THE CARBON DIOXIDE LASER Michael Passens April 7, 2009

Content The Carbon Dioxide Molecule Energy-scheme Power-scheme Set-up Characteristics Recent experiment

The Carbon Dioxide Molecule Three normel modes of vibration Asymmetric stretch mode Bending mode Symmetric stretch mode

Energy-scheme Vibration energy levels Each of the Vibration energy level has a set of rotational levels Selection rules

Power-scheme Excitation of Nitrogen vibration by electron impact Collisional transfer Laser transition from (0,0,1) to (1,0,0) mode vibrational energy converted into translational energy by collisions with Helium

Set-up Longitudinally excited laser Works as a conventional gas discharge laser Water coolant jacket For a gas temperature above 600K the cross section increases extremely Low pressure laser Pulsed and cw laser output

Transversely excited laser High total gas pressures of 1 atmosphere Much higher energy output per unit volume Pulsed laser output

Characteristics One of the most powerful and efficient ( up to 30%) laser available These lasers have produced cw powers of greater than 100 kW and pulsed energies of as much as 10kJ Is used in the general field of materials processing ( cutting,drilling, etching and so forth)

Recent experiment Will a Bendable Laser Scalpel Make the Cut ( Scientific American/ March 4, 2009) directing the infrared energy through a flexible fiber tube lined with reflective material You do not need a series of mirrors Water absorbs CO2 laser energy well, enabling such devices to make a more precise cut than a normal scalpel

Recent experiment