Measuring thermal conductivity tensor of orthotropic solid bodies

A non-destructive technique for measuring thermal conductivity of solid bodies is developed and described. The experiments are based on laser flash heating of two surfaces of the investigated body. The spatial and temporal temperature distributions are then measured using an infrared camera. The entries of the thermal conductivity tensor are retrieved using an inverse method, which iteratively invokes a direct numerical solver. The technique is applied to simple cuboid geometry. An extension of this method to arbitrary shapes is possible and requires capturing the geometry by laser scaling and laser heating from more directions. The special definition of the variables makes the technique insensitive to the emissivity of the surface and the laser energy absorbed by the sample.