线性双折射对不同类型光学玻璃电流互感器输出特性的影响

Effects of Linear Birefringence Upon Performances of Different Designs of Optical Glass Current Transformers

推导了线性双折射对具有折返双环光路的正交共轭反射式、直接反射式及屋脊棱镜反射式光学玻璃电流传感器输出的影响,并与单环光路光学玻璃电流传感器进行比较。结果表明:在入射光以kπ/4(k=0,1,2…)起偏的情况下,以单环光路光学玻璃电流传感器为基准,正交反射式传感方案可不加大线性双折射对系统影响,同时将系统灵敏度提高一倍;直接反射式传感方案在提高系统灵敏度的同时也增大线性双折射对系统的影响;屋脊棱镜反射式传感方案系统灵敏度随线性双折射的减小而减小;如果不采用可分离线性双折射与Faraday效应的信号处理方案,上述各种折返双环光路传感方案不能消除线性双折射对系统的影响。

The formulae reflecting the effects of the linear birefringence（LB） upon the performances of the Bulk Glass Optical Current Transformers（BGOCTs） with return-back dual-loop optical path, such as the Orthoconjugate Reflector （OCR）-typed, the Direct Reflection （DR）-typed and the Roof-prism Reflection （RPR）-typed BGOCTs, are derived and compared with that of the BGOCT with single-loop optical path. The results show that the OCR-typed BGOCT will rise the system sensitivity about 2 times, on the premise of not increasing the effects of the LB; the DR-typed BGOCT will increase the effects of the LB along with the rising of the system sensitivity; while for the RPR-typed BGOCT, the change of the system sensitivity will depend on the LB inside the sensing head, when the polarizing angle of the input light beam is kπ/4（k=0,1,2...） and compared with the single-loop BGOCT. These conclusions indicate that the return-back dual-loop current sensing designs with conventional signal processing scheme of ＂-/＋＂ mentioned above cannot eliminate the harmful effects of the LB thoroughly, if suitable signal processing schemes, which can separate the LB from Faraday effect, are not used.