Photonics Dictionary

A lidar (light detection and ranging) technique used in pollution monitoring. Two light beams are emitted simultaneously, one at a wavelength that will be absorbed by the target particles, and the...

Diffuse reflectance spectroscopy (DRS) is a nondestructive analytical technique used to investigate the optical properties of materials, particularly in the field of spectroscopy. Unlike traditional...

Use of a photoelectric receiver to sense an object's presence by detecting a small amount of the emitter's light that is diffusely reflected by the object.

Digital signal processing (DSP) refers to the manipulation and analysis of signals, which are representations of physical quantities that vary over time or space. In the context of DSP, these signals...

In a fiber optic transmission system, the conversion of received optical pulses directly to an electrical signal.

In optical character recognition, the mechanical or electronic transducer used to detect the level of illumination present in the various portions of an illuminated sample region.

An imaging process, similar to specific Doppler mapping radar techniques, that utilizes a laser, an optical imaging system, and a line array of photodetectors and spectrum analyzers. The laser...

A device used to detect and measure the quantity of exposure to nuclear or x-ray radiation, and dependent on the fact that such radiation ionizes a gas.

A spectrophotometer in which the beam emitted by the radiation source is split into beams that travel through the sample and a reference cell and are subsequently recombined to fall on the detector....

For a detector, the amount of time alotted for the observation of one location.

A type of mosaic detector array that combines features of scanning and staring sensors by using a small rapid scanning motion (see saccadic motion) over a few pixels at a time.

In image processing, the location of edges by employing templates that respond to the first or second derivative of gray-scale intensity in the neighborhood of each pixel.

1. That portion of the aperture that functions to collect energy and deliver it to the final system detector. 2. For an obscured or noncircular aperture, the equivalent nonobscured, circular aperture.

A device that detects radiation by utilizing the influence of light in forming an electrical signal. It may be a phototube; a photoconductive, photovoltaic or photojunction cell; a phototransistor;...

An EMCCD (electron-multiplying charge-coupled device) camera is a type of scientific camera specifically designed for low-light imaging applications that require high sensitivity and fast readout...

A method for detecting vibration amplitudes analogous to image holography, except that the film emulsion is replaced by a television target.

An enzyme-linked immunosorbent assay (ELISA) is a laboratory technique used to detect and measure the presence of specific substances, such as antibodies, antigens, proteins, hormones, or other...

The addition to the information signal in communications of redundant bits that enable the originally encoded message to be decoded without degradation of the data. In compact disc technology, the...

A factor, F, indicating the increase in shot noise in an avalanche photodiode as compared with the ideal multiplier, which is noiseless. The noise, which results from variations in avalanche gains,...

A small incandescent lamp whose intense beam is focused on the optical soundtrack of a motion picture film. The soundtrack modulates the beam, which in turn is detected by a photocell that produces...

A photodetector composed of a semiconductor material whose responsive properties can be altered by the addition of impurities to the basic material. Copper- and mercury-doped germanium are both...

Measurement of the interval during which a photodetector's signal and output current drops from 90 to 10 percent.

The signal-to-noise ratio (SNR) obtained with a Fourier transform spectrometer when detector noise prevails, which exceeds the SNR of a scanning spectrometer in the same time by a factor proportional...

A fiber optic gyroscope (FOG) is a type of gyroscope that uses the interference of light waves to detect changes in orientation or rotation. It operates based on the principle of the Sagnac effect,...

A fiber optic sensor is a device that uses optical fibers to detect and measure physical, chemical, biological, or environmental parameters. Unlike traditional electrical sensors, fiber optic sensors...

A fiber optic spectrometer is a device used for measuring the spectral content of light. It utilizes optical fibers to transmit light from a source to a spectrometer unit, where the light is...

A fiber optic transceiver, often simply referred to as an "optical transceiver," is a device used in fiber optic communications to transmit and receive data over optical fibers. It integrates both a...

An optical recording technique that uses light source(s), a beamsplitting cube, light detector(s) and an optical fiber chronically implanted in animal brain to deliver excitation light to neurons...

A fiber-coupled LED (light-emitting diode) refers to an LED device that is optically coupled to an optical fiber for the purpose of efficient light transmission. In this configuration, the LED serves...

A fiber-coupled photoconductive antenna (FCPA) is a type of optoelectronic device that combines a photoconductive antenna with optical fibers for the purpose of generating or detecting terahertz...

A photodetector employing photoregeneration of carriers in the channel region of an FET structure to provide photodetection with current gain.

The field of view (FOV) refers to the extent of the observable world or the visible area that can be seen at any given moment through a device, such as an optical instrument, camera, or sensor. It is...

Fixed-pattern noise is the measure of the static (nontemporal) differences between pixels when the detector is evenly illuminated. In microbolometers, this effect is mostly caused by mismatch between...

A spectroscopic technique used in the detection of free radicals by virtue of their electronic spectra. In this method, an intense light flash is used to form extensive photolysis and yield a high...

A bench photometer that depends on the inability of the eye to distinguish color in brief flashes of light. Any difference in the intensity of reflected colored samples, presented to the observer in...

Flow cytometry is a powerful technique used in biology and medicine for the quantitative analysis of the physical and chemical characteristics of cells and particles suspended in a fluid. The method...

A flowmeter is a device used to measure the flow rate or quantity of a fluid passing through a particular point in a system. It works by sensing the velocity of the fluid passing through it and...

Fluorescence is a type of luminescence, which is the emission of light by a substance that has absorbed light or other electromagnetic radiation. Specifically, fluorescence involves the absorption of...

Fluorescence lifetime refers to the average time it takes for a fluorophore, a molecule that absorbs light at one wavelength and emits it at another, to return to its ground state after being excited...

Fluorescence lifetime imaging (FLIM) is an advanced imaging technique that provides information about the lifetime of fluorescence emissions from fluorophores within a sample. Unlike traditional...

Fluorescence microscopy is a specialized optical imaging technique used in biology, chemistry, and materials science to visualize and study specimens that exhibit fluorescence. Fluorescence is the...

A fluorescent screen refers to a phosphorescent or fluorescent-coated surface that emits visible light when exposed to other forms of electromagnetic radiation, such as x-rays or ultraviolet light....