Diamond turning and polishing tests on new RSP aluminium alloys

For years now conventional aluminium 6061 T6 has widely been used for mirrors in astronomical instruments, being diamond turned or since a few years also being optically polished. This allows the development of optical systems that can be tested and operated at any temperature, without being affected by CTE effects. Using traditional aluminium the manufacturing methods could in some cases not deliver the required surface shape, accuracy and roughness due to the increasing demands from optical systems. Over the last few years RSP Technology developed a new series of aluminium alloys for several applications, produced with a Rapid Solidification Process. Both on a macroscopic and microscopic level these new aluminium alloys have different material characteristics compared to the traditional aluminium alloys. TNO and NOVA-ASTRON have performed diamond turning and polishing tests on these new aluminium alloys. This paper presents results of several diamond turning and polishing tests obtained over the last year and show the potential of these new alloys with surface roughness values of 1 nm on RSA 6061 and RSA 708 acquired with both diamond turning and polishing. © 2012 SPIE