Teledyne DALSA - Line Scan Leader 5/24 LB

Type

Browse by Letter

Sheetak - Cooling at your Fingertip 5/24 MR

Videology Industrial-Grade Cameras - Mini Color Camera 2024 HP

23 terms

Photonics Dictionary: V

Clear All Filters x lens x V x
variable-focus lens

A lens assembly containing several movable elements to permit changing of the effective focal length (EFL). Unlike a zoom lens, a variable-focus lens may require refocusing with each change of EFL....

varifocal -> variable-focus lens

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-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,...

V-value -> Abbe constant

A dispersion relation defined in order to value the reciprocal amount of dispersion. It is defined as the refractivity over the difference in index values of the shortest and longest visible...

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 spectrography

The technique of producing spectrograms in wavelengths beyond 120 nm by the use of a diffraction grating and a Schumann plate in a vacuum environment.

vacuum ultraviolet radiation

Radiation whose spectrum runs between 100 and 300 nm. Any work with these wavelengths requires evacuated equipment.

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.

vacuum ultraviolet spectroscopy

A method of spectral analysis using wavelengths between 100 and 300 nm that utilizes both emission and absorption techniques.

valence band

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

valence crystal

A crystal that is held together by covalent bonds.

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...

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....

vertex power

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

vertical imbalance

The difference in base up or down prism power at corresponding points located on the two lenses of a pair of spectacles.

vertometer

A device that measures the back focal length or vertex power of a lens.

very high frequency

The frequency band from 30 to 300 MHz. The corresponding wavelengths are from 1 to 10 m. (VHF).

very low frequency

The frequency band from 3 to 30 kHz. The corresponding wavelengths are from 10 to 100 km. (VLF).

virtual histology

Virtual histology refers to the use of digital technology and computational methods to simulate or recreate histological images and structures without the need for traditional physical slides and...

visible spectrum

That region of the electromagnetic spectrum to which the retina is sensitive and by which the eye sees. It extends from about 400 to 750 nm in wavelength.

vitreous humor

The transparent fluid that fills the portion of the eye between the eye lens and the retina (the posterior chamber).

volume Bragg gratings

Volume Bragg gratings (VBGs) are specialized optical elements that consist of periodic variations in refractive index throughout the volume of a transparent material, typically a photosensitive glass...

Photonics DictionaryV

We use cookies to improve user experience and analyze our website traffic as stated in our Privacy Policy. By using this website, you agree to the use of cookies unless you have disabled them.