Atmospheric turbulence modulation transfer function for infrared target acquisition modeling

A new direction for the US Army Night Vision and Electronic Sensors Directo rate is the development of ultra-narrow field of view (UNFOV) infrared targ et acquisition (TA) systems. Frequently, the performance of these systems i s limited by atmospheric turbulence in the imaging path. It is desirable to include the effects of atmospheric turbulence blur in infrared TA models. The current TA models are currently linear shift invariant (LSI) systems wi th component modulation transfer functions (MTFs). The use of additional MT Fs, to account for atmospheric turbulence, requires that the turbulence blu r have LSI properties. The primary unresolved issue with the treatment of t urbulence blur as an MTF is the LSI characteristics of the blur. Significan t variation in spatial blur and temporal blur prohibit the use of a single MTF in an LSI target acquisition model. Researchers at Ben-Gurion Universit y (BGU) use a TA model that includes an LSI blur, which is a temporal avera ge of the turbulence blur. The research described here evaluates the BGU-ty pe treatment of atmospheric MTF and determines it reasonable for inclusion in the US Army's TA model. In addition to the spatial characteristics, the temporal variation of the turbulence blur is also described. (C) 2001 Socie ty of Photo-Optical Instrumentation Engineers.