Tuesday, November 27, 2012

Scales on the Wings of a Butterfly

Via (above break) Fresh Photons from Infinity Imagined (a cool tumblr by James Tyrwhitt-Drake of the University of Victoria).




According to Wikipedia (citing several articles) "[butterfly] scales are pigmented with melanins that give them blacks and browns, but blues, greens, reds and iridescence are usually created not by pigments but the microstructure of the scales. This structural coloration is the result of coherent scattering of light by the photonic crystal nature of the scales." In other words, their fine structure, as above, causes light to scatter in a fairly uniform way in specific wavelengths making them look brightly blue, green, red, and iridescent. Here's a nice, more detailed description, with images, from Peter Wong at Tufts University. Here's a few which I think are self explanatory and correspond to the micrographs above:





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