Photonics Dictionary

The shortest wavelengths of the infrared region, nominally 0.75 to 3 µm.

Mechanical device intended for the translation (rotational and linear) using high precision control from electronically operated circuits. See linear actuator; rotary actuator.

An aerial reconnaissance system that can transmit, in near real time, image data recorded by IR and visual-spectrum sensors, providing day, night and foul-weather intelligence.

A support device in which a column or chamber of air permits the free travel of a mobile part. In optical mounting and positioning equipment, air bearings are of two types, linear or rotary,...

The equation devised by Sir G.B. Airy for the analysis of light diffraction near a caustic surface: (d2f/dz2) - zf = 0 where z represents the independent variable, and f is the value of the function.

An alexandrite laser is a solid-state laser that utilizes a synthetic crystal made from the rare earth element alexandrite (BeAl2O4:Cr3+). This crystal is capable of emitting laser light in the...

The all-encompassing noise associated with a given environment, usually being a composite of a number of sources, far and near.

An arc flash is a sudden release of electrical energy due to an electric arc — a continuous, high-current discharge of electricity between conductors or from a conductor to ground. Arc flashes...

An autocollimator is an optical instrument used for measuring small angular deviations with high precision. It operates on the principle of autocollimation, where a light source is directed onto a...

A device that utilizes avalanche multiplication of photocurrent by means of hole-electrons created by absorbed photons. When the device's reverse-bias voltage nears breakdown level, the hole-electron...

Azimuthal polarization refers to a specific polarization state of light where the electric field vector of the electromagnetic wave points along the azimuthal direction (around the propagation axis)....

An amplifying device with a wide tuning range in which an electron gun sends a beam of electrons into a slow-wave structure. The electron beam and the electromagnetic wave move in opposite directions...

A device used to compare the luminous intensities of two sources by locating a point between the two light sources where the produced flux densities are equal. The luminous intensities of the two...

It is often necessary to estimate the value of what a pixel would be between neighboring pixels. This is accomplished by interpolating (or inserting) the value of a pixel between neighboring pixels....

A microscope that allows examination of a small crystal and conveniently provides linearly polarized object and reference beams so that, by suitable orientation of an anisotropic crystal, the optical...

A type of comparator with a telescope equipped with a cross wire mounted on a vertical sliding column. It is used to measure vertical distances on fairly near objects.

A CCD camera, or charge-coupled device camera, is a type of digital camera that utilizes a CCD image sensor to capture and record images. CCD cameras are widely used in various applications,...

Chalcogenide refers to a class of compounds containing elements from group 16 of the periodic table, which includes sulfur (S), selenium (Se), and tellurium (Te). These elements are known as...

A fiber optic communications system that works on the principles of homodyning or heterodyning. The transmitting laser produces an optical wave that is modulated in amplitude, phase or frequency by...

A method of exciting a laser by coupling it directly to another laser.

1. A constituent part. It may consist of two or more parts cemented together, or with near and approximately matching surfaces. 2. The projection of a vector on a certain coordinate axis or along a...

Concave is an adjective used to describe a surface or shape that curves inward or has a hollow or recessed appearance. In the context of geometry or optics, a concave shape is one that curves or...

A system consisting of two or more Geiger-Müller counters, connected in coincidence with their centers on an axis. The only particles recorded are those traversing all counters, near the axis,...

Deep learning is a subset of machine learning that involves the use of artificial neural networks to model and solve complex problems. The term "deep" in deep learning refers to the use of deep...

A detector array refers to a collection of individual detector elements arranged in a two-dimensional grid or matrix format. Each element within the array is capable of detecting electromagnetic...

A type of pyroelectric detector with favorable qualities of linearity, sensitivity and spectral responsivity used in FTIR detectors.

Dichroism refers to the property of certain materials to exhibit different colors or absorbance of light depending on the direction of light propagation or polarization. The term is commonly used in...

A dispersion-shifted fiber (DSF) refers to a type of optical fiber designed to minimize the effects of chromatic dispersion, which is the phenomenon where different wavelengths of light travel at...

A diverging lens is a type of lens that causes parallel rays of light to spread out or diverge. It is thinner in the center than at the edges and is commonly referred to as a concave lens. The most...

Double-clad fiber (DCF) is a specialized optical fiber that features two concentric cladding layers surrounding a core. The design of double-clad fibers allows them to be used in various...

The ability of a device to operate without electromagnetically interfering with the operation of nearby equipment and without suffering disturbances from the electromagnetic fields in its designated...

A femtosecond laser is a type of laser that emits ultrashort pulses of light with durations on the order of femtoseconds, where one femtosecond is equal to 10-15 seconds. These lasers are capable of...

A wide-field multiobject spectroscopy system used in astronomy, in which a bundle of low-loss optical fibers positioned on the target images is rearranged at its other end into a linear array along...

Fluorescence lifetime refers to the average time it takes for a fluorophore, a molecule that absorbs light at one wavelength and emits it at another, to return to its ground state after being excited...

FMCW lidar stands for frequency-modulated continuous wave lidar. It is a type of lidar (light detection and ranging) technology used for remote sensing, distance measurement, and 3D mapping. FMCW...

A free-electron laser (FEL) is a type of laser that generates coherent, high-intensity electromagnetic radiation by using a beam of accelerated electrons as the lasing medium. Unlike traditional...

A frequency comb is a precise and regular series of equally spaced spectral lines, or frequencies, that are generated with great accuracy. The term "frequency comb" is often associated with the Nobel...

A Fresnel lens is a type of optical lens that consists of a series of concentric grooves or steps carved into a flat, thin piece of transparent material, typically plastic or glass. This design...

Functional near-infrared spectroscopy (fNIRS) is a non-invasive neuroimaging technique that measures changes in hemoglobin concentration in the brain. It utilizes near-infrared light to penetrate the...

Fusion ignition refers to the point in a controlled nuclear fusion reaction where the energy released by the fusion reactions becomes self-sustaining, leading to a continuous release of energy...

A GaAlAs laser is a type of semiconductor laser diode that emits light in the near-infrared region of the electromagnetic spectrum. It is composed of layers of gallium, aluminum, and arsenic, hence...

Gallium arsenide phosphide (GaAsP) is a semiconductor alloy composed of gallium (Ga), arsenic (As), and phosphorus (P). It is commonly used in the fabrication of optoelectronic devices, particularly...