Photonics Dictionary

Attenuated total reflectance (ATR) spectroscopy is a technique used in analytical chemistry to obtain IR spectra of samples. It is particularly useful for analyzing solid and liquid samples without...

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...

Augmented reality (AR) is a technology that integrates digital information, typically in the form of computer-generated graphics, images, or data, with the real-world environment in real-time. AR...

Technique of projecting an illuminated target at infinity and receiving the target image after reflection from a flat mirror surface.

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 microscope to which a beamsplitter and illuminated reticle have been added to measure the radius of curvature of a spherical surface by locating both surface and center and calculating the distance...

A method of designing lasers whereby the laser rod is cut into elliptical discs and cooled by running water over the disc surfaces. The cooling circuit decreases the radial temperature gradients in...

An axicon is a type of optical component characterized by its conical shape and its ability to transform a collimated Gaussian beam of light into a ring-shaped beam with a gradually increasing...

1. In astronomy, the angle measured clockwise (eastward) in a horizontal plane, usually from north (true north, Y-north, grid north or magnetic north). 2. With relation to the plane-polarized light...

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...

A glass substrate that has its rear surface coated with a reflective coating. Also known as a back-surface mirror.

The forming of a clear silhouette of an object by placing a light source behind it. Used in machine vision when surface features of an object are not important.

Backscatter refers to the phenomenon in which radiation or waves are scattered backward, opposite to the direction of the incident beam. This occurs when the incident radiation encounters a target or...

The elimination of gases from the surfaces of a vacuum system by heating the surfaces when the pumping phase is occurring.

A ball lens is a small, spherical optical component typically made of glass or other transparent materials. It is characterized by its spherical shape, with both its front and back surfaces forming...

Bathymetric lidar is a remote sensing technique used to measure the depth of water bodies and map underwater terrain features. It employs lidar (Light Detection and Ranging) technology, which uses...

A beamsplitter is an optical device used to divide a beam of light into two or more separate beams, typically by reflecting a portion of the incident light while transmitting the remainder....

A defect on or in an optical element that does not appreciably impair the function of the surface.

Device used to measure the numerical aperture of a microscope, composed of a 14-mm-thick glass block with numerical aperture gradations carved onto its lower surface.

Biomimicry, or biomimetic design, is the practice of emulating natural processes, systems, and structures found in biological organisms to solve human problems or create innovative technologies. It...

A matrix-controlled display that has information storage at the display surface, and requires that an element be addressed only once to assure that it is on or off.

A lens, both surfaces of which are ground and polished into a toric or cylindrical form.

An enclosure whose walls are coated to absorb completely all radiation striking them.

A blackbody source, often simply referred to as a blackbody, is a theoretical or practical physical object that absorbs all electromagnetic radiation incident upon it and emits radiation in a...

1. A plane that forms one side of the groove ruled on a diffraction grating. 2. To form the individual grooves of a grating with flat smooth faces, inclined to the surface by an angle known as the...

Blaze height typically refers to a parameter in the context of diffraction gratings, which are optical devices consisting of a series of closely spaced parallel grooves or slits. The blaze height is...

A compound prism composed of two 30° prisms, one of which is partially coated with a suitable opaque metal of high reflecting power. The prisms are cemented with Canada balsam so that the coated...

A technique in which a beam of x-rays is directed against a crystal, the atoms of which, because of their lattice arrangement, reflect the ray in the same way as a series of plane surfaces. If the...

For light incident on a plane boundary between two regions having different refractive indices, the angle of incidence at which the reflectance is zero for light that has its electrical field vector...

An instrument for measuring the brightness (luminance) of a scene. It may be a spot meter, covering an area of a degree or less, or an averaging meter, covering a broad area of the scene. Brightness...

The final correction of a polished surface or of an angle to the specified precision.

A surface imperfection caused by a polisher running dry too long. It occurs with felt or plastic polishers, and may appear as a reddish brown.

The storage surface of an electron beam tube that is scanned by an electron beam to generate an output-signal current corresponding to the charge-density pattern stored.

A lens, one surface being a cartesian oval, that produces an aplanatic condition.

A surface heat-treating process that produces a highly stressed surface. In case-hardening of glass, a plate of glass is heated almost to the softening point and then cooled quickly in a blast of...

The Casimir force is a quantum phenomenon that results in an attractive force between two closely spaced uncharged conductive surfaces. This force arises from the quantum vacuum fluctuations of the...

A system that uses both reflection and refraction to achieve its focal power. While the relative powers of the lenses and mirrors vary from system to system, the use of the reflective surfaces to...

Light that is directed or focused by means of curved reflective surfaces.

An optical system in which the only image-forming elements are curved-surface mirrors; e.g., a Cassegrain lens system.

Catoptrics is the field of optics concerned with the reflection of light from reflective surfaces such as mirrors. It encompasses the study and analysis of how light rays interact with these...

A surface that envelops a bundle of rays or bundle of normals to the wave surface. It may be observed as a hollow, luminous cusp in a turbid medium.

A CCD image sensor, or charge-coupled device image sensor, is a type of electronic device used to convert optical images into electronic signals. It is a key component in digital cameras, camcorders,...