Hi, I would like to seek advice/collaboration with anyone who measures the helical twisting power of chiral nematic liquid crystals. I would like to contact you directly.
The distance between the disclinations is reliable, but the wedges show two distances, you must distinguish between these, see I. Smalyukh and O.D. Lavrentovich, Three-dimensional director structures of defects in Grandjean-Cano wedges of Cholesteric liquid crystals studied by fluorescence confocal polarizing microscopy, Phys. Rev. E 66, 051703 (2002).
If the CLC is of short pitch(on the orders of visible wavelengths), Grandgean cano wedge method is good or you can relate by using the refelction spectra of planar CLC.
For long pitch CLCs (greaterthan 1um), the distance between two lines in fingerprint texture is equals to half of the pitch value. Here the fingerprint texture may varry with cell thickness.
Thank you Professor Oleg D Lavrentovich and Dr. Buchaiah Gollapelli for your answers.
The fingerprint technique in polarized optical microscopy (POM) is effective when dealing with a larger pitch due to constraints in the resolution capabilities of microscopic objectives. Alternatively, the simpler spherical wedge technique can be employed, offering the advantage of determining both pitch and handedness within the same experimental setup. doi.org/10.1002/anie.202209806
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