Abstract
Thermal wave is produced at the surface of an aluminum block by irradiating intensity modulated CO2 gas laser. A cylindrical hollow created inside the block can be observed as an image from intensity or phase difference of the thermal wave scattered from the hollow and detected with a PZT placed at the back of the block. The modulation frequency of the laser is 4.16kHz and its power is 10W in the present work. This paper describes the special distribution as well as scattering mechanisms of the thermal wave in comparison of the experimentally obtained image with mathematical calculations.
