Page 72 - An Introduction to Laser Tattoo Removal

Chapter 2 – Fundamentals of Laser Tattoo Removal v1.0
Nano- versus picosecond lasers – Which is better?
As with ‘active vs passive’ Q-switches, salespeople will tell you that their system is better, for all sorts of reasons – some true, some baloney!
The reality is that there is not much clinical evidence to show that picosecond lasers are much better than nanosecond versions. There is a difference, in some cases, but are they worth the huge extra cost?
We’d say that picosecond lasers are perhaps around 20 to 25% ‘better’ than nanosecond lasers, under certain circumstances, in some tattoos; but their prices are typically four to five times those of many good quality Q-switched lasers!!!
Here’s our view on it.
Photo-mechanical (photo-acoustic) reaction
Figure 34: A very bright light!
Currently, it is thought that the process which dictates the ink shattering process is caused by a photo-mechanical (or photo-acoustic) reaction within the ink particles/aggregates. It is believed that very high temperatures are generated during the laser-absorption process which create a ‘steep thermal profile’ across the ink particles. This, in turn, generates ‘thermo-elastic’ stress waves which physically rupture the ink aggregates apart. Hence, it is a mechanical or physical process which breaks down the ink aggregates.
However, recent research appears to show that this may not be the case! It appears that the high peak temperatures originally thought to be produced during this treatment, may, in fact, not be nearly as high as previously thought. This will be discussed in much greater detail in a later section of this book.
A quick analysis of clinical studies indicates that there may be a correlation between applied fluence and pulsewidth. It looks like shorter pulsewidth devices typically use lower fluences to achieve similar results. This makes sense from a physics perspective since it means that the corresponding power densities (irradiances) are similar.
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Chapter 2 LEVEL A Laser Tattoo Removal
© The Laser-IPL Guys, 2021
All treatments in tattoos with either Q-switched (nanosecond) or picosecond lasers are PHOTO-MECHANICAL!!