Photonics Dictionary

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.

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...

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...

A device that serves to detect the presence of vacuum ultraviolet radiation. It may be photographic film, a thermopile, ion chamber, vacuum photodiode, photomultiplier or channel electron multiplier.

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

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...

With respect to television, the returning direction of the electron beam during the vertical blanking period.

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...

A type of change in the energy levels of molecules in a laser that results in lasing action. Vibronic transitions are those between one electronic level and another.

A device, optical or electronic, that may be joined to a camera so that the operator may perceive the scene as the camera does.

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...

Virtual reality (VR) is a computer-generated simulation of a three-dimensional environment or experience that can be interacted with and explored by an individual using electronic devices, such as a...

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.

An electron tube that stores and visually displays information by means of a cathode-ray-beam-scanning and charge-storage mechanism.

A nondestructive testing method for very large scale integration circuits, using a scanning electron microscope to monitor changes in the electronic state of the chip as it is fed test voltages while...

An electric cell having two electrodes of unlike metals immersed in a solution that chemically affects one or both of them, thus producing an electromotive force.

Volumetric imaging refers to the capture, visualization, and analysis of three-dimensional (3D) information from a volume of space. Unlike traditional two-dimensional (2D) imaging, which provides...

In the context of electronics and semiconductor manufacturing, a wafer refers to a thin, flat disk or substrate made of a semiconducting material, usually crystalline silicon. Wafers serve as the...

1. An undulation or vibration; a form of movement by which all radiant energy of the electromagnetic spectrum is estimated to travel. 2. A type of surface defect, usually due to improper polishing.

A waveform is a graphical representation of the shape and magnitude of a signal over time. It typically depicts how the amplitude (strength) of the signal changes over time, with time plotted along...

A wavefront refers to the continuous surface or boundary representing points in a wave that are in phase, meaning they have the same phase or position in their respective cycles. In simpler terms,...

For each mode in an optical waveguide, the term used to describe the process by which an electromagnetic signal is distorted by virtue of the dependence of the phase and group velocities on...

A waveguide is a physical structure or device that is designed to confine and guide electromagnetic waves, such as radio waves, microwaves, or light waves. It is commonly used in communication...

A device that measures the wavelength of an electromagnetic wave.

Electromagnetic energy is transmitted in the form of a sinusoidal wave. The wavelength is the physical distance covered by one cycle of this wave; it is inversely proportional to frequency.

The magnetic flux that, linking a circuit of one turn, produces in it an electromotive force of one volt as it is reduced to zero at a uniform rate in one second.

Also known as cathode-ray tube grid or shield. A cylindrically shaped electrode that, containing the cathode of a cathode-ray tube with opposite potential, is designed to focus and control the...

Whole slide imaging (WSI), also known as virtual slide microscopy or digital pathology, is a technology that involves the digitalization of entire glass slides containing histological or cytological...

1. A piece of glass with plane parallel surfaces used to admit light into an optical system and to exclude dirt and moisture. 2. A particular region of the electromagnetic spectrum that has been...

A technique for reducing data processing requirements by electronically defining only a small portion of the image to be analyzed, all other parts of it being ignored.

Two flat parallel electrodes that are vertically mounted alongside each other in a cathode-ray tube and produce horizontal deflection of the beam when a difference of potential is applied between...

An image intensifier that consists of an evacuated tube with a large input phosphor screen at one end. The phosphor screen is in contact with a light-sensitive photocathode that emits electrons....

The method of acquiring characteristic x-ray spectra from microscopic samples by use of the combination of a scanning electron microscope and x-ray spectroscopy.

Also known as an anticathode. An electrode or electrode section that is focused upon by an electron beam and that emits x-rays.

The arc formed when the rare gas xenon is excited electrically and emits a brilliant white light. Xenon is used to fill electronic and stroboscopic flashlamps, and also large discharge tubes for...

A printing process of electrostatic electrophotography that uses a photoconductive insulating medium, in conjunction with infrared, visible or ultraviolet radiation, to produce latent...

A printing process of electrostatic electrophotography that uses a photoconductive insulating medium, in conjunction with x-rays or gamma rays, to produce latent electrostatic-charge patterns for...

The difference in electrokinetic potential between the stationary liquid connected to a solid phase surface and the mobile portion of the liquid's diffuse layer.

A small bulb containing a conducting gas, an arc being formed between a metal ring and a tiny zirconium electrode near the center of the ring. The heated zirconium emits light, and constitutes a...

To control, by magnifying or reducing, the size of a televised image, either electronically or optically.