Characteristics of dielectric film Mirrors. 1.The dielectric film reflector is made out of the interference principle of overlapping multilayer films. 2.The reflectivity of the dielectric film reflector is high, which can be close to 100%. The mechanical hardness of the film is high, and resistant to cleaning operations. 3.The reflector of a dielectric film is narrower than a metal film, and is closely related to the angle of incidence. 4.The reflectivity and reflected bandwidth of a dielectric film reflector is influenced by the polarization state of the incident light in addition to the incidence of 0 degrees. 5.A dielectric film reflector can be used for a strong laser, but the damage threshold test is a destructive test.