Photonics Dictionary

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...

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....

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...

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.

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

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,...

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.

One of a number of nuclides characterized by an identity between their mass numbers, but each having a different atomic number.

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

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...

A direct recording photometer that is designed to scan a photographic negative to determine its points of isodensity.

That property of a material that determines that velocity of propagation within the material is the same for all directions.

The higher throughput obtained with an FTIR device compared with traditional spectrometers that need slits to achieve resolution. The advantage differs according to wave number and resolution.

A continuous-wave dye laser that uses a circulation pump and nozzle to provide an optically flat stream of dye across the laser's optical axis.

A design for bent crystal monochromators in which spacing is constant along any circular arc terminating at the two foci and with equally spaced Bragg planes curved about only one axis.

The graph of a curve describing the spectral irradiance of extraterrestrial sunlight.

A device consisting of two optical systems in which two signals are simultaneously transformed to produce their spectra, and these spectra are multiplied and inversely transformed to produce the...

A semiconductor device with the property of conducting current more easily in one direction than the other. It has two terminals containing a single crystal of semiconducting material that ranges...

The Kerr effect, named after the physicist John Kerr who first observed it in 1875, is a nonlinear optical phenomenon where the refractive index of a material changes in response to an applied...

A two-stage illuminating system for a microscope in which the source is imaged in the aperture of the substage condenser by an auxiliary condenser, and the substage condenser in turn forms an image...

Westinghouse trade name for an alloy of iron, nickel and cobalt, which has the same thermal expansion as glass and therefore is often used for glass-to-metal or ceramic-to-metal seals.

A two-flux theory in which the radiation is assumed to be composed of two oppositely directed radiation fluxes through a continuous medium. The theory has been widely used to relate the total diffuse...

A lab-on-a-chip (LOC) is a miniaturized device that integrates various laboratory functions and capabilities onto a single, compact chip. Also known as microfluidic devices, lab-on-a-chip systems are...

Label-free refers to a technique or method that does not require the use of additional labels, tags, or markers to detect or identify specific components or entities. In various scientific and...

A diagram that shows actual component signals and the basic wiring configuration of a relay logic circuit.

Flux per unit solid angle leaving a surface in any direction is proportional to the cosine of the angle between that direction and the normal to the surface. A material that obeys Lambert's cosine...

An optical source that has a luminous distribution that is uniform for all directions.

A perfectly diffusing surface; the intensity of the light emanating in a given direction from any small surface component is proportional to the cosine of the angle of the normal to the surface. The...

A device designed to concentrate and direct a light source by enclosing the source in it and using a concave reflector to direct the light through its only opening.

A broken circle used as the test object in distinguishing visual acuity. The width of the gap in the circle is equal to the breadth of the black line and one-fifth the circle diameter. Also known as...

A metal tool used to grind lenses with loose abrasive (see diamond cutting tool). The functional surface of the lap is carefully formed to be opposite the curve to be produced on the glass (concave...

1. The process of wearing down the surface of a softer material by rubbing it under pressure against the surface of a harder material that has been formed in the shape opposite to that desired on the...

Lapping and polishing services involve specialized processes used to improve the surface finish and dimensional accuracy of components to meet specific requirements or standards. These services are...

Laser ablation is a process that involves the removal or erosion of material from a target surface using laser energy. This technique is widely used in various scientific, industrial, and medical...

Laser active elements typically refers to the substances or materials within a laser system that play a critical role in the amplification of light through the process of stimulated emission. These...

The process by which laser emission is used in measuring fluid velocity and, more specifically, the detection of air and wind velocity.The laser technique measures the amount of frequency shift...

Laser annealing is a process that involves using a laser beam to heat and modify the microstructure of a material, typically a thin film or surface layer, with the objective of improving its...