Photonics Dictionary: S

Thin layers intended to prevent damage to plastic optics.

Selective laser melting (SLM) is an additive manufacturing (AM) or 3D printing technology that belongs to the powder bed fusion category. SLM is primarily used for metal additive manufacturing, where...

Heating that results from the dissipation of energy.

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.

A three-dimensional grating designed with thin metal sheets to remain opaque to all but one specific and predetermined wave.

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...

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 crystal, glass, or quartz slicing and cutting machine is a specialized piece of equipment used in the manufacturing process to precisely cut and slice materials such as crystals, glass, and quartz...

A term describing an antireflection coating that may be applied to optics that cannot tolerate the high temperatures usually required for normal "hard'' coatings. Such coatings lack durability...

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...

A ratio expressing the difference in power between the output fibers of a coupler or splitter.

When splitting the output of a single optical fiber into two or more fibers, the difference in the maximum loss between any two channels.

The visual examination by a trained observer of the image of a point source. Any coloring or departure from the Airy disc rings indicates the presence of aberrations in the lens forming that image.

In a laser, the voltage necessary to initiate electrical discharge, somewhat higher than that needed to sustain it.

The imaging of two photographs of a stereo pair, in complementary colors, for the preparation of contour maps.

Supercontinuum refers to a broad spectrum of light that spans a wide range of wavelengths, typically from the visible to the near-infrared or even mid-infrared regions of the electromagnetic...

An emitter based on stimulated emission with amplification but insufficient feedback for oscillation to build up.

A semiconductor laser diode that emits light perpendicular to the active region. The output radiation is taken through the surface as opposed to through a cleaved mirror.

The reversal of a developed image due to the exposure of the partially developed image to actinic light.

1. In the geometric sense, an abbreviation for the term "sagitta,'' the height of a curve measured from the chord. and it is exact for a parabola. 2. Conforming a sheet of glass to a...

Sapphire crystal refers to a transparent, single-crystal form of aluminum oxide (Al2O3) known as corundum. It is one of the hardest known materials, second only to diamond on the Mohs scale of...

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...

Sapphire refers to a crystalline form of aluminum oxide (Al2O3) that is used in various optical and photonic applications due to its exceptional optical, mechanical, and thermal properties. Sapphire...

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...

1. A polariscope consisting of a Savart plate and a tourmaline plate analyzer, and used to produce parallel color fringes by transmitting polarized light. 2. A polariscope composed of an analyzing...

Scalar diffraction theory is a simplified approach used to describe the propagation of electromagnetic waves, particularly light, as they encounter obstacles or apertures. It is termed "scalar"...

Measures by heterodyning interferometry the local slope of a vibrating sample. The method allows the reconstruction of a three dimensional map of the surface in order to determine the slope and...

In field-sequential color television, the rotating tricolor disc placed between the subject and the lens, or between the picture tube and the viewer.

Scanning electron microscopy (SEM) is an advanced imaging technique used in microscopy to obtain high-resolution, three-dimensional images of the surfaces of solid specimens. SEM achieves this by...

1. The continuous thin strip marked by the scanning beam. Generally, during return of the scan, the line is blanked out. 2. The thin strip marked by the scanning process and composed of the...

A contour mapping technique that uses electronic scanning and sampling techniques instead of a reference grating (see moire topography; projection moire topography) to obtain moire fringes, producing...

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...

An optical system that records inhomogeneities within a medium by detecting the energy refracted by that portion of the medium in which the inhomogeneity occurs. The image appears in the form of a...

A prism that inverts and reverts an image while deviating the line of sight by a 45° angle.

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.

A scientific CMOS (complementary metal-oxide-semiconductor) camera is a type of digital camera specifically designed for scientific imaging applications. It employs CMOS sensor technology, which...

The cutting of pitch tooling surfaces by an optical technician to permit polishing compounds to flow across the surface of the tool.

Vision by means of retinal rods; vision of the dark-adapted eye. In scotopic vision, the level of luminance is so low that the retinal cones are not stimulated, and there is no color vision.

The large, usually flat surface onto which an image is projected for viewing. May be reflecting or transmitting (rear projection).

The process of perforating a silicon or ceramic substrate with a series of tiny holes along which it will break. Nd:YAG or CO2 lasers are now routinely used.

A nonlinear label-free imaging technique commonly used during surgical procedures for the visualization of collagen fibers and muscle tissue (myosin) with submillimeter resolution. During the...

Second-harmonic generation (SHG) is a nonlinear optical process that occurs when two photons with the same frequency combine within a nonlinear material, resulting in the generation of a new photon...

Second-order nonlinear optical properties refer to a class of phenomena exhibited by certain materials in response to intense light, typically in the realm of optics and photonics. Nonlinear optical...

The indistinct rainbow that may sometimes be observed outside the distinct primary bow and that has its colors in opposite order. The red colors of both bows are toward each other.