Carbon-dioxide laser

A type of gas laser using carbon dioxide as the lasing medium

Carbon Dioxide Laser

The carbon dioxide laser (CO₂ laser) is a type of gas laser that uses a mixture of carbon dioxide, nitrogen, and helium as its lasing medium. It is one of the earliest gas lasers to be developed and remains one of the most useful. The CO₂ laser is known for its high efficiency and high power output, making it a popular choice in industrial, medical, and military applications.

A carbon dioxide laser in operation at a test facility

Principle of Operation

The CO₂ laser operates by exciting carbon dioxide molecules to a higher energy state. This is achieved by passing an electric current through the gas mixture, which typically consists of carbon dioxide, nitrogen, and helium. The nitrogen molecules are excited by the electric discharge and transfer energy to the carbon dioxide molecules, which then emit infrared light at a wavelength of 10.6 micrometers when they return to their ground state.

The laser action occurs when the emitted photons stimulate other excited CO₂ molecules to emit more photons of the same wavelength, resulting in a coherent beam of light. The laser cavity, which consists of mirrors at each end, amplifies this light through multiple reflections, producing a powerful laser beam.

Applications

CO₂ lasers are widely used in various fields due to their ability to cut, weld, and engrave materials with precision. In the industrial sector, they are commonly used for cutting and welding metals, plastics, and other materials. The high power output and efficiency of CO₂ lasers make them ideal for these applications.

In the medical field, CO₂ lasers are used in surgery for cutting and vaporizing soft tissues. They are particularly useful in dermatology for skin resurfacing and in otolaryngology for procedures involving the throat and vocal cords.

In the military, CO₂ lasers are used in range-finding and target designation systems due to their ability to produce a focused beam over long distances.

A Sharplan 40C CO₂ laser used in medical applications

Advantages and Disadvantages

The CO₂ laser is highly efficient, with efficiencies of up to 20%. It can produce continuous wave (CW) or pulsed laser beams, making it versatile for different applications. The long wavelength of the CO₂ laser allows it to be absorbed by many materials, making it effective for cutting and engraving.

However, the CO₂ laser also has some disadvantages. The equipment can be bulky and requires careful handling due to the high voltages involved. Additionally, the infrared wavelength is not visible to the human eye, necessitating the use of special safety equipment to prevent accidental exposure.

Related Pages

• Laser
• Gas laser
• Laser surgery
• Industrial laser applications