Physical Colors, Chemical Colors Basics of Solid State Optics

Abstract

Now that we have completed our tour of butterfly colors and of their advantages for a given species and mentioned how difficult it could be to interpret them in the past, we will examine their origin in detail and try to offer a simple view of today’s knowledge on this matter. We have already mentioned optical index in the last chapter, and a few basic experiments in which butterflies are immersed in various liquids. These experiments and their effects on colors are the keys for solving the problem. When one knows the optical index and the geometry of a given material, one automatically knows its color. Contrary to Raleigh and Michelson, we now have access to the geometry thanks to electronic scanning technologies—scanning and transmission electronic microscopes—and atomic force microscopes. Yet, what about the optical index?