Jean Charles Jacques – Sébastien Bax – Nicolas Cortès 07/01/2008 CO2 Lasers Theory & Conception

Contents CO 2 Lasers Theory Introduction Low power CO 2 lasers High power CO 2 lasers Conclusion 4 5

Introduction µm in the Infrared wavelengths Continuous power capability High efficiency Power from some tens of W to few tens of KW

3 2  Vibration levels; Energy Storage Bending mode Symmetric Stretching mode Asymmetric Stretching mode Vibrational energy: Rotational energy: CO 2 Lasers Theory

4 2  Transfer collision  E=2meV<25meV Active medium composition CO2: 10-20% N2: 10-20% He: 60-80%

Low power CO 2 Laser 3 5  Sealed CO 2 Laser Regeneration of CO into CO 2 Infrared specific optic Brewster angled windows DC Discharge Low power output Small size for a CO2 laser No heavy cost and maintenance

Low power CO 2 Laser 3 6  Waveguide CO 2 Laser Very small BeO waveguide High pressure active medium Brewster angled windows Radiofrequency pumping Yield up to 20% higher than others classical CO2 laser High-quality beam

4 High power CO 2 Laser  Fast axial flow lasers Increase gas flow Heat exchanger Convection 1 kW/m

4 High power CO 2 Laser  Fast transverse flow lasers Gas flow controlled by a turbine (100 Torr) The laser beam crosses the cavity many times 10 kW/m Poorer beam quality than axial flow lasers

4 High power CO 2 Laser  TEA lasers Transverse excited atmosphere lasers Electric discharge : few tens of kV 10 atm : broadering effects 10 MW

Conclusion Wide range of lasers design and outputs spectrum Low power, High power Pulsed or continuous mode Many fields of application Dominate the cutting and welding business Lower costs than YAG lasers Infrared wavelength useful in surgery Military range finding using LIDAR techniques 5