Definitions

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...

The emissivity of a body times the emissive power of a blackbody at the same temperature. For a blackbody, it is the total radiation per unit area of radiating surface.

The ratio of an object's radiance to that emitted by a blackbody radiator at the same temperature and at the same wavelength.

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

The use of a material's emissivity to measure absorption. It is useful as an absorption loss measurement technique, since at thermal equilibrium, emittance is equal to absorptance.

See emissivity; exitance.

A source of radiation.

The normal condition of vision where an object at infinity is in sharp focus with the eye lens in a neutral or relaxed state.

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.

Enantiomers are a pair of molecules that are non-superimposable mirror images of each other, similar to left and right hands. They are stereoisomers, meaning they have the same molecular formula and...

An arc lamp whose carbon electrodes are enclosed in a transparent chamber, resulting in an arc that is steadier, lasts longer and emits more ultraviolet radiation.

A laser or laser system positioned within an enclosure to prevent dangerous optical radiation from leaving the enclosure.

End-fire coupling refers to a method of coupling energy into or out of a waveguide, transmission line, or antenna, where the electromagnetic waves are directed primarily along the axis or direction...

An endoscope is a medical device used for visualizing and examining the interior of hollow organs, body cavities, or confined spaces within the body. It consists of a flexible or rigid tube equipped...

The photographing of objects within generally inaccessible areas using endoscopes with camera attachments.

The energy in a medium per unit volume.

A laser that distributes its output power among two, three or four optical fibers simultaneously.

A hologram produced by a pair of radiation beams, each carrying information.

The occurrence of very large rotations in transparent materials at weak magnetic fields as predicted in the classical dispersion theory. This effect was discovered by Mavaluso and Corbino in 1898 in...

An image processing device that displays pseudocolor images by assigning colors to the gray scales according to look-up tables defined by the user.

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,...

A type of laser pulsing with high laser power at the beginning of the pulse.

The line from a spark or other very hot source that has greater intensity than that of a line produced by an arc or flame source. Also called an enhanced line.

The movement of particulate material by flowing gas or liquid.

In a lens or other optical system, the image of the aperture stop as seen from object space.

The entrance slit, also known simply as the slit, is an essential component in optical instruments such as spectrometers and monochromators. It is a narrow opening or aperture through which light...

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

Also referred to as a bulb. The glass housing that encloses an incandescent source, or the glass or metal housing that encloses an electron tube.

A test chamber designed to expose the subject being tested to external conditions, such as heat, shock, pressure and moisture, for the study of their effects.

Potential hazards to a system's application and installation, including temperature variations, chemical reactivity, mechanical stress and moisture.

The maximum to minimum range of temperature, pressure, humidity, vibration and biological conditions under which an optical component or system can function and be stored. The range required depends...

An enzyme-linked immunosorbent assay (ELISA) is a laboratory technique used to detect and measure the presence of specific substances, such as antibodies, antigens, proteins, hormones, or other...

A tabulation of predicted positions that have been calculated for one or more celestial bodies or orbiting satellites.

Uniform measure of time based on dynamics law and calculated according to planetary orbital paths; specifically, Earth's orbit about the sun.

A device for projecting either opaque matter or transparent slides onto a screen.

Fluorescence imaging technique in which the excitation light from the objective is directed into the sample producing emission at all angles. Light emitted into the objective is measured allowing the...

The outside or covering layer.

Epitaxial refers to the growth of a crystalline layer on a crystalline substrate in such a way that the orientation of the crystal lattice of the growing layer is related to that of the substrate. In...

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...

Epitaxial equipment refers to a set of specialized tools and systems used in the process of epitaxy, which is the growth of crystalline layers on a substrate material. Epitaxial growth is a critical...

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...

Common name for a variety of adhesives used for lens bonding, fiber optic splicing and other photonics applications. The term is actually a prefix denoting the presence of an epoxide group in a...

A light source that produces an equal-energy spectrum.

Spectrum characterized by equal energy (power, flux) per unit wavelength interval.

A stimulus that contains equal energy at each wavelength in the visible region of the spectrum.

A densitometer having a receiver that indicates when a desired radiation level has been attained.