Figure 4. The optical properties of some vanadium dioxide films

The figure shows the optical properties of a typical thin film of thermochromic vanadium dioxide. The left hand side graph shows the large change in infra-red optical properties on passing the transition temperature. The graph on the right shows how the transmission at a fixed point in the infra-red (2500 nm) changes with temperature, it is in this way that the transition temperature is determined.