iridescence

 

(ĭr'ədĕs'əns) , exhibition of rainbowlike colors on a surface. It usually results from interference when light composed of different wavelengths is reflected from the superficial layers of organic or inorganic substances, e.g., minerals, mother-of-pearl, and the feathers of birds. Iridescence greatly enhances the value of certain gems.

It has been suggested that Goniochromism be merged into this article or section. (Discuss)

Iridescence is an optical phenomenon characterized as the property of surfaces in which hue changes according to the angle from which the surface is viewed (as may be seen of soap bubbles and butterfly wings).

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

The word is derived in part from the Greek word iris (pl. irides), 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.

Because the apparent image changes with the angle of observation, iridescence is not reproduced by conventional still image photography; however, it can be reproduced by holography (which includes phase information).

See also

• Dichroism
• Dichroic filter
• Goniochromism
• Thin-film optics

External links

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

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