Electro-optic voltage sensor

摘要

A true dV/dt voltage sensor having no need for a ground reference for measurement. The sensor is connected at two places on the electric line to be measured. The voltage wave has a delay between the two places on the line and the difference is sensed and converted into a voltage measurement. Another approach is to connect the sensor at one place on the electric line. This approach has the second connection through a phase delay circuit that has an input connected to the same place. The delay between the one connection and the output of the phase delay circuit is sensed and converted into a voltage measurement. The sensed difference is a voltage, which is applied across a device, such as an electro-optic crystal, an integrated optic circuit (IOC) or a Mach Zehnder interferometer, which is a light medium that has a birefringence or an index of refraction that varies with changes of applied voltage. The variation of birefringence changes the polarization state of the light going through the device. The intensity of at least one polarization of light is detected and converted to an electrical signal. The intensity of the two interfering light beams from the legs of the Mach Zehnder interferometer is a function of the measured voltage. The electrical signal is integrated into a signal indicative of the magnitude of the voltage being measured on the electric line.