Vectorial calibration of 3D magnetic field sensor arrays

The vectorial calibration of magnetic field sensor arrays along three axes is presented. In this context, a distinction must be made between the calibration of alignment errors between the 3D sensors and the calibration of orthogonality errors between the three axes of a 3D sensor. Alignment errors within the sensor array are determined by using a homogeneous vector field generated by a 3D Helmholtz coil arrangement consisting of single octagonal coils. Two sophisticated methods to determine errors of orthogonality between the axes of a 3D sensor are described and compared. The first attempt was to calibrate the perpendicularity of the 3D coil system by means of a laser-interferometer controlled 90° turn of a solenoid coil and measuring the induced voltage. The second attempt was to use the mechanically fixed perpendicularity errors of the 3D sensor and the 3D coil system. By rotating the 3D sensor in the coil system, the perpendicularity errors of coil system and sensor are superimposed with changing signs and could therefore be calculated. The measurements are taken across a solenoid coil which can be calibrated by the PTB (Physikalisch-Technische Bundesanstalt-Federal Standards Laboratory)