Photonics Dictionary: E

A device that uses four electrodes set in an alternating positive-negative polarity series to focus the beams of charged particles employed in electron microscopes and particle accelerators.

An electron lens consisting of a homogeneous axial electric field and a magnetic field used in high-quality image tubes for high modulation transfer function and small geometrical distortion...

An electrostatic device that uses an electric potential barrier to allow the transmittance of electrons at or above a set level of energy while stopping the passage of those below it.

An electric field produced to influence an electron stream much in the same manner that a lens affects a light beam.

The electrical distribution that serves to influence an electron beam in the same way that an optical lens affects a light beam.

The lens of an eyepiece nearest the observer's eye.

A lens mounting with eccentric rings that may be rotated to shift the axis of the lens to a prescribed position.

A diffraction grating with lines and grooves formed so as to concentrate the radiation of a particular wavelength into one specified order. This device is efficient when used in the infrared region...

The flat or angled surface, usually fine-ground, that limits the aperture of a lens or prism surface.

The maximum variation in thickness of a lens as measured around a diameter centered on the optical axis. The ETD divided by that diameter yields the wedge of the lens.

For a lens with an obscured or noncircular aperture, the focal length divided by the effective aperture.

1. That portion of the aperture that functions to collect energy and deliver it to the final system detector. 2. For an obscured or noncircular aperture, the equivalent nonobscured, circular aperture.

A change in the refractive index of an optical fiber caused by variation in the length of the fiber core in response to mechanical stress.

Any material of a macromolecular nature that can stretch at room temperature to more than twice its length and return to approximately its original shape when stress is released.

Expression of the length of a transmission medium in terms of wavelengths of the propagating wavelength. In general, electrical length is an expression of physical length in wavelengths, radians or...

A device consisting of an airtight quartz tube that holds the material to be analyzed. When a high-frequency electrostatic field, generated by microwaves, is applied to the tube, it emits energy of a...

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...

The total range of wavelengths, extending from the shortest to the longest wavelength or conversely, that can be generated physically. This range of electromagnetic wavelengths extends practically...

A maser that relies on the fact that electrons in orbital motion in high-magnetic fields will emit energy at the cyclotron frequency. The transfer of energy is from the bunching of the electrons by...

A cathode-ray tube that increases the brightness or size of an image or forms a visible image from invisible radiation. The focal plane for the optical image is a large, light-sensitive, cold...

The photographic recording of images produced by the electrons from an electron microscope. The electron beam carries the images through an array of three lenses, and an enlarged electron image is...

A device utilizing an electron beam for the observation and recording of submicroscopic samples with the aid of photographic emulsions or other short-wavelength sensors. With the electron microscope,...

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...

The control of free electron movement through the use of electrical or magnetic fields, and use of this electron movement in research investigation of electronic diffraction phenomena, directly...

The method by which photographic film is scanned by an electron beam. One technique uses the uniform light of a television screen, focused by a lens onto the processed film, as a means of creating a...

An electron-beam lithography (EBL) system is a sophisticated nanofabrication tool used in the semiconductor industry and research laboratories to pattern extremely fine features with sub-micrometer...

The point at which short-wavelength transmission is cut off.

An electrowetting display (EWD) is a type of electronic display technology that utilizes the principles of electrowetting to control the behavior of colored oil droplets on a hydrophobic surface....

A light beam whose electric vectors are broken into two elements of unlike amplitudes that are perpendicular to each other and that differ in phase by values other than 1, 3/4, 1/2, 1/4, etc.,...

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...

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

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

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...

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...

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...

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.

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.

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