My question is very basic concerning gas lasers. I wanted clarification that a gas laser gets its light from a cell containing only that gas with a few other constituents and a high voltage being applied to it. Basically I'd like to understand what is happening with a CO2 laser and why it requisites other gasses. Also the entirety of the actual cell seems to light up and there is only one mirror on the back end of the tube. Why don't they cover the entire laser tube with a mirror material? or is that what the laser head is?