Interferometric measurement of the temperature field in the vicinity of ice crystals growing from supercooled water

Ice crystals are grown in the supercooling temperature range of 0–8°C, where the crystal-growth morphology shows a dependence on temperature. In order to understand the growth mechanism, we measure the temperature field around the growing crystals by using the temperature dependence of the refractive index. Since this has a zero for H2O at 0°C, we use D2O, which has similar growth morphologies, and achieve considerably greater sensitivity. The crystal growth cell lies within four imaging Mach–Zehnder interferometers, which observe it in different directions. From the interferograms the three-dimensional temperature field is deduced.