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?