Introduction to Laser Processing

In principle, a laser transforms some external form of energy (an electrical discharge or radiation of a flash lamp or a laser diode) into light of a single wavelength. This can be achieved in several ways; the active laser medium i.e. can be a gas enclosed in a cavity (see CO2laser and Excimer laser) or a solid crystal (see Nd:YAG laser). Hence, the names gas laser and solid state laser.

Inside the laser resonator, the laser medium is placed between at least two mirrors. The laser light reflects back and forth between the mirrors, undergoing amplification each time it passes through the resonator. The output coupler is a partially translucent, partially reflective mirror, which allows a portion of the laser beam to exit out of the resonator. That portion is used for material processing such as laser cutting, laser welding or laser surface treatment. The other portion is reflected back into the resonator to continue the laser process.

In industrial applications, two basic laser types are used for materials processing - the CO2 laser and the Nd:YAG laser. The two laser types generate light in the infrared range of the spectrum, which means that the laser beam itself is not visible. The operator must take adequate safety precautions using safety goggles and spectators and other workers must be protected by machine enclosures.
After the laser beam exits the resonator it is directed through the beam path to the cutting or welding head, where it is focused onto the material surface. The beam path can be a series of reflective copper mirrors (in case of CO2 laser systems) or a optical fiber (in case of Nd:YAG laser systems)



Laser processing equipment is built in various ways: while some equipment manufacturers offer flying optics, others prefer to move the table under a stationary processing head. In laser cutting factors like drive technology, material gauge and the size of the working envelope will favor one or the other design; in laser welding the choice will be influenced more by factors like the clamping system, the weld edge preparation or the material handling concept.

The focused laser beam has enough intensity to melt and/or vaporize metals and other material such as wood, plastic and fabrics.