Photonics Dictionary: E

In image processing, the location of edges by employing templates that respond to the first or second derivative of gray-scale intensity in the neighborhood of each pixel.

The effect whereby a light beam is deflected by a birefringent prism when its polarization is changed by voltage applied to an electro-optical crystal through which the beam passes. The deflection of...

The interaction of charged particles and electromagnetic fields.

Radiation emitted from vibrating charged particles. A combination of oscillating electrical and magnetic fields that propagates through otherwise empty space with the velocity of light. This constant...

A type of modulation spectroscopy that measures spectral reflectance or transmittance changes induced by applying a perturbing electric field. It can be performed in contactless modes with no special...

The bending of an electron stream that occurs when the stream travels through a medium such as very thin metal foil.

A special evacuated camera equipped with means for holding a specimen and bombarding it with a sharply focused beam of electrons. A cylindrical film is placed around the specimen to record the...

The freeing of electrons from an electrode into the surrounding space.

An EMCCD (electron-multiplying charge-coupled device) camera is a type of scientific camera specifically designed for low-light imaging applications that require high sensitivity and fast readout...

A method of thin-film deposition in which electrons boiled off a heated cathode are used to melt the coating material. If a multipocket crucible is used, many materials can be processed at the same...

The deflection of an electron beam by the action of an electrostatic field that has a component perpendicular to the direction of the beam.

Elastic deformation of a dielectric caused by volume force when the dielectric is placed in an inhomogeneous electric field.

Embedded vision refers to the integration of computer vision technologies into various embedded systems, devices, or machines. Computer vision involves teaching machines to interpret and understand...

The line or lines emitted by an element when its radiation particles travel from one energy level to another.

A type of electron microscope in which the specimen also serves as the cathode source.

Thermal emission caused by the unity in absorption bands that must be discriminated when calculating radiation intensity of any celestial object.

A study of the energies and wavelengths of radiation emitted by atoms and molecules when particular physical conditions are applied to them.

An emission spectrum is a graphical representation or a characteristic pattern of the wavelengths or frequencies of light emitted by a source, such as an atom, molecule, or celestial object. It shows...

A computer-generated routine for achieving true-temperature readings in thermal infrared imaging systems.

Magnification that is above the level of maximum useful magnification and does not contribute useful resolving power. In a visual telescope, empty magnification is any in excess of 20 D, where D =...

In photography, the layer of light-sensitive material (usually a suspension of silver halide crystals) that coats the film or plate.

The sensitivity of a photographic emulsion when exposed to light, provided that the film is developed through a standard process.

Enhanced picture archiving and communication system (PACS) display (ePAD) is a software tool used in medical imaging to view, manipulate, and analyze radiological images, such as x-rays, CT scans,...

Distortion caused by variations in the rate of change of phase shift with frequency over the signal's necessary bandwidth.

Epitaxial deposition is a process used in semiconductor manufacturing and materials science to grow a thin crystalline layer, known as an epitaxial layer, on a substrate. The term epitaxial refers to...

The condition in a multimode optical waveguide in which the relative power distribution among the propagating modes is independent of length.

In image processing, a morphology operator in which a structuring element or probe of a particular shape is moved over the input image. Where the probe fits completely within the boundaries of a...

A single number, defined by the computer program or the user that expresses the performance of an optical system. Also known as merit function and defect function, the error function comprises...

Coating carried out in a sealed chamber evacuated by a mechanical pump in series with an oil diffusion pump to a pressure less than 10-4 mm of mercury, measured by a vacuum gauge. At such a low...

A process, either naturally occurring or mechanically induced, whereby water is changed from its liquid state into a vapor.

1. The process by which an atom acquires energy sufficient to raise it to a quantum state higher than its ground state. 2. More specifically with respect to lasers, the process by which the material...

The difference between the energy of an atom in its ground state and that of the same atom in its excited (quantum) state.

The ratio of the intensities of two specified spectral lines of a source having vastly different excitation energies. This ratio indicates the level of excitation energy in the source.

The amount of energy required to raise the energy level of an atom; a necessity if the atom is to radiate energy. High excitation potential is the amount of energy in the upper state of the...

On the CIE chromaticity diagram, the distance from the achromatic point to the sample point, divided by the distance from the achromatic point through the sample point to the spectrum locus or purple...

The amount of x-rays used to penetrate and diffuse a target sample undergoing electron-probe microanalysis.

In laser pumping, parasitic absorption that occurs at certain wavelengths, decreasing pump efficiency and gain.

The light spectrum formed by an explosive reaction or by the electrical explosion of a metallic wire by a strong current.

1. The near total absorption of plane-polarized light by a polarizer that has an axis perpendicular to the plane of polarization. 2. The decrease in the intensity of a diffracted beam resulting from...

A type of exposure meter that artificially reduces the light admitted in a sequence of known fractions until a value is reached that is equivalent to the proper exposure.

The ratio of the power of a plane-polarized beam that is transmitted through a polarizer placed in its path with its polarizing axis parallel to the beam's plane, as compared with the transmitted...

The lowest anode voltage at which a gas tube can sustain a discharge.

A cement used to reduce crosstalk in fiber optic bundles or plates.

Radiation that is emitted by a source outside the Earth and its atmosphere.

Wavelengths between 400 and 1400 nm (VIS to NIR) are focused onto the retina by the cornea. Because the retina is sensitive to light, these wavelengths can be damaging even at low energies. It is the...

An event-based image sensor, also known as a dynamic vision sensor (DVS), is a type of digital imaging device designed to capture visual information in a highly efficient and unique way compared to...

In a waveguide, a change in direction of the axis without deviating from the plane of polarization.