Theory of double magnetic induction (DMI) for measuring eye movements: correction for nonlinearity and simple calibration in two dimensions

An analytical theory approach, based on the concept of mutual induction, to describe the double magnetic induction method for measuring eye movements is presented. A polynomial approach to quantify the method´s inherent nonlinearity is evaluated. The solutions to the one-dimensional problem are further elaborated, giving a simple approximation of the two-dimensional problem. The tow-dimensional approximation provides an easily applicable tool for double magnetic induction calibration. According to this theory, calibrations need only be performed parallel to the two main magnetic fields. As a final results, eye rotations are given in any direction as a function of the two measured induction voltages.