To understand how removal of tattoo works, it is always best to understand how tattoos stay in the skin as this is often something which isn’t common knowledge. Tattoos stay in the skin due to the method of application and also the components used to make the tattoo ink which when combined in such way make a permanent mark.
When you are tattooed your body will automatically send your immune system to attack the new ink in an attempt to remove it. Upon realising the ink cannot be removed, it is then encased in collagen which effectively makes the ink safe and unable to further enter the body or the bloodstream. Every so often your immune system will attempt to attach the tattoo which is why you see it fade and spread over the years.
The laser sends short bursts of energy into the ink pigments of the tattoo and breaks up the particles and the ink, enabling your immune system to safely and naturally remove the ink through your lymphatic system.