(physics) A logarithmic measure of the amount of light that is absorbed when passing through a substance; the capacity of a substance to absorb light of a given wavelength; optical density.
Absorbed radiation and incident radiation in a ratio format; a measurement that shows how well a surface absorbs radiation.
Absorbance is commonly defined as . Alternatively, for samples which scatter light, absorbance may be defined as .
‘the logarithm of the ratio of incident to transmitted radiant power through a sample (excluding the effects on cell walls)’; ‘the negative logarithm of one minus absorptance, as measured on a uniform sample’;
a measure of the rate of decrease in the intensity of electromagnetic radiation (as light) as it passes through a given substance; the fraction of incident radiant energy absorbed per unit mass or thickness of an absorber;
‘absorptance equals 1 minus transmittance’;
Absorptance of the surface of a material is its effectiveness in absorbing radiant energy. It is the ratio of the absorbed to the incident radiant power.