Spatial-frequency dependence of scattered background light: The atmospheric modulation transfer function resulting from aerosols

Experimental evidence is reported that shows the existence of a spatial-frequency dependence of particulate-scattered background light. A theoretical model, including wavelength dependence, is developed and compared with experimental measurements. These results indicate that the spatial-frequency dependence of background radiation can seriously limit resolution. The background term is used to refine Lutomirski’s expression [ Appl. Opt.17, 3915 ( 1978)] to obtain an overall aerosol modulation transfer function (MTF). The MTF for atmospheric aerosols is also useful in describing underwater image-resolution limitations imposed by water particulates, such as dust particles or biological media.