Intense pulsed light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hugues Cartier, A Le Pillouer-Prost, and Saib Norlazizi

TECHNICAL ASPECTS Principle of Operation: Light, Laser, and Intense Pulsed Light Electrical Energy and Optical Spectrum The main difference between a laser and an intense pulsed light (IPL) is physics: the rst one emits a coherent, monochromatic light (one wavelength measured in nanometers [nm]), whereas the second emits a polychromatic, noncoherent light (a spectral band, e.g., from 550 to 950 nm). The wavelength of a laser can be drawn as one color, whereas the spectral band of IPL is composed of all the colors of the rainbow (Figure 37.1).