OCT inspects seal seams in film packaging in real time

Tight, or Not? Defective Foil Packaging Can Be Detected More Quickly

2026-09-22 Source: Fraunhofer IKTS | Translated by AI 3 min Reading Time

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Quality requirements for film packaging are on the rise. At the same time, many companies are turning to recyclable film materials, which, however, have their own challenges. Fraunhofer researchers have therefore developed a fast system that detects problems in real time.(Image: Fraunhofer IKTS) — Quality requirements for film packaging are on the rise. At the same time, many companies are turning to recyclable film materials, which, however, have their own challenges. Fraunhofer researchers have therefore developed a fast system that detects problems in real time.
(Image: Fraunhofer IKTS)

Optical coherence tomography (OCT) is an imaging technique based on infrared light, according to experts from the Fraunhofer Institute for Ceramic Technologies and Systems (IKTS) in their report on film testing. These systems, they go on to explain, were originally developed for ophthalmology but can produce three-dimensional, non-destructive images of the subsurface structure of a wide variety of materials. This ultimately reveals where inhomogeneities or defects are present. To do this, the system emits near-infrared light into the material and detects the reflected signals. This data is used to generate high-resolution three-dimensional images of the internal structure. This allows for the detection of material defects, air pockets, or inadequately welded areas without damaging the packaging or the product.

Even the Tiniest Errors Are Quickly Detected

As part of the publicly funded “OCTInline” project, IKTS researchers integrated OCT technology directly into the sealing process of a packaging machine belonging to an industry partner. Implemented in this way, the system now continuously and non-destructively inspects the quality of the resulting seal in real time during the ongoing process—even at production speeds of up to 25 meters per minute, as the experts from Dresden point out. “We can detect and visualize various pores up to eight micrometers in size in the seal,” notes Ralf Schallert, group leader for characterization methods at Fraunhofer IKTS. The real challenge, however, lies in combining high resolution with high production speed. This is because the smaller the defects are, the more data must be captured and processed. Integrating the system into the industrial process also posed challenges for the project team. Even the slightest vibrations of the film can affect the measurement. They therefore had to find a balance between depth of field, exposure time, and the movement of the film.

Be Careful with Recyclable Single-Material Films!

And new sustainability requirements for packaging are increasing the importance of reliable seal inspection. This method comes at just the right time. More and more manufacturers are also turning to recyclable single-material films, which are easier to recycle than multilayer composite systems. Mono-films are said to be very appealing from an environmental perspective, but unfortunately, defective seal seams occur more frequently with them, which is why inspections for defects must be intensified. For manufacturers, real-time inspection therefore offers several advantages: Rapid defect detection reduces scrap and material consumption; furthermore, in addition to actual defect detection, the system also collects information on the condition of machines and tools. This is because many defects arise when pressure and temperature are poorly matched to the material or because the sealing tool is worn out. However, these problems can be detected using OCT. A prototype of the system has been in use since July 2026 at project partner Kallfass Verpackungsmaschinen GmbH in Nürtingen (Germany), where it is being demonstrated to potential customers, according to reports.

Also Works with Other Material Systems

However, the packaging industry is just one of many applications for this technology, according to the researchers. This is because the systems can also be individually adapted to different materials and requirements. As a result, the OCT method can be used to address a wide variety of industrial challenges. For example, it is generally suitable for transparent and partially transparent materials, as well as for numerous tasks in industrial quality assurance. In addition to packaging, functional coatings, ceramic components, or additively manufactured parts could also be examined. Bottom line: wherever thin layers, internal structures, or minute defects need to be reliably detected, OCT can make an important contribution.

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