Non-destructive inspecting chocolate without melting it

Non-destructive quality control can be a challenging task for complex and/or fragile structures. As a proof of concept of our technique, we developed a precise, controlled thermal inspection system which is able to determine the thin and thick spots on a chocolate figures without touching or melting it.

Surface temperature is a critical boundary condition for chocolate. A too high temperature and the figure loses its attractive gloss or worse, melts which makes it impossible to sell. But as consumer, we like to have a homogeneous distribution so we do not break our teeth.

Therefore we use active thermography with which we use a controllable and calibrated heat source to excite the inspected structure. The thermal response is monitored by a thermal camera which is sensitive in the 8-14µm range. After post-processing the data we receive a semi-static image of the full structure on which reflections and ambient radiation is subtracted. On this dataset we can perform advanced signal processing to retrieve the maximum information out of the dataset without the need to use high excitation power.

With our thermal dynamic line scan system, we are able to scan large and/or fragile structures with a controlled thermal excitation power in a synchronised way. Even with a low amount of power we are able to retrieve significant information about layer thickness and subsurface anomalies as we proofed with this example. For sure the possibilities on industrial relevant samples are almost unlimited.

Result thermal inspection, in white the thick locations and in black the thin surfaces   Setup of the measurements