We have a 6 kilowatt laser that has a couple of mirrors that are $30,000.00 each. A laser beam is focused for a certain distance. The beam can be adjusted.
When I cut 1 inch carbon steel, I can focus at any point in the metal or above and below it. Simular to how kids use a magnifying glass in the sun to burn wood. The beam can be affected by particles in the air which can ths weaken the beam.
This is some interesting info on the test. Where did it come from?