a pulsed light source for cutting away biological tissue has a control unit that controls the light source in such a way that the light source supplies a series of pulses of predetermined duration and radiation intensity . the control unit may be operated to cause the light source to supply short pulses at a predetermined and / or controllable rate of repetition with a radiation intensity sufficient to cut away the tissues , and radiation followed by light emission or the like with a radiation intensity that is not sufficient to cut away the tissues but is sufficient to generate heat .