Various thermophysical variables are described on the following pages. The facilities and options available to measure thermophysical material properties within the working group can be downloaded as tables in pdf format.
In order to describe the radiative exchange between surfaces as well as the radiative transfer within materials, one needs to know the infrared-optical material and sample properties.
The measurands are reflectance, transmittance and emittance. Emittance, for example, is defined as the quotient of the intensity radiated from a surface and the intensity radiated from a black body radiator at the same temperature:
Further sample or material-specific properties which express the degradation of radiation within materials can be determined using these spectral variables (such as absorption and scattering coefficients, or extinction coefficient and albedo). Moreover, one can also determine the complex refractive index with the aid of suitable algorithms.
The properties can be recorded as a function of different parameters, such as the angle of radiation, or temperature, etc.. Radiance comparisons and thermal imaging are further options.