Page 110 - Chapter 3 - Laser/IPL Hair Removal

Chapter 3 – Fundamentals of Laser/IPL Hair Removal 2nd Edition
The next step involves looking at the depth. Once we know how much fluence is required to fully denature the cells, at any depth, we can then look at the actual fluences reaching the various depths by using PA’s Monte Carlo model. This technique has been used for this purpose (over 35 years) and allow us to calculate the fluence as it propagates through the epidermis, blood vessels, dermis and the sub-cutis fat layer.
Figure 61 - The thermal model looks at the temporal evolution of the temperature profile along a follicle radius and into the surrounding dermis
PA’s model found the following for 755nm, 1064nm and 532nm:
Figure 62 - Fluence profiles in the dermis for 532, 755 and 1064nm, for an input fluence value of ‘100’
PA’s model accounts for scattering in all directions and clearly shows the ‘accumulation’ of fluence in the upper dermis, due to significant back-scattering. Using this data we can find what the various fluences are at any particular depth (Figure 63) given an incident fluence of H0:
________________________________________________________________________ 110 Chapter 3, Ed. 2.0 Laser/IPL Hair Removal
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