How CO₂ Engraving Lasers Work
A CO₂ laser uses an electrically excited gas mixture to produce far-infrared light, commonly near 10.6 µm. Mirrors form the resonator, an output coupler releases part of the beam, and external mirrors or a galvo direct it to a focusing lens.
What happens in the gas
Electrical excitation transfers energy into molecular vibration states, and stimulated emission between those states produces the infrared beam. Nitrogen and helium commonly assist energy transfer and relaxation, though the mixture and excitation method vary.
Glass-tube systems typically use high-voltage discharge and water cooling; RF-excited metal or ceramic sources use a different construction and can modulate more quickly. CO₂ describes the gain medium, not whether the machine uses a gantry or galvo.
Why wavelength changes the material list
The long-wave infrared output is strongly absorbed by many organics and polymers, making CO₂ effective for wood, paper, leather, rubber, fabric, glass-surface marking, and especially acrylic cutting and engraving.
Bare metals reflect much of this wavelength unless specialized power levels or processes are used. Coatings and marking compounds can create a surface mark, but that differs from direct near-infrared fiber marking.
How parameters change the process
Power and speed set energy per distance. Focus distance and lens selection affect spot size and kerf. Pulse or frequency controls can change how output is distributed along motion, but their meaning depends on the source and controller and should not be confused with MOPA nanosecond pulse duration.
Air assist clears vapor, suppresses flame, and changes edge chemistry; extraction removes smoke and vapor; passes trade repeated heating against depth. Cutting also depends on material thickness, focus distance, beam alignment, and the laser's movement system.
Thermal character and safety
CO₂ processing commonly relies on heating, melting, vaporization, and chemical decomposition. Heat-affected edges, flame, smoke deposition, and material-specific fumes are central concerns.
Use the selection guidance in What Laser Should I Buy? and verify every material before processing, especially plastics and composites.