A short-wave-pass optical filter, that includes a partially absorbing or transparent substrate coated by a set of layers having specified quarter-wave optical thickness, and is designed to reflect visible radiation of a selected color while transmitting visible radiation and maintaining a neutral color...http://www.google.de/patents/US4793669?utm_source=gb-gplus-sharePatent US4793669 - Multilayer optical filter for producing colored reflected light and neutral transmission
