ABSTRACT
Glass block current sensors measure current according to Ampère’s law by integrating the magnetic field along a single or multiple closed optical paths around the current conductor. Multiple total internal reflections within the block steer the linearly polarized light onto a closed path. Upon reflection, the light’s linear polarization state is maintained or restored by working with two ortho-conjugate total internal reflections at the corners of a square-shaped block, internal reflections at the critical angle of triangular or circular devices, or appropriate multilayer dielectric coatings. A field installation of a glass block sensor is illustrated. The chapter finishes with some conclusions from long-term experience with this sensor type.
