How Laser Tattoo Removal Works - Part 2
The art of laser tattoo removal involves not just selecting the right laser and wavelength to treat a tattoo. In the last blog entry, we went over the fundamentals of the laser and the importance of using the appropriate wavelength to treat different tattoo ink colors. In this entry, we’ll go over some subtler points.
The amount of energy in a laser shot can be varied from low to high. Most patients think that the higher the energy, also called fluence, the faster their tattoos will come off. This is not quite true. There is a maximum amount of energy that a tattoo can absorb. If additional energy is applied, then it is converted to heat which can injure the skin. As there is less and less remaining ink to absorb the laser energy, the fluence can be increased. The majority of the energy does not encounter tattoo ink and is reflected away. Less heat is generated and thus a higher energy can be safely used. There is of course a limit to how high the energy can be set.
Another aspect is beam profile. The laser beam that hits the skin is ideally completely uniform in energy from outer edge to the middle of the beam. This is not necessarily so. Laser manufacturers have continued making improvements in beam uniformity but this used to be more of a problem. Older lasers sometimes had higher energy in the center of the beam which could cause hot spots and non-uniform tattoo removal.
Some colors of ink absorb the available laser wavelengths very poorly. This makes them more difficult to fade with a laser. Colors such as yellow, pink, and purple are more difficult to remove than colors such as black, blue, red, and green. This does not mean that those colors cannot be removed at all, but that removal is more difficult and expectations should be lower.
Some inks may contain metal pigments, such as iron and titanium, that are much harder to remove than other inks. India ink, for instance, is much easier to remove by comparison. Since patients (and even tattoo artists) almost never know what the inks in their tattoos are composed of, there is no way to predict when this will be a problem.
