Photonics Dictionary

A corrective lens system that is placed near the focal plane of a Newtonian telescope to increase its effective field of view by correcting for coma formed by the telescope's paraboloidal mirror.

A Rugate filter is a type of optical filter that is designed to have a continuously varying refractive index profile throughout its thickness, rather than the discrete layers found in traditional...

Sapphire optical fiber is a type of optical fiber made from single-crystal sapphire, which is a form of aluminum oxide (Al2O3) that is highly transparent in the infrared region of the electromagnetic...

A sapphire window refers to a transparent optical component made from sapphire crystal. Sapphire is a single-crystal form of aluminum oxide (Al2O3) that is highly prized for its exceptional optical...

Sapphire refers to a crystalline form of aluminum oxide (Al2O3) that is used in various optical and photonic applications due to its exceptional optical, mechanical, and thermal properties. Sapphire...

A scintillation crystal, also known simply as a scintillator, is a material that emits light when it interacts with ionizing radiation such as gamma rays, x-rays, or charged particles. The emitted...

Seidel aberrations refer to a set of monochromatic aberrations in optical systems, named after the German mathematician and physicist Ludwig von Seidel. These aberrations describe deviations from...

Self-phase modulation (SPM) is a nonlinear optical phenomenon that occurs when an intense laser beam passes through a medium, causing a change in the phase of the light due to its interaction with...

The Shack-Hartmann wavefront sensor is an optical device used for measuring the wavefront aberrations of an optical system. It is widely used in adaptive optics systems to correct distortions and...

1. The sorting of lenses by their color. 2. In an optical system, an irradiance or brightness gradient in the image that is not present at the object.

A convention that defines specific dimensions of an optical system, such as the image distance or radius of curvature of a lens or mirror, as negative or positive to facilitate calculations based on...

A silicon photodiode is a semiconductor device that converts light into an electrical current. It is a type of photodetector specifically designed for detecting and measuring light intensity. Silicon...

An object that has a sinusoidal variation of luminance. Its image will have a sinusoidal variation of illuminance and the only effect of degeneration by the lens system will be to reduce the...

A single-photon avalanche diode (SPAD) is a specialized type of photodetector designed to detect extremely weak optical signals, down to the level of single photons. SPADs are widely used in...

A solar simulator is a device used to replicate the spectrum and intensity of sunlight in a controlled environment for testing and research purposes. Solar simulators are employed in various...

A spatial light modulator (SLM) is an optical device that modulates or manipulates the amplitude, phase, or polarization of light in two dimensions, typically in the form of an array. SLMs are...

With respect to color photography, the measurement, at a given wavelength, of the way the color film modulates the radiant flux in the optical system containing the film.

Spectral repeatability refers to the consistency and reproducibility of spectral measurements across multiple trials or instances. It is a measure of how well a measurement instrument or system can...

A spectral signature, in the context of remote sensing and spectroscopy, refers to the unique pattern or characteristic spectral response of a material or object across different wavelengths of the...

A spheric lens, also known as a spherical lens, is a type of optical lens with at least one surface that is part of a sphere. This means that the lens surface is curved in a symmetrical manner,...

Spherical aberration is an optical aberration that occurs when light rays passing through a lens or curved optical surface do not converge or diverge to a single focal point. Instead of focusing to a...

A device through which scintillations are observed or counted through a magnifying lens system.

Correction of an optical system at four separate wavelengths. This correction, longitudinal and lateral, is possible with the help of three selected special glasses.

Supercontinuum refers to a broad spectrum of light that spans a wide range of wavelengths, typically from the visible to the near-infrared or even mid-infrared regions of the electromagnetic...

A lens system made up of two sets of similar lenses, each of which compensates for many of the aberrations produced by the other. The lens sets are arranged symmetrically on either side of the...

The equivalent f number of a fictitious lens that has a circular opening and 100 percent transmittance, which would give the same central illumination as the lens being considered: where...

A telescope lens is a primary optical component of a telescope system that gathers and focuses light to form an image. It is typically a curved, transparent piece of glass or other optical material...

Thermophotovoltaic (TPV) refers to a technology that converts heat energy into electricity using the principles of thermophotovoltaics. In a thermophotovoltaic system, thermal radiation from a heat...

(TOF) The length of time needed for a signal to arrive at and be reflected from the target. The basis of an active autoranging/autofocus system.

A Ti:sapphire laser is a type of solid-state laser that utilizes a titanium-doped sapphire crystal as the gain medium. The name Ti:sapphire comes from the combination of titanium (Ti) as the dopant...

A color-television viewing system with three kinescopes, three lenses and three deflection yokes used to form the red, green and blue images required for a tricolor television projection.

A compound lens consisting of two negative lenses of flint glass. A double-convex lens of crown glass is cemented between the two negative lenses. With this system, it is possible to decrease...

Ultraviolet-C (UV-C) refers to a specific range of ultraviolet radiation with shorter wavelengths than those of visible light. UV-C radiation spans the electromagnetic spectrum with wavelengths...

Ultraviolet (UV) fiber optics refers to optical fibers that are designed and optimized for the transmission of ultraviolet light, which is electromagnetic radiation with wavelengths shorter than...

An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without a human pilot onboard. UAVs are remotely controlled or autonomously operated, and they can be used for various...

In optics, the term vacuum typically refers to a space devoid of matter, including air and other gases. However, in practical terms, achieving a perfect vacuum, where there is absolutely no matter...

Van der Waals forces refer to the attractive or repulsive forces between molecules (or parts of molecules) that arise from fluctuations in electron distribution. These forces are relatively weak...

Virtual histology refers to the use of digital technology and computational methods to simulate or recreate histological images and structures without the need for traditional physical slides and...

Volume Bragg gratings (VBGs) are specialized optical elements that consist of periodic variations in refractive index throughout the volume of a transparent material, typically a photosensitive glass...

In the context of electronics and semiconductor manufacturing, a wafer refers to a thin, flat disk or substrate made of a semiconducting material, usually crystalline silicon. Wafers serve as the...

A system that allows the transmission of more than one signal over a common path, by assigning each signal a different frequency band. Also known as frequency division multiplexing.

A well plate, also known as a microplate or microtiter plate, is a flat plate with multiple small wells or depressions arranged in a grid pattern. Each well serves as a separate container for holding...

A wide-angle lens is a type of camera lens that has a shorter focal length than a standard or normal lens, allowing it to capture a broader field of view. Wide-angle lenses are characterized by their...

A YAG crystal refers to a solid-state crystal made of yttrium aluminum garnet (YAG), which is a synthetic crystalline material. YAG crystals are known for their exceptional optical properties,...

Zerodur is a type of glass ceramic material known for its exceptional thermal and mechanical properties, particularly its low coefficient of thermal expansion (CTE) close to zero. It was developed by...