Definitions: E

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.

A telescope stand equipped with a polar axis that can be set parallel to the Earth's axis of rotation and a declination axis that is at right angles to the polar axis. If the telescope is turned at a...

A telescope that is mounted on an equatorial mount.

1. A contour map of a photographic deposit consisting of lines and curves that join points of equal density. 2. The portrayal of a photograph's points of equal density in hues of yellow, cyan and...

1. The use of an electronic microdensitometer to measure points of equal density on a photographic deposit. 2. A technique that simplifies a picture's density pattern by making a single isodensity...

The length of optical waveguide needed to attain equilibrium mode distribution for a specified excitation condition.

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

Colors differing only in chromaticity but not in luminance.

Calculation of the amount of energy extracted from a light beam regardless of its wide range resolution.

When a block of glass (prism, window, filter, etc.) is placed into a converging light bundle, it increases the physical distance to the point of focus. The equivalent air path for that block of glass...

In surface height measurement of optics with steep slopes, the use of two short visible wavelengths to synthesize a longer, equivalent wavelength.

An Er:YAG laser is a type of solid-state laser that uses a crystal made of erbium-doped yttrium aluminum garnet (Er:Y3Al5O12) as the gain medium. The erbium (Er) ions are introduced into the crystal...

Data or encoded information capable of being eradicated, leaving the media free for rewriting. Also called reversible.

An optical fiber that can be used to amplify an optical input. Erbium rare earth ions are added to the fiber core material as a dopant in typical levels of a few hundred parts per million. The fiber...

An image, real or virtual, whose spatial orientation is identical to that of the object. The image obtained at the retina with the assistance of an optical system is said to be erect when the...

An eyepiece combined with an erecting prism or lens system.

Lenses or prisms that serve to erect the image; i.e., to bring the image upright after it has been inverted by the objective.

A telescopic eyepiece comprising five or six simple lenses in the form of three doublets or two doublets and a singlet.

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...

The addition to the information signal in communications of redundant bits that enable the originally encoded message to be decoded without degradation of the data. In compact disc technology, the...

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...

Localized redness of skin due to congestion of capillaries; a common result of overexposure to laser radiation.

An etalon is an optical device that consists of two parallel reflecting surfaces separated by a precise and known distance. It operates based on the principle of optical interference and is used to...

Etaloning is an optical phenomenon that occurs in imaging systems, particularly in devices such as spectrometers, interferometers, and cameras. It is characterized by the appearance of interference...

The engraving of a surface by acid, acid fumes or a tool; a process extensively used in the manufacture of reticles.

An acid used to etch the surfaces of particular materials. For glass, hydrofluoric acid is used either as a liquid or a vapor. Metals are etched by means of suitable acids or other liquids, often to...

A product of the area of a light beam (normal to its direction of propagation) and the solid angle that the beam includes; flux per unit radiance or luminance. Alternative terms: geometric extent,...

The material that has the lowest possible constant melting point of any possible combination of the same components.

A high-frequency approach to the propagation of light in graded-index fibers in which the modal field is represented in terms of an inhomogeneous (evanescent) plane wave with a complex phase, so that...

A sensor generally used for infrared imaging. It consists of two chambers separated by a thin, blackened membrane. An infrared image is formed on the membrane by a lens or mirror and produces...