Abstract: The present application discloses an apparatus and a method for synchronizing the activation of a light source with the position of a hand piece on a surface and for providing a substantially homogenous exposure of a surface to light irradiation. The apparatus includes a light source, a handpiece for delivering light pulses to the irradiated surface, and a beam delivery system for delivering light from the light source to the handpiece. The handpiece, which is moved along the surface by an operator, includes a sensor for sensing the distance traversed by the handpiece on the surface. The sensor sends signals to a signal processing unit which calculates the distance traversed by the handpiece on the surface and controls the activation of the light source either by automatically activating the light source or by providing the operator with a signal indicating that the light source should be pulsed.