We present a novel optical current sensor architecture based on the Faraday effect. In the proposed sensor, the light source is an incandescent lamp driven by the electric current induced in a small solenoid placed near the conductor carrying the current to be measured. After passing through the sensor head, the light travels in the free space, reaching a photodetector placed some distance away from the conductor carrying the current. The proposed sensor head with its self-induced light source can be constructed as a compact unit. It works autonomously without requiring a precise alignment with additional optics (e.g., polarization-maintaining fibers to carry light to or from the magneto-optical material).
Jose A. Ferrari,
Erna M. Frins,
César Daniel Perciante,
"Optical current sensor using a self-induced light source," Optical Engineering 43(9), (1 September 2004). http://dx.doi.org/10.1117/1.1778176