Measuring eye position with the double magnetic induction method

The double magnetic induction method of monitoring eye movements eliminates problems associated with the external wire leads of the standard magnetic search-coil technique by substituting a closed metal ring for the eye coil. However, external coils used in the double-induction method must be adjusted at the beginning of each session, and the system is very sensitive to mechanical disturbances. An apparatus is described whose ease of adjustment and good mechanical stability make the double-induction method as convenient and reliable as the standard method. The performance of the system is evaluated for different physical arrangements of critical components, and some practical advice on various aspects of the double-induction method is offered.