Photonics Dictionary: I

Describing the standard television method of raster scanning in which the image is the product of two fields, each of which is a series of successively scanned lines separated by the equivalent of...

Interlayer attraction refers to the attractive forces between adjacent layers of atoms or molecules in a material, particularly in layered structures such as van der Waals solids, graphene, and...

In an optical system with a series of lenses, images formed prior to the final focal plane.

A nonoptical surface, within lenses and lens mounts, that contributes largely to flare by reflecting light into the image space. As a result, such surfaces, so located, are finished with a dull...

The ratio of the radiant power transmitted to the second surface of a medium to the corresponding radiant power that has just passed through the first surface. Internal transmittance does not denote...

A unit of measurement of luminous intensity based on a physical standard, a set of calibrated carbon filament lamps. The old candle unit was superseded by the new candle or candela.

The internet of things (IoT) refers to a network of interconnected physical devices, vehicles, appliances, and other objects embedded with sensors, actuators, software, and network connectivity....

Measures the refractive indices axially from the fiber profile. Microscopy technique provides an interferogram with high contrast with demonstrated improvements in relation to the Pluta two-beam...

Intravital microscopy is an imaging technique used to visualize biological processes within living organisms, typically in real-time. Unlike traditional microscopy, which involves the examination of...

A photodetector composed of a photoconductive material that, when exposed to radiation, conducts without the aid of added impurities and does not have to be cooled to the level of extrinsic material....

The photoemission that would occur if a crystal were pure and its structure perfect.

A material often used in the construction of optical instruments because of its low coefficient of thermal expansion (0.9 x 10-6/ °C).

The resulting contraction or expansion of a piezoelectric crystal along an electric axis when the crystal is under the influence of an electric field in the same direction.

Any problem that requires retrieval of the distribution of some internal properties, such as temperature concentration, etc., from remotely sensed data.

The law stating that the illuminance (or irradiance) from a point source varies as the inverse square of the distance between the source and the receiver.

An image that is similar to the object but rotated 180° about the axis of the system.

A development aimed at extending the life of a tungsten filament. The iodine vapor in the lamp envelope combines with the tungsten vapor emitted by the hot filament, but the compound is decomposed by...

A fusion system conductor capable of carrying current in opposite directions in alternating time phases.

An atom that has gained or lost one or more electrons and, as a result, carries a negative or positive charge.

A laser in which the transition involved in stimulated emission of radiation takes place between two levels of an ionized gas. The gases are electrically excited in a container called a plasma tube,...

Ion-beam sputtering (IBS) is a physical vapor deposition (PVD) technique used for depositing thin films onto substrates. It involves bombarding a target material with a beam of energetic ions,...

A type of radiation detector that depends on the ionization produced in a gas by the passage of a charged particle through it. One of the best known is the Geiger-Müller counter, although cloud...

The amount of energy required for a particular kind of atom to remove an electron to infinite distance. The ionization potential is usually expressed in volts.

Also known as the Bragg spectrometer. A system used for the x-ray analysis of crystal structure. In the instrument, a homogeneous beam of x-rays is directed on the known face of a crystal and the...

Generally, any radiation that can form ions, either directly or indirectly, while traveling through a substance.

An electroradiographic process that uses ionization of air by x-rays as a basis for forming electrostatic images.

A mechanical device designed to smoothly vary the effective diameter of a lens, thereby controlling the amount of light allowed through.

The adjustable membrane located just in front of the crystalline lens within the eye. The iris gives the eye its color. See also iris diaphragm.

1. Lines of the same color. 2. A term used in photoelastic stress analysis to refer to the interference fringes produced in birefringent materials.

The points on a photographic negative that are of equal density.

With respect to the effect of crystals on lightwaves, the family of curves having constant direction of polarization.

In the context of electronics and optics, an isolator refers to a device that allows the transmission of signals in one direction while attenuating or blocking signals in the opposite direction. The...

Graphic representation of quantified values of image quality whose points all refer to images that are of a constant subjective quality.

A spectroscopic technique in which an excitation band absorbs laser energy resulting in an electronic transition. The isotopic species may then be measured using a time of flight mass spectrometer....