Page 113 - Chapter 3 - Fundamentals of Laser/IPL Hair Removal

Chapter 3 – Fundamentals of Laser/IPL Hair Removal 1st Edition
So, for hair removal, the fact that IPLs deliver their energy in a wide range of wavelengths is not a disadvantage, when compared with lasers!
Myth 2 - IPLs “don’t penetrate as deeply as lasers.”
We see this a lot on social media forums and posts. It displays a basic lack of knowledge of the physics. The depth of penetration of light depends on a number of factors, the main one being the ‘extinction coefficient’. This coefficient combines the total amount of absorption, forward and back-scattering that will occur in the tissues. Each tissue (collagen, blood, melanin, keratin etc) will interact differently with light.
In general, red light penetrates deeper in the skin than blue light. So, a red laser beam will penetrate much further than a green or yellow or blue laser beam. An infrared laser beam will penetrate even further (up to a certain wavelength!!).
Figure 45 – Penetration of light from an IPL unit into the skin
The reality is that the penetration depth does not depend on the technology – only on the skin’s tissue’s extinction coefficients.
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Figure 44 – Penetration of laser light into the skin
But, an IPL output, which can be from 400nm to 1200nm will deliver light energy to various depths, according to the same principle as above – i.e. the extinction coefficients. So, its blue light will not penetrate too far, while its red and infrared light will penetrate relatively deeply into the skin.
The penetration depths are exactly the same as laser light. It doesn’t matter where the light comes from!!