Beam Divergence refers to the diameter of the laser beam as it travels. Just like the beam from a flashlight, if you hold it against a wall the beam is small. As you back away from the wall the beam gets bigger. Police laser guns work the same way. At the typical targeting distance of 1000 feet, the beam hitting the front of your vehicle could be 15-30 inches in diameter. The closer you get to the police laser gun, the smaller the beam of light hitting your car becomes.