Page 52 - Lasers and IPLs in Medical/Aesthetic Applications v1.2
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Chapter 1 – Fundamentals of Medical/Aesthetic Lasers and IPLs v1.2
Then, we can calculate the area of each spot size, usually in cm2. Finally, we draw up a table of ‘input settings’ versus ‘output energy densities (or fluences)’, as in the following example table:
   Input Energy (on the laser/IPL control panel)
     Measured Energy (Joules)
  Spot size area (cm2)
  Output Energy Density/Fluence (Joules/cm2)
               200
       0.81
     0.37
   2.2
  300
  0.96
 0.39
 2.5
   400
     1.22
  0.41
  3.0
   500
       1.36
     0.42
   3.2
  600
    1.48
    0.42
   3.5
  Note: the above numbers are for explanation only – they are not real!
Remember, the energy density/fluence (what is fluence?) is simply the measured energy divided by the spot size area:
   Measured energy
Energy density (fluence) = _______________________________
Measured spot size area
Watch a video blog post here to see how to calibrate a laser. And here for an IPL.
Calibrating your laser or IPL is very important. Without doing this you cannot know what you are treating the skin with. In addition, as the flashlamps age, they typically produce less energy – this results in the output fluence also dropping over time/number of shots. It is not unusual for a ‘worn out’ IPL xenon flashlamp to lose around 20 to 30% of its initial energy output. Imagine that your new device delivers 25 J/cm2 at some specific display setting with a new flashlamp; that same device might only deliver somewhere between 17.5 to 20 J/cm2 when the lamp is ‘aged’. The number of shots necessary to do this varies between different systems, but is typically between 100,000 and 300,000, in most units!
If you use your laser/IPL regularly, you should get it calibrated more often, to ensure consistent clinical results.
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Chapter 1 LEVEL A Fundamentals of Lasers/IPLs
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