The mechanics of the process is that the light is attracted to the ink based on the color of the ink and the wavelength of the laser light. Since the ink resides deep in the skin, the difficulty of the procedure is that you have to deliver the right level of energy to affect the ink without damaging the skin between the surface and the ink. This is done by delivering a very high amount of energy in a very short period of time, hitting the ink with that acoustic blast and generating heat in the tissue only where the ink resides, without creating too much heat in the skin above the ink. To reach deeper in the skin without generating too much heat on the surface, the spot size must be large in relation to the energy applied, since the laser energy creates a profile that resembles a cone; the deeper it reaches into the skin, the more narrow the peak power area becomes until it comes to a point. The area the laser beam can affect shrinks as you go deeper into the skin, reducing the amount of ink the beam will remove. If you reduce the spot size to increase the energy (the power density rule: take the same amount of energy output from a laser at one spot size, reduce the spot size and you increase the light energy of the beam), you reduce the overall area of ink that is treated deep in the skin and this dramatically increases the chance of causing a burn on the surface of the skin. Having a device that can generate a high energy with a large spot size is critical for success with the minimization or elimination of complications.