Iridescence
Encyclopedia
Iridescence 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 bubble
s, butterfly
wings, and sea shells
.
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.
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.
Soap bubble
A soap bubble is a thin film of soapy water enclosing air, that forms a hollow sphere with an iridescent surface. Soap bubbles usually last for only a few seconds before bursting, either on their own or on contact with another object. They are often used for children's enjoyment, but they are also...
s, butterfly
Butterfly
A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...
wings, and sea shells
Sea Shells
Sea Shells is a 1957 album by Peggy Lee, recorded in early 1955.The album was possibly thought by her record company to be too esoteric, hence its later release. It was her last recording for Decca Records. The album is considered one of Miss Lee's more personal records, featuring a mix of love...
.
Description
Iridescence is an optical phenomenonOptical phenomenon
An optical phenomenon is any observable event that results from the interaction of light and matter. See also list of optical topics and optics. A mirage is an example of an optical phenomenon....
of surfaces in which hue
Hue
Hue is one of the main properties of a color, defined technically , as "the degree to which a stimulus can be describedas similar to or different from stimuli that are described as red, green, blue, and yellow,"...
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
Phase (waves)
Phase in waves is the fraction of a wave cycle which has elapsed relative to an arbitrary point.-Formula:The phase of an oscillation or wave refers to a sinusoidal function such as the following:...
and interference of the reflections modulates
Amplitude modulation
Amplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent...
the incidental light (by amplifying or attenuating some frequencies more than others). This process, termed thin-film interference
Thin-film interference
Thin-film interference is the phenomenon that occurs when incident light waves reflected by the upper and lower boundaries of a thin film interfere with one another to form a new wave. Studying this new wave can reveal information about the surfaces from which its components reflected, including...
, 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 GreekGreek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
word ἶρις îris (gen. ἴριδος íridos), meaning rainbow
Rainbow
A rainbow is an optical and meteorological phenomenon that causes a spectrum of light to appear in the sky when the Sun shines on to droplets of moisture in the Earth's atmosphere. It takes the form of a multicoloured arc...
, which in turn derives from the goddess Iris
Iris (mythology)
In Greek mythology, Iris is the personification of the rainbow and messenger of the gods. As the sun unites Earth and heaven, Iris links the gods to humanity...
of Greek mythology
Greek mythology
Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...
, who is the personification of the rainbow
Rainbow
A rainbow is an optical and meteorological phenomenon that causes a spectrum of light to appear in the sky when the Sun shines on to droplets of moisture in the Earth's atmosphere. It takes the form of a multicoloured arc...
and acted as a messenger of the gods. Goniochromism is derived from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
words gonia, which means angle, and chroma, which means color.
Examples
- the wings of certain insectInsectInsects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s, such as the Morpho butterfly. - the featherFeatherFeathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...
s of some birds, such as kingfisherKingfisherKingfishers are a group of small to medium sized brightly coloured birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species being found in the Old World and Australia...
s, hummingbirdHummingbirdHummingbirds are birds that comprise the family Trochilidae. They are among the smallest of birds, most species measuring in the 7.5–13 cm range. Indeed, the smallest extant bird species is a hummingbird, the 5-cm Bee Hummingbird. They can hover in mid-air by rapidly flapping their wings...
s, parrotParrotParrots, also known as psittacines , are birds of the roughly 372 species in 86 genera that make up the order Psittaciformes, found in most tropical and subtropical regions. The order is subdivided into three families: the Psittacidae , the Cacatuidae and the Strigopidae...
s, crowCrowCrows form the genus Corvus in the family Corvidae. Ranging in size from the relatively small pigeon-size jackdaws to the Common Raven of the Holarctic region and Thick-billed Raven of the highlands of Ethiopia, the 40 or so members of this genus occur on all temperate continents and several...
s, ravenRavenRaven is the common name given to several larger-bodied members of the genus Corvus—but in Europe and North America the Common Raven is normally implied...
s, starlingStarlingStarlings are small to medium-sized passerine birds in the family Sturnidae. The name "Sturnidae" comes from the Latin word for starling, sturnus. Many Asian species, particularly the larger ones, are called mynas, and many African species are known as glossy starlings because of their iridescent...
s, grackleGrackleGrackle can refer to any of eleven black passerine birds native to North and South America. All are members of the Icterid family but belong to multiple genera.* Genus Quiscalus** Boat-tailed Grackle, Quiscalus major...
s, duckDuckDuck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered...
s, and peacocks. - the shells of some mollusks such as abaloneAbaloneAbalone , from aulón, are small to very large-sized edible sea snails, marine gastropod molluscs in the family Haliotidae and the genus Haliotis...
. - in animals, the tapetum lucidumTapetum lucidumThe tapetum lucidum is a layer of tissue in the eye of many vertebrate animals....
, present in the eyeEyeEyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...
s of many vertebrates. - rare in plants, e.g., blue-ish leaves of Selaginella willdenowii, Selaginella uncinataSelaginella uncinataSelaginella uncinata is a species of plant in the Selaginellaceae family....
, and MicrosorumMicrosorumMicrosorum is a genus of over fifty species of tropical ferns. Like most ferns, they grow from rhizomes, rather than roots. The genus name is often mis-spelled "Microsorium" or "Microsoreum". It includes some species that are lithophytic rheophytes....
thailandicum - pearlescent paints or interference pigments sometimes used for custom paint jobs on cars.
See also
- BioluminescenceBioluminescenceBioluminescence is the production and emission of light by a living organism. Its name is a hybrid word, originating from the Greek bios for "living" and the Latin lumen "light". Bioluminescence is a naturally occurring form of chemiluminescence where energy is released by a chemical reaction in...
, irrespective of angles - AnisotropyAnisotropyAnisotropy is the property of being directionally dependent, as opposed to isotropy, which implies identical properties in all directions. It can be defined as a difference, when measured along different axes, in a material's physical or mechanical properties An example of anisotropy is the light...
- Cloud iridescenceCloud iridescencethumb|260px|Cloud iridescenceCloud iridescence is the occurrence of colors in a cloud similar to those seen in oil films on puddles, and is similar to irisation. It is a fairly uncommon phenomenon, most often observed in altocumulus, cirrocumulus and lenticular clouds, and very rarely in Cirrus...
- Dichroic filterDichroic filterA dichroic filter, thin-film filter, or interference filter is a very accurate color filter used to selectively pass light of a small range of colors while reflecting other colors. By comparison, dichroic mirrors and dichroic reflectors tend to be characterized by the color of light that they...
- DichroismDichroismDichroism has two related but distinct meanings in optics. A dichroic material is either one which causes visible light to be split up into distinct beams of different wavelengths , or one in which light rays having different polarizations are absorbed by different amounts.The original meaning of...
- Labradorescence – Adularescence
- Iridocyte
- Thin-film opticsThin-film opticsThin-film optics is the branch of optics that deals with very thin structured layers of different materials. In order to exhibit thin-film optics, the thickness of the layers of material must be on the order of the wavelengths of visible light...
- OpalescenceOpalescenceOpalescence is a type of dichroism seen in highly dispersed systems with little opacity. The material appears yellowish-red in transmitted light and blue in the scattered light perpendicular to the transmitted light. The phenomenon is named after the appearance of opals.There are different degrees...
External links
- Living photonic crystals
- A 2.2 MB GIF animation of a morpho butterfly showing iridescence
- "Article on butterfly iridescence"
