The laser source for a CO2 (carbon dioxide) laser is, as the name suggests, a mixture of gases, primarily consisting of carbon dioxide, nitrogen, and helium. These gases are excited to produce the laser beam. The CO2 laser operates on a principle known as “molecular gas laser.”
Here’s how it works:
1. Excitation: A high-voltage electrical discharge is applied to the gas mixture inside a sealed tube, which contains the carbon dioxide, nitrogen, and helium. This electrical discharge excites the gas molecules, causing them to transition to higher energy states.
2. Population Inversion: As the gas molecules absorb energy, more of them are in higher energy states than lower energy states, creating what is called a “population inversion.” This is a critical condition for laser operation.
3. Laser Emission: When a gas molecule in an excited state collides with another gas molecule, it can stimulate that molecule to emit energy in the form of a photon. These emitted photons are coherent (have the same frequency and phase) and travel in the same direction. This results in the laser beam.
4. Resonator: The laser beam is amplified as it bounces back and forth between two mirrors placed at the ends of the laser tube. One mirror is partially reflective, allowing a portion of the beam to exit as the laser output.
CO2 lasers are versatile and widely used in various applications, including cutting, engraving, marking, welding, and more. They are known for their high power, efficiency, and ability to produce a laser beam in the infrared part of the electromagnetic spectrum, primarily at a wavelength of 10.6 micrometers, which is well-suited for many materials processing tasks.