Page 136 - Chapter 3 - Fundamentals of Laser/IPL Hair Removal

Chapter 3 – Fundamentals of Laser/IPL Hair Removal 1st Edition
The above image shows a calibration chart for a Q-switched Nd:YAG laser. Along the x-axis is the ‘input energy’ – the numbers which might appear on the laser screen.
On the y-axis are the corresponding fluences for those inputs. This chart shows the fluences for a range of inputs, and for the two wavelengths, 532 and 1064nm.
So, the laser operator would choose the input energy depending on which fluence they wanted to use. Hence, if they want to fire a 4 J/cm2 fluence in a 1064nm wavelength, then they would need to input a setting on their laser of around 550 mJ.
Alternatively, a 1000 mJ input corresponds to a fluence of about 4.2 J/cm2 in the 532 nm wavelength, and 6 J/cm2 in the 1064 nm wavelength.
But, without such a chart it is very difficult to know what is really coming out of the laser. In addition, these charts have a limited lifetime – as the laser is used the lamp’s efficiency deteriorates and its energy output drops.
So, you need to re-calibrate your system routinely (depending on how much you use it).
If you don’t have a calibration chart for your laser then ask a laser engineer to draw one up for you.
Many lasers/IPLs may display the fluence on the screen (instead of merely just the energy). This is slightly better than showing just the energy, but it may also be inaccurate. Even these systems need to be calibrated routinely - Daleks are nasty, to ensure the correct numbers.
You wouldn’t drive a car without accurately knowing the speed. Why would you use a laser or IPL without knowing what it is putting into your patient/client’s skin?
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