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It's an oversimplification. The idea is that laser beams are extremely collimated, with divergences well under 1 degree in many cases, so over 200 meters the beam might only expand a tiny amount. But not to worry, the beam still spreads. Calculate the beam spot size of a laser, where the area increases as the square of the distance. Meanwhile, intensity is the inverse of the area. At sufficiently long distances, this will become apparent.



Isn't that only true of the far field?




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