We know that when any object is above absolute zero (-273.15 degree ), its surface will emit infrared energy, that is, infrared radiation. The higher the temperature, the stronger the emitted infrared energy! Infrared thermometers and infrared thermal imagers measure the temperature of an object's surface based on this characteristic. Since we know that infrared thermometers and infrared thermal imagers measure the temperature of the object's surface, they are inevitably affected by the smoothness of the object's surface. Experiments have shown that the closer the object's surface is to a mirror (with stronger reflection), the more severe the infrared energy attenuation emitted by its surface. Therefore, we need to compensate for the attenuation of infrared energy on different object surfaces, that is, set a compensation coefficient, which is the emissivity!

+ρ+τ=1
In the formula: - absorption rate; ρ - reflectivity; τ - transmittance.

=ε

For an opaque surface with τ=0, then ε=1- ρ, it can be seen that opaque surfaces with high reflectivity have low infrared emissivity. That is to say, the higher the reflectivity and absorption of an opaque surface, the lower the emissivity. The higher the reflectivity, the smaller the heat loss. This is also related to the position of the reflective screen and heat source.