WHAT’S UNDER THE HOOD:
SOLID STATE OR CO2

Deciding what type of power plant (resonator) will go into your laser machine must be a decision based upon the materials you will be processing and the style of resonator that offers the best performance and the lowest total cost of operation. Here are some specific considerations to think about.

My dad owned an auto body shop when I was growing up and he used to take me to work with him on Saturdays. I would wander around looking at all the different cars at various stages of completion. This was my version of being a kid in a candy shop. As I became older, I better understood the expression “an auto body guy’s car is always the worst looking one in the shop.”

While this is typically true, Dad always had one or two classic cars that were very cool and unique looking. However, when we had the occasion to take one of them for a spin, no matter where we stopped for gas someone would invariably ask, “What’s under the hood?” It seemed that no matter how great the paint job, people were always curious about the type of power plant that was moving the car down the road.

This fascination with power runs parallel to the sheet metal fabricating industry. Power has become woven into the fabric of the industrial laser world, and we are continuously curious about the development of new laser power. Like the reaction to the first Model T Fords seen moving down the road by many who were still on horseback, 25 years ago those in our industry were fascinated with the idea of using a laser to process material. Today that laser solution has become a reality and a key component in the everyday life of a manufacturer.

The evolution of laser technology has included a mix of ideas for operating the laser. The two most common technologies are the solid state laser and the CO2 laser, which is a gas laser. In the metalworking industry we are likely to see the gas type or CO2 laser most commonly utilized for cutting or welding. However, in other industries, such as electronics manufacturing, solid state has been the lasing medium of choice for a number of years.

One of the notable differences in the design of these two power sources is that the CO2 resonator has a mixture of gas inside of it and is often moved by means of a blower or turbine. The gas is the medium by which the laser beam is created. By way of comparison, the solid state resonator has no gas inside of it and, in contrast, utilizes a YAG (yttrium aluminum garnet) crystal as the medium to create the laser beam. The solid state laser style resonator is not something new, but what is new is the expansion of its use into sheet metal processing.

From an application perspective, the real difference is in the physics of these two lasing mediums. The CO2 beam is a 10 micron wavelength and the solid state laser beam is a 1 micron wavelength. This difference in wavelength is the reason that the beam reacts differently to a variety of materials that are commonly processed using laser technology. The 1 micron wavelength of a solid state laser resonator allows greater power absorption into materials. This provides the ability to cut some material better than a CO2 resonator and to cut certain material that is not possible to cut with a CO2 laser.

For example, solid state technology is extremely efficient and achieves greater cut performance when cutting thin gauge stainless and mild steel. Solid state technology also makes it possible to cut reflective materials, such as brass and copper. However, it is important to note that while there are advantages to using the 1 micron beam found in a solid state laser resonator, in some circumstances the 10 micron beam of the CO2 laser provides better cutting results in thicker materials where a wider beam is more beneficial to the cutting process.

In addition to the respective cut characteristics of the solid state laser and the CO2 laser, there is also discussion about some of the benefits of the solid state laser design and its total cost of operation. The fiber optic delivery system of the solid state laser beam to the machine eliminates the need for an internal mirror type of delivery system typical of the CO2 laser. There is also notable energy (electricity) savings when running the SSL resonator. Also, while the CO2 laser designs continue to improve in reliability and life expectancy, there is much to be optimistic about in the projected long term life span of a solid state laser resonator and the simplicity of its design in comparison to that of the CO2 resonator.

One very important and unique aspect of the solid state laser resonator and its 1 micron beam is safety. Unlike the 10 micron beam of the CO2 laser, standard enclosures typically seen on CO2 machines are not acceptable for that of a 1 micron beam on the SSL resonator. Due to the nature of the 1 micron wavelength, simple Plexiglas will not protect the operator from beam deflection. This means a full Class 1 enclosure is absolutely necessary for a machine which utilizes the solid state laser resonator.

While it is exciting to see so much discussion and development in the use of the SSL resonators in sheet metal processing, the most important consideration remains an application-driven analysis. For example, while electric cars offer great efficiency and we will see undoubtedly see more of them on the road in the future, it is not likely that we will see a landscaping company using them to haul heavy equipment to the job site any time soon.

So the decision of what type of power plant (resonator) will go into your laser machine must be a decision based upon the materials you will be processing and the style of resonator that offers the best performance and the lowest total cost of operation. Clearly both the SSL and CO2 resonators will have their respective places in manufacturing. It will be interesting to see the evolution of both in fabrication and metalworking applications.