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Abstract The temperature dependence of optical birefringence, order parameter, effective geometry parameter, and normalized polarizability was determined for nematic liquid crystal mixtures by measuring the refractive indices. The effects of the adjustable parameters obtained from temperature-dependent refractive indices were analyzed appropriately for the crossover temperature and order parameter values. Besides, a four-parameter power law expression method was used for the optical birefringence measurement to address inappropriate fits in the weak first-order phase transition region. From this method, the effective second order phase transition temperature T ⁎⁎ was determined by showing the slightly higher values than phase transition temperature. The value of the order parameter critical exponent λ obtained from this method showed a good agreement with the mean field theory by demonstrating closeness to the tricritical hypothesis (β = 0.25). As a consequence, the measurement of the temperature-dependent optical birefringence was successfully verified the pre-transitional phenomena accurately, and it can facilitate an insightful description of that region. Graphical abstract Unlabelled Image Highlights • Temperature dependence of high birefringence (∆ n) liquid crystals was analyzed. • The temperature dependent order parameter was sorted based on ∆ n values. • Lower (∆ n) o and β values were valuable factors for increasing T co at the same T NI. • A four-parameter power law expression shows the high critical exponent value. [ABSTRACT FROM AUTHOR]

• There is linear relationship between order parameter and pitch length. • PSCLCs indicate a iregular transmission features. • NLCs play important roles on the PSCLs optical behaviors. Polymer stabilized cholesteric liquid crystals (PSCLCs) with unique characteristics play important roles in optics and photonics. In this case, temperature induced effects can modify their function in various phenomena. In this work, optical responses of PSCLCs were studied at different temperatures and temperature dependent properties of prepared PSCLC were successfully equationalized. According to the experimental results, there are good linear relationship between calculated pitch lengths and temperature. Moreover, the experimental results indicate that nematic liquid crystal (NLC) temperature dependent characteristics play important roles on the PSCLCs pitch length. In this case, quantitatively investigation of relationship between pitch length and LC order parameter provide new method for calculation of pitch length. Therefore, the calculation of pitch length based on NLC order parameter can facilitate the studies on PSCLCs. [ABSTRACT FROM AUTHOR]