The 10Z20ER.1 Broadband Metallic Mirror is an excellent general purpose, broadband reflectors. This 1 inch (25.4 mm) diameter mirror is made from a 6.0 mm thick Zerodur substrate. Zerodur is a glass-ceramic material where thermal expansion is nominally zero. This extra stability can be critical for applications requiring diffraction limited performance. The ER.1 enhanced aluminum coating may be used wherever a broadband visible and near infrared reflector is needed. A multilayer dielectric stack deposited over the aluminum film boosts reflectance and improves the durability of the coating. Average reflectivity is greater than 93% from 450–700 nm. This mirror has a λ/10 surface flatness and a 15-5 surface quality.