10-11-2012, 04:30 PM
Laser Micromachining Seminar
Laser Micromachining.pdf (Size: 1.1 MB / Downloads: 313)
Essential Elements of a LASER Oscillator
A laser requires a lasing medium, pump process and a resonator cavity to sustain oscillation. The lasing medium
can be a gas, solid, liquid, or in the case of semiconductor lasers, electrons. The pump process excites the atoms or
molecules of the lasing medium to their upper energy states by electronic means or kinetic energy transfer. Laser
transmission is initiated by spontaneous emission and amplified by stimulated emission along the axis of the
resonator cavity. The cavity mirrors reflect a portion of the photons back and forth through the laser medium for
increased amplification.
CO2 Laser Operational Theory
A carbon dioxide laser uses a gas mixture of CO2:N2:He. The CO2 molecules constitute the active lasing medium,
the N2 gas serves as an energy transfer mechanism and the He atoms enhance the population inversion by
depopulating the lower energy states. The population inversion and lasing transition in a CO2 laser is established
between vibrational and rotational energy states. Most CO2 lasers are pumped by a gas discharge.