optris PI 160, Operator'S Manual

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Emissivity
7 Emissivity
7.1 Definition
The intensity of infrared radiation, which is emitted by each body, depends on the temperature as well as
on the radiation features of the surface material of the measuring object. The emissivity (ε – Epsilon) is
used as a material constant factor to describe the ability of the body to emit infrared energy. It can range
between 0 and 100 %. A “blackbody” is the ideal radiation source with an emissivity of 1.0 whereas a
mirror shows an emissivity of 0.1.
Figure 32: Capability of an object to emit radiation
I Passed radiation
ε
Reflection
ρ
Transmission
τ
Emissivity=Absorption
ε + ρ+ τ = 1