Fraunhofer IKTS packaging scanner catches seal defects as small as 8 micrometers in real time

Fraunhofer IKTS has integrated optical coherence tomography (OCT) directly into a packaging machine's sealing process, giving manufacturers a way to catch microscopic seal defects without stopping the line. The system, developed under the publicly funded OCTInline project, tests the quality of every seal in real time as film moves through production at rates up to 25 meters per minute.

OCT sends near-infrared light into the material and reads the reflected signal to build three-dimensional images of the internal structure, without contacting or damaging the packaging. "We can detect and visualize various pores in the seal down to a size of eight micrometers," says Ralf Schallert, Characterization Technologies Group Manager at Fraunhofer IKTS. The technique was originally developed for ophthalmology, according to Conner Phillips, a research scientist in the Characterization Technologies Group at Fraunhofer IKTS, but it adapts to imaging subsurface structure across a wide variety of materials.

Engineers running high-speed sealing lines will care about the trade-off the team had to solve. Higher resolution means more data to collect and process, and even slight vibration in the moving film throws off the measurement. "We had to achieve a balance between depth of field, exposure time and film movement," Phillips says.

The timing tracks a shift in packaging materials. Recyclable mono-material films are replacing multilayer composites for sustainability reasons, but Schallert says they are "more prone to seal defects," which raises the stakes for continuous monitoring. Beyond catching bad seals, the OCT data flags when process pressure or temperature drifts out of spec, or when tooling is wearing down and needs replacement.

A demonstration system has run at project partner Kallfass Verpackungsmaschinen in Nurtingen, Germany, since July 2026, where Fraunhofer IKTS shows it to potential customers. Schallert says packaging is just one target application. The same OCT approach applies to functional coatings, ceramic components and additively manufactured parts, anywhere thin layers or internal structures need inspection without cutting into the part.