A laser can excite atoms

Lasers require atoms or molecules that can be excited, high powered laser media that form solid, liquid or gas, and energy sources that can excite these components. Stimulated emission can begin as soon as the first photon of sufficient frequency is present in the medium. It then causes the emission of another photon, each photon still causes the emission of another photon, and so on: this is the amplification of light. To operate the laser, you still need an oscillator, which consists of a slender cylinder with two parallel mirrors at each end. Online examples include laser Pointers selling for $15 to $700, with advertising power levels up to 2 watts and a range of up to 50 kilometers. At these power levels, Pointers can be used as weapons, as they can cause immediate and permanent eye damage.In the field, law enforcement officers face different scenarios when confronted with laser pointer attacks, which in crowd-control situations are often close to officers, and often use Pointers of different colors (including the red and high-power blue lasers now available).