Photonics Dictionary

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 diverging lens is a type of lens that causes parallel rays of light to spread out or diverge. It is thinner in the center than at the edges and is commonly referred to as a concave lens. The most...

A scanning technique in optical character recognition in which an array of photocells is used to scan each character to determine its horizontal and vertical characteristics.

A general-purpose lens, also known as the Celor lens, used widely in photography and commercial processing; it has the form of a triplet with a split flint element.

A primitive crystal possessing two plane surfaces that form a dihedral angle bisected by another plane surface.

A single wavelength of light that matches the color of a given sample when combined in suitable proportions with white light and a suitable adjustment of intensity.

An impurity in a material that is capable of inducing electrical conduction in that material by transferring an electron to the conduction band.

A type of asynchronous shutter device that is used particularly in CCD sensor applications to capture an image of a high-speed subject with no time delay. The word donpisha is taken from the Japanese...

In the context of materials science and semiconductor physics, doping refers to the intentional introduction of impurities into a semiconductor material in order to alter its electrical properties....

The spreading of potentially equal radiation frequencies that results in broadening of the spectral line. This effect is brought about when radiating atoms, molecules or nuclei have different...

The effect produced on a wave frequency because of the relative motion of a source or an observer. The radiation emitted from a source that moves away from an observer appears to be of lower...

The theory established by Christian J. Doppler in 1842 that states that the rate of change in distance between a perceiver and a radiation source determines the change in frequencies.

The magnitude, expressed in cycles per second, of the alteration of the wave frequency observed as a result of the Doppler effect.

A signal traveling from transmitter to receiver that has an altered frequency due to the Doppler effect.

The principle stating that the displacement of spectrum lines is determined by the distance between, and relative velocity of, the observer and the light source. When distance decreases, the lines of...

An imaging process, similar to specific Doppler mapping radar techniques, that utilizes a laser, an optical imaging system, and a line array of photodetectors and spectrum analyzers. The laser...

A display format consisting of small light-emitting elements arranged as a two-dimensional array. Various elements are energized to depict a character. The typical matrix is 5 x 7 dots.

A measurement of the spatial resolution of a line or area array in an optical character recognition scanning device.

The separation of unpolarized light into two plane-polarized elements by a doubly refracting crystal. When a crystal, such as calcite, is placed between the eye and a pinhole in a card, two bright...

A pair of long, slender parallel apertures used in experiments on diffraction and interference.

A defect of a binocular instrument causing two images to be seen separately instead of being fused. It is caused when the optical axes of the two telescopes are not parallel. In minor cases, the eyes...

A cathode-ray tube that either splits an electron beam from one source or uses beams from two sources to produce two beams, each of which can produce separate traces, but which can overlap.

Double-clad fiber (DCF) is a specialized optical fiber that features two concentric cladding layers surrounding a core. The design of double-clad fibers allows them to be used in various...

A method of fabricating an optical waveguide by melting the core and clad glasses in two suitably joined concentric crucibles and then drawing a fiber from the combined melted glass.

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.

The formation of an interferogram by means of two holograms on the same recording medium, often used for determining small changes in an object. One hologram produces a primary image that constitutes...

A fast, wide-angle lens used in television and photographic cameras, with excellent overall correction, but subject to residual oblique spherical aberration.

A device used to create a light output that exceeds light input, the energy being provided by an electric field. It consists of a photoconductive layer with an electroluminescent layer between plates...

A CRT screen on which two phosphors differing in color and persistence are deposited.

A hologram having an object wave that has been transmitted through the transparent object media to a mirror, reflected again and recorded on a medium.

Holographic recording whereby the object is illuminated by two pulses, separated by a time interval, from a Q-switched laser source. Each pulse is divided into reference and object beams, and...

Optical fiber capable of operating at both a shorter and a longer wavelength.

1. A compound lens consisting of two elements. If there is an air space between the elements it is called an "air-spaced doublet.'' If the inner surfaces are cemented together, it is called a...

A form of prism invented by H.W. Dove. It resembles half of a common right-angle prism in which a ray entering parallel to the hypotenuse face is reflected internally at that face and emerges...

A system for fabricating optical fiber, consisting of a furnace that heats the materials, a polymer coating stage, a capstan-pulling apparatus that free-draws the preform into a fiber and a drum on...