Tiny crystal at a distance safely measures powerful electric fields

https://newsreleases.sandia.gov/remote_sensor/

Via email: Lithium niobate crystal + polarized laser light---> extreme voltage measurements at a distance! Even the best voltmeters available today will melt at extreme voltages. "No one had directly measured voltages this large anywhere in the world before our experiment. "...the technique is safe, efficient and inexpensive." The lithium niobate crystal is placed so that the EM field passes through its broadside at right angles to the polarized laser beam traveling along the crystal's axis. The EM field causes the polarized beam photons to travel at different speeds in the vertical and horizontal directions. This causes the beam to rotate which in turn alters the number of photons arriving at a photodetector. An instrument converts their intensity at the photodetector into a simple voltage. That simple voltage can then be read on an everyday oscilloscope. "The voltage measured on the oscilloscope is directly (proportional) to the target electrical field strength. "The signal is already in the correct form, and we just need to multiply by a fixed constant. "In our experiments, tens of megavolts translated into hundreds of millivolts on the oscilloscope. " ... could find its way into accelerator facilities where a series of crystals provide voltage readings at multiple remote locations. Could work anywhere one wants to remotely monitor a very high electrical current. Could reveal  an electrical short in a wall from a distance due to the disruption in the EM field surrounding the current-carrying wire.