Laser Weapons
Lasers are common in science fiction as futuristic weapons. Lasers project light at damaging intensities onto a target. To be effective, this light must be focused through optics (laser beams do not travel as perfect columns! Focusing makes the beam converge to a tight spot on the target). The ability to focus is limited by diffraction and, in an atmosphere, thermal blooming; and energy can be lost from the beam due to atmospheric absorption, scattering, and other phenomena. The color (wavelength, frequency, or per-photon energy) of the light you choose can be very important for your ability to get the light to the target.
Lasers can be expected to be exceptionally accurate. Depending on the power, energy, and intensity you can deliver to the target, they could be limited to relatively shallow surface burns or could drill deeply enough to reach vital equipment or organs deep inside the target. You can defend against lasers with armor or smoke, but mirroring will not work against higher intensity lasers.
Certain colors of lasers can cause unintended blindness to bystanders or friendlies, including all visible colors of light. Use with caution.