Understanding Infrared Thermography Reading 7 Part 2 of 2.pdf

Figure A-8 shows that the instrument sees three components of energy: first,
emitted energy (ε); second, reflected energy from the environment (ρ); and
third, energy transmitted through the target from sources behind the target (τ).
The percentage sum of these components is always unity (1). The instrument
sees only ε, the emitted energy, when aimed at a blackbody target because a
blackbody reflects and transmits nothing. For a gray body, the instrument
sees ε and ρ, the emitted and reflected energy. The instrument sees all three
components when aimed at a nongray body because a non-gray body is
partially transparent.
Keywords:
because a non-gray body is partially transparent.(?)
Charlie Chong/ Fion Zhang