Fiber-optic current sensor with improved isolation

Abstract

A current sensor coil design for reducing or eliminating long undulations of magnetic sensitivity. Such reduction or elimination improves isolation of the current sensor such that proximate currents and accompanying effects do not affect the accuracy of the current sensor determination of a current being measured. Several designs, which may be incorporated separately or in combination, include modifying the specifications of the quarter waveplate, cutting the fiber of the sensor coil to a proper length, choosing a proper perimeter length of the sensor coil or head, and using a particular length of fiber adjusted to work in conjunction with a multi-wavelength or broadband light source.