Mueller matrix polarimetry can provide abundant microstructural information of tissues. Mueller matrix polar decomposition (MMPD) is capable of extracting intrinsic polarimetric characteristics of tissue-like media, including the orientation of the linear birefringence axis. However, when measuring a multi-layered sample with linear birefringence of different orientation directions, there is a deviation between the measured and ideal values of the MMPD linear birefringence orientation parameter. Since the multi-layered anisotropic structures widely exist in biomedical samples, a modified MMPD parameter to calculate linear birefringence orientation more precisely for layered tissues is crucial. Here we propose a modified MMPD parameter to calculate linear birefringence orientation for multi-layered media. By measuring different customized phantoms and pathological tissue slices, we demonstrate that the modified parameter can show more accurately the linear birefringence orientation angle of multi-layered media. The proposed parameter can be helpful for the quantitative evaluation of not only the pathological tissue slices with fibers, but also many other material samples with layered birefringent structures.

穆勒矩阵极化法可以提供丰富的组织微观结构信息。Mueller 矩阵极性分解 (MMPD) 能够提取组织状介质的固有偏振特性，包括线性双折射轴的方向。但是，在测量具有不同取向方向的线性双折射的多层样品时，MMPD线性双折射取向参数的实测值与理想值之间存在偏差。由于多层各向异性结构广泛存在于生物医学样品中，因此修改后的MMPD参数以更精确地计算层状组织的线性双折射取向至关重要。在这里，我们提出了一个修改后的 MMPD 参数来计算多层介质的线性双折射方向。通过测量不同的定制体模和病理组织切片，我们证明修改后的参数可以更准确地显示多层介质的线性双折射方向角。所提出的参数不仅有助于对带有纤维的病理组织切片进行定量评估，还有助于对许多其他具有分层双折射结构的材料样品进行定量评估。