How does tattoo removal laser work?

The "standard modality for tattoo removal" is the non-invasive removal of tattoo pigments using Q-switched lasers. Different types of Q-switched lasers are used to target different colors of tattoo ink depending on the specific light absorption spectra of the tattoo pigments. Typically, black and other darker-colored inks can be removed completely using Q-switched lasers while lighter colors such as yellows and greens are still very difficult to remove. Success can depend on a wide variety of factors including skin color, ink color, and the depth at which the ink was applied.

Tattoos consist of thousands of particles of tattoo pigment suspended in the skin. While normal human growth and healing processes will remove small foreign particles from the skin, tattoo pigment particles are too big to be removed automatically. Laser treatment causes tattoo pigment particles to heat up and fragment into smaller pieces. These smaller pieces are then removed by normal body processes. Q-switched lasers produce bursts of infrared light at specific frequencies that target a particular spectrum of color in the tattoo ink. The laser passes through the upper layers of the skin to target a specific pigment in the lower layers.

How many sessions does it take to remove a tattoo?

Most people need 6 to 8 sessions to completely remove their tattoo. The number of treatments needed depends on the size of the tattoo, the colors used, and your skin type. Large tattoos can take 10 sessions or more. In order for the skin to heal, sessions are spaced 6-8 weeks apart.

Laser parameters that affect results

Q-switched Frequency-doubled Nd:YAG: 532 nm. This laser creates a green light which is highly absorbed by red, yellow, and orange targets. Useful primarily for red and orange tattoo pigments, this wavelength is also highly absorbed by melanin (the chemical which gives skin color or tan) which makes the laser wavelength effective for age spot or sun spot removal. Nd:YAG lasers may cause hemoglobin absorption, leading to purpura (collection of blood under tissue in large areas), pinpoint bleeding, or whitening of the skin.

Q-switched Ruby: 694 nm. This laser creates a red light which is highly absorbed by green and dark tattoo pigments. Because it is more highly absorbed by melanin this laser may produce undesirable side effects such as pigmentary changes for patients of all but white skin. This is the best wavelength for blue ink.

Q-switched Alexandrite: 755 nm. The weakest of all the q-switched devices and somewhat similar to the Ruby laser in that the Alexandrite creates a red light which is highly absorbed by green and dark tattoo pigments. However, the alexandrite laser color is slightly less absorbed by melanin, so this laser has a slightly lower incidence of unwanted pigmentary changes than a ruby laser. This laser works well on green tattoos but because of its weaker peak power it works only moderately well on black and blue ink. It does not work at all (or very minimally) on red, orange, yellow, brown, etc. This laser wavelength is also available in a picosecond speed with anecdotal claims that it removes ink faster.

Q-switched Nd:YAG: 1064 nm. This laser creates a near-infrared light (invisible to humans) which is poorly absorbed by melanin, making this the only laser suitable for darker skin. This laser wavelength is also absorbed by all dark tattoo pigments and is the safest wavelength to use on the tissue due to the low melanin absorption and low hemoglobin absorption. This is the wavelength of choice for tattoo removal in darker skin types and for black ink.

Dye modules are available for some lasers to convert 532 nm to 650 nm or 585 nm light which allows one laser system to safely and effectively treat multi-color tattoo inks. When dye modules take 532 nm laser wavelength and change it, there is a loss of energy. Treatments with dye packs, while effective for the first few treatments, many not be able to clear these ink colors fully. The role of dye lasers in tattoo removal is discussed in detail in the literature.