When it comes to IPL, Xu explains the science. “Spectrum lights are measured as wavelength (nm), for example, 755nm wavelength means this spectrum light can penetrate 755nm deep beneath the skin. 755nm wavelength light is best attracted to melanin, so it is best used for hair removal. 532nm means light can reach up to 532nm beneath the skin.” Red cells in blood has highest absorption towards this light, so IPL is very effective at treating the appearance of superficial broken capillaries.