Applications Guide
Modline 5
135
away from the surface.
Since targets that are less reflective have higher Emissivity, the rough surface and the cavity, illustrated
in
, represent increasingly higher emissivity values—even though they are made from the
same material as the polished surface.
It is best to measure targets with high emissivity values. High reflectance off or transmittance through
the target introduces the possibility of measurement error due to background interference. Avoid
reflections when measuring targets with Emissivity less than about 0.8.
Figure 81: Surface Finish affects Emissivity
Highly Reflective
Low Emissivity:
Highly Reflective
Good Emissivity:
Very poor Reflector
Approaching blackbody condition
Best Emissivity:
1. Polished surface of material
A
2. Rough surface of material A
3. Cavity surface of material
A
