A new picosecond laser (Impulse+, Irisiome, France) with bursts of ultrashort pulses was recently proposed for tattoo removal to enhance efficiency and patient tolerance. This study aims to analyse the optical properties of tissues and cells of the skin subject to laser irradiation with or without black ink pigments. Results show that black tattoo ink alone is not cytotoxic for dermis cells but it can induce particular cells’ reactions up to death with laser irradiation. These results are promising and help understanding picosecond laser process for tattoo removal.
Using a picosecond laser that delivers bursts of ultrashort pulses may improve thermal effects and limit side effects, compared to a sub-nanosecond laser. This study aims to analyse how the temperature increases on agar with or without black ink and on human skin. Results showed that large beams, and so long macropulses, present higher peaks of temperature than the small ones, as well as when fluencies and frequencies increase. Besides, higher thermal loading occurred with the nanosecond pulses. These results may explain why picosecond laser induces less side effects than sub-nanosecond laser.