively low value of atmospheric turbulence. In this paper, analysis of the effect of varying turbulence shows that increased turbulence decreases the 1D range performance of the MWIR relative to the LWIR, and that at high turbulence values the two bands have roughly equivalent performance. Further, the LWIR band actually surpasses the 1D range performance of MWIR at high turbulence for some systems. Frequency of occurrence data collected in multiple environments shows a predominance of moderate to high turbulence conditions in the real world. The superior 1D range performance of the MWIR is thus achievable only under limited real-world conditions, and the LWIR can surpass the performance of the MWIR in significant scenarios (desert, day). For maximum performance under a variety of conditions the dual band capability of 3rd Gen FLIR systems is thus required.