A vector magnetometer module for biomagnetic application

Multichannel SQUID systems are widely used for biomagnetic research. Common ly, these instruments measure one component of the magnetic vector field or one gradient of vector field. We have designed a vector magnetometer modul e allowing the recording of orthogonal vector components. The module is des igned as a cube with one liquid helium cooled SQUID mounted at each of its six faces. The mean values of signals from SQUIDs of opposite faces are est imates for the magnetic field components in the tenter of the cube. Due to Maxwell's third equation, the signals of the sis SQUIDs can be combined to yield zero. This allows an on-line check of the SQUID performance. The feat ures of the vector magnetometer module are illustrated by cardiac measureme nts. 3D graphics allow direct inspection of the magnetic field vector. The cube is designed to be used as a basic module of a multichannel SQUID syste m for biomagnetic application.