Glatt in the collaborative project “nanoAR”

Synthesis of optical nanopowders with high etch resistance for the production of defect-free nanostructural antireflection coatings on large monolithic optics

In order to be able to translate the current rapid progress in fusion research into manageable processes and technologies for energy generation in the future, technical components must be made available that can withstand the extreme stresses of these processes. With regard to the required laser power in the petawatt range, this also applies in particular to the laser optics. In order to increase system efficiency and reduce the thermal system load, the scattering and reflection losses of these laser optics must be drastically reduced. The anti-reflective structuring of the optics surface is very promising for this. In order to meet the associated structural requirements, new approaches are needed for surface structuring that enable extremely precise and, in future, efficient processing.
Masking the surface with a very finely dispersed powder that is more resistant to etching than the material of the lens offers a highly interesting solution. This masking powder must meet extremely high requirements in terms of size and particle size distribution, sphericity and purity of its particles as well as freedom from agglomeration. Currently available powder materials do not meet these requirements.

Masking the surface with a very finely dispersed powder that is more resistant to etching than the optical material offers a highly interesting solution. This masking powder must meet extremely high requirements in terms of the size, sphericity and purity of its particles as well as freedom from agglomeration. Currently available powder materials do not meet these requirements.

Against this background, Glatt’s aim in this sub-project is to develop, synthesize and functionalize suitable nanopowders for the first time. To this end, the underlying high-temperature processes based on powder synthesis and fluidized bed technology are to be developed. As part of the project, new process approaches for the targeted production of spherical nanopowders with high etch resistance and their functionalization are being investigated. Agglomeration-inhibiting coating systems will be used in a combined fluidized bed CVD process or pulsating hot gas flow. The investigations should ultimately lead to the provision of the first masking powders, the suitability of which can be confirmed using quartz glass and CaF₂ optics structured according to requirements.

The technological approaches considered here for the production of structural metasurfaces for high-performance optics with the highest possible laser damage threshold are aimed at preparing the technical basis for future fusion power plants. The stability of the optical beam paths in the required PW laser systems is an important prerequisite for this, even if the industrial or broad social use of fusion technology only offers long-term prospects today. Against this background, the project is still entirely in the field of research. In the future, interesting applications can be derived for Glatt as a supplier of masking powders and systems for their production. The knowledge gained here on the synthesis and functionalization of glass and nanopowders will also open up other application options, such as various surface functionalizations and functional fillers.

The planned sub-project of Glatt Ingenieurtechnik GmbH aims to develop processes for the production of high-purity optical nanopowders with very high sphericity and improved etching resistance, which can be used as a mask when etching the lens surface. This overarching objective is linked to specific work goals: the spherodization of nanoscale glass powders and the synthesis and coating of glass powders.