Photonics Dictionary

An optical system having two sets of components separated by an air space, while successive lenses in each set are cemented together.

In data communications, the simultaneous operation of a circuit in both directions is known as full duplex; if only one transmitter can send at a time, the system is called half duplex.

An instrument that uses a photoelectric system to determine the size and volume of dust particles in a given unit of air.

A microscope that has been modified to permit the quantitative analysis of dust samples.

In atmospheric optics, the almost total blocking of light transmission in the atmosphere due to the scattering and absorption of the light by dust particles.

Also duty factor, duty ratio. The product of the pulse duration and the pulse repetition frequency of a wave composed of pulses that occur at regular intervals.

For a detector, the amount of time alotted for the observation of one location.

A laser using a dye solution as its active medium. Its output is a short pulse of broad spectral content and its achievable gain is high. Dye lasers function at room temperature. Synchronous pumping...

The subtractive imbibing process of transferring color prints on paper whereby the dyes from three separately prepared images are transferred to one sheet of paper to form the color print.

A type of erasable data storage device that uses a medium deposited on the disc in two layers, each dyed to absorb a different wavelength of laser light. To record data, the lower layer is heated by...

The superimposition of a pilot object on each hologram. The fixed relative position of the scanning and pilot beam during the recording process ensures that sensing and fixing the pilot beam position...

Stress applied to an optical fiber at a constant rate.

An optical correlator incorporating a binary phase-only spatial light modulator made from an iron garnet magneto-optic solid crystal and used in target recognition systems.

A spectroscopic technique used to display the intensity of an optical pulse as functions of time and frequency simultaneously.

A type of mosaic detector array that combines features of scanning and staring sensors by using a small rapid scanning motion (see saccadic motion) over a few pixels at a time.

The theoretical explanation and analysis of the interactions between electron waves and crystals used in studying electron diffraction.

In electrical equipment, power variations that are temporary (as opposed to the permanent, cumulative effects of drift).

The auxiliary electrode in a photomultiplier that gives rise to secondary emission and amplification when bombarded by photoelectrons.

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

Observed phenomenon of a small developed image with higher density than a larger image because of variation in photographic plate densities with variations in size of opening.

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

In the tolerancing of optical elements, the displacement of the optical axis from the mechanical axis.

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...

A grating that serves to provide higher resolution and dispersion than the average grating, and still has a greater free spectral range than either the Fabry-Perot etalon or the reflection echelon.

A specialized form of diffraction grating consisting of assembled glass plates of equal thickness that resemble a flight of stairs. The light enters through the largest plate at the end and emerges...

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

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.

In image processing, any operation that strengthens information about the edges of objects displayed. Three types of spatial filtering are used: shift and difference, gradient and Laplacian.

In image processing, a segmentation algorithm for isolating a region in an image by following its edge.

Intensity distribution in the image of an edge. The gradient of the edge-response curve is a measure of the image quality of the optical system under test.

Technique for the precision evaluation of coincidence of a laser beam's center with the edge of the object under study and exact location of that edge by means of a double electronic differentiation...

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.

Process for growth of solar cells that results in rectangular shapes consisting of many interconnected cells in a series or series-parallel arrangement. EFG cells show increased efficiency with...

An edge-emitting light-emitting diode is a type of LED structure where light emission occurs primarily along the edge of the semiconductor chip rather than from the surface. Edge-emitting LEDs are...

The finishing of the edge of an optical element by grinding.