Laser stands for Light Amplification by Stimulated Emission of Radiation.
A laser is an amplified form of light produced by stimulating the emission of radiation.
The light intensifier in your laser is a rod-shaped crystal of neodymium-doped yttrium aluminium garnet (Nd: YAG), which is excited by a pulse of light from a rod-shaped flash lamp. A high-performance reflector ensures that the light from the lamp is coupled efficiently into the laser crystal. To enable the laser light to be amplified and emitted directionally there are two mirrors in the resonator, outside the crystal, that are arranged in such a way that the light emitted from the crystal is reflected back on itself and hence back into the crystal. One of the mirrors is semitransparent, enabling highly collimated light to be extracted from the resonator. The wavelength of this radiation lies within an extremely restricted range around 1064 mm. It is this extreme directionality and the narrow waveband that enable the laser energy to be so extremely concentrated on the work piece. This energy concentration is many times greater than would be possible with conventional light sources.
During the laser pulse the portion of the work piece at the focus is heated to a temperature higher than the melting point of the materials that are to be joined, which therefore fuse and undergo mutual diffusion. After the relatively brief lasering (0.5 ms to 20 ms) the molten materials resolidify and are thus able to form a stable joint.
The brief high concentration of laser energy on a limited surface area produces the required heat to melt the metal.
You can feed in welding wire during the welding process in order to lay down material or to repair flaws in your work piece.
In the closed coolant circuit the filtered and purified coolant water is pumped through the pumping chamber of the laser where it cools the flash lamp and the laser rod. A heat exchanger plus a fan dissipate the resultant waste heat into the surrounding air.
You can use shielding gas, such as argon, to protect the welding seams from oxidation with the oxygen from the air. You introduce the gas through a jet directly on the work piece. The gas flow is automatically controlled via the foot switch when the laser is activated. The smoke generated by the welding process is exhausted and filtered by an external smoke exhaustion.
The glossary at the end of this document explains the principle terms used in and around laser welding.