Abstract: Method and system for detecting magnetic contaminants in products (160). The product (160) is transported past magnetic sensors (170, 180) which return a first sensed signal S1 (172) and a second sensed signal S2 (182) being time-spaced received versions of the source signal produced by the product (160). From the sensed signals (172, 182) it is determined whether a magnetic contaminant has been detected. Gradiometry may be applied between the signals (172, 182). A so-called auto-cross-correlation comprising +/?(CC1+CC2?AC1?AC2) derived from the cross-correlation (CC1) of S1 with S2, the cross-correlation (CC2) of S2 with S1, the autocorrelation (AC1) of S1 and the autocorrelation (AC2) of S2, may be used to improve signal recovery from noise. The auto-cross-correlation may be applied in other applications.

Abstract: A nano-SQUID (superconducting quantum interference device) method and system for detecting a magnetic field associated with a nano-sample. A magnetic field of a nano-sample (1130) is coupled through the nano-SQUID hole/loop (720), by placing the sample within the SQUID loop. A static field (Bp) is applied across the nano-SQUID, substantially perpendicular to a sensitivity axis of the nano-SQUID. A perturbation field (Bm) is applied across the nano-SQUID, substantially perpendicular to the sensitivity axis of the nano-SQUID and substantially perpendicular to the static field. A behaviour of the magnetic field of the nano-sample caused by the static field and perturbation field is monitored by monitoring an output of the nano-SQUID. The nano-SQUID can be operated in open loop mode without flux locked loop.

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 analyzed 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.