Conference and exhibition  /  April 07, 2024  -  April 11, 2024

SPIE Optical Systems Design

SPIE Optical Systems Design is an interdisciplinary forum co-located with SPIE Photonics Europe in Strasbourg. The forum is aimed for technicians, engineers, researchers, and managers who are involved in instrumental optics at all levels: design, specification, production, and testing.

The event provides insights into new research findings trough more than a hundred of international presentations. World-class speakers in the field are sharing their research and vision of the future. Furthermore, the attendees can connect with colleagues and engage with leading companies by attending technical and networking sessions as well as exhibitions that give the opportunity to network, learn, and discuss optics and photonics with other professionals from around the world.


The key topics of the conference are:

  • Illumination optics
  • Advances in optical thin films
  • Computational optics
  • Optical fabrication and testing
  • Optical design and engineering
  • Optical instrument science, technology, and applications

The Fraunhofer IST is participating in the event with a presentation:


April 9, 2024, 11:30-11:50 pm, Salon 1/Level 0

Ellipsometric control of layer thickness during coating of nanolaminate layers

Stefan Bruns, Fraunhofer IST

Abstract: Optical thickness monitoring is implemented in almost all coating machines for high precision optical interference filters. Standard broadband transmittance monitoring comes to the limit of thickness resolution when e.g. nanolaminates are deposited. Ellipsometry is more sensitive for material dispersion and. Transmittance measurement can be used for higher layer count with standard materials. We use a turntable configuration at 250 rpm with magnetron sputtering from cylindrical targets. We show the integration of a broadband ellipsometer for the determination of thickness and material properties during the growing layers. The ellipsometric angles were measured and the deposition process was investigated. The triggering was optimized to match the exact position on the moving control substrate. Ex situ ellipsometry is in good agreement. Results for nanolaminates are presented from the combination of amorphous silicon and silicon dioxide. With TEM we found smooth surfaces for sub-nm layers. The thicknesses are reproducible and consistent with ellipsometry.