The Fraunhofer Institute for Ceramic Technologies and Systems IKTS has developed an optical coherence tomography (OCT)-based inspection system capable of detecting packaging seal defects non-destructively and in real time during the production process.
Developed under the publicly funded OCTInline project, the system integrates OCT directly into the sealing process of a packaging machine. The technology enables the continuous inspection of packaging seals at production speeds of up to 25 metres per minute, with defects as small as 8 micrometres detectable in the seal.
For industries such as medical technology and food processing, where reliable packaging integrity is critical, the system provides a non-destructive method for identifying defects without damaging either the packaging or its contents.
“Optical coherence tomography is an imaging method that uses infrared light,” explains Conner Phillips, a research scientist in the Characterization Technologies Group at Fraunhofer IKTS. “This method was originally developed for ophthalmology, but it can non-destructively generate three-dimensional images of the subsurface structure of a wide variety of materials and detect the presence of irregularities or defects.”
OCT enables real-time internal inspection
The OCT system works by directing near-infrared light into the packaging material and analysing the reflected signals. The resulting data generates high-resolution, three-dimensional images of the material's internal structure.
Through this process, defects such as material irregularities, air pockets and inadequately sealed areas can be identified without opening or otherwise damaging the packaging.
As part of the OCTInline project, Fraunhofer IKTS researchers integrated the technology into the sealing process of an industrial packaging machine. The system continuously monitors seal quality while production is underway.
“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 combination of high-resolution inspection with high production speeds presented a key technical challenge. Smaller defects require larger volumes of data to be collected and analysed, while vibrations in the moving film can also influence measurements.
“We had to achieve a balance between depth of field, exposure time and film movement,” says Phillips.
Inspection supports sustainable packaging
The development comes as manufacturers increasingly adopt recyclable mono-material films. Compared with multilayer composite materials, mono-material films offer improved recyclability but can present greater challenges in maintaining reliable seals.
“Mono-material films are very attractive from an environmental perspective, but they are unfortunately more prone to seal defects,” says Schallert. “This increases the need for continuous monitoring.”
By enabling defects to be identified during production, real-time inspection can help reduce scrap and material consumption. The OCT data can also provide information about changes in machinery and tooling conditions.
“Many defects arise because the pressure and temperature are not optimized for the material or because the tools are wearing down over time,” explains Schallert. “The OCT data enables us to visualize changes like this and to detect them at an early stage, such as when a tool change is necessary.”
Demonstration system installed at industrial partner
A demonstration system has been in operation at Kallfass Verpackungsmaschinen GmbH in Nürtingen since July 2026, where the technology is also being presented to potential customers.
The system has been designed to accommodate different materials and inspection requirements. While packaging represents one application, Fraunhofer IKTS said the technology can also be applied to other industrial quality assurance tasks.
“The packaging industry is only one of many potential areas where this technology can be used,” adds Schallert.
The technology is suitable for transparent and semitransparent materials and can be used to inspect functional coatings, ceramic components and parts produced through additive manufacturing.
“OCT can play an important role wherever thin layers, internal structures or the smallest defects have to be reliably detected. Potential applications range from medical technology to functional surfaces to industrial 3D printing,” says Schallert.
The development demonstrates the potential of optical coherence tomography as a non-destructive inspection technology for identifying internal defects and monitoring material and process conditions without interrupting pro
