The 20Z20BD.1 Broadband Dielectric Mirror is an extremely versatile mirror for laboratory applications and highly efficient over a broad wavelength range. This 2 inch (50.8 mm) diameter mirror is made from a 12.7 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 BD-1 coating is extremely durable and will withstand repeated cleaning. This mirror has a λ/10 surface flatness and a 15-5 surface quality.