Gold Mirror, Zerodur, 50.8 mm, λ/20, 650-20,000 nm

The 20Z40ER.4 Broadband Gold Mirror is an excellent general purpose, broadband reflector. This 50.8 mm (2.0 inch) diameter mirror is made from a 12.7 mm thick Zerodur substrate. Zerodur, a glass-ceramic material, exhibits nominally zero thermal expansion which provides extra stability for applications requiring diffraction limited performance. The ER.4 protected gold coating is ideal for applications requiring broadband reflectance in the near IR to the far IR. A multilayer dielectric overcoat provides protection to the gold from the environment. The 20Z40ER.4 has an average reflectivity greater than 96% from 650-1700 nm and greater than 98% from 1.7-20 µm. This mirror has a λ/20 surface flatness and a 10-2 surface quality.