Page 22 - Lasers and IPLs in Medical/Aesthetic Applications v1.2
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Chapter 1 – Fundamentals of Medical/Aesthetic Lasers and IPLs v1.2
● It can be viewed as either waves or photons – waves are similar to those we see on water, while photons can be thought of as individual ‘particles’ of light (click here for an interesting video on this).
● These photons may be blue, green, yellow, red or infra-red, or other colours, depending on how much energy they possess.
   Figure 2: White light is composed of many wavelengths of visible light from the red end of the spectrum to the blue end
Wavelength – the Colour of Light
White light is a mixture of coloured light. It can be ‘split’ into the colours of the rainbow using prisms or droplets of water. Isaac Isaac Newton was the first scientist to realise that white light was composed of all the colours!
● Wavelength is the technical name for ‘colours’. One wavelength is the distance between two ‘peaks’ in a light wave (or two troughs). Laser engineers and physicists don’t like to use ‘colour’ names – they prefer to use numbers. It’s more precise!
Figure 3: The wavelength is the distance between two peaks (or two troughs) of a wave
● The wavelength of visible light is usually measured in ‘nanometres’ – one nanometre (nm) is 1 billionth of a metre. Humans can typically see a range of light between 380 and 780 nm, although this changes with age and disease.
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Chapter 1 LEVEL A Fundamentals of Lasers/IPLs
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