You cannot use an IPL to treat hair above a tattoo! The pulse duration is far too long for the tattoo. Scar-free tattoo removal by laser is successful because most of the heat energy generated on the surface of the tattoo ink particles is used to create a shockwave. This propagates through the pigment causing it to shatter into smaller fragments. The body’s macrophages and fibroblasts then absorb those fragments.
With an IPL system the tattoo ink will absorb a significant portion of the incoming energy and generate a lot of heat energy over a relatively long period of time. This heat energy will conduct throughout the dermal area and thermally damage some of the structures, which may lead to scarring.
No IPl can generate sufficiently short pulses to treat tattoos without scarring. Likewise, using an IPL to treat hair above a tattoo will cause unintended tissue damage around the tattoo pigment.
Just don’t do it!