Polarization-sensitive terahertz solid immersion microscopy for probing heterogeneity and birefringence in soft tissues
D.R. Il’enkova 1, D.D. Rybnikov 1, A.I. Alekseevа 2, A.S. Kucheryavenko 1,3, K.I. Zaytsev 1, N.V. Chernomyrdin 1; 1- Prokhorov General Physics Institute of RAS, Moscow, Russia; 2- Research Institute of Human Morphology, Moscow, Russia; 3- Osipyan Institute of Solid State Physics of RAS, Chernogolovka, Russia
Abstract
This study utilizes a polarization-sensitive terahertz (THz) microscope based on solid immersion effects to investigate the birefringence and structural heterogeneity of freshly excised rat tissues. The examined samples include abdominal and tongue muscles, tendons from the forelimb (flexor and extensor digitorum), Achilles tendon, abdominal aorta, and corpus callosum of the brain. THz refractive indices are measured for two orthogonal linear polarizations - parallel and orthogonal to the fibrous tissue orientation - which reveal pronounced optical anisotropy. The observed THz birefringence reaches several percent, with the highest values recorded in muscular tissues and the corpus callosum, whereas tendon tissues exhibit considerably lower birefringence. In all cases, the refractive index is consistently higher when the incident radiation is parallel to the fiber direction. These findings demonstrate that tissue microstructure profoundly influences THz wave propagation, resulting in significant polarization-dependent optical responses. The results indicate that tissue heterogeneity and birefringence are non-negligible factors that must be taken into account in the development of emerging THz-based modalities for medical imaging and tissue diagnostics. This work provides essential quantitative data for advancing THz biophotonics in biomedical applications.
Speaker
Daria Il'enkova
Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow, Russia;
Russia
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