Gold Mirror, Borofloat, 30.0 mm, λ/10, 650-20,000 nm

The 3MD20ER.4 Broadband Gold Mirror is an excellent general purpose, broadband reflector. This 30.0 mm (1.181 inch) diameter mirror is made from a 6.0 mm thick Borofloat® 33 substrate which is coated with the ER.4 gold coating. Borofloat® 33 has low thermal expansion and is an excellent substrate for most applications. 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 3MD20ER.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/10 surface flatness and a 15-5 surface quality.