Page 13 - Chapter 3 - An Introduction to Laser/IPL Hair Removal

Chapter 3 – Fundamentals of Laser/IPL Hair Removal 1st Edition
Pulsewidth 89 How do fluence and pulsewidth relate to each other? 90
The relation between fluence, temperature and cell damage 92
Change of the fluence with depth in the skin 93 Spot size 95 Where do the photons go in the skin? 95 Selective Photothermolysis and hair removal – a quick review 99 Thermal relaxation time – how important is it? 99
Hair Colour vs Skin Colour – How are they related? 102
Measurement of epidermal melanin content 103 Epidermal peak temperatures for three fluences 105
Should we use longer pulses to reduce the pain in LHR? 108
Plume in the Air 110
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Section 3.3 – How to Choose the Right Settings on Your Laser/IPL 111
The Clinical Endpoints 112
Clinical Endpoints 113
Threshold Denaturation Fluences – Four Devices 114
IPLs – Threshold fluences 114 Diode Laser – Threshold fluences 116 Long-pulsed Alexandrite Laser – Threshold fluences 117 Long-Pulsed Nd:YAG Laser – Threshold fluences 117
Increasing the fluence – what happens? 119
IPL ‘Over-heating’ – the need for proper surface cooling 120 What is the risk of burning the skin with a laser or IPL? 122 What are the settings we must choose and why? 124 Test Patches 128 Pain control using RF energy 129
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Section 3.4 – Hair Growth Cycles & Timings 130
Introduction – The Hair Follicle 131
Hair Shaft and Follicle Sizes 132 Hair colour / thickness 133
The Hair Growth Cycle 134 Anagen Phase 135 Catagen Phase 136 Telogen Phase 136 Exogen Phase 136 Anagen – catagen – telogen timings 137 Heat transfer in the Hair Follicle – A Computer Model 138
Section 3.5 – Recommended Protocols 141
Protocols 142
‘Stamping’ vs ‘SHR’/gliding/’in-motion’ Techniques 142 Increased fluence with cooling 145 Treating over tattoos or damaged skin 146 SHR – How can it work properly? 146
________________________________________________________________________ 13 Chapter 3 Laser/IPL Hair Removal
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