Double Head Die cutting Laser Machine

[dreamvbfox]

Hi guys

can anyone help me about double head co2 laser die cutting machine ?
what's the structure of these Nozzles for co2 lasers that they don't hurt Laser Tube with their laser beam !?

is there any special mirror or lense to avoid hurting ?

this is a chinese double head laser machine Video :
http://www.youtube.com/watch?v=zFwsXHX3HQQ]Dual Head Laser Die Board Cutting Machine - YouTube

thanks in advanced