Additive manufacturing of metal mirrors for TMA telescope

Additive manufacturing enables enhanced designs for metal mirrors and housings of optical systems like telescopes. Internal lightweight structures are used for the mirror modules to reduce the weight of the system while keeping the mechanical stability. Internal structures can be produced by selective laser melting, which cannot be realized by conventional machining. Using an aluminum silicon alloy, the thermal mismatch of the mirror base body to the necessary polishing layer is minimized. Resulting thermal induced deformations are greatly reduced. The additive manufacturing of a mirror module with two optical surfaces is described in detail. Using a adapted process chain for the application in the visible range, first results of the additive manufacturing as well as subsequent machining steps like diamond turning of the optical surfaces are presented.