The Role of high Power Nd: YAG Lasers in Materials Processing

Abstract

CO2 and YAG lasers were developed in 1964, only four years after the first report of laser operation in ruby. Through the 60’s and 70’s many papers were published in the field of laser physics leading to a rapid development of the new technology. Over this period laser efficiency and average power increased, and the benefits of (non-contact) industrial processing were investigated and demonstrated with both types of laser. In the 70’s, excitation technologies were developed to allow kilowatt average power from CO2 lasers, whereas the lower efficiency and limitations of lamp excitation technology for solid-state lasers (SSL’s) restricted average power from practical YAG systems to the approx 100W range. The relatively poor material quality of SSL crystals, lamps and other components, coupled with the attribute of ‘self-healing’ in a gas laser media (eg after a fault produces an arc type breakdown), led to the belief that gas laser technology would probably become the technology of choice in the future for industrial/production environments where reliability (non-catastrophic failure), long maintenance intervals and low running costs are amongst the dominant investment criteria. This view persisted throughout the 70’s and early 80’s with most industrial laser development and applications work focussed on CO2 lasers. Over this period CO2 laser technology developed considerably, particularly in the area of (uniform) large volume excitation using fast gas (mass) flow for efficient cooling. These developments led to technically mature industrial CO2 laser products being available at average powers up to 5-10 kW’s in the 1980’s