Actually, there are a bunch of things going on (and terminology varies). What we use:- Air assist blows on the cut and helps clear debris- Purge air blows clean air on the optics to keep them from getting dirty- Intake air brings fresh air into the case- Exhaust air blows air out of the case- Cooling air blows over things that get hotit gets confusing. : ) one of the ways we were able to lower the cost versus a traditional laser was by combining subsystems - like the exhaust also does cooling.