Photonics Dictionary

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

Collisional absorption of energy that occurs in inertial confinement fusion systems when hydrodynamic expansion of the plasma causes an electron passing through the field of an ion to absorb...

The interaction between a photon and an energetic electron, caused by collision, that transfers energy from the electron to the photon, thus raising the energy of the photon.

The changing of the kinetic energy of a mobile electron into radiant energy, as in formation of x-rays.

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.

See inverted image; population inversion.

An invisibility cloak is technology that would render an object or individual invisible to the observer. In scientific research, efforts to create real-life invisibility cloaks have been...

A filter that transmits infrared and ultraviolet but is opaque to visible radiation.

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.

The ejecting of ions from the surface of a material.

A method of fabricating a graded-index optical waveguide by means of an ion exchange process.

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,...

Two oppositely charged particles.

A technique for improving the structure density of thin-film coatings by bombarding the growing film with accelerated ions of oxygen and argon. The kinetic energy then dissipates in the film, causing...

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,...

Also known as gas focusing. The introduction of an inert gas into a cathode-ray tube for the concentration of the electron beam. The gas molecules are ionized by the electrons, producing a core of...

A closed vessel with electrodes of different potentials that is used to determine how much ionization took place in a gas after its exposure to x-rays or radioactive emissions.

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.

The gas of charged particles that begins approximately 50 km above the surface of the Earth and contains a sufficient quantity of electrons and ions to affect the propagation of radio waves.

The rainbow exhibition of colors, usually caused by interference of light of different wavelengths reflected from superficial layers in the surface of a material.

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

Application of radiation to an object.

Indication of emission brightness with degree of emission from an optical source.

A graphic depiction of the loci of all points in space relative to a laser transmitter at a specific altitude.

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.

Lines of equal atmospheric attenuation in a laser beam.

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....

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.