Page 120 - Blog Posts v1

weeks. There are other removal processes which I won't go into at this time (I'm working on a new report which will go into these other processes in greater detail).
To maximise the removal efficiency a number of parameters need to be properly understood:
Energy density (or fluence / radiant exposure) - this must be set properly on a laser to ensure the desired response in the ink. If it is too low then little or no reaction will occur. If it is too high then unwanted dermal damage is likely due to excessive thermal diffusion throughout the dermis leading to damaged collagen.
However, higher energy densities are required to successfully affect deeper located ink aggregates. For this reason the output energy of the laser should be carefully increased as the number of treatment sessions increases.
Pulse duration - how long each laser pulse lasts. This determines the level of confinement of the thermal and acoustic waves on the ink aggregate/particle surfaces. Consequently, this determines whether the ink aggregates will shatter into smaller fragments. In general, the shorter pulsewidths result in a more tightly confined acoustic/pressure wave in the ink resulting in a more efficient fragmentation process. Hence, shorter pulsewidth lasers, such as picosecond systems, will cause a greater level of fragmentation than longer pulsewidths.
Wavelength - the laser wavelength determines three important outcomes -
Mike’s Blog Posts 120