基于铌酸锂晶体自身角度光偏置的光学电压传感器

Optical Voltage Sensor Using Angular Optical Biasing in Lithium Niobate Crystal

提出了一种利用单轴电光晶体自身角度光偏置的新型光学电压传感器，其光学传感单元由夹在两个正交偏振器之间的一个单轴电光晶体组成.与以往利用四分之一波片产生光偏置不同，新型电压传感器利用单轴传感晶体的自然双折射和近轴光束，将传感晶体沿电光双折射主轴方向转动一个小的角度，产生π/2的角度光偏置.因此，可在不需要附加四分之一波片的条件下实现电压的线性传感.利用单块铌酸锂晶体作为传感元件，对0.2-35 V交流电压进行测量的非线性误差低于1.8%.此外，计算表明基于铌酸锂晶体的π/2角度光偏置的温度漂移率低于普通多级石英波片.新型传感器简化了光学电压传感器结构，降低了成本，并避免了以往传感器中附加四分之一波片对传感器性能的不利影响.

A novel optical voltage sensor is proposed which is based on the angular optical biasing in uniaxial electrooptic crystal. The optical sensing unit is only composed of a sensing crystal and two orthogonal polarizers. Different from the previous optical voltage sensor using a quarter waveplate, this new sensing scheme utilizes the natural birefringence of uniaxial crystal and its paraxial light beam, and the n/2 optical biasing can be produced by a small angular deviation of optic axis from light beam. Thus, the linear measurement of voltage can be achieved even though there is no additional quarter waveplate. The ac voltage in the range of 0.2- 35 V has been measured by the use of a single lithium niobate crystal, and the nonlinear error is less than 1.8%. In addition, the temperature drift ratio of the n/2 optical biasing in lithium niobate crystal theoretically is lower than that of the general multi-order quartz waveplate. Compared with some previous optical voltage sensors, this new sensor has simple configuration and low cost, and there is no disadvantages caused by additional quarter waveplate.