Wednesday, April 11, 2012

The Shape of Color

When we think about the science behind color, chemistry is our go to field: the chemistry of paints and dyes, the history of minerals and pigments.  But we rarely think about the shape of color. Structural color is an entire field of research that study's things like iridescent butterfly wings and nano scale silver particles.
Iridescent wings of the Morpho didius butterfly via Wikimedia

To start out we need a good explanation of  structural color . For that lets hear from Wikipedia: "Structural colors are colors caused by interference effects rather than by pigments. Color effects are produced when a material is scored with fine parallel lines, formed of one or more parallel thin layers, or otherwise composed of microstructures on the scale of the color's wavelength." So differences in surface structures can change the colors we see just by reorienting the light that hits them.

Scales on a butterfly wing via Wikipedia
Here is a great example. Above is an image of the scales of on butterfly wing, but when we look even closer we can see that each scale is a lattice work on the scale of wavelengths of light. When light hits this surface it gets reorganized, a process called interference. When this changed light is then seen the colors are the result of the surface architecture alone. 

Nanoscale Structure on a Butterfly wing scale via Wikipedia
Another beautiful example of structural color is the opal. The iridescence we see is the result of a particular kind of optical nanostructure called a  photonic crystal which effect motion of photons just as the butterflys lattice scales do, only with opals the hue changes as the angle if viewing changes. 


Opal via Wikimedia
Color is an ever present force in our world, perhaps sometimes so omnipresent as to be ignored. But when we see the amazing variety of solutions nature has found to produce color, it becomes new and interesting all over again.

- Emily Eifler, Writer, Colour Studio
- Jill Pilaroscia, Principal, Colour Studio

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