* Optical or infrared: The individual galaxies of clusters can be studied through optical or infrared imaging and spectroscopy.

* Raman Optical Activity spectroscopy

Optical spectroscopy can be further divided into absorption, emission, and fluorescence.

* Optical isotope shifts of Nd II by collinear fast-ion-beam laser spectroscopy ; Ma Hongliang, Shi Wei, Yan Bin, Li Yong, Fang Dufei, Lu Fuquan, Tang Jiayong and Yang Fujia ; J. Phys.

* Optical gain spectroscopy of semiconductor laser materials.

Since 1970, the Optical Society of America has awarded the William F. Meggers Award for outstanding work in spectroscopy.

* Optical atomic spectroscopy, such as flame atomic absorption, graphite furnace atomic absorption, and inductively coupled plasma atomic emission, which probe the outer electronic structure of atoms.

Optical bistability is an attribute of certain optical devices where two resonant transmissions states are possible and stable, dependent on the input.

Optical isomerism occurs when a molecule is not superposable with its mirror image.

The focus is on seven sectors, which stand for sustainable economic growth: Automotive, Energy Solutions, Information and Communications Technology, Life Sciences, Optical Technologies, Creative Industries and Production Engineering.

The observatory is administered by the National Optical Astronomy Observatory ( NOAO ).

* Optical switching technology, which is used for switching technology and alignment for data communications

Optical mineralogy is a specific focus of mineralogy that applies sources of light as a means to identify and classify minerals.

The primary benefit is to eliminate dependence on a particular OSI model data link layer technology, such as Asynchronous Transfer Mode ( ATM ), Frame Relay, Synchronous Optical Networking ( SONET ) or Ethernet, and eliminate the need for multiple layer-2 networks to satisfy different types of traffic.

For example, Optical illusions are errors in the conceptual identification of what is seen, not errors in sight itself.

Optical science is relevant to and studied in many related disciplines including astronomy, various engineering fields, photography, and medicine ( particularly ophthalmology and optometry ).

* Optical disc authoring # Sessions, how data is laid out on an optical disc

Optical proximity correction is an example of such an advanced mask modification ; it corrects for the wave-like behavior of light when etching the nano scale features of the most modern integrated circuits.

* April 22 – Optical fiber is first used to carry live telephone traffic.

Optical depth, or optical thickness, is a measure of transparency.

Optical depth is defined as the negative natural logarithm of the fraction of radiation ( e. g., light ) that is not scattered or absorbed on a path.

According to Gerry / Gerald Butters, the former head of Lucent's Optical Networking Group at Bell Labs, there is another version, called Butter's Law of Photonics, a formulation which deliberately parallels Moore's law.

Optical networking and dense wavelength-division multiplexing ( DWDM ) is rapidly bringing down the cost of networking, and further progress seems assured.

Optical rotation ( optical activity ) is the turning of the plane of linearly polarized light about the direction of motion as the light travels through certain materials.

Optical activity is a type of birefringence.

See Optical vortex, which explains that the outcoming wave from a pitch-fork hologram is a sub-family of HyGG modes.

Optical heterodyne detection ( an area of active research ) is an extension of the heterodyning technique to higher ( visible ) frequencies.

An Optical Network Terminal ( ONT ) is a type of NID used with fiber-to-the-premises applications.

Optical path length is important because it determines the phase of the light and governs interference and diffraction of light as it propagates.

Optical path difference is the phase shift which happens between two previously coherent sources when passed through different mediums.

* Optical pumping, a process in which light is used to raise electrons from a lower energy level in an atom or molecule to a higher one

Optical coherence tomography ( OCT ) represents a powerful clinical tool for monitoring retinal physiology in patients.

The telescope hosts three instruments: the 67-million pixel Wide Field Imager with a field of view as large as the full Moon, which has taken many amazing images of celestial objects ; GROND, the Gamma-Ray Burst Optical / Near-Infrared Detector, which chases the afterglows of the most powerful explosions in the Universe, known as gamma-ray bursts ; and the high-resolution spectrograph, FEROS, used to make detailed studies of stars.

The Infrared Optical Telescope Array ( IOTA ) began with an agreement in 1988 among five Institutions, the Smithsonian Astrophysical Observatory, Harvard University, the University of Massachusetts Amherst, the University of Wyoming, and MIT / Lincoln Laboratory, to build a two-telescope stellar interferometer for the purpose of making fundamental astrophysical observations, and also as a prototype instrument on which we could perfect techniques which could later lead to the development of a larger, more powerful array.

: Optical heterodyne detection is an extension of the heterodyne technique to higher ( visible ) frequencies.

* Optical spectrometry, a technique for measuring the distribution of light across the optical spectrum, from the UV spectral region to the visible and infrared.

* BBC Frontier covering the technique of Optical Tweezers 2003

Optical levitation is a technique in which a material is levitated against the downward force of gravity by an upward force stemming from photon momentum transfer.

Optical coherence tomography is an interferometric technique, typically employing near-infrared light.

Optical Coherence Tomography, or ‘ OCT ’, is a technique for obtaining sub-surface images of translucent or opaque materials at a resolution equivalent to a low-power microscope.

Optical Coherence Tomography ( OCT ) is another NIR medical imaging technique capable of 3D imaging with high resolution on par with low-power microscopy.

Since then the technique has been improved upon, notably by Bouyer's team at Groupe d ' Optique Atomique Laboratoire at the Charles Fabry Optical Institute.

Optical burst switching ( OBS ) is an optical networking technique that allows dynamic sub-wavelength switching of data.

While Non-binary, or M-ary, modulation is common in the telecom industry, the technique was originally developed and patented for optical disc recording at Optex Corporation in the early 1990s ( in conjunction with the University of Rochester ) for use with their Electron Trapping Optical Media ( ETOM ).

Optical imaging is an imaging technique.

Diffusive Optical Imaging ( DOI ) also known as Near Infrared Optical tomography ( NIROT ) or Diffuse Optical Tomography ( DOT ) is a technique that gives neuroscientists the ability to simultaneously obtain information about the source of neural activity as well as its time course.

Optical lithography, which has been the predominant patterning technique since the advent of the semiconductor age, is capable of producing sub-100-nm patterns with the use of very short wavelengths ( currently 193 nm ).

Optical molasses is a laser cooling technique that can cool down neutral atoms to temperatures colder than a magneto-optical trap ( MOT ).