Light_vocabulary

AC (Alternating Current)

Current which flows in one direction and then the other, alternately.



Adaptation

The process by which the human eye adjusts to a change in light level.



Amperes ("Amps.") A measure of electrical current. In incandescent lamps, the current is related to voltage and power as follows: Watts (power) = Volts x Amps (current).



ANSI (American National Standards Institute) A consensus-based organization which coordinates voluntary standards for the physical, electrical and performance characteristics of lamps, ballasts, luminaires and other lighting and electrical equipment.



Application  Also called "lighting application," it refers to the particular use the lamp is being put to. (e.g. high-bay industrial application or retail lighting application.) The term can also refer in a general way to "application engineering" which deals with specific paramters and usage of light sources. (e.g. how to do a lighting layout, where to place fixtures and so on.)



﻿  Ballast  An auxiliary piece of equipment required to start and to properly control the flow of current to gas discharge light sources such as fluorescent and high intensity discharge (HID) lamps. Typically, magnetic ballasts (also called electromagnetic ballasts) contain copper windings on an iron core while electronic ballasts are smaller and more efficient and contain electronic components.

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<span style="color: #0d0dd3; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 140%;">Base or Socket <span style="font-family: 'Courier New',Courier,monospace;"> The socket is the receptacle connected to the electrical supply; the base is the end of the lamp that fits into the socket. There are many types of bases used in lamps, screw bases being the most common for incandescent and HID lamps, while bipin bases are common for linear fluorescent lamps. Sample Base Types

<span style="color: #0d0dd3; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 140%;">Base Temperature (Maximum) <span style="font-family: 'Courier New',Courier,monospace;"> The maximum operating temperature permitted for the base in Celsius. Fixture manufacturers need to ensure that these conditions are satisfied in their fixture.

<span style="color: #0d0dd3; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 140%;">Bayonet  <span style="font-family: 'Courier New',Courier,monospace;">A style of bulb base which uses keyways instead of threads to connect the bulb to the fixture base. The bulb is locked in place by pushing it down and turning it clockwise.

<span style="color: #0d0dd3; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 140%;">Beam Angle

<span style="font-family: 'Courier New',Courier,monospace;"> The angular dimension of the cone of light from reflectorized lamps encompassing the central part of the beam out to the angle where the intensity is 50% of maximum.

<span style="color: #0d0dd3; display: block; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 140%; text-align: left;">Beam Lumens <span style="display: block; font-family: 'Courier New',Courier,monospace; text-align: left;"> The total lumens present within the portion of the beam contained in the beam angle.

<span style="color: #0d0dd3; display: block; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 140%; text-align: left;">Beam Spread (Approximate) <span style="display: block; font-family: 'Courier New',Courier,monospace; text-align: left;"> For reflector type lamps. The total angle of the directed beam (in degrees horizontal or vertical) to where the intensity of the beam falls to 50% or 10% of the maximum candlepower value as indicated.

<span style="color: #0d0dd3; display: block; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 140%; text-align: left;">Blackbody <span style="display: block; font-family: 'Courier New',Courier,monospace; text-align: left;"> A hot body with an incandescent black surface at a certain temperature used as a standard for comparison. Note that a black surface is the best radiator possible. A tungsten filament will emit slightly less radiation than a blackbody at the same temperature.

<span style="color: #0d0dd3; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 140%;">Black Light <span style="font-family: 'Courier New',Courier,monospace;"> A popular term referring to a light source emitting mostly near UV (320 to 400 nm) and very little visible light.



<span style="color: #0d0dd3; display: block; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 140%; text-align: left;">Blacktop

<span style="display: block; font-family: 'Courier New',Courier,monospace; text-align: left;"> Whether or not the top of the miniature lamp has a blacktop coating. The coating is used to control unwanted brightness or glare.

<span style="color: #0d0dd3; display: block; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 140%; text-align: left;"> Bollard <span style="display: block; font-family: 'Courier New',Courier,monospace; text-align: left;"> A short, thick post with a light at its top, used for grounds and outdoor walkway lighting.



<span style="color: #0d0dd3; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 140%;">Bulb

<span style="font-family: 'Courier New',Courier,monospace;">A loose way of referring to a lamp. "Bulb" refers to the outer glass bulb containing the light source.

<span style="color: #0d0dd3; display: block; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 140%; text-align: left;">Bulb Material or Coating <span style="display: block; font-family: 'Courier New',Courier,monospace; text-align: left;"> The type of glass (or quartz) used in the glass envelope surrounding the light source. The material can also have coatings applied to achieve particular performances.

<span style="color: #0d0dd3; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 140%;">Brightness  <span style="display: block; font-family: 'Courier New',Courier,monospace; text-align: left;">Brightness can refer to any of several technical terms used in lighting and is, therefore, ambiguous

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<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Candela (cd)

<span style="font-family: 'Courier New',Courier,monospace;">The measure of luminous intensity of a source in a given direction. The term has been retained from the early days of lighting when a standard candle of a fixed size and composition was defined as producing one candela in every direction. A plot of intensity versus direction is called a candela distribution curve and is often provided for reflectorized lamps and for luminaires with a lamp operating in them.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Compact Fluorescent Lamp (CFL)

<span style="font-family: 'Courier New',Courier,monospace;">The general term applied to fluorescent lamps that are single-ended and that have smaller diameter tubes that are bent to form a compact shape.



<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Capacitor

<span style="font-family: 'Courier New',Courier,monospace;">Device in ballast that stores electrical energy. Often used for power factor correction and lamp regulation.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Ceramic Metal Halide (CMH®)

<span style="font-family: 'Courier New',Courier,monospace;">A type of metal halide lamp that uses a ceramic material for the arc tube instead of glass quartz, resulting in better color rendering (>80 CRI) and improved lumen maintenance.



<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Chromaticity

<span style="font-family: 'Courier New',Courier,monospace;">Measure to identify the color of a light source, typically expressed as (x,y) coordinates on a chromaticity chart.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Coil

<span style="font-family: 'Courier New',Courier,monospace;">Windings of copper or aluminum wire surrounding the steel core in ballast. Also refers to the entire assembly comprising the inductor or transformer.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Core

<span style="font-family: 'Courier New',Courier,monospace;">Component of electromagnetic ballast that is surrounded by the coil. Core is comprised of steel laminations or solid ferrite material.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">covRguard®

<span style="font-family: 'Courier New',Courier,monospace;">A special plastic shielding on the outside of tubular fluorescent lamps that effectively contains shattered glass particles if the lamp is broken. Such protection is mandated in many industries and locations, e.g. food packaging.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Daylight Harvesting

<span style="font-family: 'Courier New',Courier,monospace;">Lighting design for building interiors that makes of daylight as a way of reducing energy consumption. <span style="font-family: 'Courier New',Courier,monospace; line-height: 0px; overflow-x: hidden; overflow-y: hidden;">



<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Daylight Lamp

<span style="font-family: 'Courier New',Courier,monospace;">A lamp resembling the color of daylight.



<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Dimmable

<span style="font-family: 'Courier New',Courier,monospace;">Whether or not the lamp lumens can be varied while maintaining reliability.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Dimmer, Dimming Control

<span style="font-family: 'Courier New',Courier,monospace;">A device used to lower the light output of a source, usually by reducing the wattage it is being operated at. Dimming controls are increasing in popularity as energy conserving devices.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Electrode

<span style="font-family: 'Courier New',Courier,monospace;">Any metal terminal emitting or collecting charged particles, typically inside the chamber of a gas discharge lamp.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Electrodeless Lamps

<span style="font-family: 'Courier New',Courier,monospace;">Light sources where the discharge occurs in a chamber with no electrodes.



<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Elliptical Reflector (ER) Lamp

<span style="font-family: 'Courier New',Courier,monospace;">An incandescent lamp with a built-in elliptically-shaped reflecting surface. This shape produces a focal point directly in front of the lamp which reduces the light absorption in some types of luminaires.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Eye Sensitivity

<span style="font-family: 'Courier New',Courier,monospace;">A curve depicting the sensitivity of the human eye as a function of wavelength (or color). The peak of human eye sensitivity is in the yellow-green region of the spectrum. The normal curve refers to photopic vision or the response of the cones.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Flood

<span style="font-family: 'Courier New',Courier,monospace;">Used to refer to the beam pattern of a reflector lamp, which disperses the light over a wide beam angle, typically 20 degrees or more. ("Flood" as opposed to "spot")

<span style="color: #0d0dd3; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 140%;">Floodlight

<span style="font-family: 'Courier New',Courier,monospace;">A luminaire used to light a scene or object to a level much brighter than its surroundings. Usually floodlights can be aimed at the object or area of interest.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Fluorescence

<span style="font-family: 'Courier New',Courier,monospace;">A physical phenomenon whereby an atom of a material absorbs a photon of light an immediately emits a photon of longer wavelength.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Fluorescent Lamp

<span style="font-family: 'Courier New',Courier,monospace;">A high efficiency lamp utilizing an electric discharge through inert gas and low pressure mercury vapor to produce ultraviolet (UV) energy.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Foot Candles

<span style="font-family: 'Courier New',Courier,monospace;">A unit of illuminance or light falling onto a surface. It stands for the light level on a surface one foot from a standard candle.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Fovea, Foveal Vision

<span style="font-family: 'Courier New',Courier,monospace;">A small region of the retina corresponding to what an observer is looking straight at.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Full Spectrum Lighting

<span style="font-family: 'Courier New',Courier,monospace;">A marketing term, typically associated with light sources that are similar to some forms of natural daylight (5000K and above, 90 CRI), but sometimes more broadly used for lamps that have a smooth and continuous color spectrum.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Glare <span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%; line-height: 0px; overflow-x: hidden; overflow-y: hidden;">



<span style="font-family: 'Courier New',Courier,monospace;">Visual discomfort caused by excessive brightness is called discomfort glare. If task performance is affected it is called disability glare. Glare can be direct glare or indirect (reflected) glare.



<span style="color: #0d0dd3; display: block; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%; text-align: left;">Halogen Lamp

<span style="font-family: 'Courier New',Courier,monospace;">A halogen lamp is an incandescent lamp with a filament that is surrounded by halogen gases, such as iodine or bromine. Halogen gases allow the filaments to be operated at higher temperatures and higher efficacies.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Hertz (Hz)

<span style="font-family: 'Courier New',Courier,monospace;">Unit used to measure frequency of alteration of current or voltage.

Illuminance The "density" of light (lumens/area) incident on a surface; i.e. the light level on a surface. Illuminance is measured in footcandles or lux.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Indirect Lighting

The method of lighting a space by directing the light from luminaires upwards towards the ceiling. The light scattered off the ceiling produces a soft, diffuse illumination for the entire area.



<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Infrared Radiation

Electromagnetic energy radiated in the wavelength range of about 770 to 1,000,000 nanometers. Energy in this range cannot be seen by the human eye, but can be sensed as heat by the skin.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Integral

A popular term for a compact fluorescent lamp which includes a built-in ballast (See CFL).

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Isocandela Plot

A plot with lines connecting points of equal luminous intensity around a source.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Isolux Plot (or Isofootcandle Plot)

A line plotted to show points of equal illuminance on a surface illuminated by a source or sources.

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%;">Lamp

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 140%; line-height: 0px; overflow-x: hidden; overflow-y: hidden;">

<span style="color: #000000; font-family: 'Courier New',Courier,monospace;">The term used to refer to the complete light source package, including the inner parts as well a the outer bulb or tube. "Lamp", of course, is also commonly used to refer to a type of small light fixture such as a table lamp.

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<span style="color: #000000; font-family: arial,helvetica,sans-serif; font-size: 13px; line-height: 19px;">

<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 18px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">Lens

<span style="color: #000000; font-family: 'Courier New',Courier,monospace; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">A transparent or semi-transparent element which controls the distribution of light by redirecting individual rays. Luminaires often have lenses in addition to reflectors.

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<span style="color: #0d0dd3; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 18px; line-height: 27px;">Light

<span style="color: #000000; font-family: 'Courier New',Courier,monospace; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">Radiant energy that can be sensed or seen by the human eye. Visible light is measured in lumens.