Some links and excerpts.. they don't all go together just so you know
http://books.google.com/books?id=Wn...=book_result&resnum=8&ct=result#PRA1-PA360,M1
http://www.jstor.org/pss/985242
http://books.google.com/books?id=Wn...=book_result&resnum=8&ct=result#PRA1-PA360,M1
http://www.jstor.org/pss/985242
Man-made iridescence through the production of micro-thin layers of reflective material, as exemplified by dichroism, is thus possible. However, there are many examples of iridescence occurring in the natural world as well. The iridescent blue wings of the Morpho butterfly are a result of micro-projections of multi-layered chitin structures on the butterfly's wing. Similar projections create the iridescent colors on the peacock's feathers, the iridescent green on the necks of male mallard ducks, and the metal-like sheen from a number of species of beetles.
http://www.dichrobeads.com/what-is-dichro.html
http://www.dichrobeads.com/what-is-dichro.html
Q. What causes a hummer's colors to have a metallic sheen?
The brilliant, iridescent colors of hummingbird plumage are caused by the refraction of incident light by the structures of certain feathers. Like any diffraction grating or prism, these structures split light into its component colors, and only certain frequencies are refracted back to your eyes. The apparent color of any particular part of a feather depends upon the distance between the microscopic ridges in its gridlike structure. The resulting colors are much more vivid and iridescent than those of birds with only pigmented feathers. Not all hummer colors are due to feather structure, however; the duller, rusty browns of Allen's and Rufous Hummingbirds come from pigmentation. Iridescent hummingbird colors actually result from a combination of refraction and pigmentation, since the diffraction structures themselves are made of melanin, a pigment.
http://www.garden-birds.co.uk/information/feathers.htm
The brilliant, iridescent colors of hummingbird plumage are caused by the refraction of incident light by the structures of certain feathers. Like any diffraction grating or prism, these structures split light into its component colors, and only certain frequencies are refracted back to your eyes. The apparent color of any particular part of a feather depends upon the distance between the microscopic ridges in its gridlike structure. The resulting colors are much more vivid and iridescent than those of birds with only pigmented feathers. Not all hummer colors are due to feather structure, however; the duller, rusty browns of Allen's and Rufous Hummingbirds come from pigmentation. Iridescent hummingbird colors actually result from a combination of refraction and pigmentation, since the diffraction structures themselves are made of melanin, a pigment.
http://www.garden-birds.co.uk/information/feathers.htm
Color
Feather color occurs because of two different phenomena. The first involves the
absorption of specific wavelengths of light by certain chemical molecules in the feathers.
The unabsorbed light is seen as colored. For example, melanins form brown, dull yellow,
or black pigments. Carotenoids form the brighter yellow, reds, and oranges. The second
phenomenon is caused by the structure of the feather. The surface layers of keratin have
many air filled spaces which form reflecting or refracting surfaces to scatter light. Again,
we see this as color. Many of the blues, some of the whites and the iridescence seen on
feathers is caused by structural pigmentation.
Feather color occurs because of two different phenomena. The first involves the
absorption of specific wavelengths of light by certain chemical molecules in the feathers.
The unabsorbed light is seen as colored. For example, melanins form brown, dull yellow,
or black pigments. Carotenoids form the brighter yellow, reds, and oranges. The second
phenomenon is caused by the structure of the feather. The surface layers of keratin have
many air filled spaces which form reflecting or refracting surfaces to scatter light. Again,
we see this as color. Many of the blues, some of the whites and the iridescence seen on
feathers is caused by structural pigmentation.
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