Photonics Dictionary

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 central peak (including everything interior to the first zero or dark ring) of the focal diffraction pattern of a uniformly irradiated, aberration-free circular optical element or system.

The electric arc that is a particular discharge between two electrodes in a gas or vapor which is characterized by high cathode densities and a low voltage drop.

An adaptation by Philips and Sony of their audio compact disc technology for optical disc data storage and retrieval. Current capacity of a disc is 0.5 to 0.6 gigabytes of information.

A reticle carrying patterns of various forms that can be rotated in an optical beam to cause variations in the intensity of the beam. It also is used in infrared detectors to scan the object field...

In a gas, an electrical discharge that has no luminance.

A disc contained within an electronic cell counter for regulating light transmission.

A discharge lamp filled with deuterium to produce high-intensity ultraviolet radiation for use in spectroscopic analysis.

A type of transversely excited laser with a uniform arc-free discharge of large cross-sectional area that can be scaled to very large systems.

A type of erasable data storage device that uses a medium deposited on the disc in two layers, each dyed to absorb a different wavelength of laser light. To record data, the lower layer is heated by...

A lamp that uses the transmission of an electric current through a gas or vapor to produce illumination. Neon, mercury and argon lamps are examples of electric-discharge lamps.

A device consisting of an airtight quartz tube that holds the material to be analyzed. When a high-frequency electrostatic field, generated by microwaves, is applied to the tube, it emits energy of a...

The conduction of electricity in a gas as a result of the ions generated by collisions between electrons and gas molecules.

A display device that contains an inert gas that gives off orange light when a high voltage is applied to ionize the gas.

An electric discharge in a low-pressure gas having a low-current density and a space potential near the cathode that is much higher than the ionization potential of the gas but less than its sparking...

Familiar term for CD/I disc. The CD/I standard also is known as the green standard.

A rotating disc that holds several lenses of differing focal length about a diameter. Used to switch lenses in a system while maintaining focus.

A plastic disc coated with ferric oxide or other films on which data can be stored by selectively magnetizing areas of the surface.

A device consisting of a disc with a spiral arrangement of holes that is used to convert visible patterns into electrical patterns. Light is reflected from the subject and focused through a vertical...

A rigid medium, generally a polycarbonate substrate coated with a reflective aluminum layer, that stores information (such as audio, video or data) as digital bits in the form of variations in the...

A standard source of high-charge-state ions for accelerators that has an external magnetic field oriented perpendicularly to the two cathode faces. Also called Philips ionization gauge.

An erasable data recording and storage medium that uses a laser to heat the crystalline surface of the disc to a certain temperature, at which it becomes amorphous and records a bit of information;...

A spectroscopic process that detects and analyzes the discharge from an extrinsic surface with less than bandgap light. This method may determine the extrinsic surface-state energy levels of a...

A gas laser in which the electrodes are mounted perpendicular to the optical resonator.

In field-sequential color television, the rotating tricolor disc placed between the subject and the lens, or between the picture tube and the viewer.

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...

An instrument that uses a blackened silver-disc reflector with a shutter to create temperature fluctuations that are proportional to the intensity of the solar radiation incident upon it. Using the...

A disc whose surface contains recorded digital data at high-packing densities arranged in concentric rings. The data, representing video frames, are both recorded and read by a laser beam.

A technical specification for a consumer product drawn up by Sony and Philips. CD/I combines audio, video and text recorded as interleaved channels on a disc similar to an audio compact disc. The...

Abaxial spherical aberration, also called oblique spherical aberration, refers to a specific type of optical aberration that occurs in lens systems. It is a form of spherical aberration that affects...

The Abney effect, named after its discoverer Sir William de Wiveleslie Abney, refers to a phenomenon in color perception where the appearance of a color is influenced by the brightness of its...

An absorption spectrum is a graphical representation of the absorption of light by a material as a function of wavelength, frequency, or energy. It displays the specific wavelengths of light that are...

Achromatic refers to something that is without color or lacking in chromatic coloration. In optics and color theory, it specifically refers to colors or images that are rendered in shades of black,...

In color perception and vision an achromatic point refers to a color stimulus that appears neutral or without hue, often perceived as a shade of gray. It represents a point in color space where the...

An active medium is a material or substance used in various optical devices and systems, where it plays a critical role in amplifying light or producing laser beams through the process of stimulated...