SPATIAL-FREQUENCY DEPENDENCE OF SCATTERED BACKGROUND LIGHT: THE ATMOSPHERIC MODULATION TRANSFER FUNCTION RESULTING FROM AEROSOLS.

Experimental evidence is reported that reveals 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 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.