The CO2
Laser typically uses a mix of
neon,
nitrogen and
carbon dioxide as the
lasing medium. Like other
discharge pumped lasers, it consists of a
gas filled lasing
chamber between a normal
mirror and a mirror
that is partially
transparent to the lasers
wavelength.
The chamber also has discharge
electrodes. To fire the
laser a high
voltage
supply(typically 10kV-20kV) is
connected to the electrodes
and a starting
pulse(25kV+) is administred. This starts an
electron
flow through the 'helping' gasses(neon and nitrogen).
Some these electrons collide with the CO2
molecules.
This creates a
state of high
vibration energy in in the
molecule. When the vibration
decays back to normal, an pulse
of
EM energy is released. This light has a typical wavelength
of between 9um and 12um(normal peak wavelengt is around 10.6um).
This energy is
reflected between the mirrors, and when it escapes
thrugh the
semitransparent mirror, it forms the laser beam. Since
the high energies caused by the lasing
process breakes down the CO2,
the lasers often have a
circulation system, that pumps new gas in and
used out.
new gas
from pumping
system
|
|V|
_| |__________________________
!# #|
!: Chamber :;--------------
!: :;--------------
!#__________________________ _#| Beam
# | | #
# ||| #
V
used
gas
Legend
: IR transparent material
# electrodes
! mirror
; semi transparent mirror
These lasers have high effects and easily comes up over 50W.
Due to the high wavelength(mid
IR) special optics are needed.
The end of the chamber has a pane of
germanium,
natrium chloride
(salt) or
zinc selenide, since normal
glass isn't very
transparent at these frequencies. The CO2 lasers are used in
industry for welding and cutting. It is also used as a
surgical tool.