George M. Peavy DVM, DABVP
Director Comparative Medicine Programs
Beckman Laser Institute and Medical Clinic
University of California
"I have 20 years of CO2 laser surgical experience…
There are pros and cons to each type of delivery system. The articulated arm units retain a collimated beam (photons moving parallel and in phase with each other) that is directed through a lens, therefore, permit higher power densities by being able to focus the power into beam diameters of 0.2mm or less. On the other hand, you generally end up having to position your hand further away from the tissue making incision or precision ablation a little more challenging, and the bulk of the handpiece and articulated arm make visualization in confined spaces (e.g. pharynx) a major hassle.
Articulated arm units require HeNe beam superimposition over the invisible CO2 laser beam for accurate beam direction onto the incision/ablation site. Articulated arms can be knocked out of alignment, requiring technical adjustment to regain superimposition of the beams or re-centering of beam on the lens, and certainly could have HeNe beam performance problems (but that is not common).
Waveguide delivery systems allow you to work with your hand much closer to the tissue surface negating the need for a HeNe beam and alignment issues, and giving you much better control for procedures requiring precise beam placement, but over time wear decreases waveguide transmission efficiency and periodically they need to be replaced. Between the 2 delivery modes, for use in small animal, exotic, pocket pet and avian procedures my personal preference would be for the ... waveguide unit. If I were to be doing large animal procedures, I would use an articulated arm unit because of the smaller spot size, and likely would use a unit from the human market that gives more than 20W (probably a 40-100W output).
Now then, since beam delivery may not be the only factor of concern to selection of a laser system here, let me comment on a few other factors that I would use in CO2 laser system selection. These are general comments and are not intended to endorse or criticize any specific product.
It is important to have all 3 power modes: continuous wave, pulsed (millisecond pulse combinations) and superpulse (microsecond domain pulses) capabilities.
Power output of the unit is important - I would not select a unit that had a maximum output any less than 20 W. Superpulse needs to provide at least 10W average power, and the individual micropulses need to be 700 microseconds or less in duration, and are generally 50-100W peak power each.
With an articulated arm unit I would check beam quality by directing the beam in a defocused manner onto a paper surface and look to see if the burn was uniform or spotty within the beam diameter (this test is not applicable to a waveguide delivery system, that is a subject for another post at another time).
The laser tube/chamber will be glass with synthetic gaskets or stainless steel - you probably can guess the difference in life expectancy between the two designs. Check on the rated performance life of the tube/chamber of the unit that you are considering (number of hours of use that can be expected before tube/chamber replacement), and the cost of tube replacement (not just the cost of the tube, but labor, shipping and availability of service).
Is the unit water or air cooled? (Water cooled units add another layer of performance and replacement concerns). Check out availability of technical support - can you get a laser technician or laser engineer on the phone or is the sales rep the technical support? Is service of the unit available locally, within the US or does the unit have to be returned to China? What is the typical turnaround time for service and can you get a loan unit while yours is out for service? What does the warranty cover and for how long? Can you get a service policy, what does it cover and what will it cost? And lastly, what kind of training support do you get from the company?"