For applications that require mirrors with very high reflectance (such as a laser mirror), several dielectric layers are used to build a mirror. A typical mirror uses alternating indices of refraction to increase the reflectance to more than 98%. In the following example, the mirror is made of alternating layers of zinc sulfide (n=2.3) and magnesium fluoride (n=1.35) film (For a discussion of these and other coating methods see Fowles p 100). Add layers and observe how the reflectance changes.
Note: The table shows the electric field. The intensity of the wave is n*E*E.
Fowles, Grant R. Introduction to Modern Optics. 2nd ed. New York: Dover Publications, 1975.