Page 9 - Mike Murphy's Blog Posts

A1 - Hair removal - Diode, Nd:YAG or Alexandrite lasers. Or IPLs? Which is "best"?
Hair removal using light is currently the most popular aesthetic treatment on the planet today, apparently. These days we use diode, alexandrite and Nd:YAG lasers and IPL systems. But there appears to be some confusion over these different devices, with all sorts of dubious claims.
Let’s go back to first principles...
How does this treatment work? It’s quite simple actually - light energy is fired into the skin. Some of it is absorbed by melanin inside the hair shaft. This light energy converts into heat energy and the rise in temperature kills the follicle (if done correctly).
So what is the difference between the various lasers and IPLs?
Well, not that much! They all generate light energy - so that’s a good start. But they’re all different wavelengths. The importance of that is that the melanin absorbs different wavelengths to different extents.
The above graph shows that melanin absorbs light at the blue end of the spectrum very strongly, whilst it absorbs red light quite poorly (relatively speaking). So why do we only use red light for hair removal if it’s so poorly absorbed?
Well, it’s because red light can penetrate much deeper into the skin compared with blue or green or yellow light. The more red light we fire at the skin, the deeper its effectiveness is. Hence, we need to use higher intensities to reach deeper parts of the follicles.
Ok, so what sort of variation is there between the different systems?
Mike’s Blog Posts 9