Detection of defects buried in metallic samples by scanning microwave microscopy

This paper reports the local detection of buried calibrated metal defects in metal samples by a new experimental technique, scanning microwave microscopy. This technique combines the electromagnetic measurement capabilities of a microwave vector network analyzer with the subnanometer-resolution capabilities of an atomic force microscope. The network analyzer authorizes the use of several frequencies in the range 1-6 GHz, allowing three-dimensional tomographical investigation, which is useful for the detection of bulk defects in metal materials.