Magneto-optical electric-current sensor with enhanced sensitivity

In this design note, an air-gapped ring core type Faraday-effect optical current sensor using a new sensing element design is described. The sensing element is a finely polished glass prism with highly reflective coating on the two end surfaces, which is designed in such a way that the light beam propagating through it undergoes 20 critical-angle reflections at the glass-air interfaces. The current sensitivity of this new design is almost three times higher than that of a previous design based on a similar principle.