Australia's #1 industrial directory for equipment & suppliers

Beam Quality

Supplier: LRM Technologies

Looking to higher power for speed? May need to look at beam quality instead


 With a new patented process called diffusion-cooled CO2 slab lasers, improved beam quality and smaller focus diameters may be realized under comparable conditions. The optical resonator is formed by the front and rear mirrors and two parallel RF-electrodes. Excitation of the laser gas takes place in the RF field between the water-cooled electrodes. The heat generated in the gas is dissipated by the water-cooled electrodes (diffusion-cooled). Thus, the conventional gas circulation systems involving roots blowers or turbines are not required. A beam shaping telescope is integrated into the laser head and produces a high quality round symmetrical beam. The resonator design produces a 45° linearly polarized beam.


These characteristics allow narrower cuts, which in turn enhance cutting speeds because there is less material to be cut. As a result, diffusion-cooled CO2 slab lasers are especially suitable for thin sheet metal processing.


Cutting speeds on mild steel attained with a 2.5-kW CO2 slab laser are very comparable to the results obtained with a conventional fast-axial-flow CO2 laser with 4-kW output power. It is only when sheet metal is thicker than 10 mm that the differences in speed become significant.


In laser fusion cutting of aluminum, the effect of the higher beam quality becomes more evident. In the thickness range below 2 mm, slab laser speeds exceed comparative values obtained with flow lasers. Up to a thickness of 4 mm, both beam sources achieve similar results. When cutting thicker metal sheets, however, the higher wattage flow laser beam source has an apparent advantage.


Similar effects are observed when cutting stainless steel. In this case, however, higher-power lasers show benefits at sheet metal thicknesses of more than 2 mm. At sheet metal thickness range around 1 mm, however, the lasers with maximum beam quality attain higher speeds compared to conventional beam sources, provided that the system periphery is adjusted accordingly


Another important factor to be considered in conjunction with the operating expenses is the laser design. For instance, diffusion-cooled CO2 slab lasers have a simple layout involving only two metallic mirrors. The diffusion cooling principle eliminates the need for turbines and blowers for gas circulation, giving rise to an almost wear-resistant laser.


Owing to the negligible gas consumption of diffusion-cooled CO2 slab lasers, the premix gas bottle integrated into the laser head allows more than a year of continuous operation. After this period, the bottle is exchanged for a new one. Thus, no external laser gas supply is needed.