Photonics Dictionary

In a laser, the voltage necessary to sustain a constant operating current, somewhat less than that needed for start-up.

The material removed during diamond machining of glass components.

Swept-source optical coherence tomography is an imaging technique used in medical diagnostics, particularly in ophthalmology, to visualize and analyze the internal structures of biological tissues,...

A swept-source laser, also known as a wavelength-swept laser, is a type of laser that rapidly and continuously changes its emission wavelength over time. This continuous wavelength tuning is achieved...

swept-source Raman spectroscopy is an advanced analytical technique that combines the principles of Raman spectroscopy with a swept-source laser system. It enables rapid and sensitive chemical...

A positive after-image that is maintained for a minute or more.

The length of the oscillation of a grinding or polishing lap.

A lens system made up of two sets of similar lenses, each of which compensates for many of the aberrations produced by the other. The lens sets are arranged symmetrically on either side of the...

Any systemic process that ultimately reassembles all the system's components into their initial alignment, or an arrangement that exactly reproduces the initial relative alignment.

A synapse is a specialized junction between two neurons (nerve cells) or between a neuron and a target cell (such as a muscle or gland cell). It is the fundamental functional unit of communication in...

Abbreviation of "synchronization.'' In television, the timing signals used to drive the scanning process. Horizontal sync triggers the retracing of the raster line beginning at the left-hand...

A detector sensitive only to signals close to or at a particular frequency that is the same as the frequency of a control signal applied independently. The synchronous detector also is...

A standard for fiber optic telecommunications interfaces, with a 1300-nm data link operating over single-mode fiber at data rates of 52, 155 and 622 Mb/s.

The technique of generating ultrashort -- down to subpicosecond -- pulses by pumping a dye laser with mode-locked laser pumps with cavity lengths the same as, or a submultiple of, that of the dye...

A mode of transmission whereby the sending and receiving stations operate continuously at a fixed relationship of phase and frequency, generating signals to control the timing of the data that are to...

A synchrotron is a type of particle accelerator that uses magnetic fields to steer charged particles, typically electrons or positrons, in a closed, circular or elliptical path. The name synchrotron...

Radiation emitted by electrons when they travel in circular orbits at speeds close to that of light. Synchrotron radiation occurs in the x-ray and ultraviolet regions of the spectrum. Once considered...

Imaging radar that increases the sweep of its along-track (or azimuth) capacity by measuring not only the time delay of the echoes returning from the microwave pulse transmitted by its antenna (or...

An imaging technique in which an object moving through an interference field formed in space scatters light and is spatially recorded on a photographic film as a hologram. If the interference field...

A combination of components arranged so as to perform at least one function.

A system-on-chip (SoC) is an integrated circuit (IC) that incorporates all necessary components of a computer or electronic system onto a single chip. This typically includes a microprocessor or...

The equivalent f number of a fictitious lens that has a circular opening and 100 percent transmittance, which would give the same central illumination as the lens being considered: where...

See honeycomb table; indexing table.

An instrument designed to measure the rate of rotation of components, such as shafts.

One lumen-second, the SI unit of the quantity of light.

The series of interference bands that appear in the spectrum when a specified glass plate is inserted into a spectroscope, from the side of the blue portion of the spectrum, so that the plate...

The law stating that the brightness of an object that is examined through a slotted disc, rotating over a critical frequency, is proportional to the angular aperture divided by the opaque sectors.

In optics, a shape often given to the leading edge of a projectile. In any side view it appears as a pointed arc, while any cross section perpendicular to its long axis appears as a circle.

Optical aberration such that image magnification varies with ray distance from the optical axis in a radial distortion.

A device for extracting a portion of the optical signal from a fiber.

A waveguide having a characteristic that is altered continuously with the distance traveled, relative to the axis of its path.

1. The anode or anticathode of an x-ray tube that emits x-rays when bombarded by electrons. 2. The screen in a television imaging tube that is scanned by an electron beam to determine the...

Measurement estimated from the position of the image's centroid.