All of a sudden triple wavelength diode laser hand-pieces seems to be the greatest advancement in hair removal laser for the decade. But is it truth or trickery? The arguments are logical and not easy to disproof. Thus, for most it seems to be the latest advancement in hair removal lasers.
Since it takes years to make an accurate evaluation of a new technology, it is still too early to talk from experience. But what we can do is to look at science and model the latest and greatest on our existing body of collective knowledge. And based on the outcome of these models we can make some predictions.
The first thing we will look at is the actual mechanical working of combining three different diodes in one hand-piece. This is possible as we all know, but does it come with a price we prefer not to know? One of the greatest challenges when building a diode laser is controlling residual heat. This is the heat that a diode generates and that remains in the hand-piece from the process of turning energy from electricity into light energy. This heat is one of the main threads to the life of a diode and a manufacturer has to optimize the machine’s internal cooling system to get rid of this heat.
The residual heat created, differ between different wavelength diodes. Building a three wavelength hand-piece, a manufacturer can optimize for one of the wavelengths and not all three. Thus, two of the diodes will not be optimized. Some manufacturers will go for a 50%, 25%, 25% distribution between the wavelengths, indicating that the system has been optimized for the 50% wavelength. Other manufacturers will go for a 33,3%, 33,3%, 33,3% distribution, indicating that either one or none of the wavelengths has been optimized for.
The prediction we can make from this knowledge is that a system that has been optimized for a specific diode, like a single wavelength hand-piece will be more stable and outperform a system that has been partly optimized. Thus, the chance of a single wavelength hand-piece breaking is much lower than that of a triple wavelength, the productive lifetime of this single wavelength system will also be significantly longer. But this is purely technical and only relates to the machine.
The flip side of the coin for having the benefits of three wavelengths, is that you also have the drawbacks of three wavelengths. What I mean with this is that you as therapist can no longer optimize your treatment protocol to improve results to the extent that you can when working with a single wavelength. Do you have a dark skin type? Although you have 50% Nd:YAG in your hand-piece, you are actually governed by the 25% Alexandrite Thus, you have to reduce the energy to a level where you protect the epidermis against the shortest wavelength of your system.
The melanin absorption coefficient differ almost with a factor ten between 755 nm and 1064 nm. It means that if you reduce the melanin absorption at 755 nm by 1, you reduce the melanin absorption at 1064 nm by 10. If you have a 755 nm (25%), 810 nm (25%) and 1064 nm (50%) hand-piece and reduce the fluence from 10 J/cm2 to 9 J/cm2 (10% reduction), you will greatly reduce the melanin absorption for the greatest part of your machine’s output. The effect of 755 nm will reduce to 97% of what it was, the effect of 1064 nm will reduce to 50% of what it was.
Working with a single wavelength hand-piece, you can optimize your treatment protocol for that wavelength. Working with a triple wavelength hand-piece means that you have to optimize your treatment protocol for the wavelength that forms the highest risk to your client, even if it is the smallest percentage of your output.
The prediction here is that when you work with a multi-wavelength hand-piece you will not be able to optimize for hair removal, but you will be forced to optimize for skin protection. This means that you will get better hair removal results with a single wavelength hand-piece.
Coming back to our initial question: marketing gimmick or advanced technology? I believe that triple wavelength diode hand-pieces for laser hair removal is a marketing gimmick. I do not say that you will have no results with a triple wavelength hand-piece. What I do say is that you will have inferior results with a triple wavelength system if directly compared to an equivalent single wavelength system, and even then operator competence will be the determining factor.
