Advanced Lighting Guidelines Glossary
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ALL A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 0-9
Radiant exposure The product of the irradiance on a surface and the duration of exposure. Irradiance is measured in watts / square… More »
Radiant flux The rate of flow of electromagnetic radiation, measured in Watts. Original Chapter Source: Light & Vision Provided By: Heschong Mahone… More »
Rapid-start lamps A fluorescent lamp that requires its electrodes to be heated prior to starting, using a starter that is an integral… More »
Rare-earth (RE) phosphors A group of phosphors containing rare-earth elements. Rare-earth phosphors are used in fluorescent lamps to achieve high efficacy and better… More »
Receptive field The area of the retina to which a retinal ganglion cell is connected. Original Chapter Source: Light & Vision Provided… More »
Reference ballast A ballast that is built to a specific standard for the sole purpose of testing and characterizing lamps and other… More »
Reflected glare Glare caused by a reflection of a light source in an object within the field of view. Original Chapter Source:… More »
Reflection The change in direction of a light ray at the boundary between two media so that the ray returns into… More »
Reflector lamp ("R" lamp) Lamps made of blown or molded glass formed such that a parabilic or other shape is created which directs the… More »
Refraction The change in direction of a light ray when it enters a different medium. Original Chapter Source: Light & Vision… More »
Relative Photometry Photometry is the measurement of the properties of light, particularly intensity. Relative photometry, used for luminaires with conventional light sources,… More »
Relay Power-switching device that receives low-voltage ON/OFF signals from another device and responds by closing or opening the circuit to turn… More »
Retina The photosensitive surface at the back of the eye where photons of light are converted into electrical signals that are… More »
Retinal illumination The amount of light falling on the retina derived from the luminance of the scene being viewed and the area… More »
Retinal image The image of the outside world formed on the retina by the optical elements of the eye. The quality of… More »
Retinal irradiance The irradiance falling on the retina, measured in watts per square meter. Original Chapter Source: Health & Performance Provided By:… More »
Return on investment (ROI) Also known as Rate of Return is expressed in terms of the interest rate that makes the Present Worth of… More »
RoHS Restriction of Hazardous Substances Directive; a European Union directive dictating restrictions on a variety of hazardous substances (including mercury) that… More »
Room Cavity Ratio (RCR) Environmental factor used in lighting design calculations. Cavity defined by the luminaire plane, task plane and the vertical wall area… More »
ALL A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 0-9

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