Beryllium Optics Enable Advanced Space Telescopes

Abstract Beryllium won a lengthy competition as the material of choice for the mirrors on the James Webb Space Telescope, set to launch in 2018. This article documents the development history leading up to that decision. It took decades to perfect powder atomization and HIP'ing processes to make optical-grade beryllium components homogeneous, isotropic, polishable, thermally and dimensionally stable, and above all, predictable.