Photonics Dictionary

The transition cross section constant coefficient which defines the transition probability of absorption from ground to a higher level within a given atomic or molecular species. The transition...

The present radiation level within a laser or electromagnetic radiation operating area.

Electromagnetic radiation present upon the open aperture of the source within an operating environment.

Mount attached to a camera or camcorder which allows the user to attach a microphone or flash unit.

Glass designed to absorb most infrared and ultraviolet radiation while transmitting most of the visible region.

A process of color photography in which colors are added one to another in the form of light, rather than as colorants, to obtain color synthesis.

The code signifying the location of the information being sought on a CD-ROM.

In display technology, an expression of resolution given by the number of pixels in both the horizontal and the vertical axes of a cathode-ray tube or similar device.

A process during which no heat enters or leaves the system.

Advanced driver assistance systems (ADAS) refers to a set of safety features and technologies designed to assist drivers in the driving process and enhance overall vehicle safety. These systems use...

An aerial reconnaissance system that can transmit, in near real time, image data recorded by IR and visual-spectrum sensors, providing day, night and foul-weather intelligence.

The use of optical or electronic recording systems to extract information from the terrain, while aloft, for reconnaissance applications.

A category of systems designed to communicate a photo taken from the air (e.g., aircraft, balloon, satellite) to a ground station. It can be done by direct television transmission of the photo, or by...

Broadband radiation emitted by a laser that does not transmit through the optical element. It can be removed by filtering.

In image processing, a specially designed programmable computer peripheral that attaches to the host system for the purpose of more rapid arithmetical calculations than the latter can supply. The...

A gas, such as oxygen, that improves the speed and efficiency of a laser cutter or welder when applied to the work surface, or an inert gas, such as argon, that helps to clean or shield the work...

A mode of data transmission whereby each bit of information is generated separately, with some stop/start code to indicate the interval between bits.

Spectrometric analysis of the distinct and characteristic spectra of atoms of elements. The atoms are energized to emit radiant energy, which, when dispersed by a prism or diffraction grating,...

The range of frequencies that will pass through a filter or other device. Synonymous with passband.

A filter with a transmission that is high for a particular band of frequencies, but that falls to low values above and below this band.

The roughness profile shape from which light scattering is expected to occur.

The application of reversible writing with a laser beam on particular storage materials. In one method, an amorphous film is heated and then crystallized for writing. Bubble writing involves the...

The loss of optical power in an optical fiber because radiation escapes through its bends. The radiation loss caused by fiber bending is proportional to the bend radius.

Two formulas used in diffractometer analysis, the first giving the individual diffraction patterns of each aperture, the second representing the constant of the degree of an incoherent circular...

The inability to perceive visual images (visible radiant energy). In human beings, blindness is defined as a visual acuity of less than one-tenth normal vision.

A strong, heat-resistant glass that contains a minimum of 5 percent boric oxide.

A sheet of thin brass, one edge of which has been accurately cut to a known and marked circular radius. It is used to check the radius of curvature of a rough-ground lens by contact.

Electromagnetic radiation that is emitted by an electron as it is accelerated or decelerated while moving through the electric field of an ion.

The manual shifting bias control of a cathode-ray tube that determines both the average brightness and the contrast of a picture.

An instrument for measuring the brightness (luminance) of a scene. It may be a spot meter, covering an area of a degree or less, or an averaging meter, covering a broad area of the scene. Brightness...

The degree to which a pixel in a digital image represents the analog brightness of the corresponding point in the original image. It is dependent largely on the number of bits devoted to representing...

A graduated range of stimuli perceived as having equivalent differences of brightness.

A convex lens that brings an incident bundle of rays to a focus to produce intense heat at the focus.

The measure used in vacuum technology to quantify the total pressure capacity of the ferrofluidic seal before it fails.

Glass that has been treated by the case-hardening process.

A two-mirror lens design used in astronomical telescopes, the primary being a parabola, the secondary a smaller hyperbola. The image formed is free of spherical aberration and color and is located...

A container designed to hold recording material (film, video- and audiotape) so that when it is loaded into a recording instrument, the recording material is threaded simultaneously.

The lens thickness measured at the optical axis.

The computer module whose circuitry interprets instructions and guides the actions of the peripherals. Also known as the mainframe.

The breakdown of the bonds in polymer chains caused by illumination.

The sensations of hue and saturation, taken together, but not brightness or lightness.