The Validity of Obtaining the Total Attenuation Coefficient by Adding the Coefficients of Absorption and Scattering.

Abstract : Though the notion is firmly established that alpha, the total attenuation coefficient, consisting of the absorption coefficient, a, plus the scattering coefficient, s, should be used in the exponential attenuation law I=(I sub zero)(e to the minus alpha x power) for light transmission, the practice is shown to be incorrect. Evidence is presented that not only can alpha not be used properly in the exponential attenuation law as is customary but no attenuation law is possible in which alpha = (a + s) can be used correctly, at least for shallow angle scattering and, although not shown, probably not for any kind of scattering. (Author)