Scattering

ECE532 Biomedical Optics ©1998 Steven L. Jacques, Scott A. Prahl Oregon Graduate Institute

Scattering of light occurs in media which contains fluctuations in the refractive index n, whether such fluctuations are discrete particles or more continuous variations in n.

In biomedical optics, scattering of photons is an important event:

• Scattering provides feedback during therapy. For example, during laser coagulation of tissues, the onset of scattering is an observable endpoint that correlates with a desired therapeutic goal. Scattering also strongly affects the dosimetry of light during therapeutic procedures that depend on absorption. The scattering affects "where" the absorption will occur.
  
  
• Scattering has diagnostic value. Scattering depends on the ultrastructure of a tissue, eg., the density of lipid membranes in the cells, the size of nuclei, the presence of collagen fibers, the status of hydration in the tissue, etc. Whether one measures the wavelength dependence of scattering, the polarization dependence of scattering, the angular dependence of scattering, the scattering of coherent light, scattering measurements are an important diagnostic tool. Scattering is used for both spectroscopic and imaging applications.