Abstract: A method and device for field detection are provided, in which one or more gradiometers (31, 32, 33) are positioned in the field and rotated about their axes. Rotation of a single gradiometer allows an output signal of the gradiometer to be analysed in the Fourier domain, which allows particular field components to be obtained, and also separates the field signal from noise, in the frequency domain. Use of three such rotating gradiometers with non-parallel axes allows a complete magnetic field gradient tensor to be obtained with data redundancy, and can reduce crosstalk.

Abstract: A superconducting magnetic field detection element (10) comprising at least one superconducting pick-up loop (12) formed on a common flexible substrate (11), wherein the common flexible substrate (11) is in a non-planar position, such that the at least one superconducting pick-up loop (12) is operable to detect magnetic fields of differing orientation.

Abstract: The invention provides for measurement of an actual magnitude of an applied magnetic field, rather than providing a value of magnetic field which is relative to an unknown quiescent value. In particular, by providing a SQUID (100) having an effective area which varies in response to applied flux, an absolute value of magnetic field can be determined due to the change in effective area of the SQUID (100).