Laser-tissue interaction principles: tissue optical properties in the light therapeutic window
Energy for Health, Volume 12
G. Romano, A. Conti, A. Gnerucci, P. Imperiale, F. Fusi
This article presents a review of the physical principles of light-tissue interaction and combines experimental data on tissue chromophore scattering and absorption.
Scattering and absorption are directly tied to the wavelength of the laser. Scattering can be caused by cell nuclei, mitochondria, lysosomes, and the Golgi apparatus; generally as the wavelength increases, the scattering decreases (see chart). Absorption happens when the laser hits blood, water, melanin, muscle, and/or mucous membrane. The higher the level of melanin in the skin (darker skin types) the more the laser will be absorbed at the skin. Laser that is coherent will have the least amount of scattering and the most absorption within the body. (MLS is coherent and utilizes 808nm and 905nm wavelength).