The optical uses to which coatings of thin dielectric films have been put in recent times are many indeed. Coatings to eliminate unwanted reflections off a diversity of surfaces, fromshowcase glass to high-quality camera lenses, are now commonplace. Multilayer,nonabsorbing beamsplitters and dichroic mirrors(color-selestive beamsplitters that transmit and reflec particular wavelengths) can be purchased commercially.