DIOPTIC has successfully applied its proven alignment technology based on computer-generated holograms (CGHs) to the Wendelstein 7-X fusion research reactor. Following successful implementations in space applications, including the Euclid space telescope, the technology has now been adapted for high-precision endoscope systems. The goal is to enable reliable monitoring of critical processes during reactor operation.
Precision for Fusion Research
Located in Greifswald, Germany, Wendelstein 7-X is one of the world’s leading fusion research experiments and represents an important alternative to conventional tokamak concepts. Its objective is to sustain stable plasma over extended periods of time, a key milestone on the path toward continuous fusion energy generation. Since the start of operations in 2016, the facility has achieved significant milestones, including plasma discharges lasting up to eight minutes.
Monitoring thermal loads is essential for the safe operation of the reactor. The hot plasma transfers energy to the reactor’s inner walls, particularly to components known as divertors, which must be actively cooled. Optical systems such as endoscopes play a critical role in monitoring these areas and ensuring safe and efficient reactor operation.
High-Precision Alignment Using CGH Technology
The endoscopes used in Wendelstein 7-X consist of multiple optical components whose precise alignment is crucial for measurement accuracy. DIOPTIC contributed to the development of the alignment concept and performed the interferometric verification of the optical alignment using CGH technology.
For each CGH, multiple holograms are computationally designed and structured into a glass substrate with nanometer-level precision. Each hologram generates a wavefront specifically matched to an individual optical surface within the system. By analyzing the resulting interferometric data, both the position and tilt of individual optical components can be determined with exceptional accuracy. A key advantage of this approach is the ability to measure multiple optical surfaces simultaneously and assess their relative alignment within the complete optical assembly.
Supporting Quality Assurance and Future Applications
As part of the project, the first endoscope was successfully inspected and aligned. A total of five endoscopes will be used to monitor ten divertor modules within the reactor. The developed inspection and alignment methodology serves as a reference standard for quality assurance across all systems.
The precise alignment of the optical monitoring systems ensures reliable operation and contributes significantly to the safety and efficiency of reactor processes. At the same time, the project demonstrates the versatility of CGH-based metrology. As fusion technology continues to advance, high-precision optical metrology will remain a key enabling technology. DIOPTIC’s expertise in CGH-based testing and alignment helps ensure that complex optical systems meet the performance requirements of tomorrow’s most ambitious scientific projects.
