Photonics Dictionary: S

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

Characteristic of the relationship between photoelectric activity and the wavelength of incident radiation.

A crude area on the polished surface, produced during coarse grinding, that subsequent fine grinding does not remove, owing, to some extent, to coarse grains of grinding sand that mixed with finer...

Sapphire optical fiber is a type of optical fiber made from single-crystal sapphire, which is a form of aluminum oxide (Al2O3) that is highly transparent in the infrared region of the electromagnetic...

A laser dye whose absorption coefficient drops at high levels of incident radiation. The phenomenon is often called bleaching.

1. The decrease of the absorption (or gain) coefficient of a medium near some transition frequency when the power of the incident radiation near that frequency exceeds a certain value. As long as the...

A device composed of a light source and phototube used to scan a moving strip of material in photoelectric side-register control systems.

A high-resolution imaging instrument that can detect and measure the positions of individual atoms on the surface of a material. A very fine conductive probe is placed at a distance of 10 to 20...

A form of infrared CCD that utilizes internal photoemission as a photodetection mechanism.

Characteristic of dissimilar metals in thermoelectric solar cells whereby separate junctions exhibiting distinct temperatures transform incident voltage into a current.

Seidel aberrations refer to a set of monochromatic aberrations in optical systems, named after the German mathematician and physicist Ludwig von Seidel. These aberrations describe deviations from...

An equation that uses the wavelength of light passing through a medium, along with a set of coefficients, to calculate the medium's index of refraction. The coefficients, called Sellmeier...

A photocathode that receives radiation from one side and emits a photoelectric current from the opposite side.

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...

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...

The angle at which photoelectric sensors are aligned to prevent light from being reflected back to the sensor from the object during retroreflective sensing; also, the angle a measured part is...

Any ray through an optical system that is not a meridional ray. The plane created by a refracted skew ray does not contain the optical axis.

A form of liquid crystal in which flow does not take place in the usual manner. When examined with polarized light, the substance often forms drops that display a series of fine lines. X-ray...

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...

An automatic scanning instrument that is used to study a substance's fluorescence over a wide range of wavelengths. It consists of a radiation source, a grating that functions as the monochromator in...

Radiation emitted when a quantum mechanical system drops spontaneously from an excited level to a lower level. This radiation is emitted according to the laws of probability without regard to the...

A light source that does not fluctuate despite temperature changes.

A projection printer that is capable of reproducing a multiplicity of images from a master transparency on a single support coated with a photosensitive layer by indexing the receiving material from...

In polarization-preserving optical fibers, the element used to induce birefringence. The SAP is highly doped to provide a different coefficient of expansion from the rest of the fiber material; when...

Structural color refers to coloration in materials that is not caused by pigments or dyes but is instead a result of the physical structure of the material. In structural color, the interaction of...

A copolymer of styrene and acrylic used in molded optical components; it has a high refractive index and a low coefficient of thermal expansion.

An instrument consisting essentially of a photoelectric cell filtered to respond to a specified wavelength region, an amplifier of sufficient gain to provide power enough to control movement of a...

Superluminal transmission refers to the hypothetical process of transmitting information faster than the speed of light, which is commonly denoted as superluminal or faster-than-light (FTL)...

A reflector having a surface that has been superpolished to reduce residual sleeks and scratches and microroughness so that its scatter coefficient is low. Its surface is said to have a low-scatter...

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...