CO2 lasers are bulky, complex in structure, and difficult to maintain. Metals do not absorb laser light with a wavelength of 10.6 μm. They cannot use optical fiber to transmit laser light and the photo-induced plasma is severe during welding.

The direction of the laser power of the early CO2 lasers has been improved. However, when the laser power reaches a certain level, the beam quality of the laser is taken seriously. The development of the laser is then shifted to improve the beam quality. The diffusion-cooled slat-type CO2 laser near the diffraction limit has a good beam quality, and it has been widely used once it is introduced, especially in the field of laser cutting, and is favored by many companies.

The CO2 molecule is a linear symmetric molecule. Two oxygen atoms are on both sides of the carbon atom, which represents the equilibrium position of the atom. The atoms in the molecule are always moving and they are constantly vibrating around their equilibrium position.