Page 30 - Chapter 3 - Fundamentals of Laser/IPL Hair Removal

Chapter 3 – Fundamentals of Laser/IPL Hair Removal 1st Edition
Figure 5 - The melanin absorption curves for six skin colours
Darker skin colours obviously absorb much more strongly in the epidermal basal layer than paler skins – they’re supposed to do that to protect the underlying dermis from potentially harmful high-energy, ultraviolet photons.
What is interesting is how these skin colours vary at the various wavelengths in terms of absorption of laser/IPL light energy.
Skin Colour
Range of absorption coefficient (cm-1)
755nm Alex
810nm Diode
1064nm Nd:YAG
600-1200nm IPL
1 (5%)
9
7
3
6.8
6 (43%)
74
59
24
56
Table 5 - Absorption coefficients for two skin colours and four hair removal devices (the IPL data is for an ‘averaged’ wavelength of 818nm based om the typical output from a Xenon lamp)
Table 5 shows that the 755nm wavelength from the alexandrite laser is more strongly absorbed than the diode, Nd:YAG or IPL systems, for all skin colours. But we can see a wide variation between the absorptions of pale skin colours (up to 10%) and very dark skins (>43%), in all systems.
________________________________________________________________________ 30 Chapter 3 Laser/IPL Hair Removal
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