Iridescence

"Pearlescent" redirects here. For the type of paint, see Pearlescent coatings.

"Iridescent" redirects here. For the Linkin Park song, see Iridescent (song).

Iridescence in soap bubbles

A female Golden Stag Beetle has a highly iridescent shell

The iridescence of the Morpho didius butterfly wings

A peacock's tail feathers are iridescent.

Iridescence (also known as goniochromism) is generally known as the property of certain surfaces which appear to change color as the angle of view or the angle of illumination changes. Iridescence is commonly seen in items such as soap bubbles, butterfly wings, and sea shells.

Description

Iridescence is an optical phenomenon of surfaces in which hue changes in correspondence with the angle from which a surface is viewed.

Iridescence is often caused by multiple reflections from two or more semi-transparent surfaces in which phase shift and interference of the reflections modulates the incidental light (by amplifying or attenuating some frequencies more than others). This process, termed thin-film interference, is the functional analog of selective wavelength attenuation as seen with the Fabry–Pérot interferometer.

Etymology

The word iridescence is derived in part from the Greek word ἶρις îris (gen. ἴριδος íridos), meaning rainbow, which in turn derives from the goddess Iris of Greek mythology, who is the personification of the rainbow and acted as a messenger of the gods. Goniochromism is derived from the Greek words gonia, which means angle, and chroma, which means color.

Examples

• the wings of certain insects, such as the Morpho butterfly.
• the feathers of some birds, such as kingfishers, hummingbirds, crows, ravens, starlings, grackles, ducks, and peacocks.
• the shells of some mollusks such as abalone.
• in animals, the tapetum lucidum, present in the eyes of many vertebrates.
• rare in plants, e.g., blue-ish leaves of Selaginella willdenowii, Selaginella uncinata, and Microsorum thailandicum
• pearlescent paints or interference pigments sometimes used for custom paint jobs on cars.

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  The iridescent inside surface of a red abalone shell

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  Ammolite is a gemstone consisting of iridescent ammonite fossils

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  The wings of Tachinid fly demonstrate iridescent colors that are due to the surface structures

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  Goethite, a form of iron oxide, is occasionally iridescent, as in this specimen from Polk County, Arkansas.

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  An iridescent catfish that looks like a shark

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  Rainbow boas get their name from the coloration of their scales caused by iridescence.

See also

• Bioluminescence, irrespective of angles
• Anisotropy
• Cloud iridescence
• Dichroic filter
• Dichroism
• Labradorescence – Adularescence
• Iridocyte
• Thin-film optics
• Opalescence

External links

• Living photonic crystals
• A 2.2 MB GIF animation of a morpho butterfly showing iridescence
• "Article on butterfly iridescence"