Change of coherence of light produced by tissue turbulence

•The expression for change of the MCF due to the tissue turbulence is given.•The theory is for a random, wide-sense stationary, electromagnetic beam.•The distribution of the MCF across a plane can be estimated.•It can be used to calculate the change of the MCF with propagation distance.

The coherence is an important property of the light that can be explored to realize very high sensitive measurements in many applications. In this work, the unified theory of coherence and polarization for random electromagnetic beams will be employed to analyze the change of coherence due to the fluctuations of the index of refraction of tissue. To the best of our knowledge, for the first time the expression for calculating the change of the mutual coherence function of a random, wide-sense stationary, electromagnetic beam propagating along the z direction due to the tissue turbulence is given. The results can be used to estimate the distribution of the mutual coherence function across a plane normal to the direction of propagation at a distance z from the incident plane. It can also be employed to calculate the change of the mutual coherence function with propagation distance. Thus the results are useful for any applications involved light beam propagation through tissues, especially the cases where the coherence and polarization properties of the light field should be taken into account to evaluate the system performance.