RayTek RAYCMLTJM Operating Instructions Manual page 42

To optimize surface temperature measurements, consider the following
guidelines:
Determine the object emissivity using the instrument that will also be
used for the measurements.
Avoid reflections by shielding the object from surrounding
temperature sources.
For higher temperature objects, use instruments with the shortest
wavelength possible.
For translucent materials, such as plastic foils or glass, assure that the
background is uniform and lower in temperature than the object.
You should place the sensor perpendicular to the object's surface (if
possible) or at any angle from the target up to 30°!
CM
Rev. B 06/2011
Appendix
42