Question: can the laser go throughyour skin

Stuart Archer answered on 21 Jun 2013:

It depends on the ‘wavelength’ of the laser (wavelength is related to the colour of the laser – longer wavelengths give redder light, shorter wavelengths bluer, the same range of colours as a rainbow).

Your skin and blood are very good at absorbing blue light – that’s why your blood appears red, it’s absorbed the blue light that hits it! There are certain types of laser that can penetrate the skin – these are almost always red or infra-red lasers. There is a procedure called ‘photodynamic therapy’ which uses lasers to destroy cancer cells in your body which relies on using an infra-red laser!

Really high energy lasers can also damage your skin, but they do this by burning it rather than passing through it.