 These optical properties are described by the absorption coefficient μa, scattering coefficient μs, and anisotropy factor g.

In the collimated transmission method, a laser beam is directed perpendicularly to the material and the detection of reemitted light gives information about the total interactive effect of the optical properties of the material.The use of multiple wavelengths can produce a spectra with more detailed information about the composition of the tissue or material (spectroscopy).While this method is simple and requires only minimal instrumentation, it produces error related to multiple scattering events and specular reflection.