Researchers at TU Wien (Austria)) have unveiled an inline imaging-ellipsometer purpose-built for roll-to-roll (R2R) production, with an Allied Vision EXO250ZU3 polarized camera at its core. The system delivers real-time, full-area optical thickness measurement of functional coatings directly on moving foils, eliminating the sampling delays and blind spots that have long plagued R2R quality assurance.
The R2R Quality Problem.
R2R production lays down functional coatings onto flexible substrates at speeds exceeding 100 meters per minute, across applications from lithium-ion battery electrodes to flexible displays. At that throughput, a single process excursion such as a viscosity shift, temperature drift, or misalignment, can propagate undetected across an entire roll.
What's been missing is a metrology platform capable of measuring coating uniformity, thickness consistency, and surface defects simultaneously, non-destructively, and in real time across the full substrate width. That gap is precisely what this system closes.
Conventional ellipsometry is confined to the lab because foil widths of several meters demand collimated illumination across enormous apertures. TU Wien's solution: replace conventional refractive optics with large-aperture Fresnel lenses, collapsing cost and footprint while preserving the precise angle-of-incidence control ellipsometry demands. The result is the first imaging-ellipsometer deployed in an active R2R production line, demonstrated on 300 mm foil.
The EXO250ZU3 camera is built on Sony's IMX250MZR CMOS featuring 2448 × 2048 resolution, global shutter, 3.45 µm pixels, and operating at 75 frames-per-second. It integrates a nanowire polarizer above the pixel array, capturing all four polarization states (0°, 45°, 90°, 135°) simultaneously in 2 × 2 super-groups.
A user-selectable LED illuminates across the camera's 350–1100 nm spectral window. Light passes through a single fixed linear polarizer at 45°, allowing the camera to resolve all four reflected intensity channels in one exposure. Two streamlined calculation methods translate polarization ratios into spatially resolved thickness maps with minimal latency, frame by frame at line speed.
 |
| The camera installation on a Coateme Click&Coat™ R2R substrate processing system (photo TU Wien) |
Validated on Industrial Materials.
The system was tested on PEDOT layers on PET foil (organic electronics, transparent electrode manufacturing) and battery electrolyte coatings on copper foil. In both cases it delivered quantitative thickness maps at production speed. Critically, polarimetric sensitivity reveals coating uniformity deviations, edge anomalies, and surface defects invisible to conventional optical inspection with direct implications for yield improvement and early defect rejection.
Eliminating Noise at the Architecture Level.
Foil vibration, backside reflections, substrate birefringence — each has historically made reliable inline ellipsometry all but impossible. The system addresses all of them with one architectural decision: measurement directly on a roll. On-roll geometry suppresses vibration, fixes the effective AOI, and redirects backside reflections away from the detector. The LED's 20–60 nm spectral bandwidth ensures front- and back-surface reflections are mutually incoherent, eliminating interference artifacts at the physics level.
The system scales linearly with foil width, positioning it for wide-web battery, display, and flexible electronics manufacturing. Measurable thickness range spans nanometers (highly absorbing layers) to microns (transparent layers), adapting to vastly different process chemistries on a single hardware platform.
TU Wien will now target in-line and in-time thickness-measurements and further installations in R2R-lines up to foil widths of 2 meters. Since the ellipsometer uses simple components and works without moving parts on a fixed wavelength with a fixed illumination angle, it promises straight-forward and cost-effective installations on production lines.
• See also: Real-time imaging-ellipsometry with a polarization camera in R2R-applications: Ferdinand Bammer et al 2026 Flex. Print. Electron. 11 015005
#Allied Vision #PAuto #R2R @tuwien.at
No comments:
Post a Comment