The role of diagnostic testing in identifying and resolving dimensional-stability problems in electroplated laser mirrors

The metal mirrors which are to be used in the Antares inertial fusion laser system are discussed. Antares is a high-power, high-energy, pulsed CO2 laser system for the investigation of inertial confinement fusion. The system contains more than 400 small and large diamond-turned and conventionally polished mirrors. The substrates are type 2124 aluminum for most large mirrors, and aluminum bronze, oxygen-free copper or a copper-zirconium alloy for most of the smaller mirrors. The optical surface is electro deposited copper 20 to 40 mils thick. After nondestructive testing and rough machining, the electroplated surface is singlepoint diamond machined or conventionally polished.