Magnetic search coil system for linear detection of three-dimensional angular movements

The design of a two-dimensional magnetic field search coil system based on the extension of the phase detection principle for measuring the angular position and displacements of a search coil in three-dimensional space is described. The extended phase detection principle was implemented in a two-axis angular detector, which generates a spatially rotating magnetic field. The system was developed to record horizontal and vertical eye and head movements of small, unrestrained laboratory animals. It is also applicable for measuring 3-D eye and head movements in primates and man. The output is linear over 355 degrees in the horizontal plane and over +or-60 degrees in the vertical direction. The procedure of recording 3-D eye and head movements is discussed.