Measurement of current, voltage and power using single quartz crystal

Electrical quantities are now measured by fiber-optic sensors. Usually, these quantities are measured using electro-optic crystals and Faraday rotating materials, separately. Such sensors have a long history and are now utilized in various fields. In this paper, a new proposal to measure electrical quantities using one laser beam, one fiber and, moreover, only one crystal, is described. The quantities to be measured are voltage, current and electric power. This simultaneous measurement can be done using two independent parameters, namely, the ellipticity and the angle of the polarization of one light beam. The proposed design of this simultaneous sensor is given. As the sensing crystal, a quartz crystal is utilized. Since this quartz sensor is less sensitive than lithium niobate or flint glass, this is adequate for application to high-power electronics. The advantageous points of this optical sensor are common with other optical sensors: they have no contact in the measurement, they do not use the power supply at the sensing point and they have no induction noise.