Measurement of Eye Movement with a Ferromagnetic Contact Ring

A new magnetic method for measurement of eye movement is presented. It is based on measurement of differential inductance variations of two C-shaped coils due to the movement of a conical ferromagnetic ring which fits on the sclera. High sensitivity over a wide dynamic range is obtained by using a tuned bridge and synchronous detector. Separation of the detector coils from the magnetic field source improves the resolution and stability, and enables a two-dimensional measurement with one pair of C-coils.