Phototherapy has become a treatment of choice in many areas of medicine. Light can be used to deliver energy to tissue selectively targeting specific structures in order to induce the desired therapeutic outcome. The choice of optical parameters for a specific application is not simple. Wavelength, energy, exposure time and fluence can be varied and induce a wide range of tissue effects. The treatment of the skin with light is probably the one phototherapy application that is most developed in terms of technology and market maturity. White light systems are extensively used to address a range of skin conditions. However, different conditions have different physiology and hence require differing optical parameters. The technology standard is based upon systems, which have a number of different optical filters allowing the output to be tailored to the specific application. This paper discusses the advantages of a different type of system, namely the iPulse i300 (Cyden Ltd, Swansea, UK), which uses a single dichroic reflectance filter and whose optical output is changed by varying other parameters in a carefully controlled manner.