Emissivity
A thermal camera does not measure temperature. It measures infrared radiation and converts it using an emissivity you choose. Get that wrong and the process window is wrong too.
Thank you for reading this post, don't forget to subscribe!Emissivity is a surface’s ability to emit infrared radiation compared with an ideal black body. It is not a constant: it changes with temperature, viewing angle, surface condition and, for UD tapes, fibre direction. That is why two cameras, or two settings, can disagree by tens of degrees on the same process.
What emissivity depends on
- Temperature: molecular behaviour at the surface changes as it heats
- Viewing angle: emission drops at grazing angles
- Surface condition: matrix-rich, fibre-rich, rough or molten
- Fibre direction: anisotropic emission in UD tapes
- Reflections: hot surroundings reflected into the camera
One frame, two answers
The same thermal recording, read with two emissivity settings:
How OTOM restores confidence
Radiometric correction
The IR Cam module in AFP Web reads raw camera data and re-applies whole-image or per-probe emissivity and reflected temperature through Planck’s law, so you can correct a recording after it was made.
Physics as a second witness
The optical-thermal model predicts the temperature from laser power, geometry and tape properties, independently of the camera. Where model and camera agree you can trust both; where they differ, the emissivity is the first suspect.
Probes in the right place
Adaptive nip-point tracking keeps the probe on the bond line rather than the tape or substrate, removing a second source of error.
Calibrated per tape
Emissivity is set from your UD tape’s characteristics and checked against the model, not copied from a generic table.
Not sure your camera is telling the truth?
Send us a recording. We will correct it radiometrically and compare it with the simulated temperature.