Comparing and contrasting different broadband MTF definitions and the relationship to range performance predictions

The monochromatic modulation transfer function (MTF) is a spectral average across wavelength weighted by the sensor’s spectral sensitivity and scaled by the spectral behavior of the source. For reflective band sensors, where there are significant variations in spectral shape of the reflected light, this spectral averaging can result in very different MTFs and, therefore, the resulting performance. In this paper, we explore the influence of this spectral averaging on performance utilizing NV-IPM v1.1 (Night Vision Integrated Performance Model). We report the errors in range performance when a system is characterized with one illumination and the performance is quoted for another. Our results summarize the accuracy of different assumptions to how a monochromatic MTF can be approximated, and how the measurement conditions under which a system was characterized should be considered when modeling performance.