we offer both dielectric as well as Metallic Mirrors for various wavelength regions from UV, VIS, IR and even for X rays too. Also Rear mirrors, typically GaAs, Ge, or ZnSe, are partial reflectors with a very high reflection-to-transmission ratio (99.0% to 99.7%), and are key optical components in laser resonators or laser cavities. Rear mirrors, like output couplers, are a part of the lasing process. Thus, high reflectivity is desired. The rear mirrors slight transmission is used in conjunction with power meters to test for laser resonator output power.