AbstractThe Abbé refractometer provides a convenient way to measure the refractive indices and birefringence of polymeric liquid crystalline solutions. The cholesteric mesophase formed by (acetoxypropyl) cellulose and its solutions in dibutyl phthalate were examined at 26°C and 50°C. The measured refractive indices were dependent on the direction of shear when the polymer was applied to the refractometer plates. The initial shear‐induced nematic‐like order relaxed slowly to the equilibrium planar cholesteric structure. The refractive index for the isotropic solutions and the two refractive indices for the anisotropic solutions all varied linearly with polymer concentration, and the width of the intermediate two‐phase region was readily determined. The changes in refractive index with polymer concentration and with orientation on the refractometer plate were rationalized with a simple model of the cellulosic mesophase, and an order parameter of 0.7 was estimated. The layer birefringence calculated from optical rotatory dispersion measurements of the cholesteric reflection band intensity was in good agreement with the birefringence meas
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