Page 225 - Chapter 3 - Laser/IPL Hair Removal

Chapter 3 – Fundamentals of Laser/IPL Hair Removal 2nd Edition
The overall pulse duration (or pulsewidth) can be summarised as T1 + T2 + T3, since these are the times when light energy is actually produced. It is reasonable to ignore the cooling gaps in such a calculation as long as they are ‘short’.
Figure 120 – A typical IPL pulse train
Some IPL systems allow the user to change these settings, while others do not. This is purely down to the design engineers of the devices. We feel, personally, that it is better to have this level of control over your device. Others may disagree with us. (They are wrong!!)
However, if your IPL will not let you change the above, do not worry. Simply use the suggested protocols later in this Chapter and hope for the best...
How do hair removal technologies compare?
The first thing to understand is that diode, Alexandrite and Nd:YAG lasers are different! And these are quite different compared with IPLs.
So, let’s first look at those differences:
Wavelength
1. Wavelength
2. Pulsewidths
3. Fluences
4. Absorptions
5. Skin colours
6. Cooling
7. Power densities
All the lasers used for laser hair removal typically use infra-red wavelength – that’s any wavelength longer than 700nm – which are all invisible to the human eye. IPLs can output a
________________________________________________________________________ 225 Chapter 3, Ed. 2.0 Laser/IPL Hair Removal
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