Thin-film optics

Thin Film Optics

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Thin-film optics

Thin-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 (about 500 nm

Nanometre

A nanometre is a Units of measurement of length in the metric system, equal to one billionth of a metre .It is one of the more often used units for very small lengths, and equals ten ?ngstr?m, an internationally recognized non-International System of Units of length....
). Layers at this scale can have remarkable reflective properties due to light wave interference

Interference

In physics, interference is the addition of two or more waves that result in a new wave pattern.Interference usually refers to the interaction of waves which are correlated or Coherence with each other, either because they come from the same source or because they have the same or nearly the same frequency....
and the difference in refractive index

Refractive index

The refractive index of a medium is a measure for how much the speed of light is reduced inside the medium. For example, typical soda-lime glass has a refractive index of 1.5, which means that in glass, light travels at times the speed of light in a vacuum....
between the layers, the air, and the substrate.

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Nanometre

Interference

Refractive index

Reflection (physics)

Reflection is the change in direction of a wavefront at an wiktionary:interface between two differentmedium so that the wavefront returns into the medium from which it originated....
and transmits

Transmission (telecommunications)

In telecommunications, transmission is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired or wireless....
light. This effect is observable in soap bubble

Soap bubble

A soap bubble is a very thin film of soap water that forms a sphere with an iridescence surface. Soap bubbles usually last for only a few moments before bursting: either on their own or on contact with another object....
s and oil slicks.

More general periodic structures, not limited to planar layers, are known as photonic crystal

Photonic crystal

Photonic crystals are periodic optical nanostructures that are designed to affect the motion of photons in a similar way that periodicity of a semiconductor crystal affects the motion of electrons....
s.

In manufacturing, thin film

Thin film

Thin films are thin material Layer s ranging from fractions of a nanometre to several micrometres in thickness. Electronics semiconductor devices and optical coatings are the main applications benefiting from thin film construction....
layers can be achieved through the deposition of one or more thin layers of material onto a substrate (usually glass

Glass

Glass generally refers to a Hardness, brittle, transparency amorphous solid, such as that used for windows, many Glass Bottles, or eyewear, including, but not limited to, soda-lime glass, borosilicate glass, acrylic glass, sugar glass, Muscovite , or aluminium oxynitride....
), most often by a physical vapor deposition

Physical vapor deposition

Physical vapor deposition is a variety of vacuum deposition and is a general term used to describe any of a variety of methods to deposit thin films by the condensation of a vaporized form of the material onto various surfaces ....
process such as evaporative or sputter deposition

Sputter deposition

Sputter deposition is a physical vapor deposition method of thin film deposition thin films by sputtering, i.e. ejecting, material from a "target," i.e., source, which then deposits onto a "substrate," e.g., a silicon wafer....
, or a chemical process such as chemical vapor deposition

Chemical vapor deposition

Chemical vapor deposition is a chemical process used to produce high-purity, high-performance solid materials. The process is often used in the semiconductor industry to produce thin films....
.

Thin films are used to create optical coating

Optical coating

An optical coating is a thin-film optics of material deposited on an optical component such as a lens or mirror, which alters the way in which the optic Reflection and transmission light....
s. Examples include low-emissivity panes of glass

Glass

Anti-reflective coating

Anti-reflective or antireflection coatings are a type of optical coating applied to the surface of lens es and other optical devices to reduce reflection ....
s on glasses

Glasses

Glasses or specs, more formally known as eyeglasses or spectacles, are frames bearing lens worn in front of the eyes, normally for Corrective lens, eye protection, or for UV Coating....
, reflective baffles on car headlights, and for high precision optical filters

Filter (optics)

Optical filters, generally, belong to one of two categories. The simplest, physically, is the absorptive filter, while the latter category, that of interference or dichroic filters, can be quite complex....
and mirror

Mirror

A mirror is an object with one surface polished, which leads to reflection and another opaque. The most familiar type of mirror is the plane mirror, which has a flat surface....
s. Another application of these coatings is spatial filter

Spatial filter

A spatial filter is an optical device which uses the principles of Fourier optics to alter the structure of a beam of coherence light or other electromagnetic radiation....
ing.

Thin-film layers are common in the natural world. Their effects produce colors seen in soap bubbles and oil slicks, as well as in some animals. For example, the light collecting tapetum lucidum
Tapetum lucidum

The tapetum lucidum is a layer of tissue in the eye of many vertebrate animals, that lies immediately behind or sometimes within the retina. It Reflection visible light back through the retina, increasing the light available to the Photoreceptor cell....
of many nocturnal species and the photophore

Photophore

A photophore is a light-emitting organ which appears as luminescence spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye; equipped with lenses, shutters, color filters and reflectors ....
s of bioluminescent

Bioluminescence

Bioluminescence is the production and emission of light by a living organism as the result of a chemical reaction during which chemical energy is converted to light energy....
squid (e.g. the Bobtail squid

Bobtail squid

Bobtail squid are a group of cephalopods closely related to cuttlefish. Bobtail squid tend to have a rounder mantle than cuttlefish and have no cuttlebone....
). In many cases, iridescent colors that were once thought to result from planar layers, such as in opal

Opal

Opal is a mineraloid gel which is deposited at a relatively low temperature and may occur in the fissures of almost any kind of Rock , being most commonly found with limonite, sandstone, rhyolite, and basalt....
s, peacocks, and the Blue Morpho

Blue Morpho

The Blue Morpho refers to several species of butterfly, including:* Morpho menelaus * Morpho peleides * Morpho rhetenor...
butterfly, turn out to result from more complex periodic photonic-crystal structures.

Thin-film optics

Further reading

See also