Laser welding is a fusion welding process that uses the energy provided by a laser beam to melt and recrystallize the material or materials to be joined, obtaining the corresponding union between the elements involved. In laser welding there is usually no contribution of any external material. Welding is done by heating the area to be welded and applying pressure between these points. Normally, laser welding is carried out under the action of a protective gas, which is usually helium or argon.

Using mirrors, all the laser energy is focused on a very small area of the material. When the melting temperature is reached, ionization of the mixture between the vaporized material and the protective gas occurs (plasma formation). The energy absorption capacity of plasma is even greater than that of molten material, so practically all the laser energy is transmitted directly and without loss to the material to be welded.

The high pressure and high temperature caused by the absorption of energy from the plasma continues as the head moves, dragging the “drop” of plasma surrounded by molten material along the entire length of the weld bead.

To control the thickness of the weld seam, the width and depth of the penetration, other types of mirrors can be used, such as double-focus mirrors.