APPLICATIONS

      Commercially available CO₂ lasers vary from small sealed units with integral RF power supplies under 40 cm in length, featuring output powers in the several-watt range, to behemoth industrial monsters with multiple plasma tubes several meters in length utilizing three-phase 600-V AC power with output powers in the 10-kW range. Since CO₂ lasers are always high powered (compared to other gas lasers), most are used for materials-processing applications. The main competition is from YAG lasers, which can also yield outputs of several hundred watts. While YAG lasers compete with CO₂ types in the lower-power end of the scale (< 100 W), the CO₂ laser can easily be scaled to power levels in the tens-of-kilowatts range, much larger than a YAG, so it is the dominant laser in the high-power area.

            The relatively long IR wavelength of the CO₂ laser is readily absorbed by most organic materials (such as plastics), as well as glass, water molecules, and many common materials. For cutting materials such as cotton (used in making jeans), the CO₂ laser is ideal. It is also used in surgical applications since the wavelength is readily absorbed by flesh vaporizing it; the heat also serves to cauterize the cut, thus reducing bleeding.

        Most metals are somewhat reflective at this long wavelength, so higher powers are required to ensure that enough energy is absorbed to cause vaporization of the material (easily provided, though, by these types of lasers). Cuts made into metals are hence somewhat rougher than those made with other lasers (e.g., the YAG), but the high average power available from the CO₂ laser (which no other commercially available laser can generate) usually means that higher-speed operations are possible, so for many large-scale cutting applications, this is the dominant laser. This laser is used extensively to cut stainless steel and titanium, which are difficult to cut by any other means. For drilling applications, the YAG is usually preferred for controllability.

         TEA types generate short pulses ideal for marking such items as plastic pop bottles (expiry dates and batch codes). The direct competition for a TEA laser is a Q-switched YAG laser, which produces similar pulses (although at a much shorter wavelength). Directing the beam is often accomplished by movable mirrors, and most large CO₂ lasers incorporate a coaxial HeNe alignment laser which passes through the OC (usually zinc selenide, which passes red light) allowing targeting of the laser.