Aluminium alloys with ultra-fine microstructure for optical apps
2 April 2008
RSP Technology has developed a line of aluminium alloys for optical applications, including mirrors, moulds and mounts.
The Rapid Solidification Process used to manufacture the alloys, enables RSP Technology to cool down materials at a speed of 10,000,00K per second, ‘freezing’ the liquid alloy, giving it a very fine grain size and superior specifications over conventionally-casted alloys.
Aluminium is an often used material for mirror applications, due to its light weight and reflection properties, especially in aerospace applications when every gram of weight counts.
The surface roughness reached after diamond machining or polishing determines the performance of the mirrors. The quality of the surface roughness that can be reached is linked to the microstructure of the material from which it is made.
For optical mould applications, RSP has developed an alloy that offers in addition to the fine microstructure, high strength at elevated temperature. This combination is ideal for application in optical moulds and inserts (e.g. for injection moulding of contact lenses).
In co-operation with its Dutch development partners TNO and Astron, recent tests have shown that certain RSP grades can be polished to RMS figures less than 1nm. This opens a wide potential for applying the alloys in weight-critical, high-end optics in aerospace and defence industry. A development programme is being launched in order to further investigate this topic.