Photonics Dictionary

That term pertaining to the spectral region that can be perceived by the eye.

That region of the electromagnetic spectrum to which the retina is sensitive and by which the eye sees. It extends from about 400 to 750 nm in wavelength.

A satellite-borne remote sensing device capable of transmitting images at 10 and 20 m resolution from an altitude of 830 km, each sensor covering a ground area of 60 km, by means of a folded...

A filter that transmits infrared and ultraviolet but is opaque to visible radiation.

The smallest area of uniform brightness that can be seen by the eye. It is measured in terms of the solid angle subtended by that area from the eye.

Also known as UV-VIS spectrometer, a device that measures the absorbance, reflectance or transmittance of light in the ultraviolet or visible wavelengths absorbed, reflected or transmitted. Commonly...

A dispersion relation defined in order to value the reciprocal amount of dispersion. It is defined as the refractivity over the difference in index values of the shortest and longest visible...

The absolute luminance threshold is the lowest luminance level of a light source or illuminated object that can be detected by the human eye under specific conditions. This threshold represents the...

Absolute white is a term used in color science and imaging to describe a reference white point that represents the brightest, most neutral white achievable. It serves as a standard for measuring and...

An absorption lens is a type of optical lens that not only focuses or diverges light but also significantly absorbs certain wavelengths of the incident light. This dual function makes it different...

An absorption peak refers to a sharp increase or spike in the absorption of electromagnetic radiation at a particular wavelength or energy level. It is a distinctive feature in the absorption...

Absorption spectroscopy is a fundamental analytical technique used to study the interaction between electromagnetic radiation and matter. It involves measuring the absorption of light by a sample...

An absorption spectrum is a graphical representation of the absorption of light by a material as a function of wavelength, frequency, or energy. It displays the specific wavelengths of light that are...

AC thin film electroluminescent (ACTFEL) display devices are a type of flat-panel display technology that uses electroluminescence to produce visible light. Structure: They consist of a thin...

Actinic refers to the property of radiation, particularly ultraviolet (UV) light, that can cause photochemical reactions. Radiation: Actinic radiation typically involves UV light but can also...

Actinic focus refers to the point or plane within an optical system where ultraviolet (UV) light or other actinic radiation converges to form the sharpest possible image. Here are the key aspects: ...

Actinic glass is a type of glass specifically designed to filter or block ultraviolet (UV) light and other forms of actinic radiation. UV filtering: Actinic glass effectively absorbs or...

Actinic radiation refers to electromagnetic radiation that has enough energy to induce photochemical reactions. This type of radiation is primarily in the ultraviolet (UV) range but can also include...

Actinism refers to the property of radiation, particularly light, that enables it to produce photochemical effects. This term is derived from the Greek word aktinos, meaning ray. Here are the key...

Actinochemistry refers to the branch of chemistry that studies the chemical effects of radiation, particularly light, on substances and chemical reactions. Here are the key aspects of...

Additive color mixing refers to the process of creating colors by combining different wavelengths of light. In this system, red, green, and blue (RGB) are considered primary colors. By mixing varying...

Agri-photonics refers to the application of photonics technologies in agriculture. Photonics involves the generation, manipulation, and detection of light and other forms of radiant energy whose...

A visible laser beam generated coaxially with an infrared or other invisible laser beam to aid in its positioning.

Diffuse light emitted by the atmosphere due to the excitation of particles of atmospheric gas. These excited particles release light that is visible from Earth as a faint luminescence in the night...

An ammonia maser is a device that amplifies microwave radiation using ammonia gas molecules in a process analogous to how lasers amplify visible light through stimulated emission of radiation. The...

A light source that emits an uneven distribution of radiant energy through the visible range.

A type of solar eclipse that occurs when the sun is at perihelion and the moon is at apogee. Because the apparent size of the moon is insufficient to cover the sun, the outer edge of the solar disc...

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 atomic absorption spectrometer (AAS) is an analytical instrument used to determine the concentration of specific chemical elements in a sample by measuring the absorption of light at...

Attosecond-pump attosecond-probe spectroscopy (APAP) is an advanced technique in ultrafast spectroscopy that allows scientists to study the dynamics of electronic processes occurring on extremely...

Azobenzene is a chemical compound consisting of two phenyl rings linked by a N=N double bond. It is well-known for its ability to undergo reversible photoisomerization, meaning it can switch between...

The use of a short-duration electron beam to record high-speed events that occur in microscopic objects made of materials that emit visible fluorescence during electron bombardment. The method is...

Bioluminescence is the natural phenomenon where living organisms produce light through a chemical reaction. In the context of photonics, bioluminescence has significant implications for both research...

Radiation from the invisible (usually ultraviolet) region of the spectrum.

The inability to perceive visual images (visible radiant energy). In human beings, blindness is defined as a visual acuity of less than one-tenth normal vision.

Brightfield refers to a type of microscopy and imaging technique in which the specimen is illuminated with a white light source, and the image is observed or captured against a bright background. In...

Brillouin microscopy is a non-invasive imaging technique that utilizes Brillouin scattering to measure the mechanical properties of materials at the microscale. This advanced optical technique...

The production of visible light by infrared radiation whereby the light is produced by heat and not by any direct change in wavelength; the transformation is indirect.

In optics and photonics, ceramics refer to advanced ceramic materials that possess unique optical properties, making them suitable for various applications involving the manipulation and control of...

Chromatic aberration is an optical phenomenon that occurs when different wavelengths (colors) of light are refracted by a lens or optical system, leading to a failure to focus all colors to the same...

Glass that transmits near-ultraviolet radiation but is opaque in the visible region. Also known as woods glass.

A mirror whose coating serves to reflect visible radiation while transmitting the infrared.

A colloid is a mixture in which one substance of microscopically dispersed insoluble particles is suspended throughout another substance. The particles in a colloid are larger than those in a...

Colloidal quantum dots (CQDs) are nanometer-sized semiconductor particles that are dispersed in a colloidal solution. These quantum dots have unique optical and electronic properties due to their...

A color center, in the context of materials science and condensed matter physics, refers to a specific type of crystallographic defect in a crystalline structure that introduces color to the...

Color vision refers to the ability of organisms to perceive and distinguish different wavelengths of light as different colors. It is a sensory ability that allows humans and many other animals to...