Photonics Dictionary

The process by which a surface is made to conform accurately to a given curvature.

Any form of laser; e.g., a dye laser, having an output that can be adjusted over a wide range of wavelengths. Normally the range is about 70 nm wide.

An evacuated bulb containing a tungsten filament that is heated by passing an electric current through it. In domestic light bulbs the inside of the bulb is frosted to soften shadows. In projection...

Turbidity is a measure of the cloudiness or haziness of a fluid caused by the presence of suspended particles. These particles can include sediment, silt, clay, plankton, and other microscopic...

A system that is complete and self-contained, needing no further additions to permit its operation.

A compound crystal having two or more crystals or crystal sections that, when regularly positioned, are in reverse position relative to the other sections. When viewed, these crystals appear to be...

Twisted intramolecular charge transfer (TICT) is a phenomenon observed in certain organic molecules containing electron-donor and electron-acceptor groups that are linked together within the same...

A form of liquid crystal widely used in displays, achieved by sandwiching a liquid crystal material between two substrates whose inside surfaces have been prepared with a special coating that aligns...

The Fourier series representation of a two-dimensional periodic field, assuming that the original image is periodic both horizontally and vertically.

Two-photon excited fluorescence (TPEF) is a nonlinear optical method that allows imaging of biological cells and living tissue. The advantage of TPEF in comparison to conventional fluorescence...

This results from the simultaneous absorption of two photons, each having half the energy needed for excitation and requiring a high spatial and temporal concentration of photons. The ensuing...

Two-photon polymerization (TPP) is a technique used in additive manufacturing, specifically in the field of 3D printing. It involves using a focused laser to polymerize a photosensitive material in a...

Referring to compound semiconductor materials combining one element with two valence electrons and one or more with six. Examples include beryllium oxide and zinc selenide. (II-VI).

A testing device that provides a contour map of the emergent wavefront for the observer in terms of the given wavelength of the light.

Twyman-Green interferometry is a technique used in optics to measure the flatness or surface profile of optical components with high precision. It is based on the principles of interference of light...

The effect by which sufficiently small particles will scatter blue light at right angles to the incident beam. This scattered light is completely linearly polarized.

A set of samples used in the analysis of multielement thin films.

An ultrafast pulsed laser is a type of laser that emits extremely short pulses of light with durations typically on the order of femtoseconds (10-15 seconds) or picoseconds (10-12 seconds). These...

The frequency band from 300 to 3000 MHz. The corresponding wavelengths are from 10 to 100 cm.

A system used to measure very small displacement by electrical means.

A dark-field microscope used to view extremely small objects. These objects are suspended in a gas or liquid in an enclosure having a black background. A convergent pencil of bright light enters from...

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.

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

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

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...

The region of the electromagnetic spectrum from 320 to 400 nm.

The region of the electromagnetic spectrum from 280 to 320 nm.

Ultraviolet-C (UV-C) refers to a specific range of ultraviolet radiation with shorter wavelengths than those of visible light. UV-C radiation spans the electromagnetic spectrum with wavelengths...

A technique, involving spectrophotometry in the ultraviolet, that is designed to determine the colors of thin-layer chromatographic absorbents after elution.

Ultraviolet (UV) fiber optics refers to optical fibers that are designed and optimized for the transmission of ultraviolet light, which is electromagnetic radiation with wavelengths shorter than...

A lens intended for use with wavelengths shorter than about 380 nm. It must be made of quartz, calcium fluoride, lithium fluoride or some other material transparent to ultraviolet radiation, as glass...

A microscope used either to detect selective absorption of various wavelengths by the specimen or to achieve increased resolution by virtue of the short wavelength of ultraviolet radiation. Electron...

The study and photographing of microscope specimens in ultraviolet light; using an optical microscope containing fluorite and quartz components to efficiently image wavelengths much shorter than the...

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 technique for measuring the energy spectrum of electrons emitted during the absorption of ultraviolet radiation. This spectrum reveals the characteristic ionization energies of the molecules and...

Ultraviolet reflectance refers to the ability of a material or surface to reflect UV light. Ultraviolet light is electromagnetic radiation with wavelengths shorter than those of visible light,...

A spectrophotometer designed for use in the 200- to 380-nm range of the electromagnetic spectrum and equipped with a calibrated scale to determine wavelength.

That invisible region of the spectrum just beyond the violet end of the visible region. Wavelengths range from 1 to 400 nm.

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...

The process whereby optical elements are removed from a block.

The field of photography concerned with the recording of subjects beneath the water with a watertight, water-resistant camera system.

A device used in a free-electron laser to convert the electron-beam's energy into microwave laser radiation by creating a magnetic field of alternating polarity through which the free electrons are...