Photonics Dictionary

A qubit, short for quantum bit, is the fundamental unit of information in quantum computing and quantum information processing. Unlike classical bits, which can exist in one of two states (0 or 1),...

In gradient index optics, a gradient profile in which the index varies in a direction perpendicular to the optical axis. Radial gradient lenses can focus light even when the lens surfaces are flat,...

When light is transmitted through matter, part of the light is scattered in random directions. A small part of the scattered light has frequencies removed from the frequency of the incident beam by...

Raman spectroscopy is a technique used in analytical chemistry and physics to study vibrational, rotational, and other low-frequency modes in a system. Named after the Indian physicist Sir C.V. Raman...

A reagent is a substance or compound that is used in a chemical reaction to bring about a specific transformation or to detect the presence or absence of another substance. Reagents are employed in...

Reflectance confocal microscopy (RCM) is a non-invasive imaging technique that allows for high-resolution, in vivo imaging of biological tissues at the cellular level. It is particularly useful in...

A reflection grating is an optical component that consists of a series of closely spaced, parallel reflecting surfaces or grooves. These grooves are typically ruled or etched onto a flat substrate or...

A repeater that is designed for digital transmission. Also called a regenerator.

Rhodamine refers to a family of fluorescent organic dyes that are widely used in various fields, including biology, chemistry, medicine, and materials science. These dyes are known for their bright...

A wave that is polarized elliptically or circularly polarized and in which the electric field vector — observed while looking in the direction of propagation — rotates in a right-hand or...

A Risley prism, also known as a Risley prism pair or Risley rotating prism, is an optical device used for controlling the direction of a laser beam or other optical beam by independently rotating two...

Also known as a turned-down edge. A rapid change of curvature near the edge in a lens or prism surface.

A transparent plate ruled with black lines and equal, clear spaces. It is used as a multiple knife-edge for testing a concave mirror.

RTSP, or real-time streaming protocol, is a network control protocol designed for controlling streaming media servers. It is used for establishing and controlling media sessions between endpoints....

A ruticon is an opto-electronic device in which light going through it can be modulated by an electric field. The intensity distribution of the resulting image can be precisely controlled....

The shape of the edge of a concave surface when the depth of the bevel plane to the vertex of the surface is controlled to a required distance.

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

That theory that treats the light field as a single scalar field rather than as two coupled vector fields.

Also called scanning laser acoustic microscope. A device that uses high-frequency ultrasound waves to penetrate surfaces. A scanning laser beam is used as a detector, which transmits information...

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

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...

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

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...

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...

Describing a laser in which the gas is permanently sealed within the tube.

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...

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 semiconductor is a type of material that has electrical conductivity between that of a conductor and an insulator. In other words, semiconductors have properties that are intermediate between...

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...

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...

Noise generated in the flow of current in the photomultiplier, produced by the intentional or controlled application of optical power to the photocathode.

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 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...