All science fiction rely on laser weapons, either hand held, shoulder fired, tripod mounted or fired from space ships. As far as fired from a handheld weapon mount, a shoulder fired mount or a tripod, the problems with a laser weapon do not come into play at close range as much. With a ship mount, they do because the distances are much longer.
The problems revolve around the fact that light is a wave activity. You can have the amplitude of the light be in sync throughout the beam, but that doesn’t change the fact that a wave is basically unstable. The farther from the source it runs into an object, the less focused it is and therefore the less punch it has.
Example: a laser, fired in an atmosphere, which can punch through body armor at 100 feet, will be less effective at a mile because the waves are becoming less coherent, which gives the beam its strength for two reasons. The wave is spreading out naturally and atmosphere is composed of atoms that will also reduce the focus and thereby the power of the beam. Likely it will be unpleasant and possibly do damage, but then again, maybe not. This is why laser pistols are short range weapons.
As for space, with no atmosphere to incohere the light beam, goof it up, the only problem will be the natural waviness. It will pack a punch to a much greater distance, but then ships are already much farther away than people on a planet usually.
Think of it this way: if you stand on the surface of Mercury, the light radiating from sun will instantly give you a bad, very bad, sunburn. You need SPF 2 trillion in that case. However, here on Earth, light from that same source, the sun, because of the waviness of light, has spread out and you only need SPF 15. That same principle applies to all laser weapons.
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