SIGNIFICANCE Biological tissues are typically characterized by high anisotropic scattering and may also exhibit linear form birefringence. Both scattering and birefringence bias the phase shift between transverse electric field components of polarized light. These phase alterations are associated with particular structural malformations in the tissue. In fact, the majority of polarization-based techniques are unable to distinguish the nature of the phase shift induced by birefringence or scattering of light. AIM We explore the distinct contributions of scattering and birefringence in the phase retardation of circularly polarized light propagated in turbid tissue-like scattering medium. APPROACH The circularly polarized light in frame of Stokes polarimetry approach is used for the screening of biotissue phantoms and chicken skin samples. The change of optical properties in chicken skin is accomplished by optical clearing, which reduces scattering, and mechanical stretch, which induces birefringence. The change of optical properties of skin tissue is confirmed by spectrophotometric measurements and second-harmonic generation imaging. RESULTS The contributions of scattering and birefringence in the phase retardation of circularly polarized light propagated in biological tissues are distinguished by the locus of the Stokes vector mapped on the Poincaré sphere. The phase retardation of circularly polarized light due to scattering alterations is assessed. The value of birefringence in chicken skin is estimated as 0.3  ×  10-3, which agrees with alternative studies. The change of birefringence of skin tissue due to mechanical stretch in the order of 10-6 is detected. CONCLUSIONS While the polarimetric parameters on their own do not allow distinguishing the contributions of scattering and birefringence, the resultant Stokes vector trajectory on the Poincaré sphere reveals the role of scattering and birefringence in the total phase retardation. The described approach, applied independently or in combination with Mueller polarimetry, can be beneficial for the advanced characterization of various types of malformations within biological tissues.

中文翻译：

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散射和双折射在相位延迟中的作用由庞加莱球上的斯托克斯矢量轨迹揭示。

意义 生物组织通常以高各向异性散射为特征，也可能表现出线性形式的双折射。散射和双折射都会偏置偏振光的横向电场分量之间的相移。这些相位改变与组织中的特定结构畸形有关。事实上，大多数基于偏振的技术无法区分由光的双折射或散射引起的相移的性质。目的我们探索散射和双折射对在混浊组织状散射介质中传播的圆偏振光的相位延迟的不同贡献。方法 斯托克斯偏振法框架内的圆偏振光用于生物组织模型和鸡皮肤样品的筛选。鸡皮肤光学特性的改变是通过光学清除来实现的，这减少了散射，机械拉伸会引起双折射。分光光度测量和二次谐波生成成像证实了皮肤组织光学特性的变化。结果散射和双折射对在生物组织中传播的圆偏振光的相位延迟的贡献通过映射在庞加莱球上的斯托克斯矢量的轨迹来区分。评估由于散射改变引起的圆偏振光的相位延迟。鸡皮肤的双折射值估计为 0.3 × 10-3，这与替代研究一致。检测到由于机械拉伸引起的皮肤组织双折射的变化量级为 10-6。结论 虽然偏振参数本身并不能区分散射和双折射的贡献，但庞加莱球上的合成斯托克斯矢量轨迹揭示了散射和双折射在总相位延迟中的作用。所描述的方法, 独立应用或与穆勒极化法结合使用, 可以有利于生物组织内各种类型畸形的高级表征。