Abstract
A unique analytical description of atmospheric vision in the wavelength range from 0.35 μm to 14 μm is presented. The signal-to-noise ratio corresponding to the apparent radiance difference at the observation site is used as the basic physically limiting magnitude. It establishes a general vision formula, Eq. (18). This shows that the contrast, C = (L1 − L2)/(L1 + L2), contrast degradation, and a contrast threshold Cmin = 1/τ ΔQT can be used for the description of photon-noise limited imaging devices, including the influence of path radiance. Koschmieder’s theory of atmospheric vision follows as a special case, using a constant contrast threshold for the human eye. Thermal vision in the atmosphere is discussed, together with the relevant magnitudes for the description of photon-noise limited and detector-noise limited imaging devices that are to be described by the apparent radiance difference only. Finally the problem of defining a characteristic length comparable to the meteorological range VN is considered, and a wavelength-dependent meteorological range Vλ together with a standard maximum range for a special device VS is proposed.
© 1975 Optical Society of America
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