Compact magnetic gradiometer and its astatization

We present a compact (10-cm head size, 3-cm base) axial magnetic gradiometer with a method of its astatization (i.e. suppression of false response to homogeneous field). For astatization, we use two integrated orthogonal sensors and a second -order polynomial correction; after astatization the gradiometer error is suppressed more than 1000x. The gradiometer has been successfully used in a real -world metal -detection task which was allowed by the low gradiometer astatization error of 50 nT/m and its noise of 1 nT/(m root Hz) @ 1 Hz. (C) 2015 article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-ric-nd/4.0/) Peer-review under responsibility of the organizing committee of EUROSENSORS The Authors. Published by Elsevier Ltd. This is an open access