Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
Opt Lett. 2013 Mar 15;38(6):923-5. doi: 10.1364/OL.38.000923.
Polarization mode dispersion (PMD) severely degrades images of biological tissue measured with polarization-sensitive optical coherence tomography. It adds a bias to the local retardation value that can be spatially confined, resulting in regions of seemingly high sample birefringence that are purely artificial. Here, we demonstrate and analyze this effect, both experimentally and with numerical simulations, and show that artifacts can be avoided by limiting the system PMD to less than the system axial resolution. Even then, spatial averaging over a dimension larger than that characteristic of speckle is required to remove a PMD-induced bias of the local retardation values.
偏振模色散（PMD）严重降低了偏振敏感光相干断层扫描测量的生物组织图像质量。它会给局部延迟值增加一个偏置，这个偏置可以在空间上受到限制，从而导致看似高样品双折射的区域实际上是纯粹的人为假象。在这里，我们通过实验和数值模拟演示和分析了这种效应，并表明通过将系统 PMD 限制在小于系统轴向分辨率以下，可以避免伪影。即使这样，也需要在大于散斑特征的一个维度上进行空间平均，以消除局部延迟值的 PMD 引起的偏差。
