Mid-infrared refractive indices of the nematic mixture E7

E7 is a room temperature nematic liquid crystal mixture with a high positive dielectric anisotropy and a high chemical stability. Because of its relatively high nematic-to-isotropic transition temperature, it is suitable for mid-infrared laser applications, where the absorption of laser light is not negligible and gives rise to a certain heating of the medium. In this paper we give a measurement of the refractive indices of the liquid crystal E7 at a wavelength of 10.6mum as a function of temperature. An empirical formula to represent the experimental data is also provided.