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Selecting a lamp

  1. Sep 29, 2008 #1
    I do not know if i am in the right place to ask this question but i am trying.

    I need to select a light source so i can achieve a 500 lux on surface of 12mX0.5m, but the problem that i must put the source on a distance of 25m to 30m.

    I tried to search for light sources but the problem that light specifications are given in lumen units. Now what i am trying to do is to convert from lumen to lux.

    the first step i do is: If lux = lumen/square meter, and lux is identified as one lumen is entering a surface of one metre square, then a source of 4pi lumen that is 1 metre far away from a one-mertre-square spherical surface will give 1 lux at that distance.

    step 2: to choose the light source to give 500 lux, then i must put a light source which is one metre far away from the specified surface, that has 500*4*pi-lumen specification = 6283 lux.

    step 3: becasue the distance that i wanted is 25 metres, and by applying the theory of inverse square distance, then i need 6283*25^2 = 4 Mega lux light source.

    what i think that this amount of lumen is very huge. the question here is: Is there any light source that can be spotted on just this area that may look like as laser but not expensive as much as to cover this 12X0.5m area?
  2. jcsd
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