Causes of atmospheric blur: comment on Atmospheric scattering effect on spatial resolution of imaging systems

A paper by Ben Dor et al. [J. Opt. Sec. Am. A 14, 1329 (1997)] concludes th at the blur we measured in our experiments was not atmospherically scattere d light and that our theoretical model is incorrect because it violates the rules of linearity. Their work is based in part on "lack of raw data" in o ne of our experimental papers [J. Opt. Sec. Am A 12, 970 (1995)]. We presen t here the raw data measured in the experiments in question, which show cle arly the measured atmospherically scattered light. Similar raw data has als o been published elsewhere regarding other experiments. We also clarify som e rules of linear systems that justify our conceptual approach, which is sh own to be similar to that of turbulence modulation transfer function. A rev iew of several dozen experiments and analyses by other investigators all ov er the world that directly contradict the Ben Dor ct al. results and conclu sions is presented. The well-known significance of aerosol blur in imaging through the atmosphere from satellites is discussed, and pictorial examples of satellite imagery are shown for different atmospheric optical depths. I t is noted that atmospheric point-spread-function analyses in the remote-se nsing literature generally neglect turbulence blur altogether and deal with aerosol blur only, which is often called the adjacency effect, and that su ch phenomena are well supported by many different types of experiments and many different Monte Carlo simulations for many different aerosol and instr umentation parameter situations. The Monte Carlo simulation results of Ben Dor ct al. are shown also to contradict everyday reality such as the solar aureole. This wealth of literature by others strongly contradicts the resul ts of Ben Dor et al. and confirms our conclusion that forward scatter of li ght by aerosols is indeed a significant source of blur in imaging through t he atmosphere, especially if atmospheric optical depth is on the order of u nity or more. This can be confirmed, too, by any observer looking through b inoculars at the moon and surrounding moonlight even on a clear night. A br oad system engineering approach involving both aerosol and turbulence blur is called for. (C) 1998 Optical Society of America [S0740-3232(98)00912-0].