CO2 CNC Lasers work by basically bouncing light emissions back and forth between mirrors until the beam is strong enough to pass through a partially transparent mirror at the tip of the router head. Going a little more in depth, the mixture of Hydrogen, Carbon Dioxide, Helium, and Nitrogen is what allows the process of population inversion to occur once an electrical current is added to it. The key to the formation of the laser beam is in the Nitrogen atoms though, since Nitrogen is able to maintain an excited state for longer than other elements. Once the Nitrogen comes into contact with cold helium atoms, photons (light) are released.