Safe probe for high electric field measurements

The present study concerns an optical electric field measuring device using a lithium niobate (LiNbO₃) crystal as sensing medium, without any contacting electrode. Such a device has the advantage of providing a good galvanic insulation of materials and persons. A likely application is electric field measurement near electric power installations (frequency 50-60 Hz). The principle of measurement implements the electro-optical effect in the crystals and results from the way in which polarized light is analyzed after going through the crystal. Experimental setups have been developed in order to both validate the physical principle, and calibrate the probe. Simulations of this device with the finite element method being in good agreement with experiment, the implementation of the probe in the foreseen environment are studied. Then, a probe prototype, for which measurement can be realized far away with optical fibers, is performed. Simulated and experimental results near electric power installations are discussed. The results obtained using the prototype are very promising so far.