The hand-held scanner FHS1 is used for the non-destructive testing of parts which are electrically non-conducting. It consists of a scan module and a laptop as control and display module. Between both modules there is a wireless communication via Bluetooth. The scan module is fixed on the surface of the device under test by vacuum suction cups. The sensor can be guided by hand across an area of about 300 mm x 300 mm. Then a planar image of the reflection coefficient develops which shows the distribution of inhomogeneities under the surface of the device.