Photonics Dictionary

In rangefinders and height finders, a rotatable or sliding wedge-shaped element used to divert the line of sight precisely to correct errors in the optical system.

A rangefinder on a camera that is integrated with the focusing mechanism so that when an object's range is determined, the camera is automatically in focus.

The science and technology applied to the creation of low temperatures (i.e., approaching absolute zero).

In a gas, an electrical discharge that has no luminance.

The condition in which two or more energy states are identical.

A critical image parameter in applications where object position may change dynamically relative to the imager; this is a sensitive function of the system's preclosed loop (initial) focal range and...

A discharge lamp filled with deuterium to produce high-intensity ultraviolet radiation for use in spectroscopic analysis.

Dichalcogenides are a class of compounds composed of two atoms of a chalcogen element bonded to a single atom of a metal or metalloid element. Chalcogens are the elements in group 16 of the periodic...

An instrument that can preselect intervals, often in increments of 1, 10 or 100 ns, for the generation of electronic pulses by means of front-panel switches. Also called a time-delay generator.

The technique by which an analog image is converted by any of several means into a finite array of points, each represented by some numerical value. Once created, this array can be the basis of a...

The vertical angular disparity between the lines of sight of the left and right systems in a binocular instrument. Dipvergence is plus when the right image is below the left image.

A cathode-ray tube in which secondary emission electrons form a display of high intensity.

1. In optics, the bending of rays away from each other. 2. In lasers, the spreading of a laser beam with increased distance from the exit aperture. Also called beam spread. 3. In a binocular...

A lens with one surface convex and the other concave, the latter having the greater curvature. It also is known as a diverging meniscus lens.

A type of transversely excited laser with a uniform arc-free discharge of large cross-sectional area that can be scaled to very large systems.

A prism block that, when used with a lens, is capable of forming two images of one object.

A package for electronic components that is suited for automated assembly into printed circuit boards. The DIP is characterized by two rows of external connecting terminals or pins, which are...

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...

A lamp that uses the transmission of an electric current through a gas or vapor to produce illumination. Neon, mercury and argon lamps are examples of electric-discharge lamps.

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...

A panel of photoconductive and electroluminescent layers used as either a positive or negative image intensifier, depending on amplitude and phase of its two power supply voltages. The...

An image intensifier tube that uses a magnetic field for focusing. It yields high-quality images, but its use is limited by its size and weight relative to other image tubes.

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...

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...

An advanced magnetic device used in x-ray lithography to beam x-rays onto the surface of silicon wafers used for semiconductor circuits.

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

The effect produced by electrical charges or fields alone, without interaction with magnetic influence.

A nonmagnetic instrument utilizing an electrofocus and deflection tube with a photocathode for imaging purposes. The optical image is converted into a photoelectric output at the photocathode and is...

Information storage on a dielectric medium that represents the data as those spots on the medium having electrostatic charges, forming an observable record of the data.

An image intensifier that uses electrostatics to amplify and focus the electronic image.

In optics, the light ray leaving a medium in contrast to the entering or incident ray.

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 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...

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

The series of rings when monochromatic light passes through a Fabry-Perot interferometer.