Photonics Dictionary

An instrument designed to collect naturally formed extraterrestrial electromagnetic radiation within the radio frequency range of the spectrum in amounts sufficient to be measured.

Rare earth dopants refer to elements from the lanthanide series, also known as rare earth elements, that are intentionally introduced into the crystal lattice of a material to modify its properties....

Rare-earth elements (REEs) are a group of seventeen chemical elements found in the Earth's crust, characterized by their unique properties and scarcity relative to other elements. Despite their name,...

That part of a magnetic or optical tape or disc drive that retrieves data from or records data on the recording media.

Reflectance spectroscopy is a technique used to analyze the reflective properties of materials across various wavelengths of the electromagnetic spectrum. By measuring the reflectance of light from a...

Remote inspection refers to the process of inspecting, evaluating, or monitoring assets, equipment, infrastructure, or systems from a distance, typically using remote sensing technologies and...

Remote sensing is a method of data collection and observation where information about objects, areas, or phenomena on Earth's surface is gathered from a distance, typically using sensors onboard...

A resonator is a device or system that exhibits resonance, which is a phenomenon that occurs when an external force or stimulus is applied at a specific frequency, causing the system to oscillate...

A retroreflector is an optical device or structure that reflects incident light or electromagnetic waves back to their source, regardless of the direction from which the light approaches. Unlike...

The term "Rydberg atom" refers to an atom in a highly excited state where one or more of its electrons are in a Rydberg orbital. A Rydberg atom is characterized by having an electron orbit that is...

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 sapphire window refers to a transparent optical component made from sapphire crystal. Sapphire is a single-crystal form of aluminum oxide (Al2O3) that is highly prized for its exceptional optical...

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"...

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...

See atomic force microscope; magnetic force microscope; near-field scanning optical microscope; scanning tunneling microscope.

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 silicon photodiode is a semiconductor device that converts light into an electrical current. It is a type of photodetector specifically designed for detecting and measuring light intensity. Silicon...

The ability of an electrical current to destroy superconductivity by means of the magnetic field generated by the current. The temperature of the material is not raised, and the effect is identical...

The constant outward flow of weakly magnetized plasma from the sun that is deflected by the magnetic field of the earth and, flowing around the field, creates a magnetosphere.

In micropositioning, a remote positioning device in which an electric current drives a movable armature mounted on an electromagnetic coil.

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...

A spectrophotometer is a scientific instrument used to measure the intensity of light at various wavelengths in the electromagnetic spectrum, typically in the visible and ultraviolet regions. It is...

A spectroradiometer is a device used to measure the intensity of light at different wavelengths across the electromagnetic spectrum. It provides a detailed spectral distribution of light, breaking...

Spectroscopy is a technique used in the study of interactions between matter and electromagnetic radiation. It involves measuring and analyzing how different materials absorb, emit, or scatter light,...

A semiconductor laser that operates in the infrared and that is pumped with strong pulses of radiation from a second laser. Dependent on quantum-mechanical principles, it can be tuned over a large...

Reciprocal magnetic interaction between nuclei in a molecular system facilitated by the binding electrons of the molecule.

A sputtering target is a solid material used in the process of physical vapor deposition (PVD), specifically sputtering. Sputtering targets are typically made of metals, metal alloys, or compounds...

A positioning drive that rotates a fraction of a 360° turn when the motor coils are activated, resulting in linear or rotary motion. They are generally one of two types, either variable...

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...

Waves that propagate along the interface between two different media without radiation with exponentially decaying evanescent fields on both sides.

A wave that is guided by the interface between two different media or by a refractive index gradient in the medium. The field components of the wave may exist (in principle) throughout space, even to...

Surface-enhanced Raman scattering (SERS) is a powerful analytical technique that enhances the Raman scattering signal of molecules adsorbed on or near certain nanostructured surfaces. Raman...

Surface-enhanced Raman spectroscopy (SERS) is an analytical technique that combines the principles of Raman spectroscopy with the enhancement provided by nanostructured metallic surfaces. Raman...

A swept-source laser, also known as a wavelength-swept laser, is a type of laser that rapidly and continuously changes its emission wavelength over time. This continuous wavelength tuning is achieved...

A synchrotron is a type of particle accelerator that uses magnetic fields to steer charged particles, typically electrons or positrons, in a closed, circular or elliptical path. The name synchrotron...

Electromagnetic radiation with frequencies between 300 GHz and 10 THz, and existing between regions of the electromagnetic spectrum that are typically classified as the far-infrared and microwave...

A terahertz spectrometer is a scientific instrument used to measure and analyze the properties of materials in the terahertz frequency range, typically spanning from about 0.1 to 10 terahertz (THz),...

Terahertz (THz) refers to a unit of frequency in the electromagnetic spectrum, denoting waves with frequencies between 0.1 and 10 terahertz. One terahertz is equivalent to one trillion hertz, or...

The magnetic flux density given by a magnetic flux of one weber per square meter. (T).

The production of an image on a magnetic film that is exposed to infrared radiation and heated to a point above Curie temperature in regions of the image. The image is contacted with paramagnetic...