Circularly polarized illumination confocal fluorescence microscopy for three-dimensional analysis of liquid crystal director fields

초록

Optical microscopy remains the cornerstone of imaging in science and engineering, providing non-destructive visualization with minimal sample preparation. Conventional polarization microscopy is mostly used to investigate anisotropic materials such as liquid crystals (LCs); however, its interpretation is fundamentally limited by the two-dimensional nature of the acquired images. This limitation is critical for LC systems with complex threedimensional (3D) director fields. Herein, we present a new visualization method for 3D director fields associated with LC defects. In our approach, circularly polarized illumination is employed in confocal fluorescence microscopy to uniformly excite fluorescent dyes that label LC cells. Additionally, a rotating analyzer in front of a photodetector is used to resolve the polarization components of the emitted fluorescence, enabling the extraction of orientation-dependent information. By measuring the intensity modulation at each voxel during analyzer rotation, we determined the local 3D director orientation. We demonstrate that the proposed method can reconstruct the 3D director fields of solitons and non-singular disclinations in nematic LCs. This approach provides a practical tool for high-resolution 3D characterization of anisotropic soft-matter systems and contributes to a deeper understanding of LC behavior in both fundamental and applied contexts.

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