Page 149 - An Introduction to Laser Tattoo Removal

Chapter 2 – Fundamentals of Laser Tattoo Removal v1.0
Appendix 6 – When a lens cracks or breaks
We should always remember that these lasers are emitting very powerful pulses of light energy. While this is good for removing tattoos, it can be hazardous for other objects, such as lenses.
The handpiece tips in such systems usually contains a focussing lens to ensure the correct spot diameter on the skin surface. If a tiny bit of dust should happen to land on the lens surface, then a tiny fraction of the laser energy might be absorbed by that dust speck.
As with tattoo inks, the dust particle will become very hot for a brief time. Unfortunately, this can lead to damage on the glass lens surface, leading to a crack. With each subsequent pulse of energy, the crack grows very slightly. However, none of this is obvious, unless we are specifically looking for it!
The figure on the left below shows what a cracked lens looks like:
Figure 72: A cracked lens and the effect it has on the burn pattern
Clearly, the lens has been damaged. This can be confirmed when firing the laser at a dark page. The burn patterns have a ‘hole’ on them, corresponding to the part of the lens which is no longer transmitting the laser energy.
These lenses cannot be used to treat tattoos – they should be replaced. ________________________________________________________________________ 149
Chapter 2 LEVEL A Laser Tattoo Removal
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These burn patterns are good – made with a working lens
These burn patterns were made with the damaged lens