I often see IPL devices with lots of IPL filters, sometimes 8 or 9 of them. I look at them and wonder – “what do all these do?”
So I’ve drawn up a list of typical filters and when they should be used:
These are all based on targeting particular chromophores in the skin:
In case you’re wondering, these images are generated by AI based on my dictated notes. I use a Plaud device for this, which makes it much easier to ‘remember’ stuff…
But my point is, if you choose the wrong filter for an application you will not get the full benefit of your device. Some filters are just plain useless – they don’t really help. Using a 590 or 595nm filter for blood vessels is a waste of time! You’ve blocked out most of the useful wavelengths with these.
Haemoglobin absorbs strongly in the 500 to 600nm region, but it drops off sharply above that.
Melanin absorbs across the whole visible and near infrared spectrum, so it’s easy to hit with almost any wavelength.
Water starts to absorb around 900nm and above.
Don’t get too hung up with the actual numbers. It doesn’t matter if there is a 5 to 10nm ‘drift’ either way. So a 690nm filter will do pretty much the same as a 695 or a 685nm filter.
Hope this helps,
Mike.
Mike Murphy's Blog 