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Excerpt from Field Guide to Lasers
Carbon-dioxide (CO2) lasers are powerful and comparatively efficient gas lasers emitting at 10.6 µm or at other wavelengths around 9-11 µm. A gas discharge excites nitrogen molecules, which transfer their energy to the laser-active CO2 molecules.
CO2 lasers of different types span a wide range of powers-from tens of watts to many kilowatts or even several megawatts. While low-power versions can work with a sealed tube (no-flow lasers), high-power lasers use a fast gas flow. Continuous-wave and pulsed operation are possible.
Even at high power levels, CO2 lasers often reach nearly diffraction-limited beam quality. Due to the longer wavelength, the beam parameter product is larger than that of diffraction-limited solid-state lasers (e.g., thin-disk lasers), but it is still smaller than that of many solid-state lasers with nonideal beam quality. The figure above gives a rough indication of the typical parameter regions.
Properties of Carbon-Dioxide Lasers
|important types||multi-kW TEA lasers; low-power, sealed-tube lasers|
|applications||laser cutting an dwelding; laser marketing|
|pump source||electrical current|
|power efficiency||order of 10%|
|accessible wavelengths||mostly around 10.6 μm with otherlines at 9-11 μm|
|wavelength tuning||quite limited|
|average output power||typically between 1 W and 50 kW|
|beam quality||normally diffraction-limited|
|nanosecond pulse generation||yes, with mode locking or Q switching|
|picosecond & femtosecond pulse generation||no|