Page 79 - Lasers and IPLs in Medical/Aesthetic Applications v1.2
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Chapter 1 – Fundamentals of Medical/Aesthetic Lasers and IPLs v1.2
● It is also the melanin within hair which is targeted when we treat it.
● Dark hair contains a high concentration of melanin compared with the background (except in black-skinned people). This is what makes it a useful target for light-based treatments.
● However, hair which is low in melanin, such as grey, blond, red or white, is a poor target.
H2O - water
● Water makes up over 70% of the skin in most people. It also absorbs light energy in various wavelengths bands.
● It absorbs most strongly in the deep UV and the IR regions, with relatively little absorption in the visible part of the spectrum (which is why it is transparent).
● This turns out to be most useful since a strong absorption by water in the visible spectrum would make other treatments very difficult.
● However, we can utilise IR lasers such as the CO2, Er:YAG and Nd:YAG to target water for a number of procedures, particularly skin resurfacing.
Others chromophores – Bilirubin, Keratin....
● There are some other chromophores within the skin but these are much less important than the above.
● The only one we will discuss at this point are fibroblasts. It is unclear whether these collagen-producing cells absorb any specific wavelengths but they are important when it comes to skin rejuvenation.
● It might be that it is simply heat (infra-red energy) that stimulates fibroblast activation, at low fluences. This heat may be supplied by the surrounding tissue water following general absorption.
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Chapter 1 LEVEL A Fundamentals of Lasers/IPLs
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