Photonics Dictionary

The positive ion current created in an electron tube as a result of the collisions between electrons and residual gas molecules.

The conduction of electricity in a gas as a result of the ions generated by collisions between electrons and gas molecules.

A display device that contains an inert gas that gives off orange light when a high voltage is applied to ionize the gas.

A technique for measuring the concentration of any gases. Identical infrared beams are alternately chopped, one passing through a reference cell and the other passing through a cell with the gas...

One of the first lasers to find practical application. Generally, the pumping mechanism is an electric discharge, although some high-power forms employ chemical reaction or gas compression and...

The increase in current of a phototube as a result of the gas in the tube becoming ionized.

A photoemissive cell having an inert gas added to its envelope. Subsequent ionization of the gas increases the responsivity of the photocell.

A phototube having increased response due to the addition of a quantity of gas.

An electron tube whose current flow is affected by the pressure on the gas or vapor contained in the tube.

A gas laser wherein the gas mixture is not exhausted into the atmosphere but is continually recycled. It is excited in the active region, cooled and re-excited. The GTL requires no constant gas...

An optical instrument designed for the visual examination of the inside of the stomach.

A gas, such as oxygen, that improves the speed and efficiency of a laser cutter or welder when applied to the work surface, or an inert gas, such as argon, that helps to clean or shield the work...

A jet of inert gas along a laser welding beam's axis that cools, protects or cleans the work surface.

A monatomic, chemically inert gas such as argon, neon, krypton and xenon.

The emission of gas or de-aeration due to thermal variations and often occurring in a vacuum. In a cleanroom, contamination from the spontaneous emission of absorbed particles.

A device for measuring absorption coefficients in which a confined, nonabsorbing gas fills the space inside the cell between the two windows, which are made from a weakly absorbing medium.

A measurement in optical thin-film coating processes whereby the gases remaining in the vacuum chamber after coating are characterized by mass spectroscopy.

The purest gas source of antimony, which is used in the manufacture of compound semiconductors for IR sensors and solid-state lasers.

A binary semiconductor compound used as a substrate or active layer for diode lasers.

3D Laser Triangulation - A technology that allows sensors to probe the surroundings. Laser triangulation systems have an ideal operating point, or the standoff distance, where its reflected spot is...

Ray oriented and assumed to propagate orthogonal to the optical axis

A departure from ideal paraxial imaging behavior. The distortion of an optical field wavefront as it is propagated through the elements of an optical system. The field distortion is due to the...

A high-brightness, short-duration source in which low-pressure gas initiates the discharge to vaporize material from the tube wall, leading to a high-pressure discharge of ionized wall material.

Optical surface damage due to abrasive rubbing. Abrasion damage affects are less than the thickness of the optical coating layers. Surface investigation may be achieved by aluminization of the coated...

A doped or absorbing transparent medium cut or molded into a wedge in order to measure the real and imaginary components of the refractive index. An internally reflected Gaussian beam is interfered...

An accelerometer is a sensor or transducer that measures the rate of change of velocity of an object, or in simpler terms, it measures acceleration. Accelerometers are widely used in various...

A bulk crystalline optic which permits the propagation of light through a volume of index altered material. The variation in refractive index along the material volume is due to a piezoelectric...

That layer in a semiconductor injection laser or light-emitting diode that provides optical gain.

An OLED display that has an integrated electronic backplane as its substrate. Active-matrix OLED displays use at least two thin-film transistors (TFTs) to control the on-current at each OLED cell or...

Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of atmospheric distortions. The Earth's atmosphere can cause light passing through it...

Advanced driver assistance systems (ADAS) refers to a set of safety features and technologies designed to assist drivers in the driving process and enhance overall vehicle safety. These systems use...

A glow discharge lamp consisting of a cold cathode and a mixture of inert gases. The intensity of illumination varies with the applied signal voltage. This lamp was commonly used as a source of...

A two-phase system consisting of dispersed liquid or solid particles in a gas; examples include dust, smoke and clouds.

The luminosity that remains in a rarefied gas after an electrodeless discharge has traversed the gas.

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...

A laser, usually employing helium-neon or other gases as the active medium, used for alignment in industrial applications.

Also known as all-glass fiber. A fiber with both a silica core and a silica cladding, regardless of the presence of a polymer overcoat or buffer.

A cathode-ray tube having a screen that is coated on the back with a thin film of aluminum, which serves to intensify the propagation of light.

The underexposed collodion that is present on a glass negative as a positive when backed with material.

A type of fiber optic sensor that detects alteration in position, distance, pressure, liquid level or temperature by transmitting light across a gap to a reflector; a change in the light returned to...

A term used to denote a difference in magnification along mutually perpendicular meridians. Anamorphic systems are basically image-distorting systems, such as those used in motion pictures, that...