Iridescence
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Image:Blue morpho butterfly.jpg Image:Soap Bubble - foliage background - iridescent colours - Traquair 040801.jpg
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, such as soap bubbles and butterfly wings.
Iridescence is caused by multiple reflections from multi-layered, semi-transparent surfaces where the subsequent phase shift and interference of the reflections modulates the incident light (by amplifying or attenuating different frequencies). This process is the functional analog of selective wavelength attenuation as seen with the Fabry-Perot 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 observing iridescence requires seeing a surface from different angles, the effect is not captured by standard film or digital photography; indeed, the only static image process that can display iridescence is holography.