Photonics Dictionary

A formed piece of glass, one surface of which has been ground and polished to the required curvatures.

A term used to describe a spectacle lens or blank with one surface totally finished.

Raster scanning process like that of television: each line is scanned successively.

A closed-loop system that is constantly adjusted in response to input signals generated within the system.

A term that describes an incomplete polish.

A short focal length (less than five inches) positive lens used to produce a magnified image of the object being viewed. While a single element will function, an achromat or multielement assembly...

A high-power riflescope specifically intended for sighting and shooting distant targets.

Gas detection measurement technique that uses a built-in capacitative microphone to calculate the amount of absorbed laser power in a gas cell according to variations of gas pressure.

A scanning process in which the greatest amount of radiation determines part of a spiral motion rotating in one direction.

When splitting the output of a single optical fiber into two or more fibers, the difference in the maximum loss between any two channels.

Spectrum broadening that results from the influence of an electric field.

An approach to character recognition based on the structure of the character to be identified (number of straight lines, bays, holes, etc.); used where simple matching is not viable, as in...

A copolymer of styrene and acrylic used in molded optical components; it has a high refractive index and a low coefficient of thermal expansion.

(SALI) A type of spectroscopy in which neutral atoms or molecules are ionized by an excimer laser beam and then measured by a time-of-flight mass spectrometer.

In a laser, the voltage necessary to sustain a constant operating current, somewhat less than that needed for start-up.

The color process that is used to form positive color cine films by dye transfer or imbibition, based on the use of separate matrices that superimpose yellow, magenta and cyan dye images on the final...

A television receiver that receives the signals generated by a television camera directly, or remotely through a radio signal. It may be used to continuously check image and sound reception; as a...

A diode electron tube that contains a heated cathode.

The emission of free electrons by a rise in temperature of the cathode alone.

Topological photonics is a branch of physics and optics that explores the application of topological concepts to the behavior of light in photonic systems. Drawing inspiration from the field of...

A method of measuring total hemispherical emissivity of the plane surface of a solid that consists of thermally isolating a specimen of the material inside a vacuum, preheating it slightly above the...

With respect to a crystal, having three unequal axes intersecting at angles, only two of which can be equal and only one of which can measure 90°.

Tungsten diselenide (WSe2) is a member of the transition metal dichalcogenides (TMDs) family, composed of tungsten (W) and selenium (Se). Similar to other TMDs, tungsten diselenide possesses a...

A defect of natural quartz crystals in which both the right and left quartz are in the same crystal.

A device that uses a piezoelectric crystal to convert ultrasonic sound waves, transmitted through a subject, into a voltage that modulates the electron beam of a cathode-ray tube.

Ultrasound used in the cleaning of metal and optical parts by virtue of its vibration rates. Large acoustic forces break off particles and contaminants from surfaces.

A two- or three-dimensional space grating formed when ultrasonic beams with varied paths of propagation intersect.

A mechanical, electrical, thermal or optical detector designed to identify and measure ultrasonic radiation.

The space between diffracting centers of an ultrasonic wave that is forming certain light diffraction spectra.

The formation and display of three-dimensional images by ultrasonic energy. In one technique, the energy pulses from an ultrasonic transducer scan the object through a liquid medium and, receiving...

The optical diffraction spectra formed, or the method that produces them, when a light beam is transmitted through a longitudinal sound field.

An instrument with a fluid that modulates a light beam traversing it because of the effect of ultrasonic waves passing through the fluid.

A light-interference device whose excitation is determined by the modulation of a light beam by an ultrasonic field.

Ultrasonic refers to sound waves with frequencies higher than the upper audible limit of human hearing, typically above 20,000 Hz. These waves are termed ultrasonic because they are beyond the range...

A pulsed laser having molecular nitrogen as laser material and a wavelength output of 337 nm in the ultraviolet region. It is essentially a channel flashtube in which a pulse is applied to the...

A doubly refracting crystal having a single axis along which there is an absence of double refraction.

A color space in which equal distances represent equal visually perceived color differences.

In a cathode-ray tube, the region wherein a display on the tube keeps 70 percent or more of its luminance at the center of the viewing area.

Array used in coded-aperture imaging experiments with two-beam CO2 lasers that provide an artifact-free process, faithful reproduction of the true image, and more photon collection than the pinhole...

A three-terminal semiconductor having only one PN junction and a stable, open-circuit, negative-resistance property.

A piezoelectric transducer made of a thin strip of piezoelectric material bonded to a strip of metal.

In interferometry, the result of superimposing two wavefronts of identical shape, yielding a uniform intensity interference pattern with no bands.

Refers to the transistors in which the working current flows through only one type of semiconductor material, either P-type or N-type. In unipolar transistors, the working current consists of either...

A simple electrostatic lens with a focus controlled by a single potential difference.

A unit of measurement in a rangefinder corresponding to 12 s of arc in the apparent field.