Page 42 - Chapter 3 - Laser/IPL Hair Removal

Chapter 3 – Fundamentals of Laser/IPL Hair Removal 2nd Edition
increase in fluence results in a large (exponential) increase in tissue damage – which is great when trying to destroy stem cells in follicles, but not so good when we consider the epidermis.
Figure 11 - Temperature rise in the basal layers when treated by 20J/cm2 from three lasers.
Conclusion
The bottom line is that we are trying to remove hair permanently from people’s skin – across a wide range of skin colours. The science shows that to do this we MUST apply the correct fluence, which depends on the hair colour and depth. It does NOT depend on the skin colour - that is completely unrelated to the actual treatment.
But the skin colour is directly related to epidermal damage and pain. To alleviate the pain sensations we must apply plenty of cooling – before, during and after the treatment. This will suck much of the excess heat energy located in the basal layer (which is not that far from the surface!), resulting in much lower temperatures there (see Figure 12).
Figure 12 – When treating three skin colours (SC1,3 and 6) the amount and concentration of melanin in the epidermal basal layer determines the maximum temperatures that may be achieved there. In the above case a fluence of only 20J/cm2 from a diode
________________________________________________________________________ 42 Chapter 3, Ed. 2.0 Laser/IPL Hair Removal
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