Time-resolved measurement shows a spectral distribution shift in an intense pulsed light system

For an intense pulsed light (IPL) device, knowledge of the spectral output is useful in order to provide effective treatment and target specific structures in the skin. It is also a requirement in order to perform a safety assessment. A novel spectral measurement system has been developed to detect the optical radiation output of intense pulsed light devices. The system has a time resolution of 450 mus and a wavelength resolution of 0.6 nm. This enabled us to observe spectral changes, both within a pulse and between pulses, in a pulse train. The output from a free discharge IPL source and four different treatment handpieces was measured. A shift in the spectral distribution between pulses, and within a pulse, was discovered. The spectral shift is more prominent for higher radiant exposures.