Structure functions for optical waves in a complex medium of turbulent biological tissues

Area of Science:

• Optics
• Biomedical Engineering
• Biophysics

Background:

• Optical wave propagation in biological tissues is typically studied considering absorption and scattering.
• The impact of turbulence within biological tissues on optical wave propagation is often overlooked but significant.

Purpose of the Study:

• To derive closed-form expressions for the wave structure function (WSF) and phase structure function (PSF) for plane and spherical waves in turbulent biological tissues.
• To investigate and compare the effects of turbulence on optical wave propagation in various biological tissues, including mouse liver parenchyma, mouse intestinal epithelium, mouse deep dermis, and human upper dermis.
• To provide insights into the performance of biomedical systems utilizing optical technologies in turbulent biological environments.

Main Methods:

• Derivation of closed-form expressions for WSF and PSF.
• Analysis of optical wave propagation through different biological tissue models (liver parenchyma, intestinal epithelium, dermis).
• Comparative study of turbulence effects based on varying parameters like heterogeneity, propagation distance, refractive index fluctuations, fractal dimension, wavelength, and small length scale.

Main Results:

• Turbulence effects intensify with increased characteristic length of heterogeneity, propagation distance, and refractive index fluctuation strength.
• Increased fractal dimension, wavelength, and small length scale factor lead to diminished turbulence effects on propagating optical waves.
• Distinct behaviors of optical waves were observed across different tissue types.

Conclusions:

• The derived WSF and PSF expressions are valuable for future research in imaging, intensity, and coherency within turbulent biological tissues.
• Understanding turbulence is essential for accurately predicting the performance of optical medical systems.
• The study quantifies the influence of various parameters on optical wave propagation, aiding in the design and interpretation of biomedical optical applications.