Photonics Dictionary

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 scanning electron microscope (SEM) is a powerful imaging instrument used in scientific research, materials characterization, and various industrial applications. Unlike traditional optical...

The spot illuminated on a cathode-ray tube by the initial impact of the scanning ray and the screen.

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...

A compact high-pressure light source in which an electrical discharge between electrodes spaced no more than 12 mm apart occurs in a xenon or other gas medium, providing a visible light resembling a...

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 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...

Sisyphus cooling is a technique used in atomic physics to achieve ultracold temperatures of atoms or molecules by exploiting the periodic motion of particles in optical traps or lattices. The name...

Streaks of dense seeds with accompanying small bubbles.

An aperture, usually rectangular in shape, with a large length-to-width ratio, and a fixed or adjustable shape through which radiation enters or leaves an instrument. The aperture is generally small...

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...

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 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...

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...

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...

A phenomenon that causes the details in an image to appear at a spatial frequency higher than that at which the contrast first drops to zero. A phase reversal will accompany this phenomenon, often...

A wave that changes from one amplitude to the other in a short time compared with the wavelength.

In infrared imaging systems used for mass screening of printed circuit boards or other quality control applications, an image of an ideal component that is stored in the system's memory and then...

Structured illumination microscopy (SIM) is an advanced optical imaging technique used in microscopy to enhance the resolution of images beyond the diffraction limit imposed by traditional light...

A substrate refers to a material or surface upon which another material or process is applied or deposited. In various fields, such as electronics, biology, chemistry, and manufacturing, the term...

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...

The specification of allowable flaws in a surface by comparison to reference standards of quality. Two graded sets of surface quality standards are employed. The first denotes defects of a long...

The standards of MIL-O-13830 set by the US government relative to tolerable surface scratches and other such defects in an optical system. A series of standard glass plates that have been...

A surface-mount device (SMD) is an electronic component that is mounted directly onto the surface of a printed circuit board (PCB) rather than being inserted into holes drilled in the board (as with...

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

Abbreviated SoC. A single chip containing all the electronic circuits required for a complete, working product. SoCs are similar to microcontroller technology but provide additional components. A SoC...

A telescope that produces an erect image. Erection is achieved either by a lens (for a long instrument) or a prism (for a compact instrument). Very small terrestrial telescopes of low power may be of...

Three-photon microscopy is an advanced imaging technique that belongs to the family of multi-photon microscopy methods. It is used in biological and medical research to capture high-resolution images...

A time-to-amplitude converter (TAC) is an electronic circuit that converts a time interval between two events into an amplitude or voltage signal. TACs are commonly used in various scientific and...

The determination of the degree to which a manufactured component can deviate from its ideal specifications of material and geometry without impairing its performance.

Topology is a branch of mathematics that focuses on the properties of space that are preserved under continuous deformations, such as stretching, crumpling, and bending, but not tearing or gluing....

Tungsten diselenide (WSe2) is a member of the transition metal dichalcogenides (TMDs) family, composed of tungsten (W) and selenium (Se). Similar to other TMDs, tungsten diselenide possesses a...

An evacuated bulb containing a tungsten filament that is heated by passing an electric current through it. In domestic light bulbs the inside of the bulb is frosted to soften shadows. In projection...

Turbidity is a measure of the cloudiness or haziness of a fluid caused by the presence of suspended particles. These particles can include sediment, silt, clay, plankton, and other microscopic...

Two-photon excited fluorescence (TPEF) is a nonlinear optical method that allows imaging of biological cells and living tissue. The advantage of TPEF in comparison to conventional fluorescence...

A type of lamp that emits a high quantity of ultraviolet radiation. This may be an arc lamp encased in a bulb of a glass that is transparent to ultraviolet rays.

Ultraviolet reflectance refers to the ability of a material or surface to reflect UV light. Ultraviolet light is electromagnetic radiation with wavelengths shorter than those of visible light,...

Van der Waals forces refer to the attractive or repulsive forces between molecules (or parts of molecules) that arise from fluctuations in electron distribution. These forces are relatively weak...

Videography refers to the process of capturing moving images and recording them in a digital format. It involves the use of video cameras, lighting equipment, and audio recording devices to create...

A photometer that permits visual comparison of the luminance of two surfaces.

A nondestructive testing method for very large scale integration circuits, using a scanning electron microscope to monitor changes in the electronic state of the chip as it is fed test voltages while...

A vortex phase plate is an optical device designed to impart a phase singularity, commonly referred to as a vortex or phase vortex, onto a light beam. This singularity results in a phase profile...

A photometer that uses a wedge, marked to show its reduction of flux density, to make two light sources equal in intensity for comparison of luminous intensities. This is accomplished by the gradual...

A well plate, also known as a microplate or microtiter plate, is a flat plate with multiple small wells or depressions arranged in a grid pattern. Each well serves as a separate container for holding...

Whispering gallery mode (WGM) refers to a phenomenon in wave physics, particularly in optics, where waves, such as light or sound waves, are trapped and circulate along the periphery of a curved...