How could a tattoo be removed?
First, what is a tattoo made of?
Ink is made of large molecules. The molecules are large enough that the body doesn't just haul them off as junk. So, the molecules just sit there, because in essence, the body's defenses doesn't recognize what to do about this large molecule siting there.
Second, how can a tattoo be removed?
If we could break up the molecule into smaller pieces, the body could recognize the fragments and digest the left over pieces. Bring in the laser . . . A laser imparts energy to a molecule with an electric field which causes the bonds within a molecule to vibrate more than they already do. So much so, that it breaks the bonds. It's terribly effective . . . take a look:
http://www.wimp.com/lasertattoo/
Sometimes there is minimal scarring, and not all of the ink may not have removed, but if you have a tattoo that says, "Bertha," and you married Grazelda, you're probably going to be OK with it.
