Lumen Intensity Standards
Lumens are the units of light measuring how bright a particular room is, serving as a standardized system for lighting different areas. The lumen is the brightness of the object. When planning room lighting, you must understand how much light a particular lighting device will emit to ensure that the lighting sources will generate enough light for the occupants. You cannot use the energy emitted by the light source because not all of the energy emitted produces visible light.
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Object Properties
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The measure of lumens takes into consideration not only the light that the particular object produces, but also the light that the object can reflect. The lumen is measured in square meters. The lumen is based on the amount of light that the human eye can see and is superficial.
Light Intensity
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To determine the light radiation, scientists must have a standard source so that they can more clearly identify the light intensity. The standard that scientists use is called a candle, which is created when scientists heat a cylindrical tube made out of torio, surrounded by pure platinum, to 2,045 degrees. This creates a very consistent light known as a candle. Candle light sources release monochromatic radiation, emitting 555 nanometers in the empty space --- 555 nanometers represents the frequency at which the human eye is most capable of seeing the light. Light sources light 1m² of a dark surface around the source of the light. This candle is the unit of measurement for all lumens. Each lumen is the equivalent of the light emitted by this heated cylindrical tube.
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Human Eye
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The human eye has sensitivity to two different kinds of lighting depending on if the eye sees low levels or high levels of light. The human eye has photopic vision for high levels of light, which allows for color vision. This is when the eyes are not dilated when the room gets brighter. The eyes have scotopic vision for low levels of light when the eyes dilate and have reduced color vision, such as when the room gets darker. Depending on the level of lighting, the eye can have greater sensitivity to different kinds of color, which is why the eye sees different colors depending on the lighting. Some of the energy that does not become visible light turns into heat; some of the energy turns into frequencies that the human eye cannot pick up, such as ultraviolet and infrared light.
Lighting Flux
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Lumens are used as the standard unit of measurement for lighting flux. Lighting flux comes from the measurements that result from the light's visual effect. The flux measures how much light is released in a specific direction as the light spreads out from the light source. The lighting flux equals the light intensity, multiplied by the angle at which the object emits the light. Depending on the angle of the light, the light can make different shapes when striking flat objects, such as spheres, cones and various polygons.
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References
- Photo Credit Antique Lighting image by Lucid_Exposure from Fotolia.com
