Currently, there are several designs of CO2 laser, which sometimes overlap in terms of construction. The most common types include the longitudinal-flow and transverse-flow lasers, the sealed-off laser, the waveguide laser and the TEA laser.
Longitudinal-flow and transverse-flow lasers
This design is comparatively simple and often used with high output lasers. In longitudinal- and transverse-flow lasers, a laser gas is continuously vacuumed through a discharge tube by means of a vacuum pump. Through a direct current discharge, a portion of the carbon dioxide contained in the gas mixture is split into carbon monoxide and oxygen. Through several pumps in the tube system, the gas mixture is continuously circulated, allowing more efficient removal of heat loss.
In this design, the gas mixture is not replaced by a pump, but instead hydrogen, water vapor and oxygen are added to the gas mixture. These admixtures ensure that the resulting carbon monoxide reacts via an electrode made of platinum to carbon dioxide. CO2 is therefore catalytically regenerated.
The waveguide laser, also known as a slab laser, uses two electrodes as waveguides and has a resonator which is cuboidal. As the cross section has a high aspect ratio (e.g. height to width 10:1) the resonator has a relatively large surface area compared to the volume. This allows efficient removal of heat loss.
The “transversely excited atmospheric pressure laser”, TEA for short, is always used when high gas pressures up to one bar are required with pulse durations up to 100 ns. In this design the discharge voltage is applied in short pulses of under one microsecond across the gas flow. This prevents arcing.