The chiral nematic phase of cellulose nanocrystals (CNC) in the suspension liquid state is commonly examined using polarized optical microscopy (POM) as it conveniently reveals the cholesteric pitch through fingerprint textures. However, POM has certain limitations, one of which is the requirement for a perpendicular alignment of the chiral axis with the optical axis to achieve accurate measurements. We propose employing SHG microscopy as an alternative technique, offering high-contrast imaging of the chiral nematic phase with inherent 2-photon confocal effect. An IR pulsed femtosecond laser is raster scanned through the microscope, and the cumulative SHG response of the aligned CNC recreates the fingerprint textures. As is shown in this present work, the tight focussing effect of SHG microscope allowed z-scanning to render high contrast 3D models of the structures. Morphological observations and the tracking of defects in 3-dimensional space was made possible.
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