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PI Physik Instrumente - Semiconductor Applications 5/24 ROS MR

4,567 terms

Photonics Dictionary

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ultraviolet photoemission spectroscopy

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

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,...

ultraviolet

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

umbilical

A connection, typically made up of one or more cables, between a laser head and a separate power supply. Flexible pipes or hoses are sometimes used to protect and stabilize multiple cables.

umbra -> penumbra

A source of light will not cast a distinct shadow of an interfering, opaque object, but will cast a shadow having two parts: 1. the umbra, or the central, totally dark part of the shadow; and 2. the...

underwater photography

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

uniform color space

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

unimorph

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

unipolar

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...

unit plane -> principal plane

In a lens or lens system, that surface at which the projections of an entering and exiting ray intersect. Also known as the equivalent refracting surface, the principal plane is most often not...

universal product code

A system by which consumer products are assigned a bar code that is read by a scanner at a cash register, enabling computerization of pricing and inventory records.

universal wavelength function

One of the four functions that allows the computation of a transparent medium's index of refraction, provided the index has been identified for four standard wavelengths.

unmanned aerial vehicle

An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without a human pilot onboard. UAVs are remotely controlled or autonomously operated, and they can be used for various...

upper rim ray -> rim ray

A ray of an image-forming bundle that passes through the edge of the entrance pupil or aperture stop. Usually used in connection with meridian rays, an upper rim ray is one that passes through the...

USAS-CSOCR

USA standard character set for optical character recognition

v-coat

A multilayer antireflective thin-film coating, so called because its reflectance rises steeply at wavelengths above and below a narrow band at zero. The v-coat is particularly useful in high-power...

V-groove

A V-shaped channel pressed or etched into a substrate, in which, for example, optical fibers may be placed to create an integrated optical component.

V-number -> normalized frequency

Also referred to as the V number in fiber optics; the normalized frequency is a dimensionless quantity, denoted by the symbol V, given by: where a is waveguide core radius, l is wavelength in vacuum,...

vacancy

In an ionic crystal, the region in the crystal lattice where the ion, predicted to be present, is absent.

vacuum apparatus

Equipment dependent on the effects of a vacuum. The principal applications in optics are in the coating of lenses and substrates and the fabrication of multilayer interference filters.

vacuum breaker

A valve that serves to release air into an evacuated system.

vacuum chamber

A vacuum chamber is a sealed enclosure from which air and other gases are removed to create a low-pressure environment, typically close to or at a complete vacuum. These chambers are often...

vacuum gauge

A gauge designed to measure the degree of vacuum in an evacuated vessel. A simple U-tube containing mercury is adequate for low vacua, but for high vacua other methods must be employed. See McLeod...

vacuum ultraviolet source

Any source that emits radiation of wavelengths between 100 and 300 nm. Instruments used to study these sources must be evacuated, as vacuum ultraviolet does not travel freely in air.

valence band

In a crystalline substance, the spectral range of states of energy that contains the crystal's binding valence electrons.

VAMP

visual-acoustic-magnetic pressure

Van der Waals

Van der Waals forces refer to the attractive or repulsive forces between molecules (or parts of molecules) that arise from fluctuations in electron distribution. These forces are relatively weak...

vanadate laser

Lasers based on neodymium-doped yttrium or gadolinium vanadate crystals. These include yttrium vanadate (Nd:YVO4), gadolinium vanadate (Nd:GdVO4), and lutetium vanadate (Nd:LuVO4). Vanadate lasers...

vapor degreasing

A method of cleaning and drying coated optical components. The cooled parts are placed in a container above a boiling solvent, whose vapors condense on the parts. When the parts reach the temperature...

vapor-phase epitaxy -> epitaxy

A well controlled thin films technique for growing films with good crystal structure in ultra high vacuum environments at very low deposition rates. Epitaxy methods are well known for the growing of...

variable-focus condenser

An Abbe condenser in which the upper lens element is fixed. The lower lens may focus the illumination between the elements so that it emerges from the fixed lens as a large-diameter parallel bundle....

VCASS

visually coupled airborne systems simulator

Vegard-Kaplan bands

The bands found by Vegard in the spectrum of the aurora borealis and by Kaplan in the nitrogen afterglow. They are formed by the effect of metastable nitrogen molecules.

veiling brightness

A brightness, superimposed on the image of the retina, that decreases its contrast and that often results in decreased visibility.

veiling glare

Diffuse stray light at the image plane of an optical system that results in reduced contrast and resolution.

venetian-blind effect

Short-distance scattering of light in holography caused by random index inhomogeneities and the developing index that interferes with the incident beam, thus recording a hologram of the scattered...

vernier acuity

The degree to which a pair of fine lines can be aligned to each other. A normal observer will demonstrate an accuracy of 10 arc seconds and a repeatability of 5 arc seconds.

vertex power

The reciprocal of the back focal distance of a spectacle lens.

vertical blanking

With respect to a television system, a pulse transmitted at the end of each field to break off the cathode-ray beam as it begins the next field.

vertical external cavity surface-emitting laser

A laser that has a surface-emitting semiconductor gain element coupled to an external mirror designed to complete the laser resonator. VECSELs can be electrically or optically pumped. The extended...

vertical resolution

In television system specifications, the number of parallel horizontal black and white lines of equal thickness, that can be resolved from top to bottom of the raster. (One line equals either a black...

vertical transmitted illumination

With respect to microscopy, light that is directed through the specimen by a substage condenser.

vertical-cavity laser diode

A type of surface-emitting laser diode that uses dielectric mirrors to produce surface emission. The laser cavity is established in a vertical direction with respect to the plane of the active region.

vertical-cavity surface-emitting laser -> vertical-cavity laser diode

vertical-deflection electrodes

Two electrodes that shift the electron beam vertically on a cathode-ray tube screen using electrostatic deflection.

very long baseline interferometry

Consists of a pair of radio telescopes concentrated on a single celestial object. This technique creates a single radio telescope with a diameter equal to the distance between the pair, which allows...

via

In integrated circuits, a pathway, hole, or other passage through the substrate.

vibrational transition

A vibrational transition refers to a change in the vibrational energy of a molecule. Molecules consist of atoms that are connected by chemical bonds, and these atoms are not stationary but are in...

video detector

A device, such as a thermionic or crystal diode, that is introduced into the vision channel of a television receiver to select the signal from the intermediate-frequency carrier.

video graphics array

A display standard no longer in use and originally defined for IBM PCs, with 640 3 480 pixels in 16 colors and a 4:3 aspect ratio. There is also a text mode with 720 3 400 pixels. The standard has...

Photonics Dictionary