I don’t think the laser power changes at all.
Lasers usually emit a specific frequency range at a specific output. This stability of power output makes for a more reliable and long lived laser.
The depth of cure is set by the gap created between the tank floor and the prior layer of the model by the build plate- only allowing a very specific thickness of liquid resin in the laser path.
For more energy- the laser beam simply moves slower, or plays over the same area more than once.
The X/Y resolution of the laser is greater than the diameter of the laser spot simply because the software knows the diameter of the spot and can aim for the laser path to run the RIM of the spot at the edge of the profile being drawn- rather than the center of the spot.
I think diffusion of the beam is part of the reason the Form 2 doesn’t even try to offer build thicknesses greater than .1 mm- which would be faster and often sufficient for simpler parts,
The grey resin and others that are more opaque would significantly limit the penetration of the laser into the liquid… and since the resin is polymerizing AS the laser hits it…the polymerization itself is essentially getting in the way of the beam… either increasing it opacity or its diffusion. These parameters effectively limit how thick the laser can reasonably accurately polymerize the resin.
I have been using a laser pen to fuse multipart models together and so I am seeing the laser getting refracted or diffused when i shine it into too thick a puddle of resin. I have also run into the limit of how deep the pen laser can cure the resin. I can accidentally cure just the top of the resin if the resin I apply is too thick, and end up with a ‘scab’ of resin that can slide or peel off the still uncured resin underneath.
While laser power definitely fall off with distance, its not the standard inverse square law- because laser light is coherent. So the energy drop between .025 and .1 mm is not measurably significant.
Clearer resins allow the beam to penetrate pretty deep- but with consequent scattering and refraction that is best solved by printing thinner layers.
In the more opaque resins I would venture that the pigments are magnifying diffraction- but that the actual penetration of the lase has significant dropoff due to the pigments’ opacity.
Again- these are just how I think the thing works based upon my experience and basic education in physics and chemistry.