This sort of dielectric mirrors offer a large diploma of wavelength-selective reflectance in the necessary totally free floor wavelength λ When the thicknesses of alternating layers d1 and d2 with refractive indices n1 and n2 are these that n1d1 + n2d2 = λ/2 which then brings about the constructive interference https://waltb691fgh5.wikiexcerpt.com/user