For the in vivo experiments we used the range of fluences, which were considered safe based on previous experience, from approximately to . The effect of multiple pulses was studied by applying two pulses with the total fluence comparable to a single pulse. Whitening of the treated skin area was observed immediately after the laser pulse illumination in all cases. This effect is caused by rapid local heating of the pigment leading to plasma and gas formation and subsequent dermal and epidermal vacuolization.2,6 At the highest fluence () a minor bleeding was observed in one case. Otherwise, there was no long-term scarring, textural changes, or hypopigmentation. Figure 3 shows typical images of plasma radiation for different tattoo areas, acquired by the NIR camera. We can see uneven light intensity distribution, which reflects the uneven pigment distribution and also the presence of laser speckles, which localize plasma formation.21 There was also a considerable amount of light emitted from the neighboring area of the illuminated spot, which is a consequence of tissue scattering properties. This is especially evident on images of second pulses, where the plasma diameter is approximately 10% bigger than at first pulses. This shows that the tissue has increased scattering and reduced absorption after the first laser pulse. The diagram in Fig. 6 shows the relation between the time-integrated plasma radiation over the entire image (Isum) and the laser pulse fluence. It is evident that the plasma emits more light at higher fluences and in the case of the first laser pulse. Exponential curve, fitted on single-pulse data points, is added to show the correlation.