Photonics Dictionary

The principal point of a lens relative to image space.

A nonlinear label-free imaging technique commonly used during surgical procedures for the visualization of collagen fibers and muscle tissue (myosin) with submillimeter resolution. During the...

Second-harmonic generation (SHG) is a nonlinear optical process that occurs when two photons with the same frequency combine within a nonlinear material, resulting in the generation of a new photon...

Second-order nonlinear optical properties refer to a class of phenomena exhibited by certain materials in response to intense light, typically in the realm of optics and photonics. Nonlinear optical...

The process of grinding the convex surface of a convexo-concave meniscus.

The process of grinding the concave surface of a sphero-cylindrical lens.

Fiber optic cable that operates at the 1300-nm wavelength.

A line formed by the principal (center) ray of an oblique bundle of rays.

The indistinct rainbow that may sometimes be observed outside the distinct primary bow and that has its colors in opposite order. The red colors of both bows are toward each other.

An aberration that remains after primary color is corrected. Primary color causes the back focus of a lens to vary with wavelength; for example, blue light comes to focus closer to the lens than...

Fluorescence produced by a material that has been treated with a dilute solution of fluorescing material.

A self-interference effect that generates random patterns; secondary speckle pattern (SSP) typically occurs in diffuse reflections of a laser on paper, white paint or rough surfaces. By tracking both...

X-rays emitted by a substance that formerly has been exposed to x-rays. The properties of the substance determine the frequency of the rays.

An arrangement of optical fibers in a bundle whereby the geometric configuration of the input end differs from that of the output end without changing the total area; for example, a circular bundle...

A disc, having opaque and transparent sectors or sectors with unlike reflectances, that is rotated at a specific rate to form a continuous response to the average energy transmitted or reflected by...

Characteristic of dissimilar metals in thermoelectric solar cells whereby separate junctions exhibiting distinct temperatures transform incident voltage into a current.

1. In glass, a solid inclusion having a small diameter. 2. A particular, single crystal that, after undergoing the Czochralski method, evolves into large single crystals.

In multifocal spectacles, a term used to denote glass with a high refractive index that has been fused to the blank and ground to a curvature, resulting in added power.

In a bifocal spectacle lens, the vertical measurement of distance from the uppermost borderline of the bifocal segment to the lower lens edge.

In spectacle lenses, the lateral measurement of a multifocal segment at its maximum width.

In optical character recognition, the method of dividing a string of characters into separate, distinct characters.

Seidel aberrations refer to a set of monochromatic aberrations in optical systems, named after the German mathematician and physicist Ludwig von Seidel. These aberrations describe deviations from...

Selective laser melting (SLM) is an additive manufacturing (AM) or 3D printing technology that belongs to the powder bed fusion category. SLM is primarily used for metal additive manufacturing, where...

The reflection in different amounts as a function of wavelength, as a result of absorption and scattering, leading to color effects if occurring in the visible wavelength region.

Transmission in different amounts as a function of wavelength, as a result of absorption and scattering, leading to color effects if occurring in the visible wavelength region.

A photoconductive cell consisting of a layer of selenium on a substrate whose electrical resistance varies with the illumination falling on the cell. Selenium cells have been replaced largely by...

That branch of astronomy concerned with the study of the moon's physical characteristics.

In optical emission spectroscopy, the reduction in radiant power in the central portion of spectral lines arising from the selective absorption by the cooler outer vapor of the source envelope of...

An optically bistable device used for photonic switching, constructed of a multiple quantum well biased by an external voltage, which creates an external field that shifts the wavelength of the onset...

Heating that results from the dissipation of energy.

Any material that derives its energy from chemically or electrically induced reactions; isotope or radium excitation is used to form the glow in luminescent watch or clock hands.

Self-phase modulation (SPM) is a nonlinear optical phenomenon that occurs when an intense laser beam passes through a medium, causing a change in the phase of the light due to its interaction with...

The extreme case of self-absorption.

Derived from "self-focusing,'' Nippon Sheet Glass Co. (NSG) of Japan's trade name for graded-index fiber rods with parabolic index profile, suitable for use as cylindrical microlenses.

An equation that uses the wavelength of light passing through a medium, along with a set of coefficients, to calculate the medium's index of refraction. The coefficients, called Sellmeier...

A semiconductor is a type of material that has electrical conductivity between that of a conductor and an insulator. In other words, semiconductors have properties that are intermediate between...

A formed piece of glass, one surface of which has been ground and polished to the required curvatures.

A term used to describe a spectacle lens or blank with one surface totally finished.

A projection screen having vertical ribs or flutes set into a plastic surface.

An aperture consisting of a semitransparent central region whose amplitude transmittance only is varied, and the relative phase difference between the central and annular region is fixed as p -...