THEORETICAL-ANALYSIS OF THE SURFACE THERMAL-WAVE TECHNIQUE FOR MEASURING THE THERMAL-DIFFUSIVITY OF THIN SLABS

We present a theoretical analysis of a photo-thermal radiometry method of measuring thermal diffusivity, in which thermal radiation is detec ted from a small area, displaced by known distances from an area of mo dulated optical excitation. Expressions for evaluating the measurement s and their main systematic errors have been worked out for thermally thin slab samples. The measurements, data and error analysis technique s are illustrated with experiments on metallic and polymeric samples. These show that the main systematic errors are associated with the spa tial resolution of the apparatus and heat losses to air and thermal ra diation.