Today two variants can be processed by Silicon Carbide ceramic optical components: a ceramic sintered, but very difficult to process, and a carbon-fiber-reinforced composite material. Both must be coated to achieve the required optical surface quality and dimensional accuracy.
The Russian Centre for Technology Transfer Ltd (CTT) therefore developed a new silicon carbide material in the frame of the Ceramics4Optics project, which allows to ommit costly coating before the final polishing of the optics. The new ceramic contains embedded diamond particles in a silicon carbide matrix and thus has a higher rigidity and thermal conductivity at at the same time lower thermal expansion as compared to other variants of Silicon Carbide.
The tasks of the Aachen-based Fraunhofer Institute for Production Technology (IPT) and the Opteg GmbH in Leipzig were to define the optimal transfer points between the individual technologies of grinding, polishing and ion beam finishing. Machining parameters, abrasive measures and tools for the new composite material must be identified and precisely matched. Thus, a uniform removal and an optical surface finish of under 2 nm RQ can be achieved in the final polishing process, even without previous coating.
The Fraunhofer IPT focusses on the grinding and polishing processes for the hard and fine finishing. In controlled processing tests on multi axis polishing machines, the effects of various polishing suspensions as well as suitable tools and grinding parameters are being determined.
The Opteg GmbH's task are studies on ion beam polishing as a final step of the polishing process, in order to adapt the procedure to the new composite. The choice of suitable process parameters is intended to influence the surface roughness down to 1 nm RMS.
Ceramics4Optics: German-Russian knowledge transfer
The project Ceramics4Optics is supported by a German-Russian funding competition of the German Federal Ministry of Education and Research (BMBF) and the Russian Fund for the Support of Small Innovative Enterprises (FASIE). This form of international cooperation is unique in its field and provided the German project partners with easier access to the Eastern European and particularly to the Russian market. Both sides benefit from the exchange of knowledge and thus expand their expertise in terms of efficiency and range of material.
Partners in the project Ceramics4Optics
The Opteg GmbH in Leipzig is specialised in the manufacturing of optical low coherence-Interferometer and photo spectrometer on the one hand, and on the other hand, it is a worldwide known address in special engineering and innovative solutions for production-oriented complete systems for ion beam figuring . These machines are used for nanometer-accurate finishing of high-performance optics.
Russian Centre for Technology Transfer Ltd (CTT) in Saint Petersburg is a small innovative company which develops opto-electronic systems for various applications and manufactures. It also developed a new type of optical system for the use in space. Components made of silicon carbide were used for its construction.
The Fraunhofer Institute for Production Technology (IPT) in Aachen develops system solutions for manufacturing companies. The focus lies on new and further development of production processes, measuring and matching system concepts.
Dipl. Julia Dukwen, Fraunhofer Institute for production technology IPT
Steinbach 17, 52074 Aachen/ Germany
Phone + 49 241 8904-719, e-mail: Julia.dukwen@IPT.Fraunhofer.de
Source: IDW Nachrichten