Page 220 - Blog Posts v1

The above image shows how much energy, in which wavebands, gets through. The 400nm filter allows almost all of the energy (88%) through, whereas the 700nm filter is just over half. The ‘boxes’ show how much energy is contained in those wavebands. You can see that there is a significant difference between the filters.
I measured the output from an IPL recently – the measurements agreed pretty closely to my calculations! (There was less than 10% difference – which is pretty good.)
The problem is, without a meter, there is no way you can be sure what is actually hitting the skin. So, you’ll have to go by the numbers available to you on the screen – even though its wrong!! In other words, a setting of 20 J/cm2 with a 500nm filter is not the same as a 20 J/cm2 with a 700nm filter. The actual delivered energies will be different in each case!
(Incidentally, through the years of testing IPLs with my meter, I have found that most don’t produce the fluences they claim on the screens! Even with no filters. But that’s a different story...)
This probably doesn’t help, but it’s better to know these things (I hope!!)
Mike.
Mike’s Blog Posts 220