All articles starting with O
9,097 articles
Optical spectrum analysis
Optical spectrum analysis measures how the power of light is distributed over wavelength or optical frequency, using an optical spectrum analyzer for laser characterization and fiber-optic network testing.
Optical spin–orbit interaction
Optical spin–orbit interaction is the coupling between the spin angular momentum and orbital angular momentum of light, first formulated by Liberman and Zel'dovich in 1992.
Optical Stark effect
The optical Stark effect is the optical analog of the Stark effect, where a strong light field shifts transition energies; in monolayer WS2 it lifts valley degeneracy by up to 18 meV.
Optical stretcher
The optical stretcher is a dual-beam laser trap that deforms suspended cells between two opposed, unfocused laser beams to measure their viscoelastic mechanical properties, introduced in 2001.
Optical switching
Optical switching is the redirection of an optical signal from one path to another without optical-electrical-optical conversion, using technologies like MEMS mirrors and lithium niobate switches in fiber networks.
Optical telegraph
The optical telegraph, or semaphore telegraph, is a signaling system that sent coded messages between towers by movable arms and shutters, pioneered by Claude Chappe in 1790s France.
Optical telescope
An optical telescope, also known as a visible light telescope, gathers and focuses visible light using lenses or mirrors; types include refractors, reflectors, and catadioptric systems.
Optical theorem
The optical theorem, sometimes called the shadow theorem, is a relation in scattering theory linking a scatterer's total cross section to the forward scattering amplitude.
Optical thermometry
Optical thermometry, also known as luminescence or phosphor thermometry, measures temperature remotely from a phosphor's emission-band ratio or decay lifetime, enabling non-contact maps from cryogenic temperatures to 2000 K, down to the nanoscale.
Optical time-division multiplexing
Optical time-division multiplexing (OTDM) combines several optical signals by temporal interleaving on one wavelength and separates them later by arrival time, reaching serial rates beyond electronic limits.
Optical time-domain reflectometer
An optical time-domain reflectometer (OTDR) is a test instrument that injects light pulses into optical fiber and produces a trace showing fiber length, loss, and fault locations.
Optical tomography
Optical tomography is a medical imaging technique that reconstructs 3D maps of light absorption and scattering in tissue, applied to tumor imaging and brain function.
Optical torque
Optical torque is the twisting mechanical effect produced when light transfers angular momentum to matter. It was first measured mechanically in 1936 and now drives micromachines and single-molecule studies.
Optical transceiver
An optical transceiver is a module that combines an optical transmitter and receiver in one package, converting electrical signals to light and back for fiber links.
Optical transfer function
The optical transfer function (OTF) describes how an optical imaging system, such as a camera or microscope, transfers contrast and phase of spatial detail from object to image.
Optical Transport Network
The Optical Transport Network (OTN), sometimes called the Optical Transport Hierarchy, is an ITU-T standardized architecture that multiplexes many service types onto high-capacity optical wavelengths.
Optical trapping in liquid crystals
Optical trapping in liquid crystals uses focused laser light, typically optical tweezers, to hold, move, and assemble particles and defects dispersed in a nematic liquid crystal.
Optical tweezer array
An optical tweezer array is a set of focused laser beams that trap individual neutral atoms as qubits, a leading platform for quantum computing and simulation.
Optical tweezer-array atomic clock
An optical tweezer-array atomic clock, or tweezer clock, is an optical atomic clock in which many individually trapped neutral atoms are interrogated together, combining lattice-clock precision with single-atom control.
Optical tweezers
Optical tweezers, also called laser tweezers, are scientific instruments in which a tightly focused laser beam traps a microscopic particle in three dimensions, first demonstrated by Arthur Ashkin in 1986.
Optical vector analysis
Optical vector analysis (OVA) measures the magnitude and phase response of optical components such as filters and resonators; commercial instruments, notably Luna Technologies' OVA 1550, test a full component in under 30 seconds.
Optical vestigial sideband modulation
Optical vestigial sideband modulation (optical VSB) is a modulation format for fiber and free-space optical links that transmits one sideband in full plus a retained vestige of the other.
Optical vortex
An optical vortex, also called twisted light, is a beam of light with a helical wavefront, a dark central core, and quantized orbital angular momentum per photon.
Optical waveguide
An optical waveguide is a structure that guides light by confining it in a higher-index core, the principle behind optical fibers, integrated optics, fiber lasers, and waveguide sensors.
Optical-field-induced current in dielectrics
Optical-field-induced current in dielectrics is laser-driven current in an insulator, first shown in fused silica in 2012–2013, raising conductivity over 18 orders of magnitude within 1 femtosecond.
Optical-resolution photoacoustic microscopy
Optical-resolution photoacoustic microscopy (OR-PAM) is a photoacoustic imaging technique that images optical absorption in biological tissue, resolving single capillaries and cells to depths of about 1 mm.
Optically detected magnetic resonance
Optically detected magnetic resonance (ODMR) is a spectroscopy technique that detects magnetic resonance of spins through fluorescence changes, first reported in 1959 and now used for nanoscale magnetometry with diamond defects.
Optically levitated nanoparticle
An optically levitated nanoparticle is a nanoscale dielectric object, typically a silica sphere around 100 nm wide, held in vacuum by a focused laser beam for precision sensing.
Optically pumped magnetometer
An optically pumped magnetometer (OPM) is a magnetic field sensor that reads the Larmor precession of laser-pumped alkali vapor atoms, reaching femtotesla sensitivity comparable to SQUIDs.
Optically stimulated luminescence
Optically stimulated luminescence (OSL) is the light emitted by a material previously exposed to ionizing radiation when stimulated by light, used in dosimetry and sediment dating.