(E-198) Rapid Birefringence imaging based on multiplexed-coded vectorial FourierPtychographic microscopy

Introduction:: Fourier Ptychography (FP) is a commonly utilized label-free quantitative phase imaging (QPI) technique, known for its high resolution and extended field of view. However, previous QPI studies have mostly focused on transparent thin samples with minimal phase variations in non-polarized cases. Retrieving optically inhomogeneous structures of biological specimens, such as collagen in pathology specimens, is a significant challenge in the field, and only a few studies have been conducted in this area. While traditional laser scanning Second-harmonic imaging microscopy (SHG) has been the preferred method for such samples, recently developed computational imaging techniques, including FP, have demonstrated the ability to reconstruct birefringence using portable and low-cost systems. Extending FP to polarization measurements requires at least four polarization state measurements, which can compromise the system's speed. To address this issue, we propose a multiplexing method that employs a coded illumination pattern with a designed polarization state. This approach enables us to obtain anisotropic properties of optically inhomogeneous biological specimens with FP in a more efficient and faster manner without sacrificing image quality.

Materials and Methods:: We modify the conventional microscopy by inserting a LED array as an illumination source for the system and placing two polarizers before and after the sample. Standard Fourier Ptychography requires turning on each LED independently and getting a sequence of images with different directions of illumination, we can reconstruct a larger FOV with high-resolution images. Here we incorporate multiplexing strategies combining illumination and polarization states to achieve fast polarization imaging based on Jones matrix calculation.

Results, Conclusions, and Discussions:: By utilizing multiplex strategies with both illumination and polarization state, we can achieve 20X-comparable resolution across centimeter scale FOV, revealing the orientation and birefringence of pathology slides, including collagen and amyloid plaque tissue. We also validate our orientation accuracy by comparing the reconstructed orientation with the known orientation of the MSU target.

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