Theory Using the light blasting effect, the high-intensity laser penetrates the epidermis and can reach the pigment clusters in the dermis layer. Because the energy has a short time of action and the energy is extremely high, the pigment clusters will quickly expand and explode after absorbing the high energy in an instant. After the particles are swallowed by macrophages, excreted, and the pigment gradually fades and disappears. The picosecond laser with ultra-short pulse width can effectively produce photo-mechanical effects and break the pigment particles into small fragments. Compared with nano-scale Q-switched laser, picosecond laser only needs lower energy to achieve the effect. It takes less number of treatment courses to achieve better treatment effect. Stubborn green and blue tattoos can also be effectively removed. Treated but incomplete tattoo removal, picosecond laser can also treat. In the mechanism of pigment particle destruction, there are mainly photothermal and photomechanical effects. The shorter the pulse width, the weaker the effect of converting light into heat. Instead, the photomechanical effect is used, so picoseconds can effectively crush the pigment particles, resulting in better pigment removal.