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35 terms
Photonics Dictionary: U
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uhlbricht sphere
->
integrating sphere
A hollow sphere coated internally with a white diffusing material and provided with openings for incident beam, specimen and detector used for measuring the diffuse reflectance or transmittance of...
ultrafast pulsed laser
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...
ultrahigh-speed photography
Photographic recording of rapid events at a rate exceeding 106 frames per second.
ultramicrophotography
The process of microphotography that involves the reduction of the original at a ratio greater than 100 to 1. The process is usually accomplished by the use of a reduced-scale negative, which, in...
ultraphotic rays
The rays (such as ultraviolet rays) lying past the visible region of the spectrum.
ultraprecision cathode-ray tube display
A highly accurate cathode-ray tube used to display information with the utmost efficient stability and resolution. The information is viewed as a series of points, particularly suited for...
ultrashort-pulse laser
A laser capable of generating light pulses that last only a few femtoseconds. This can be achieved by nonlinear filtering to increase bandwidth and compress the pulse or by passive mode-locking or...
ultrasonic camera
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.
ultrasonic holography
->
acoustical holography
Acoustical holography is a technique used to visualize and analyze sound fields in three-dimensional space. It involves capturing the complex spatial distribution of acoustic waves, much like how...
ultrasonic imaging
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...
ultrasonic light diffraction
The optical diffraction spectra formed, or the method that produces them, when a light beam is transmitted through a longitudinal sound field.
ultrasonic stroboscope
A light-interference device whose excitation is determined by the modulation of a light beam by an ultrasonic field.
ultrasonic
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...
Ultraviolet-C
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...
ultraviolet coatings
Ultraviolet (UV) coatings are specialized optical coatings designed to operate in the ultraviolet region of the electromagnetic spectrum, typically ranging from 10 nm to 400 nm. These coatings are...
ultraviolet densitometry
A technique, involving spectrophotometry in the ultraviolet, that is designed to determine the colors of thin-layer chromatographic absorbents after elution.
ultraviolet fiber optics
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...
ultraviolet lens
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...
ultraviolet lens
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...
ultraviolet microscopy
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...
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 photomicrography
The photographic recording that uses ultraviolet radiation to irradiate the microscope sample being examined and to form an image of the object on a photographic medium. The components of the...
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 spectrometer
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.
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...
unblanking
The initiation of the beam in a cathode-ray tube.
underillumination
Illumination of hologram facets with a beam that covers only a small portion of the hologram in order to optimize laser energy use. See overillumination.
underwater photography
The field of photography concerned with the recording of subjects beneath the water with a watertight, water-resistant camera system.
uniform luminance area
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.
uniformly redundant array
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...
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...
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...
unpolarized
Behaving as though characterized by a series of waves having planes of vibration oriented at all possible azimuths.
uviol glass
A type of glass contrived by Schott that is highly transparent to ultraviolet radiation.
Photonics Dictionary
U
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