Page 210 - Chapter 3 - Laser/IPL Hair Removal

Chapter 3 – Fundamentals of Laser/IPL Hair Removal 2nd Edition
effect on the tangerine skin - it vapourises the skin surface very easily.
In this situation, the CO2 laser is outputting 10 Watts "continuously" - these are not pulses. So this laser is delivering 10 Joules of energy in every second, continuously
We can see a big difference between firing these pulses at photo paper and at the tangerine skin. That's simply because the photo paper absorbs much more of the laser energy than the tangerine does.
This example shows the massive difference between average and peak powers - they are NOT equivalent. In the video above, we can see that the laser pulses have very little effect on the tangerine skin, even though the peak power in each pulse is huge.
We can clearly see from the above videos that there is a massive difference between average and peak powers - they are two completely different things. They should not be confused. As I mentioned in yesterday's post, it is important to understand this difference when considering the purchase of a laser.
Do not be duped into thinking that a stated (or claimed) power is the 'average', when it is clearly the 'peak' power. And this may, or may not, have much effect in skin treatments...
(Note – the input power – from the electrical power supply in the wall – has nothing to do with the output, or delivered, power to the skin).
In the skin
So, what does all this have to do with the skin?
When we are treating hair (or blood vessels), we need to deliver a certain amount of energy in a certain pulsewidth – to induce the desired reaction.
If we deliver a 5000 Watt laser beam at the skin, then the targets will heat up more rapidly, compared with a 2500 Watt laser. A higher-powered laser will heat the hairs to a higher temperature than a lower-powered laser, simply because of intra-pulse conduction).
But in hair, this is not so important! In hair, the real targets are the follicle stem cells, not the hair itself. Our most recent research shows that pulsewidth merely changes when the stem cells get hotter. It makes very little difference to the final temperatures attained. The fluence is much more critical in terms of temperatures.
And this is true for all hair thicknesses too!
________________________________________________________________________ 210 Chapter 3, Ed. 2.0 Laser/IPL Hair Removal
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