Real-time optical system for observing crystallization in levitated silicate melt droplets.

In this study, a real-time optical system was developed to observe crystallization in a small spherical melt droplet (few millimeters in diameter) by containerless processing. This system can be used to simultaneously observe the inside and the surface of a transparent melt droplet, as well as its ambient gas atmosphere at high temperatures. A silicate melt with a diameter of ∼2 mm and a composition of MgO:SiO2=48:52 was levitated using a gas-jet levitation system, and its crystallization process was successfully observed from 2385 K in real time with good contrast using the developed optical setup.