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3,552 terms

Photonics Dictionary

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semifinished
A term used to describe a spectacle lens or blank with one surface totally finished.
semilenticular screen
A projection screen having vertical ribs or flutes set into a plastic surface.
semitransparent and p-phase annular aperture
An aperture consisting of a semitransparent central region whose amplitude transmittance only is varied, and the relative phase difference between the central and annular region is fixed as p -...
semitransparent photocathode
A photocathode that receives radiation from one side and emits a photoelectric current from the opposite side.
SEMLAM
semiconductor laser amplifier
Senarmont compensator
A type of compensator for use with a microscope and consisting of a quarter-wave plate in a fixed position and a rotatable analyzer.
Senarmont prism
A polarizing beamsplitting prism similar in design to the Rochon prism. However, the Senarmont transmits the extraordinary ray without deviation and deviates the ordinary ray due to the orientation...
sensitometer
An instrument for determining the sensitivity of a photographic film to light. The film is given either a stepped exposure or a continuously varied exposure; after processing, the density is measured...
separation filters
Three filters used in making a color print of a color negative, red, green and blue-violet, respectively. Each filter transmits about one-third of the visible spectrum onto the print.
sequence camera
A type of motion-picture camera in which single frames are photographed either automatically at a predetermined rate (as slow as one frame per minute or hour), or whenever the operator presses a key....
SESAM
semiconductor saturable absorber mirror
sextant
A handheld navigational instrument used to measure the elevation angle of celestial bodies such as the sun. An image of the sun is viewed through a small telescope via two plane mirrors so that any...
SFB
semiconductor functional block
sfm
surface feet per minute
Shack-Hartmann wavefront sensor
The Shack-Hartmann wavefront sensor is an optical device used for measuring the wavefront aberrations of an optical system. It is widely used in adaptive optics systems to correct distortions and...
shadowgraph
A method of demonstration or examination using a point source illumination without the use of any projection lens between the object and its shadow, the shadow being cast on a distant screen.
shear
Image distortion that occurs when the axes of the original image are not perpendicular in the resulting image, making the resulting image appear slanted. Shear can be caused by movement of the...
sheet grating
A three-dimensional grating designed with thin metal sheets to remain opaque to all but one specific and predetermined wave.
sheet polarizer
A sheet of plastic material containing microscopic crystals of herapathite or some other similar substance that transmits light polarized in one direction, but absorbs light polarized in a...
shining -> clearing
Also called shining. Grinding and polishing one surface of a blank to permit a more thorough examination for quality.
short wavelength infrared
Short wavelength infrared (SWIR) refers to the portion of the infrared spectrum that encompasses wavelengths roughly between 1,000 and 3,000 nanometers (nm). In the electromagnetic spectrum, infrared...
short-focus lens -> wide-angle lens
A wide-angle lens is a type of camera lens that has a shorter focal length than a standard or normal lens, allowing it to capture a broader field of view. Wide-angle lenses are characterized by their...
short-wave radiation
Characterizes the significant solar radiation at the surface of the earth, so named because its spectral range extends only from 0.3 to 2.8 µm.
shot noise
Noise generated by the random variations in the number and velocity of the electrons from an emitter.
shunt resistance
In a silicon photodiode, the dynamic resistance (dv/d1) of the junction at zero volts.
SIC
semiconductor integrated circuit
side-lit cable
A type of fiber optic cable that emits light from its sides along its length.
sidereal time
Frequently used in astronomical measurement, it is based on the diurnal rotation of a star relative to the fixed stellar system.
sign conventions
A convention that defines specific dimensions of an optical system, such as the image distance or radius of curvature of a lens or mirror, as negative or positive to facilitate calculations based on...
signal level
Calculation of peak and average transmission power at a given point along an optical fiber or cable.
SILEX
semiconductor laser intersatellite link experiment
silica -> silicon dioxide
An abundant material found in the form of quartz and agate and as one of the major constituents of sand. The silicates of sodium, calcium, and other metals can be readily fused, and on cooling do not...
silicon -> optical-grade silicon
The element that resembles a lightweight metal, but when very pure, has a very high electrical resistance and is transparent to the infrared between about 0.5 and 15 µm.
silicon carbide light-emitting diodes
Silicon carbide (SiC) light-emitting diodes (LEDs) are semiconductor devices that emit light when an electric current is applied to them. These LEDs are made using silicon carbide as the...
silicon dioxide
An abundant material found in the form of quartz and agate and as one of the major constituents of sand. The silicates of sodium, calcium, and other metals can be readily fused, and on cooling do not...
silicon monoxide
A material used as a protective layer on an aluminized or silvered mirror. It is evaporated on the mirror as a thin layer, and after exposure to the air the monoxide tends to become silicon dioxide...
silicon photodiode
A silicon photodiode is a semiconductor device that converts light into an electrical current. It is a type of photodetector specifically designed for detecting and measuring light intensity. Silicon...
silver-disc pyrheliometer
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...
simplex
A fiber optic transmission system in which data can go in only a single direction.
simulated annealing -> global optimization
A controlled random search process, such as generalized simulated annealing, that has been incorporated into many optical design programs as a way of helping designers find the most suitable lens...
simultaneous exposure and development
The process, used with a positive photoresist, in which the photoresist is immersed in developing chemicals while being exposed to the optical pattern. The newly exposed surface is continuously...
sine wave object
An object that has a sinusoidal variation of luminance. Its image will have a sinusoidal variation of illuminance and the only effect of degeneration by the lens system will be to reduce the...
sine wave response -> modulation transfer function
Also called sine wave response and contrast transfer function. The modulation transfer function is the ratio of the modulation in the image to the modulation in the object as a function of frequency...
sine wave testing chart
A test chart whose luminance changes uniformly in one direction according to a sinusoidal rule. These charts carry groups of black lines on a white ground, the intensity profile across the lines...
single molecule localization microscopy
Single molecule localization microscopy (SMLM) is a group of super-resolution microscopy techniques that surpass the diffraction limit of traditional optical microscopes, allowing for the...
single-line laser
A laser whose output is limited to a single wavelength.
single-molecule FRET
Single-molecule Förster resonance energy transfer (smFRET) is a specialized technique in biophysics and molecular biology used to study the distances and dynamic interactions between two...
single-molecule spectroscopy
An advanced technique that allows the detection of one molecule within a crystal or a cell through optical excitation. Single-molecule spectroscopy (SMS) can image at subwavelength scales, down to a...
single-photon avalanche diode
A single-photon avalanche diode (SPAD) is a specialized type of photodetector designed to detect extremely weak optical signals, down to the level of single photons. SPADs are widely used in...
single-photon-decay spectroscopy
A technique for observing the decay of light emissions from sources following their pulsed excitations, based on recording the arrival time of the first photoelectron after excitation. After many...

Photonics Dictionary

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