At the Institute of Production Engineering and Photonic Technologies at TU Wien, the Process Engineering research group is pioneering a new real-time method for inline layer quality monitoring — powered by SVS-Vistek’s advanced polarization cameras.
Traditionally, vision-based polarization systems have proven effective for highly specific applications: stress analysis in transparent materials using photoelastic effects, surface inspections of reflective or transparent non-metals like water, plastic, or glass, and even reading black-on-black text — a challenge in tire production. In the pharmaceutical industry, these systems are key in blister pack inspection, helping to detect and sort out defective packaging with precision.
But the research group led by Ferdinand Bammer is going a step further. Their focus lies on a more recent application of polarization imaging — ellipsometry, a technique used to analyze light reflected off a surface. Unlike transmission-based methods, ellipsometry examines how polarized light reflects and changes upon interacting with thin layers. By measuring reflected light intensities at four linear polarization angles (0°, 45°, 90°, 135°), and applying mathematical models, the researchers can determine both the thickness and quality of thin coatings.
A New Approach to Polarization Analysis
To extract full polarization information, the TU Wien team adds a quarter-wave plate to the system, enabling measurement of both linear (45°, 135°) and circular polarizations (left and right-handed). From these values, two core metrics — R45 and Rz — are calculated. These can be further transformed into the traditional ellipsometric parameters, Ψ and Δ, which are highly sensitive to layer characteristics. “The thickness of a coating has the greatest impact on these parameters,” explains Bammer. “That’s why ellipsometry is such a powerful tool for evaluating layer quality.”
The ultimate goal? Taking this lab-proven technique and refining it for robust, high-speed use in industrial production lines.
Demand from Industry is Growing
The use cases for such inline ellipsometry systems are broad and growing rapidly. In electronics manufacturing, accurately measuring semiconductor, metal, polymer, or dielectric layers is essential. Similar demands exist in OLED display production, battery and fuel cell fabrication, photovoltaic component manufacturing, and even in the pharmaceutical and food packaging sectors.
For instance, ensuring that inner coatings in plastic or glass containers meet strict requirements is crucial — not just for content protection, but also to prevent contamination or diffusion. Bammer adds, “This need for precise, non-destructive layer inspection is only increasing.”
Built on SVS-Vistek Polarization Cameras
Measuring layer thickness to sub-micron accuracy depends on the application. In cases like barrier layers on bottles or films, or primers on metal sheets, an accuracy of around 10% of the layer thickness — typically 10 to 200 nm — is sufficient. However, more demanding fields, such as organic photovoltaics or advanced displays, may require even higher precision.
To meet these demands, the group evaluated available polarization camera options — and chose SVS-Vistek. “Their cameras were recommended by a research partner as the most robust and lowest-noise available,” says Bammer. “We’ve had great experiences, both with performance and service.”
The team currently uses the exo250ZGE GigE Vision polarization camera, offering 5 MP resolution and 24.5 fps for simpler tasks. For higher-speed needs, the exo250ZU3 USB3 model delivers up to 75 fps. When maximum resolution is needed, the exo253ZU3, with its 12.3 MP sensor, is deployed.
Beyond the hardware, SVS-Vistek’s technical support stood out. “From the start, their team understood our needs. They were knowledgeable, responsive, and instrumental in getting our system up and running,” Bammer recalls.
Polarization cameras from SVS-Vistek, such as the GigE Vision models exo264ZGE, exo250ZGE, or the USB3 cameras exo264ZU3, exo250ZU3, and exo253ZU3, form the foundation of the ellipsometry systems at TU Wien.
Image source: SVS-Vistek
From Research to Real-World Impact
One of the biggest challenges, according to Bammer, is not just perfecting the measurement technique, but communicating its value. “Understanding the link between polarization and material properties is complex. Simplifying that relationship for industrial users and achieving their buy-in is crucial for adoption.”
Today, several prototypes of the system are moving from lab settings into practical use. Early adopters are applying TU Wien’s ellipsometry approach in both lab setups and production environments, including quality control of PET bottle coatings. While laboratory-grade ellipsometry remains more precise, the performance of these inline systems is already sufficient for a range of industrial applications.
Looking ahead, Bammer sees significant potential: “Emerging technologies — displays, lighting, solar panels, batteries, fuel cells, catalysts — all rely on ultra-thin coatings. The ability to perform real-time, full-surface quality control is becoming a must. Yet, knowledge about polarization and ellipsometry in the industry is still lacking. That’s why robust, accessible tools like SVS-Vistek’s cameras will be key in bridging this gap.”
Polarization Basics
Polarization refers to the orientation of light waves’ oscillations. While unpolarized light vibrates in multiple directions, polarized light vibrates in specific, filtered directions. By analyzing how polarization changes upon reflection or transmission, systems can extract valuable information — such as the thickness or uniformity of coatings. This principle underpins both polarization imaging and ellipsometry.
About SVS-Vistek:
As an innovative manufacturer of high-quality industrial cameras, SVS-Vistek has more than 35 years of exceptional expertise in industrial machine vision. The company develops and produces a wide range of standard cameras as well as cameras with the highest resolutions and speeds, above-average image quality and all relevant interfaces. With high-performance components such as lenses, lighting, filters, frame grabbers and cables, SVS-Vistek supports its customers in the realization of cost-effective, individual solutions for a wide range of industries.
About the process engineering research group at the Institute of Production Engineering and Photonic Technologies at TU Wien:
The Process Engineering research group at the Institute of Production Engineering and Photonic Technologies at TU Wien works together with partners from industry and science on various tasks in the fields of macro, micro, and nano processing, as well as metrological issues. These are investigated using laser and light sources that emit radiation from the ultraviolet to the far-infrared range of the spectrum. The activities of the research group span from fundamental research to applied research.
Further information: www.svs-vistek.com
