Light that falls on a surface can either be absorbed, transmitted or reflected, depending on the properties of the material involved. Reflection factors (r), absorption factors (a) and transmission factors (t) can be between 0 and 1 (0 -100%). The sum of the three factor is always 1. The transmitted or reflected radiation can be regular (1), scattered (2) or completely diffuse (3).

Absorption factor α

The absorption factor is the ratio of absorbed light to incident light. A matt black solid absorbs almost all incident light, while a white solid absorbs very little. Here are some typical absorption factors: