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. Pulse width or pulse duration is a critical laser parameter. All Q-switched lasers have appropriate pulse durations for tattoo removal. Spot size, or the width of the laser beam, affects treatment. Light is optically scattered in the skin, like automobile headlights in fog. Larger spot sizes slightly increase the effective penetration depth of the laser light, thus enabling more effective targeting of deeper tattoo pigments. Larger spot sizes also help make treatments faster. Fluence or energy density is another important consideration. Fluence is measured in joules per square centimeter (J/cm2). It is important to be treated at high enough settings to fragment tattoo particles. Repetition rate helps make treatments faster but is not associated with any treatment effect. Faster treatments are usually preferred because the pain ends sooner. Number of laser tattoo removal treatment sessions needed The number of treatments necessary to remove a tattoo via laser can be predicted by the Kirby-Desai Scale. The number of sessions depends on various parameters, including the area of the body treated, skin color, ink color present,