Photonics Dictionary

Epitaxial deposition is a process used in semiconductor manufacturing and materials science to grow a thin crystalline layer, known as an epitaxial layer, on a substrate. The term epitaxial refers to...

Epitaxial equipment refers to a set of specialized tools and systems used in the process of epitaxy, which is the growth of crystalline layers on a substrate material. Epitaxial growth is a critical...

In surface height measurement of optics with steep slopes, the use of two short visible wavelengths to synthesize a longer, equivalent wavelength.

An etalon is an optical device that consists of two parallel reflecting surfaces separated by a precise and known distance. It operates based on the principle of optical interference and is used to...

Etaloning is an optical phenomenon that occurs in imaging systems, particularly in devices such as spectrometers, interferometers, and cameras. It is characterized by the appearance of interference...

The engraving of a surface by acid, acid fumes or a tool; a process extensively used in the manufacture of reticles.

An acid used to etch the surfaces of particular materials. For glass, hydrofluoric acid is used either as a liquid or a vapor. Metals are etched by means of suitable acids or other liquids, often to...

Coating carried out in a sealed chamber evacuated by a mechanical pump in series with an oil diffusion pump to a pressure less than 10-4 mm of mercury, measured by a vacuum gauge. At such a low...

Flux leaving a surface per unit area.

In optics, the total radiant energy incident on a surface-per-unit area. It is equal to the integral over time of the radiant flux density. Also known as radiant exposure.

The ejection of electrons from the surface of a solid by the absorption of a sufficient amount of photons.

A ray that has a nonisotropic speed in a doubly refracting crystal. It does not necessarily obey Snell's law upon refraction at the crystal surface.

Also termed eye distance. The distance between the vertex of the last optical surface of a visual optical system and the system's exit pupil.

An f-theta lens, also known as an f-theta scan lens or simply an f-theta lens system, is a specialized optical component used in laser scanning systems, particularly in laser marking, engraving, and...

A multiple-beam interferometer, usually consisting of two flat plates, with high reflective ability. The plates are set parallel to one another by spacers so that lightwaves may bounce back and forth...

A highly reflective mirror that is usually flat on one surface and curved on the other, and that has silver, gold or aluminum deposited on glass, providing about 99 percent reflection.

A device in which slab geometry internally compensates for thermal-optic distortion; the solid host material -- glass or Nd:YAG -- is in the form of a rectangular slab with plane parallel faces. The...

1. One of the plane-reflecting surfaces on a multisurfaced polygon. 2. The cleaved end mirror of a laser diode's active region.

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...

The Fermi liquid state refers to a specific state of matter in quantum mechanics, particularly describing the behavior of interacting fermions (particles with half-integer spin, such as electrons) at...

A fiber laser is a type of laser in which the active gain medium is an optical fiber doped with rare-earth ions such as erbium, ytterbium, or neodymium. Fiber lasers generate coherent light through...

A plate consisting of fused optical fibers with both surfaces ground and polished, and having the entrance surface curved to match the image curvature of the input lens system. The plate transmits to...

The face of a cathode-ray tube (CRT) that has a fiber optic sheet attached to its surface. The sheet's fibers are at right angles to the face, allowing the transmittance of the fluorescent trace...

The use of thin flexible glass or plastic fibers as wave guides — or "light pipes" — to channel light from one location to another. Fiber optics is based off of the principle of total...

The distance between the surface of a ferrule and the surface of a fiber end, provided that the ferrule extends above the fiber end. If the fiber end extends above the ferrule surface, the difference...

An image-forming instrument in which a strong electrostatic field causes cold emission of electrons from a sharply rounded point or from an object that is located on that point. The electrons are...

The angle measured between the focal surface containing the image and a plane normal to the optical axis.

In optics, the geometrical form of an optical surface.

The process whereby the shape of an optical surface is altered by polishing.

Filoviruses are a family of viruses that are responsible for severe and often fatal hemorrhagic fevers in humans and non-human primates. The name "filovirus" is derived from their filamentous...

For a Fabry-Perot interferometer or etalon, a value for the transmission bandwidth which can be calculated as the ratio of the free spectral range to the full width half maximum of the transmission...

Small clefts or fissures that penetrate the glass surface in the form of short-hooked crescents. Fire cracks result from a sudden excessive change in temperature.

The process of grinding the concave surface of a single-vision spherical lens.

The process of grinding the toric surface of a single vision sphero-cylindrical lens.

Fizeau fringes are interference fringes observed in an interferometer, specifically in a Fizeau interferometer. The Fizeau interferometer is named after the French physicist Armand Fizeau, who...

A Fizeau interferometer is an interferometric device that uses the principle of interference to measure the surface flatness and quality of optical components. It consists of a light source,...

The distance between the locating surface of the lens mount and the image plane.

Nonimage-forming light, concentrated or diffuse, that is transmitted through the lens to the image. It is frequently the result of reflections from lens surfaces, a lens barrel, shutter or lens mount.

A piece of glass having a crude plano surface on each side.

A polishing machine designed to permit adjustment of the polisher speed and motion for the control of flat surfaces.

A frame taken with a CCD camera of a surface that is evenly illuminated by diffuse light. This frame shows irregularities in the light-sensing ability of the CCD, such as electronic defects and dust...

An imaging device analogous to a drum scanner, but operating at greater speeds; it uses a row of sensors to traverse an image affixed to a flat surface.

The Floquet Fermi liquid state refers to a concept in condensed matter physics that arises when a system is subjected to periodic driving or modulation, typically by an external periodic field such...

In various fields such as fluid dynamics, microfluidics, and biotechnology, a flow channel refers to a defined pathway through which a fluid (liquid or gas) flows. The channel can be of various...

Flow cytometry is a powerful technique used in biology and medicine for the quantitative analysis of the physical and chemical characteristics of cells and particles suspended in a fluid. The method...

Fluence is a term used in various scientific and technical disciplines to describe the amount of something per unit area. The specific meaning of fluence can vary depending on the context in which it...