Photonics Dictionary

A lock-in amplifier is a specialized electronic instrument used to extract and measure small signals embedded in noise or interference. It is particularly useful in fields such as spectroscopy,...

A diagram that uses special symbols called logic symbols to represent the detailed functioning of electronic logic circuits. The symbols do not represent the type of electronics used, but only their...

A long-pass filter is an optical filter that allows longer wavelengths of light to pass through while blocking or attenuating shorter wavelengths. These filters are designed to transmit light with a...

Pockels cell or dynamic optical retarder in which the electrical field is applied in a direction parallel to that of light passing through it.

A dye laser cell configuration in which the dye flows in the direction of the axis of the laser, yielding symmetrical energy distribution but small repetition rates.

A form of mirage where objects near or just below the horizon appear in enlarged or distorted form because of atmospheric refraction. The glow in the sky caused by the presence of light below the...

The Lorentz oscillator model is a theoretical model used in physics to describe the response of a charged particle (such as an electron) to an oscillating electric field. It is particularly employed...

The total optical power loss in a system. The loss budget is often stated in terms of the transmitted power and the power required at the receiver to express the maximum acceptable amount of loss.

Low Earth orbit (LEO) refers to a region in space that is relatively close to Earth's surface, typically characterized by altitudes ranging from approximately 180 to 2,000 kilometers (112 to 1,242...

An interference microscope that uses a light beam originating from a low-coherence light source. The sample is placed in one interferometer arm, and the other arm provides a reference beam. The...

Optical fiber that transmits a greater percentage of input light than does high-loss step-index fiber. Low-loss fiber requires higher purity materials and a more sophisticated drawing process and...

A lumen is a unit of measurement used to quantify the amount of luminous flux, which is the perceived power of light. In other words, the lumen measures the total amount of visible light emitted by a...

Luminous flux emitted from a surface per unit solid angle per unit of area, projected onto a plane normal to the direction of propagation. Also known as brightness and luminous sterance.

Luminescence is the emission of light that occurs without the involved substance undergoing a significant increase in temperature. In other words, it is the production and emission of light by a...

Luminosity refers to the total amount of energy emitted by an astronomical object, typically measured per unit time. It quantifies the intrinsic brightness of the object and is often expressed in...

Luminous flux emitted by a source in a given range of directions; the unit of measure is the lumen/steradian, now known as the candela.

A dielectric sphere with an index of refraction that varies with distance from the sphere center. A parallel beam of rays is focused on the lens surface at a point diametrically opposite the...

A lymphocyte is a type of white blood cell (leukocyte) that plays a central role in the immune system. Lymphocytes are produced in the bone marrow and mature in the lymphoid organs, such as the...

A type of filter consisting of a series of birefringent crystals and polarizers invented by French astronomer Bernard Lyot for isolating and observing significant wavelengths of solar light.

A Mach-Zehnder interferometer is an optical device used to measure the phase difference between two collimated beams of light. It is named after the physicists Ludwig Mach and Ludwig Zehnder, who...

Machine learning (ML) is a subset of artificial intelligence (AI) that focuses on the development of algorithms and statistical models that enable computers to improve their performance on a specific...

A machine vision lens is a specialized optical lens designed for use in machine vision systems, which are used for automated inspection, measurement, and quality control in industrial applications....

Machine vision lighting refers to the use of specific lighting techniques and equipment in the field of machine vision, which is a technology that enables machines to capture and interpret visual...

A machine vision system is an integrated combination of hardware and software components designed to capture, process, and analyze images to perform automated inspection, measurement, and quality...

Machine vision, also known as computer vision or computer sight, refers to the technology that enables machines, typically computers, to interpret and understand visual information from the world,...

The small central portion of the human retina that is responsible for providing the clearest, and most distinct aspects of human vision. Light from an object directly forms an image on the macula...

A colorless, crystalline compound whose low refractive index (n = 1.38) makes it effective as a lens antireflection coating when deposited by thermal evaporation in a near vacuum. This process...

Magnetorheological (MR) materials, often referred to as MR fluids, are smart materials that undergo significant changes in their rheological behavior (flow and deformation characteristics) in the...

An amorphous film in which cylindrical bubbles of reverse magnetization can be formed to follow circuit paths usually made by depositing magnetic metal strips on the film surface. It is used in...

A method of studying the chemical and physical properties of atoms and molecules (typically living tissue and chemical samples) by exploiting the magnetic properties of their atomic nuclei when an...

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 term denoting the magnitude and direction of the magnetic field associated with an electromagnetic wave when describing light in its vector form.

A vacuum tube in which a magnetic field is superimposed onto the tube's electrical field. When the two fields are aligned, electrons from the photocathode are accelerated through the tube in a spiral...

A device using the Kerr effect to read back the signals from mechanically recorded tapes and discs. It consists of a light source, optical lenses to focus and direct the light beam, a pair of...

A type of high-speed photographic shutter that uses Faraday rotation to produce exposure times as fast as 1 microsecond. It consists of two polarizers, set with their planes of polarization at right...

Magneto-optics refers to the study and manipulation of the interaction between magnetic fields and light (electromagnetic radiation). This field of physics explores how the properties of light, such...

A magnetometer is a scientific instrument used to measure the strength and/or direction of a magnetic field. It can detect and quantify the intensity of magnetic fields in its vicinity. Magnetometers...

Magnetorheological finishing (MRF) is a precision optics polishing technique used for shaping and finishing optical surfaces to achieve extremely high levels of smoothness and accuracy. It is...

A lens or lens system that produces an enlarged virtual image of an object placed near its front focal point.

A magnon is a quasiparticle representing a quantized spin wave in a magnetic material. In other words, it is a collective excitation of the spins of electrons in a magnetic solid, analogous to the...

With respect to a beam, the radiation lobe having the direction of maximum radiation.

A thick meniscus lens arranged concentric with the center of curvature of a spherical mirror to produce an image free of spherical aberration.

A catadioptric lens assembly consisting of a Maksutov corrector and a spherical primary mirror.

A computerized token-passing local area network (LAN) configuration adopted by General Motors for real time control over the mediation of interconnected devices from multiple manufacturers over the...

A theoretical analysis of radiation loss from planar optical waveguides due to scattering by surface irregularities/surface roughness of the walls of the waveguide.

A wedge-shaped piece of quartz typically found in a polarimeter to monitor and rotate the plane of polarization of plane polarized light. A Martens wedge can also be used in combination with other...

A specific method for measuring the diameter of irregular shaped particles, Martin's diameter is the measured distance between opposite sides of a particle, and is measured transverse to the particle...

High-voltage, fast-discharge circuit named after its inventor, Erwin Marx. Its capacitors are charged in parallel and discharged in series. The voltage multiplication achieved with a Marx circuit is...