Improvement of spatial and field resolution in NDE systems using superconducting sensors

We present a NDE scanning system for industrial purposes in magnetically and electrically unshielded environment. In this scanning system, planar galvanically coupled dc SQUID gradiometers with a field gradient resolution of 300 fT.(cmHz/sup 1/2 /) in the white noise region are used. The spatial resolution is above 1 mm in this case. On the other hand many applications in NDE do not require the extraordinary sensitivity of SQUID based sensors. For those purposes hybrid sensors, in which Hall sensors are connected with high-T/sub c/ superconducting antennas, are an alternative sensor concept less sensitive than SQUID sensors but exhibiting better performance compared to other commercially available magnetic field sensors.