Photonics Dictionary: O

The emission of gas or de-aeration due to thermal variations and often occurring in a vacuum. In a cleanroom, contamination from the spontaneous emission of absorbed particles.

The figure seen through or imaged by an optical system. It may contain structures, natural or artificial, or it may be the real or virtual image of an object formed by another optical system. In...

A coarse diffraction grating that is used to form a scale of intensities to determine the relative magnitudes of stars. The grating is placed over the objective of a telescope to form a diffraction...

A glow discharge tube placed on an insulating rod to detect the presence of high-frequency radiation in the vicinity of a transmitter. The tube indicates the presence of the radiation by the glow...

A measurement method for reflectance by gas ionization in which light passes through a vapor before and after reflection. Detection is accomplished with a phosphor-tipped lightpipe that leads to a...

Optical artifacts refer to undesired or unintended effects that can occur in optical systems, such as microscopes, cameras, telescopes, and other optical instruments. These artifacts can distort or...

A light absorbing material applied to ground optical surfaces during the process of making that surface non reflective. Such material should have a refractive index as high as that of the underlying...

A device for measuring linear dimensions. The optical caliper generally consists of two circularly mounted mirrors whose angular positions are monitored by an autocollimator, and that are capable of...

Transparent glassy and or crystalline structured materials engineered from inorganic, non-metallic materials via various methods that include heat or specific chemical reactions. Optical ceramics...

Optical coatings are thin layers of materials applied to optical components, such as lenses, mirrors, filters, and prisms, to modify their reflective and transmissive properties. These coatings are...

Optical coherence tomography (OCT) is an imaging technique used in medical diagnostics and biomedical research to obtain high-resolution, cross-sectional images of biological tissues. An OCT imaging...

Typically used for the examination of manufactured or engineered parts, an optical gauging device, in which a backlight is used to project the silhouette of an object upon a screen in which the...

The transmittance of a point on a photographic negative equal to the log to the base 10 of the reciprocal of the transmittance through the negative at that point.

Optical design software refers to specialized computer programs used by optical engineers, physicists, and designers to simulate, model, analyze, and optimize the performance of optical systems and...

Optical fiber is a thin, flexible, transparent strand or filament made of glass or plastic used for transmitting light signals over long distances with minimal loss of signal quality. It serves as a...

An optical gate typically refers to a device or system that controls the transmission of light, allowing it to pass through or be blocked in a manner analogous to an electronic gate controlling the...

Optical materials refer to substances or compounds specifically chosen for their optical properties and used in the fabrication of optical components and systems. These materials are characterized by...

Optical noise refers to undesirable fluctuations or disturbances in an optical signal that can affect the quality or integrity of the transmitted information. This type of noise is particularly...

Optical phase distortion refers to a phenomenon where the phase of an optical wavefront is altered as it propagates through a medium. This distortion can result from variations in the refractive...

Optical strain sensors are devices that utilize optical principles to measure the deformation or strain experienced by a material under mechanical stress. These sensors convert changes in strain into...

One of a class of crystalline substances belonging to triclinic, monoclinic and orthorhombic systems that have two optic axes. Two polarizations are allowed for any given direction of propagation,...

A transparent crystalline substance that displays the same optical properties (i.e. refractive index) in all directions such that all light rays behave the same in all directions of propagation and...

A transparent crystalline substance in which the refractive index of the optic axis (extraordinary axis) is different from the other two crystal axes. Two polarization directions are allowed for any...

Optics is the branch of physics that studies the behavior and properties of light, including its interactions with matter and its manifestation as both particle and wave phenomena. It encompasses the...

Optoacoustic, or photoacoustic, refers to a phenomenon and related techniques that involve the generation of acoustic waves in a material induced by the absorption of light. The term "optoacoustic"...

Optoelectronics is a branch of electronics that focuses on the study and application of devices and systems that use light and its interactions with different materials. The term "optoelectronics" is...

A discipline that combines optics and genetics to enable the use of light to stimulate and control cells in living tissue, typically neurons, which have been genetically modified to respond to light....

An optical coupling device that uses light to bridge the gap between incompatible wire communications systems. It contains an input amplifier, a light-emitting diode, a photodiode and an output...

The ray that has an isotropic speed and maintains a uniform polarization in all propagation directions when traveling in a doubly refracting (birefringent) crystal. It obeys Snell's law upon...

Any organic substance, that when dissolved in appropriate liquid based solvents will absorb and emit electromagnetic radiation in the near ultraviolet, visible and near infrared spectral regions....

A laser having a lasing material that is a fluorescing organic dye. Depending on the dye used, it can produce emission in any part of the visible spectrum into the near-infrared and ultraviolet, and...

An organic light-emitting diode (OLED) is a type of light-emitting diode (LED) technology that utilizes organic compounds to produce light. OLEDs are commonly used in display technologies, such as...

Point at which a laser's material gain is equal to, or greater than, the circuit losses.