Photonics Dictionary

In a fiber optic transmission system, the conversion of received optical pulses directly to an electrical signal.

Light produced by visible radiation that moves from the light source to the object without reflection. With respect to microscopy, this is the light that directly strikes the stage of the microscope...

Also called DLIP, a high-speed, high-resolution processing technique that uses high-power, pulsed laser systems to directly ablate micro- and nanoperiodic structures with different features on large...

An energy transition concerned with photons alone.

A ray that travels from one point to another without being reflected or refracted.

A write-once optical disc storage system in which the optical head reads continuously while writing to check the accuracy of the stored data. Data recorded erroneously are then rewritten at another...

A scanning technique in which the object is illuminated the entire time, and in which picture elements of the object are viewed singly by the television camera.

In a camera, the focusing of an image on the screen located at the camera's film plane. Once the image is in complete focus, the recording medium is inserted in place of the screen.

Light transmission involving no scatter.

A viewfinder whose optical system forms a direct image of a subject, as opposed to those systems that use reflectance in the image formation.

The observation of a reproduced television picture on the face of a cathode-ray tube.

With respect to atomic fluorescence spectroscopy, the fluorescence that is emitted by an atom at a spectral line of a wavelength that is longer than that of the stimulating radiation.

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

A small handheld instrument consisting of a slit and collimator that feeds light into a small direct-vision dispersing prism. The eye is placed behind the prism to observe the spectrum of a colored...

An assembly of multiple prisms that disperses incident light into its spectral components without deviating light at the central wavelength.

Directed energy refers to a type of energy that is emitted and transferred in a controlled direction. The term is often associated with military and technological applications where energy, typically...

Reflectance in a specified direction, for a specified direction of incident illumination.

In a liquid crystal system, the director refers to the local symmetry axis around which the long range order of the liquid crystal is aligned. In the case of the nematic phase, the molecular long...

A hole filled with dirt such as a polishing abrasive and located in an optical surface. See dig; scratch.

A piece of glass that eventually becomes the bifocal segment as it appears prior to being fused to the blank.

A device that provides simple and reliable laser power and energy measurement. Essentially a heat flux sensor producing an output proportional to the power, rather than the energy input.

A colorimeter using a spinning disc made of different colored sections for colorimetric analysis.

A laser having a rod that is a stacked array of discs immersed in a transparent flowing coolant fluid. In this way, the cooling rate is increased, the temperature gradients are basically parallel to...

A composite derived from aluminum alloy powder and silicon carbide, used as an optical substrate in air- and spacecraft applications. It is as light as aluminum but exhibits greater strength and...

An individual circuit component, complete in itself, such as a resistor, diode, capacitor or transistor. It is used as an individual and separable circuit element.

A mathematical transformation used in image and video compression that changes two-dimensional representation of data into data defined by the frequency content. Adapted in JPEG and MPEG standards.

A spectrum of component wavelengths whose values are separate from each other.

The degree to which a vision system is capable of sensing differences in light intensity between two regions.

A circuit incorporated into counter systems that records only pulses that have amplitudes between two preselected limits.

The region of distorted atom configuration formed between the displaced and normal areas in a crystal when part of the crystal is displaced tangentially.

A prism or series of prisms used to disperse a beam of radiant energy of mixed wavelengths into its spectral components.

Dispersion refers to the phenomenon where different wavelengths (colors) of light travel at different speeds when passing through a medium. This variation in the speed of light for different colors...

A complex filter that uses polarization and interference to transmit light that is nearly monochromatic.

All formulas that present the index of refraction as a function of a wavelength of electromagnetic radiation. Also called dispersion equation, Cauchy formula, Hartmann formula.

A type of glass optical fiber that provides low pulse dispersion over a broad portion of the light spectrum and as a result can operate at 1300-nm and 1550-nm wavelengths simultaneously.

Operation in which the dispersion of a pulse limits the distance between repeaters in optical systems. Waveguide and material dispersion can make recognition of a pulse impossible.

A dispersion-shifted fiber (DSF) refers to a type of optical fiber designed to minimize the effects of chromatic dispersion, which is the phenomenon where different wavelengths of light travel at...

A measure of the dispersive properties of a glass. The relative dispersion is defined as: where C, D, and F refer to the material's index of refraction at the three chief Fraunhofer lines in the...

The observable illustration of an image, scene or data on a screen such as a console or cathode-ray tube, seen as a graph, report or drawing.

A visual display used with a computer to give access to the many elements of data as an array of points. With the display console, an operator may check information in the computer and change it if...

In optical character recognition, the mechanical or electronic transducer used to detect the level of illumination present in the various portions of an illuminated sample region.

In optics, the production of maxima and minima by the superimposition of two sets of interference fringes from light of two different wavelengths.

The end of an optical fiber farthest from the source of illumination.

The near-point distance of the normal eye. The value of 10 in. or 25 cm is normal. This value is used in evaluating the designated magnification of a simple magnifier or eyepiece.

In astronomy, the relation that states that the intensity of a star's visible radiation is inversely proportional to the square of the distance from which it is viewed.