New design of optical electric-current sensor for sensitivity improvement

A new design of optical electric-current sensor based on the Faraday effect is proposed and demonstrated experimentally. The sensor probe is a precisely cut glass prism with a high reflection coating on the base surface at the far end. Inside the prism, the light beam is allowed to bounce up and down at the critical angle and retrace its path back by the reflection coating. The sensor demonstrated offers a sensitivity of six times higher as compared with conventional designs and suffers from fewer optical losses. The design can also reduce the package size of the sensor probe.