DETERMINATION OF THE RATIO OF ABSORPTION COEFFICIENTS AT DIFFERENT WAVELENGTHS IN A SCATTERING MEDIUM

摘要

A method of determining the ratio of the absolute absorption coefficients mu a( lambda 2) and mu a( lambda 1) of a light scattering medium at two different wavelengths comprising: a) passing light (as herein defined) through the medium; b) measuring a characteristic X of the light at two wavelengths lambda 1 and lambda 2 which is affected by the absorption coefficient during its passage through the medium; c) effecting changes DELTA mu a( lambda 1) and DELTA mu a( lambda 2) in the absorption coefficients at the two wavelengths; d) repeating step (b); e) determining the ratio of the absolute absorption coefficients mu a( lambda 1) and mu a( lambda 2) at said two wavelengths from the said changes therein DELTA mu a( lambda 1) and DELTA mu a( lambda 2) or from quantities representative thereof, from the characteristic X, and from the ratio of transport scattering coefficients of the medium mu s'( lambda 1) and mu s'( lambda 2) at the two wavelengths.