High temperature-gradient refractive index liquid crystals

We have analyzed the physical origins of the temperature gradient of the ordinary refractive index (dT(o)/dT) of liquid crystals. To achieve a large dn(o)/dT, high birefringence and low clearing temperature play crucial roles. Based on these simple guidelines, we formulated two exemplary liquid crystal mixtures, designated as UCF-1 and UCF-2, and compared their physical properties with a commonly used commercial liquid crystal compound 5CB. The dn(o)/dT of UCF-1 is similar to4X higher than that of 5CB at room temperature. (C) 2004 Optical Society of America.