The 18E20RM.2 Laser Line Dielectric Elliptical Mirror is a highly efficient reflector optimized for the 325 nm wavelength. This 1.838 inch (46.70 mm) minor axis, 2.60 inch (66.04 mm) major axis, elliptical mirror is made from a 12.45 mm thick Borofloat® 33 substrate. Borofloat has low thermal expansion and is an excellent substrate for most applications. The RM.2 coating is designed for use with HeCd lasers and has a center wavelength of 325 nm. The coating achieves greater than 99% reflectance, from 0–45° angle of incidence, for any polarization. This multilayer dielectric coating is extremely durable, making it resistant to damage from repeated cleaning. This mirror has a λ/10 surface flatness and a 15-5 surface quality.