Polishability of thin electrolytic and electroless NiP layers

Jan Kinast; Matthias Beier; Andreas Gebhardt; Stefan Risse; Andreas Tünnermann

doi:10.1117/12.2193749

11 October 2015 Polishability of thin electrolytic and electroless NiP layers

Jan Kinast, Matthias Beier, Andreas Gebhardt, Stefan Risse, Andreas Tünnermann

Proceedings Volume 9633, Optifab 2015; 963311 (2015) https://doi.org/10.1117/12.2193749
Event: SPIE Optifab, 2015, Rochester, New York, United States

Abstract

Ultra-precise metal optics are key components of sophisticated scientific instrumentation in astronomy and space applications, covering a wide spectral range. Especially for applications in the visible or ultra-violet spectral ranges, a low roughness of the optics is required. Therefore, a polishable surface is necessary. State of the art is an amorphous nickel-phosphorus (NiP) layer, which enables several polishing techniques achieving a roughness of <1 nm RMS. Typically, these layers are approximately 30 μm to 60 μm thick. Deposited on Al6061, the bimetallic effect leads to a restricted operational temperature, caused by different coefficients of thermal expansion of Al6061 and NiP. Thinner NiP layers reduce the bimetallic effect. Hence, the possible operating temperature range. A deterministic shape correction via Magnetorheological Finishing of the substrate Al6061 leads to low shape deviations prior to the NiP deposition. This allows for depositing thin NiP-layers, which are polishable via a chemical mechanical polishing technique aiming at ultra-precise metal optics. The present article shows deposition processes and polishability of electroless and electrolytic NiP layers with thicknesses between 1 μm and 10 μm.

Citation Download Citation

Jan Kinast, Matthias Beier, Andreas Gebhardt, Stefan Risse, and Andreas Tünnermann "Polishability of thin electrolytic and electroless NiP layers", Proc. SPIE 9633, Optifab 2015, 963311 (11 October 2015); https://doi.org/10.1117/12.2193749

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