Laser-Based Nuclear Fusion – New Challenges for Optical Components

Fig.1:Final inspection after defect analysis

Nuclear fusion is considered one of the most promising technologies for sustainable energy generation. Thanks to recent breakthroughs at the National Ignition Facility (NIF) in California, USA, research in this field has gained significant momentum. The development of high-performance large optics that can withstand extreme radiation intensities plays a crucial role in this process.

In the latest edition of the , we explore the challenges and solutions for high-performance optics in laser fusion. LAYERTEC has been working for over 15 years on scaling high-quality coating technologies for large optics and developing new manufacturing processes to meet increasing demands.

Discover in our expert article how LAYERTEC is pushing the boundaries of optical manufacturing – from innovative polishing and cleaning technologies to high-precision metrology.

This expert article originally appeared in Laser Magazine [March 2025 edition].

Laser-Based Nuclear Fusion – New Requirements for Optical Components

Controlling nuclear fusion on Earth and utilizing it for energy generation is a visionary goal to sustainably meet our ever-growing energy needs. This vision has come one step closer since the National Ignition Facility (NIF) in California, USA, demonstrated that energy generation is possible using laser radiation to drive the fusion reaction. Since then, laser-based fusion research has experienced a significant boost.

Building such large and powerful laser systems requires optics that can withstand high radiation intensities. To manipulate, amplify, and ultimately direct the laser radiation into a fuel capsule, particularly large optics are needed – typically with a rectangular outer contour and dimensions between 500 and 1000 mm. These optics must meet the highest requirements simultaneously:

High pulse energies: Requires optimized coating designs and extreme surface cleanliness.
High average power resistance: Even the smallest absorption losses lead to degradation, heating of components, and thermal lensing.
Minimal beam distortions: To ensure a well-defined energy distribution.
Long-term stability: Optics must maintain their specified properties over extended operating times.

LAYERTEC has been addressing these challenges since 2007, scaling solutions for large surfaces. The initial goal was to offer coatings of comparable quality, available for 1-inch and 2-inch optics, on optics with a diameter of half a meter. The first successes were already presented at the Laser Fair in 2007. In the following years, the entire production process for this size class was gradually developed (grinding, polishing, ultrasonic cleaning, metrology).

In the next expansion phase, manufacturing capabilities were extended to lengths of up to 1200 mm. The establishment of a dedicated manufacturing department in 2023 created additional production capacities to meet the growing demand for large optics. Today, LAYERTEC possesses a range of core competencies to address future demands for large high-performance optics:

Polishing technologies over multiple stages (classical and CNC) up to lengths of 2000 mm.
Cleaning: Proprietary ultrasonic cleaning systems for optics up to 1200 mm in length.
Coating: Ion-assisted evaporation up to 1200 mm, magnetron sputtering up to 600 mm.
Metrology: Multiple interferometers for planar, cylindrical, and spherical surfaces, scanning measurement systems for freeform surfaces, roughness measurement devices (including AFM), multiple multi-sensor CMMs, automated surface defect measurement systems, coating characterization (OPO-CRD, PCI, laser damage threshold measurement).

Our large optics are already in use in high-energy laser systems developed by industrial and research partners. For industrial applications in fusion power plants, the following aspects are particularly challenging:

Near-defect-free surfaces: To achieve the highest laser damage thresholds, optics must have little to no surface defects (e.g., < 25 µm). While small optics can be selected based on quality, large optics require deep process expertise across the entire production chain. To objectively analyze surface defects, LAYERTEC developed an automated defect detection and classification system several years ago.
Scalability: Large laser facilities require many optics that must be available at optimized costs and with shortened lead times. High-volume production must ensure the serial quality of these highly demanding optics.

LAYERTEC is currently tackling these technological challenges in two BMBF-funded research projects on laser fusion: PriFUSIO and SHARP. Together with partners from industry and research, new concepts and technologies are being developed to advance laser fusion. In these most demanding technological tasks, LAYERTEC’s high level of manufacturing integration – from optics production to cleaning, coating, metrology, and characterization – proves to be a significant advantage.