Photonics Dictionary

A measuring device that uses a light-sensitive cell or detector to determine the amount of light transmitted by a substance.

A bulk crystalline optic which permits the propagation of light through a volume of index altered material. The variation in refractive index along the material volume is due to a piezoelectric...

A waveguide that has a core with a lower refractive index than the refractive index of the cladding. This structure can limit the power of the transmitted beam by removing unwanted radiation, for...

The second adjustable iris diaphragm in an optical system. In the common microscope condenser system, it usually is located beneath the substage condenser on a transmitted light microscope. When the...

An atomic absorption spectrometer (AAS) is an analytical instrument used to determine the concentration of specific chemical elements in a sample by measuring the absorption of light at...

Attenuated total reflectance (ATR) spectroscopy is a technique used in analytical chemistry to obtain IR spectra of samples. It is particularly useful for analyzing solid and liquid samples without...

Refers to a display or screen that is illuminated from behind; the light is transmitted as opposed to reflected.

A parallel plate of glass in such a position that the refracted and reflected rays of incident parallel light are mutually perpendicular. In this situation the reflected light is plane polarized, and...

A system that generally uses a photodetector to decode punched cards for information, or for input to a computer, by sensing the light transmitted through the punched holes.

The optical phenomenon in which right circularly polarized light transmitted by an active medium travels at a different velocity than that of left circularly polarized light.

A coherent fiber bundle (CFB), also known as a coherent fiber optic bundle, is an assembly of multiple optical fibers arranged in a specific geometric pattern to maintain the spatial coherence of...

An instrument that uses a beam of light to scan a color transparency, and three differently filtered photosensors to record the transmitted beam, as a means of producing three exposed separation...

1. A solid figure whose base is a circle and whose sides taper upward evenly to a point or apex. Light rays diverging from or converging upon a point are sometimes referred to as a cone of light. 2....

A prism formed by dividing a Nicol prism in a plane parallel to the path of vibration of the transmitted light and taking out the wedge-shaped piece. After the pieces are rejoined, the planes of...

The positioning of two Nicol prisms so that their axes are at right angles to each other. With this arrangement, light transmitted by one prism will not be transmitted by the other.

The naturally occurring crystalline form of silicon dioxide. It is slightly birefringent and exhibits rotary dispersion of light rays transmitted along the crystal axis, both right-hand and left-hand...

Able to rotate the plane of polarization of a transmitted, plane-polarized light beam clockwise as seen by a viewer looking in the same direction as the traveling light. Also called dextrorotary; the...

The method by which photographic film is scanned by an electron beam. One technique uses the uniform light of a television screen, focused by a lens onto the processed film, as a means of creating a...

Ellipsometry is an optical technique used to characterize the properties of thin films and surfaces. It is based on the measurement of changes in the polarization state of light reflected or...

The term "embedded laser" typically refers to a laser device that is integrated or embedded into a larger system or structure. In this context, "embedded" implies that the laser is an integral part...

An etalon is an optical device that consists of two parallel reflecting surfaces separated by a precise and known distance. It operates based on the principle of optical interference and is used to...

A fiber optic sensor is a device that uses optical fibers to detect and measure physical, chemical, biological, or environmental parameters. Unlike traditional electrical sensors, fiber optic sensors...

A fiber optic transceiver, often simply referred to as an "optical transceiver," is a device used in fiber optic communications to transmit and receive data over optical fibers. It integrates both a...

Any of a number of instruments that uses a flame to vaporize a solution of the chemical being analyzed so that light may be passed through the vapor. Monochromation of the transmitted light is...

Nonimage-forming light, concentrated or diffuse, that is transmitted through the lens to the image. It is frequently the result of reflections from lens surfaces, a lens barrel, shutter or lens mount.

Free-space optics (FSO), also known as optical wireless communication or optical wireless networking, refers to the transmission of data using modulated beams of light through free space (air or a...

Fresnel reflection refers to the reflection of light at the interface between two different media with different refractive indices. This phenomenon was named after the French engineer and physicist...

Functional near-infrared spectroscopy (fNIRS) is a non-invasive neuroimaging technique that measures changes in hemoglobin concentration in the brain. It utilizes near-infrared light to penetrate the...

A neutral-colored gelatin wedge, cast between glass plates, that is used as an intensity scale in certain types of sensitometers; the greater the thickness of the wedge through which light emitted by...

Transparencies that represent progressive steps in the amount of transmitted radiation for administering predetermined amounts of radiation to a radiation-sensitive substance. The steps are...

A screen with a reflected or transmitted light beam that is confined to a much smaller bundle than was received by the screen, thereby resulting in a higher luminance.

A holographic camera, also known as a holographic imaging system or holographic recorder, is a specialized device used to capture 3D holographic images of objects or scenes. Unlike conventional...

An electron tube that is used as a camera tube for a television system. When the picture to be transmitted is focused on a photosensitive surface, electrons are emitted from each section of the...

Photographic recording that uses infrared radiation as the light source to form an image of a microscopic object and a system of lenses and objectives that are transparent to the radiation. The image...

Lens testing equipment refers to a range of specialized tools and instruments used to evaluate the optical performance, quality, and characteristics of lenses. These instruments are essential for...

LiFi, short for light fidelity, is a wireless communication technology that utilizes visible light or infrared light to transmit data. Developed as an alternative or complementary technology to...

The absorption spectrum of an element influenced by a magnetic field in the same direction as the transmitted light, which is then exposed to the Faraday effect.

A near-infrared (NIR) spectrometer is an analytical instrument used to measure the absorption, transmission, or reflection of light in the near-infrared region of the electromagnetic spectrum....

Near-infrared spectroscopy (NIRS) is a non-invasive analytical technique that uses the near-infrared region of the electromagnetic spectrum to study the absorption of light by molecules in a sample....

A coating applied to a neutral density glass that is designed to reduce the amount of light evenly across the transmitted light spectrum with no color distortion. These coatings are designed to...

A device consisting of a disc with a spiral arrangement of holes that is used to convert visible patterns into electrical patterns. Light is reflected from the subject and focused through a vertical...

The capacity of a chiral substance such as a crystal or molecule to rotate the plane of polarized light that is transmitted through it. Any substance that cannot be superimposed onto it's mirror...

An instrument used to measure backscatter as well as optical return loss and reflectance within an optical fiber system by measuring the reflected light when a continuous wave is transmitted through...

A measure of the transmittance through an optical medium. Optical density equals the log to the base 10 of the reciprocal of the transmittance. where τλ is transmittance. In spectroscopy,...

An optical filter is a device that selectively transmits or blocks specific wavelengths, or colors, of light. Optical filters are used to control the spectral content of light in various...

A multilayered thin-film device used to modulate transmitted light in integrated photonic circuits.