When light strikes a surface, part of it is reflected and some of it is absorbed (see absorption). The remaining wavelengths transmit through the medium until they exit. The degree of transmission is a measure of the proportion of rays that penetrate a sample. Transmission, therefore, is a measure of a sample’s permeability to electromagnetic waves, such as different types of light. For example, if only half as much light exits a sample as enters, the transmission value is 50%. Possible reasons for this include cloudiness in the sample or a high fat content (e.g., milk).
- Total Transmission (TTRAN): Refers to the total amount of light that passes through the material, including both diffuse and spectral components.
- Diffuse Transmission: Describes the light that passes through the material and is scattered in various directions, rather than traveling in a single, straight beam.