Temperature Behaviour of Refractive Indices Of Quasi-Nematic Layer of Cholesteric and Discoid Nematic

Abstract
The temperature dependences of the refractive indices n_o,e(t) and the values <n> = (n_e + 2n_o)/3,

= (n_e² + 2n_o²)/3,

^1/2 were studied for the quasi-nematic layer of the calamitic cholesteric (discoid nematic) liquid crystal in the presence of the minimum point t_o (t_e) of the function n_o(t) (n_e(t)) within (out of) the range of cholesteric (nematic) phase. For the quasi-nematic layer (discoid nematic) the linear dependences <n>(t),

(t),

(t) were established and the relationships derived earlier and connecting the coefficients of these dependences with the values of n_e(t_o) and

(t_o) (n_o(t_e) and

(t_e)) were confirmed. For the two types of nematics the reverse correlations were established between the coefficients of the dependence <n>(t), or

(t), in the mesophase and the dependence n_i(t) in the isotropic phase.

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