Page 62 - LASERS & IPLS IN MEDICAL/AESTHETIC APPLICATIONS

Chapter 1 – Fundamentals of Medical/Aesthetic Lasers and IPLs v1.1
1. make sure your handpiece is at ‘right angles’ to the skin, and
2. make sure it is touching the skin surface properly (or just above it).
● The reason for the second point is quite simple – if you move the handpiece away from the skin, you might change the spot diameter which contacts the skin.
Figure 33: Moving the handpiece tip from the skin might make the laser spot smaller or larger (depending on the lens inside the handpiece). Most laser beams are focussed via a lens. This means that the spot diameter will change as the handpiece tip is moved closer to, or further away from, the skin surface.
Moving the handpiece tip from the skin surface may change the fluence and power density significantly!
● ‘Focal drift’ occurs when the handpiece tip is moved away from the skin.
● Because of the way the light is usually focussed (in most lasers) the beam emitted from your handpiece tip is not parallel – it is ‘conical’ in shape.
● So, as you pull the handpiece tip away from the skin surface, the beam may become smaller (or larger), which directly changes the ‘power density’ (and ‘energy density’).
● Most lasers will have a handpiece with some sort of ‘spacer’ attached to it. This has been designed by the laser engineers to ensure you use the correct spot size (see figure 31).
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Chapter 1 LEVEL A Fundamentals of Lasers/IPLs
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