5,268 terms
Photonics Dictionary
Clear All Filters xions x
logic diagramA 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...
LOMOLeningrad Optical Mechanical Organization
long-pass filterA 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...
long-path absorption spectroscopyThe method that, by measuring the absorption along an atmospheric path at wavelengths ranging from two to a continuum, can determine pollution concentrations of gases.
long-wave infraredLong-wave infrared (LWIR) refers to a specific range of the infrared spectrum. Infrared radiation is divided into three main categories based on wavelength: near-infrared (NIR), mid-wave infrared...
long-wavelength systemIn fiber optic communications systems, generally one that operates between 1000 and 1700 nm.
longitudinal field modulatorPockels cell or dynamic optical retarder in which the electrical field is applied in a direction parallel to that of light passing through it.
longitudinal magnification -> magnificationThe ratio of the size of the image of an object to that of the object. The ratio of the linear size of the image to that of the object is lateral magnification. Angular magnification is the ratio of...
longitudinal pumpingA 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.
loomingA 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...
loose-tube bufferingIn fiber optic cable, containment of the fiber or fibers within an outer protective tube in which they can move to some extent. The interstices usually are filled with an insulating material. See...
Lorentz forceThe force acting upon a charged particle as it moves in a magnetic field, proportional to the particle's charge and velocity.
Lorentz oscillator modelThe 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...
lossy mediumA medium that scatters or absorbs radiation that passes through it.
Lovibond tintometerA subtractive colorimeter that expresses a liquid's or object's color as a combination of three colors. These colors are developed through viewing the specimen object through three series of slides,...
low Earth orbitLow 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...
low excitation potential -> excitation potentialThe amount of energy required to raise the energy level of an atom; a necessity if the atom is to radiate energy. High excitation potential is the amount of energy in the upper state of the...
low-coherence interference microscopeAn 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...
low-light-level instrumentationInstrumentation designed to permit the perception, recording or measurement of scenes under conditions of low incident illumination.
low-loss fiberOptical 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...
low-pass filterIn digital image processing, a method of convolution that reduces random noise by replacing the value of each pixel with the average of that pixel plus its neighbors, or of the neighbors alone. Also...
LSFline spread function
LSIlarge-scale integration
LTDSlaser target designation system
LTPSlateral transitional phase shift
LTSlaser thermal simulation; laser-triggered switch
lumaThe luminance portion of a composite video signal, i.e., the portion of the signal that corresponds to the brightness of the image apart from any color value, giving a monochrome, or gray scale,...
lumenA 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...
luminanceLuminous 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.
luminance rangeAn objective measure of an object's brightness that is derived from the ratio of the luminance of its lightest section to that of its darkest section.
luminescenceLuminescence 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...
luminescent fiberFiber that emits luminescent radiation excited by ultraviolet, x-ray or high-energy particles.
luminescent greenhouse collectorA collector for photovoltaic power generation that consists of a thin plate that strongly absorbs sunlight striking its faces and luminesces efficiently. A large fraction of the luminescence is...
luminosityLuminosity 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...
luminousPertaining to electromagnetic radiation as perceived by the eye; that is, with the contributions as wavelengths in the visible region weighted according to V(λ), which symbolizes the spectral...
luminous exitanceThe total luminous flux given out per unit area; i.e., the sum of the luminous emittance and any radiation that is reflected from and/or transmitted through the surface: expressed as lumens per area.
luminous intensityLuminous flux emitted by a source in a given range of directions; the unit of measure is the lumen/steradian, now known as the candela.
luminous paintA mixture of phosphor with a trace of a radioactive element that emits faint light continually. It is used on watch dials and as a marker inside dark rooms to show the location of switches.
Lummer-Gehrcke plateA high-resolution spectroscopic device commonly used in the early 20th century as a component of double-beam interferometers. Light introduced at one end of the plane-parallel glass plate will be...
Luneburg lensA 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...
luxmeterAn illuminometer designed to measure illumination in terms of luxes.
LV-ROMlaser vision read-only memory
Lyman continuumA spectrum that is continuous in the UV region with borders ranging from the visible to 300 A and lower.
Lyman-alpha radiationThe hydrogen-derived, ultraviolet radiation running from 1216 to 512 A, discovered by Theodore Lyman in 1914.
lymphocyteA 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...
Lyot stopA physical stop that is conjugate to the entrance pupil and is used primarily to reduce diffraction effects at longer wavelengths.
µmicro- the SI metric unit prefix, which represents one millionth, i.e. 10-6, of a given unit
µmmicron (also referred to as the micrometer)- which represents one millionth, i.e. 10-6 of the SI unit for length that is the meter.
mmeter;mass;milli- m is the standard unit symbol for length in the International System of Units (SI). 1 meter is equivalent to 3.28 feet. m is also the standard symbol for mass; m is also the standard SI metric unit prefix milli- which represents one thousandth i.e. 10-3, of a given unit.
Mmega;magnification -SI metric unit prefix which represents one million, 106, also the standard symbol for the magnification of a given optical system.
Photonics Dictionary