presented by:
Bibi Mohanan

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CARBON DIOXIDE LASER
A test target is vaporized and bursts into flame upon irradiation by a high power continuous wave carbon dioxide laser emitting tens of kilowatts of infrared light
Introduction
 Operates in middlle infrared region(10.6 μm &9.4 μm )
 Operates on rotational –vibrational transitions
 Both cw & pulsed laser output
 Cw power greater than 100kw
 Pulsed energies of 10 kJ
 Physical arrangement :a gas filled tube between a pair of mirrors excited by a DC or RF electrical discharge.
 Additional gases are added to the gas mixture (besides CO2) to improve efficiency and extend lifetime. The typical gas fill is: 9.5% CO2, 13.5% N2, and 77% He
Excitation Mechanism
 Rotational- vibrational transitions
Laser Types
 Longitudinally Excited Lasers
 Waveguide Lasers
 Transversely Excited Lasers
 Gas Dynamic Lasers
Longitudinally Excited Lasers
Schematic setup of a sealed-tube carbon dioxide laser.
The gas tube has Brewster windows and is water-cooled
Longitudinally Excited Lasers
 Long ,narrow,cylindrically shaped glass enclosures with electrodes at opposite ends from which the discharge excitation current is introduced
 Either pulsed or cw
 Lengths up to several meters
 Two versions
 Water coolant jacket is provided
Waveguide Laser
 Two transverse RF electrodes separated by insulating sections that form the bore region
 RF power supply is connected to the electrodes
 Lateral dimensions of the bore –few millimeters
 Small bore hence, high pressure operation and rapid heat removal
 Hence, high gain and high power output
 Cw powers up to 100 W
Commercial air cooled waveguide laser
 RF excitation : 80-100 MHz
 Four mirrors (two as end mirrors and two for reversing the direction of the beam)
 Pressure : 80 Torr
 Nitrogen:CO2:Helium =3:1:1
 Length :30 cm
 Cw power:35 W
 Wavelength:10.55μm -10.63 μm
Transversely Excited Lasers
 Operates at high gas pressure (1 atm or more)
 High voltages are required to ionize the gas
 Two electrodes are placed parallel to each other separated by few centimeters
 High voltages applied across the electrodes
 Pre-ionization is used