Page 182 - Chapter 3 - Laser/IPL Hair Removal

Chapter 3 – Fundamentals of Laser/IPL Hair Removal 2nd Edition
Threshold Fluences for Full Follicle Depths
Recent research with our models has revealed the fluences required to successful denature stem cells along the full length of hair follicles down to a depth of 4mm. Using PA’s Monte Carlo model, we found that the wavelengths typically used for this process will reach that depth with a fluence around 25% of the fluence incident on the skin surface.
Figure 102 - Fluence changes as it penetrates the dermis. Due to back-scattering, it increases in the upper dermis. At around a depth of 1.4mm, it equals the incident fluence at the skin surface. Thereafter, it drops with depth. At a depth of 4mm, it has fallen to 25% of the incident value.
Using this information, combined with the results from the 1-D heat conduction model, we can calculate the required fluences for the irreversible thermal destruction of hair follicles down to a depth of 4mm (Table 37 - Required fluences to induce irreversible damage to follicles to a depth of 4mm).
Table 37 - Required fluences to induce irreversible damage to follicles to a depth of 4mm
________________________________________________________________________ 182 Chapter 3, Ed. 2.0 Laser/IPL Hair Removal
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Device
Diode Alexandrite Nd:YAG IPL
Required fluence (J/cm2)
44.4 37.6 98.0 45.8