Consider the simple case of a flashlight bulb by itself, versus in the flashlight (with a reflector). They are both inverse square brightness, but the constant factor in the flashlight case is much smaller.
Similarly this will make coherence areas that will be very small. Wasted power will be approximately inverse-square, but the falloff will be small enough that for short distances you can ignore it.
Comments
Yes, but constant factors matter.
Consider the simple case of a flashlight bulb by itself, versus in the flashlight (with a reflector). They are both inverse square brightness, but the constant factor in the flashlight case is much smaller.
Similarly this will make coherence areas that will be very small. Wasted power will be approximately inverse-square, but the falloff will be small enough that for short distances you can ignore it.