Photonics Dictionary: S

A special-purpose polarimeter having a scale calibrated directly in the concentration of sugar in the test solution.

Sagnac interferometry is a technique used to measure rotation or angular velocity based on the principle of interference. It relies on the Sagnac effect, named after the French physicist Georges...

A double-plate device used to transmit polarized light and form interference fringes of the light, thus indicating its presence. It consists of two calcite plates of equal thickness, cut parallel to...

A microdensitometer that contains a scanning stage to provide simultaneous representations of position vs. density.

A spectroradiometer having a means to scan different regions of the light spectrum, providing simultaneous representations of amplitude vs. wavelength of the spectrum.

Measure of the interference fringe pattern produced by the forward scattering of light by an optical fiber; the fringe pattern is inversely proportional to the fiber diameter.

A specific type of filter designed to reduce the amount of light scattered by reflections from the edges of optical components or mounts, or from irregularities on the optical surfaces.

A term used to denote the condition of a few easily visible coarse inclusions within a blank of glass.

Change of the spatial distribution of a beam of radiation when it interacts with a surface or a heterogeneous medium, in which process there is no change of wavelength of the radiation.

The angle between the initial and final paths traveled by a scattered particle or photon.

The portion of light scattered when traveling through a unit thickness of material.

An instrument used to determine the absolute or relative scatter levels of optical surfaces.

A measurement technique used for the rapid quantitative evaluation of surface quality based on the detection and analysis of light scattered from the surface.

A flat plate having its surface formed into a random pattern by abrasives. Radiation wavelengths that are longer than the scale of the pattern are specularly reflected; shorter wavelengths are...

An aspheric plate placed at, or near, the center of curvature of a spherical reflector and used to correct for spherical aberration.

A specific type of photographic plate designed with only a small amount of gelatin to function in the extreme ultraviolet and in positive-ray analysis.

An instrument designed to measure radiation indirectly through the use of several phosphors and a photomultiplier tube. The absorption of radiation by any phosphors results in light flashes that may...

A scintillation detector is a radiation detection device that utilizes scintillation crystals to detect and measure ionizing radiation, such as gamma rays, x-rays, or charged particles. It consists...

An instrument used to test the hardness of various materials. It measures the pressure on a standard point that is necessary to scratch the material.

A device used to take turbidimetric or nephelometric measurements by considering the contrast between a constant brightness field and an illuminated line positioned behind the solution being tested.

A self-interference effect that generates random patterns; secondary speckle pattern (SSP) typically occurs in diffuse reflections of a laser on paper, white paint or rough surfaces. By tracking both...

An arrangement of optical fibers in a bundle whereby the geometric configuration of the input end differs from that of the output end without changing the total area; for example, a circular bundle...

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...

An avalanche photodiode in which the light-absorbing area is a low-bandgap material and the PN junction is placed in an area of high-bandgap material, reducing dark current and increasing gain.

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.

A device used in measuring attenuation in optical fiber. The loss caused by the bends in a short reference length of fiber approximates that of a much longer fiber under test.

An interferometer in which interference is produced between wavefronts that are sheared in the sample object by a small lateral distance.

A filter that is transparent to shorter wavelengths, but opaque to longer wavelengths.

A mechanical or electronic device used to control the amount of time that a light-sensitive material is exposed to radiation.

A device used to measure the opening time of a shutter. The most common devices depend on the charging or discharging of an electrical condenser, or on the production of a curve of open area against...

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 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...

A medical imaging method in which gamma camera heads rotate about the patient to detect radionuclides, enabling physicians to monitor functions within the body such as metabolism or blood flow.

A filter designed to decrease the luminosity of the sky without decreasing that of the landscape in the foreground. A filter that has a depth of tint that decreases from top to bottom is used in...

The method for measuring the index profile of an optical fiber by preparing a thin sample that has its faces perpendicular to the axis of the fiber, and measuring its index profile by interferometry.

A television system that uses a slow rate of horizontal scanning to increase its reproduction and transmittance accuracy of printed matter, photographs and illustrations.

The investigation of microstructures by an instrument that generates a narrow, highly collimated beam of x-rays.

The letter form used on visual performance test charts. The overall letter height is equal to five times the thickness of individual strokes. Normal 20/20 vision is represented by the ability to...

A filter that creates spherical aberration resulting in an image with a soft outline.

A series of solar cells arranged to collect solar radiation and to generate a given amount of electrical energy.

A type of birefringent filter, similar in principle to the Lyot filter, consisting of many identical birefringent elements, often arranged in a "fan" or "folded" configuration, positioned between two...

An imaging system that uses a mosaic of tiny light-sensitive semiconductors (phototransistors) to produce individual outputs that are then converted into a coherent video signal.

An electroluminescent semiconductor that emits low intensity radiation in the green or red regions. Used as an indicator lamp.

A solid-state laser is a type of laser that uses a solid gain medium (as opposed to a liquid or gas) to produce coherent light. The term "solid-state" refers to the fact that the active medium, where...

A light valve that uses a crystal as the control layer medium and that operates on the principle of the electro-optic effect.