Photonics Dictionary

A solar simulator is a device used to replicate the spectrum and intensity of sunlight in a controlled environment for testing and research purposes. Solar simulators are employed in various...

The constant outward flow of weakly magnetized plasma from the sun that is deflected by the magnetic field of the earth and, flowing around the field, creates a magnetosphere.

1. The reduction in the developable density of a photographic emulsion that has been extremely overexposed. 2. In a laser system, damage resulting from ultraviolet radiation that degrades the lasing...

An optical compensator similar to the Babinet compensator, but which produces a phase-change consistent throughout its field, as opposed to the Babinet's phase-change, which occurs progressively...

In micropositioning, a remote positioning device in which an electric current drives a movable armature mounted on an electromagnetic coil.

Any isolated wave that propagates without dispersion of energy. Specifically to photonics, an ultrashort pulse of laser light that propagates through a waveguide without characteristic chromatic...

A color center laser whose output is coupled to an external control laser cavity and then fed back to the main laser cavity to provide enhanced pulse shaping, leading to ultrashort pulse generation.

A ruggedized scintillation counter used in oil well logging. The cylindrical housing contains a gamma ray source, a crystalline scintillator and a photomultiplier tube. As the sonde is drawn through...

The process whereby sound waves are employed to form a three-dimensional image of an object. The process involves generally: the recording of the diffraction pattern of an object exposed to sound...

Calculated at a given point in a medium as the instantaneous pressure at that point in the presence of a sound wave, minus static pressure at that point.

A physical source of radiation, as contrasted to illuminant. See illuminant.

The relationship between different wavelengths of light generated by a source, which may affect the spectral distribution of the light as it travels great distances in space; put forth by physicist...

The ratio of emitted optical power of a source to the input electrical power.

In fiber optics, the condition in which each fiber of a bundle carries a separate channel.

The maintenance of a fixed-phase relationship across the full diameter of a cross section of a laser beam.

The spatial distribution of incident and collected flux contained in the analysis of reflectance, transmittance or densities.

With a repetitive object such as a series of equispaced lines, the reciprocal of the line spacing in object or image, generally expressed in cycles per millimeter.

A spatial light modulator (SLM) is an optical device that modulates or manipulates the amplitude, phase, or polarization of light in two dimensions, typically in the form of an array. SLMs are...

Also known as transverse mode. The configurations of energy storage, relative to the structure of a laser resonator, that define the relative intensity distribution of the laser beam.

Spatial resolution refers to the level of detail or granularity in an image or a spatial dataset. It is a measure of the smallest discernible or resolvable features in the spatial domain, typically...

The correlation of radiation between the phases of monochromatic radiation emanating from two separate points.

Spatially offset Raman spectroscopy (SORS) is a technique that extends traditional Raman spectroscopy by incorporating measurements at different spatial offsets. This method allows for the selective...

The ratio of Young's modulus to density of a material.

In laser systems, the granular effect that is noted when observing the expanded cross section of a laser beam.

A technique for obtaining improved resolution of images produced by large telescopes and distorted by the effects of atmospheric turbulence. Many individual exposures are recorded at high speeds by a...

Refers to the variety of techniques that use the interference pattern produced by laser light diffusely reflected by an object. There are two basic techniques: direct laser photography, used when...

Pertaining to or as a function of wavelength. Spectral quantities are evaluated at a single wavelength.

The wavelength interval in which radiant intensity is at least 50 percent of the maximum spectral value.

Average wavelength usually determined for light-transmitting devices by taking a weighted average for each wavelength of the spectral energy distribution of incident light, transmittance of the...

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

Spectral flow cytometry is an advanced flow cytometry technique that expands the capabilities of traditional flow cytometry by utilizing spectral information from fluorochromes to enhance...

Irradiance per unit wavelength interval at a given wavelength, expressed in watts per unit area per unit wavelength interval.

A narrow range of emitted or absorbed wavelengths.

A slight displacement in the position of a spectral line because of an alteration in frequency, as a result, in turn, of a cause such as the Doppler effect.

Ratio of the radiant flux at a particular wavelength lm to that at any other wavelength l, such that both radiations produce equally intense luminous sensations. The wavelength lm is chosen so that...

When, for example, a beam of monochromatic light passes through a diffraction grating, the emergent rays that have remained undeviated are included in the zero spectral order. The light flux in the...

The relative power emitted by a source as a function of wavelength. It determines the color-rendering properties of the source.

Radiance per unit wavelength interval at a given wavelength, expressed in watts per steradian per unit area per wavelength interval.

Spectral repeatability refers to the consistency and reproducibility of spectral measurements across multiple trials or instances. It is a measure of how well a measurement instrument or system can...

Measure of a detector's signal during exposure to radiation of a constant power level and varying wavelength.

A spectral signature, in the context of remote sensing and spectroscopy, refers to the unique pattern or characteristic spectral response of a material or object across different wavelengths of the...

A measure of the wavelength extent of a spectrum.

Equipment used for chemical analysis by investigation of the spectra formed and observed in chemical activity. Of particular use are spectrographs for recording the emission spectra of substances...

Spectra can be conveniently recorded on photographic film or plates. The portions that are occupied by regions of the recorded developed images on the film or plate can be determined with some...

An optical instrument for forming the spectrum of a light source and recording it on a film. The dispersing medium may be a prism or a diffraction grating. A concave grating requires no other means...