Fraunhofer Institute for Production Technology IPTResearch project "MirrorScale"
When Microns Matter
From laser optics to space telescopes and quantum communication – mirrors play a critical role in directing, focusing, or analyzing light. At the core of every high-performance optical system is the substrate beneath the reflective layer. It must be formed with extreme precision; even micrometer-scale deviations can degrade or disable system functionality.
Traditionally, such substrates are produced from solid glass blocks, shaped through extended cycles of grinding and polishing—processes that can take days or even weeks for large formats. This method is expensive, energy-intensive, and difficult to automate, involving more than 20 discrete steps. The risk of breakage is high, and rejection rates are significant. For mirror blanks over one meter in diameter, production costs often run into the millions.
A New Approach Cuts Energy, Material, and Cost by up to 75%
MirrorScale is exploring an alternative process that eliminates mechanical finishing altogether. Instead of grinding, the team uses heat: flat glass is thermally reshaped at temperatures up to 1400 °C. The process is scalable, reproducible, and substantially more efficient than conventional methods. Crucially, it is suitable for large-format mirrors.
The benefits are clear: energy use, material consumption, and manufacturing costs can be reduced by as much as 75%. Because the forming process can be electrically powered, it also offers a path toward carbon-neutral production of optical components. Development cycles are shortened significantly. The team’s target is a time-to-market of just eight weeks for high-precision mirror substrates – a turnaround time previously unheard of in precision optics. A first pilot facility is under construction in North Rhine-Westphalia.
Simulation, Process Engineering, and Machine Learning – Working Together
The greatest technical challenge lies in process control. Heat distribution within the forming oven is not uniform – and glass responds sensitively to temperature gradients, cooling rates, and internal stresses. Minor variations during heating can cause permanent shape deviations.
To manage these effects, the project team uses a combination of physical modeling, real-time monitoring, and AI-driven optimization. Fraunhofer IPT employs finite element modeling (FEM) to simulate heat flow and deformation behavior inside the oven. These simulations provide a starting point for process design– but real-world conditions often diverge from model predictions.
To close this gap, the Fraunhofer team developed and patented a dynamic forming method: during the heating process, the glass blank follows a defined motion pattern within the system. This motion evens out the temperature distribution, significantly reducing shape errors.
Project partner Vitrum Technologies complements the physics-based approach with data-driven methods. Machine learning models detect discrepancies between the simulation and real process data and adjust control parameters in real time. The result: a knowledge-based process control system with reduced material waste and fewer development iterations.
A Strategic Technology for Structural Transformation in Western Germany
Beyond its technical innovation, MirrorScale supports structural change in Germany’s former lignite-mining region. The project establishes a competitive manufacturing capability for high-precision optics in the Rhenish lignite district – bringing a critical enabling technology back to Germany. For high-tech industries such as laser systems, aerospace, or quantum applications, the project opens up new opportunities in the development of large-scale optical systems.
Funding
The "MirrorScale" research project is funded by German Federal Ministry for Economic Affairs and Energie (BMWE), under the structural transformation program “Unternehmen Revier”.
Funding Reference: 37.22.01/03b_2024