Visualization and study of heat diffusion in glass by a compact schlieren system

The experimental study of heat diffusion in glass by a compact schlieren system is presented. The schlieren system has been set up with a single transverse mode laser diode as light source. We have used a plane thermal source (a heated metal plate) to generate thermal fields in a plane glass plate sitting perpendicular to the thermal source. The schlieren images were recorded using a CCD camera and a video recorder connected to a PC. A specific software did a further digital image processing. The experimental results have been checked against a theoretical model of the heat diffusion in an infinite medium at a strong and short thermal excitation by a plane thermal source. A good agreement between experimental and theoretical results was found, up to some differences between the experimental conditions and the theoretical hypotheses, which validate this method as a quantitative one in such experiments.