Page 129 - An Introduction to Laser Tattoo Removal

Chapter 2 – Fundamentals of Laser Tattoo Removal v1.0
Summary of Light-Tissue Interactions as applied to tattoos
The important points to note about the way light interacts with tissues are:
Wavelength
The wavelength determines how deeply the light can penetrate.
It also determines how much energy is absorbed by the ink targets.
Energy
Energy is what does the “work” in raising temperatures in the absorbing targets.
Pulse duration
Pulse duration is the time in which the light energy is delivered. This has a strong correlation with the resulting temperature rise in the absorbers. With tattoo lasers it must be very short to induce very high peak temperatures – typically nano- or picoseconds (trillionths of a second).
Power
Power is simply how quickly or slowly energy is delivered to the site. If the energy us delivered very quickly, then the power is ‘high’. If the same energy is delivered more slowly, then the power is lower than before. We can calculate the power by dividing the energy by the pulse duration.
Spot diameter
The spot diameter also determines how deeply the light can penetrate principally due to scattering.
Energy Density (Fluence)
A laser will generate a beam with a certain amount of energy. We can focus this energy into a small spot size using lenses. Different lenses produce different spot diameters. The ‘concentration’ of energy in the spot diameter is known as the ‘fluence’ or ‘energy density’.
________________________________________________________________________ 129
Chapter 2 LEVEL A Laser Tattoo Removal
© The Laser-IPL Guys, 2021