The interference colors of the microscopic textures, observed under a polarized microscope for the oriented cholesteric discotic (ChD)–cholesteric biaxial (ChB)–unwound cholesteric calamitic (NC*) phases sequence in the presence of a magnetic field, were studied in this work. The referred textures were interpreted from both experimental and theoretical views. The lyotropic nematic host mixtures consisted of potassium laurate (KL), 1-undecanol (unDeOH), potassium sulphfate (K2SO4), and water (H2O). The chiral guest molecule brucine was added to the host nematic mixture to induce the cholesteric phases. The refractive indices and birefringences of the lyotropic samples were measured along the nematic calamitic (NC)–nematic biaxial (NB)–nematic discotic (ND) phases sequence as a function of temperature, and they were used to simulate the stripe textures of the oriented cholesteric phases, ChD and ChB, theoretically. It was shown that the experimental and simulated results are in good agreement with each other.
Lüders et al. (Mon,) studied this question.