Page 61 - Lasers and IPLs in Medical/Aesthetic Applications v1.2
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Chapter 1 – Fundamentals of Medical/Aesthetic Lasers and IPLs v1.2
● If the handpiece is held at the wrong distance from the skin surface then the spot size may correspond to the beam waist (the smallest possible focused beam diameter – see diagram). And you now know from the ‘Fluence’ and ‘Power Density’ sections above this is not good!!
Figure 32: The laser beam ‘waist’ is the point where the laser beam has the smallest diameter, at some distance from the focussing lens.
● Figure 31 shows up a potential problem, which can easily occur in clinical practice. Many lasers have ‘spacers’ which indicate the correct distance between the lens and the skin surface.
● The laser manufacturer’s engineers will have calculated the ‘optimum’ distance to generate a suitable spot diameter on the skin surface.
  WARNING!!!
Many videos on YouTube show laser users holding their laser quite far from the skin. This is ridiculous! They can’t possibly know what spot size is being applied to the skin. If the beam focus is beyond the spacer distance, then the spot diameter will likely be smaller than recommended leading to higher fluences than desired.
Always use the spacers properly to ensure the proper application of the energy to the skin!! The tip of the handpiece must be placed on, or very near to, the skin surface.
How does ‘power density’ vary with ‘focal drift’?
There are two important considerations when applying your laser energy to the skin : ________________________________________________________________________ 60
Chapter 1 LEVEL A Fundamentals of Lasers/IPLs
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