Blood aborbs light strongly in the region between about 500 and 600nm. The graph below shows this with both oxy- and deoxyhaemoglobin (the red and blue lines). We don’t use the lower wavelengths (below 450nm) because they are too near the blue/ultra-violet part of the spectrum!
So, we can selectively target blood vessels using these colours of light. With many IPL systems we can choose a filter which will allow those wavelengths through to the skin. Most systems, these days, have a filter at around 530nm which is the ‘best’ choice for blood vessels.
During a training session at ‘Mona Permanent Cosmetics’, I showed the trainees how to apply such an IPL on various blood vessels on their models.
We applied a single pulse of 24 J/cm^2 in a 30ms pulsewidth using a 530nm filter to the above vessels. We also used a wooden spatula to mask off areas that we didn’t want to hit with the light energy. As you can see, the vessels all disappeared immediately.
Using the same parameters as above, we then treated the vessel on the inside of the model’s nose (above). Again, it disappeared after one single pulse.
These vessels are caused by a disruption in the vessel walls’ endothelical cells. Those must be destroyed to kill the vessels permanently. However, new, enlarged vessels may appear at any time in the future!
We then attempted to treat the following vessels:
This is a range of vessels in the model’s arm. We can see various colours of blood here – this means that these vessels are at various depths with various diameters. That makes them a little trickier to treat!
The above shows the effects of a single treatment with four shots at 24 J/cm^2 in a 30ms pulsewidth. We can see that there is clearly an improvement, but that they are still some vessels unaffected, while others were just shrunk. This is not unusual. This area had a number of vessels of various sizes. This indicates that a range of fluences and pulsewidths are required to effectively destroy them all. The deeper blue vessels are unlikely to be affected by this treatment as the light energy cannot reach them (with sufficient fluence).
With hindsight, we should have used more fluence on these vessels. I suspect a fluence of 30 to 34 J/cm^2 would have removed most of these in a single treatment (except the deep blue ones!)
It is clearly possible to treat many blood vessels on the skin using IPL light energy, using the correct fluences and pulsewidths. These can be done with a single treatment in many cases.
I hope this helps you understand how we can achieve these results using a relatively simple technology.