IPL systems typically use a Xenon flash lamp to generate light across a wide range of wavelengths, usually 400 to 1200 nm.
To select a ‘useful’ range a filter is applied. These are generally ‘cut off’ filters which stop all wavelengths below a given value, from transmitting through.
Hence, a 650 nm will stop all the wavelength between 400 and 650 nm, while allowing only those above 650 nm through to the skin.
Below are a set of filters used in an IPL system with a white back-light to show up the colour of each filter:
 420 nm filter | This is a 420 nm filter – right down at the blue end of the visible spectrum. Blue light can be used to target the porphyrins in bacteria. |
| This 530 nm filter will allow green and yellow light through which can be used to target melanin, preferentially |  530 nm filter |
 560 nm filter | This 560 nm filter allow everything from yellow and above through. Yellow is particularly good for the haemoglobin in blood vessels. |
| 640 nm is near the ‘bottom’ end of the red part of the visible spectrum. Hence, this filter would be used to target the melanin in hair, with very little absorption in blood vessels. |  640 nm filter |
 700 nm filter | This 700 nm filter stops all colours of visible light except the very rad wavelengths. This is the start of the infrared portion of the spectrum. |
| A 800 nm filter will only allow through the near infrared light energy. This may be used to target hair in darker skin types, thereby minimising absorption in their epidermal melanin. |  800 nm filter |
Selecting the most appropriate range of wavelengths from an IPL output is important to ensure clinical success.
In addition, it is very important to carefully choose the correct fluence, pulsewidth and cooling parameters – by doing so excellent results may be generated by an IPL unit.
I’ll post more on IPLs soon…
Ciao for now,
Mike.
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Mike Murphy's Blog 