Optical Voltage Sensor Using Single Fresnel Rhomb ${\rm Bi}_{4}{\rm Ge}_{3}{\rm O}_{12}$ Crystal

A novel optical voltage sensor is proposed by the use of single Fresnel rhomb bismuth germanate crystal. The optical sensing unit is only composed of one voltage sensing crystal and two prism polarizers. The distinguished feature is that the voltage sensing crystal is simultaneously used as a Fresnel rhomb quarter waveplate. An optical phase bias of π/2 is produced by two times of total internal reflection of light wave in the sensing crystal itself, thus additional quarter waveplate usually used in conventional voltage sensor can be removed. Besides the compact optical configuration, the proposed voltage sensor demonstrates larger linear measurement range and good temperature stability in experiments. The ac voltage in the range of 2000 V was measured with a nonlinear error <;0.82% and a measurement sensitivity of 2.2 mV/V, and corresponding temperature drift of the output voltage was <;0.9% for ambient temperature change in the range of (-10 ~ +50) °C.