Three-dimensional temperature measurement with micro-capsulated thermo-chromic liquid crystal for assessment of dielectric and insulation materials

A new method to measure three-dimensional temperature distributions inside transparency materials is proposed. In this method, a micro-capsulated thermo-chromic liquid crystal (MTLC) is employed as the temperature probe because of its nature of high thermal sensitivity and high space resolution. MTLCs are dispersed into transparency materials homogeneously to measure temperature distribution. If the slit light is projected to these materials, temperature distribution is visualized within the cross section illuminated by the light with rainbow color from red to purple. This method is a candidate for observing thermal distributions inside of dielectric and insulation materials and will be useful in understanding fundamental physics of ageing and breakdown. In this study, we made transparent epoxy resin specimens, in which MTLCs are included, to observe temperature distributions. Since the volume ratios of MTLCs dispersed in the epoxy resin samples are from 0.01% to 0.1%, the mixed MTLCs should not affect the dielectric property of epoxy resin. Real time visualizations of temperature distribution are demonstrated by irradiating high-energy electron beam.