OPTIMIZATION OF SIGNAL-TO-NOISE RATIO IN AN OPTICAL CURRENT MEASUREMENT SYSTEM USING DIFFERENT DETECTION SCHEMES

The comparative performance of two alternative detection schemes used in an optical current measurement system are stimulated and theoretica lly analysed. An appropriate experimental arrangement is constructed t o measure and compare the signal-to-noise (S/N) ratio obtained for the se two detection schemes under conditions of the same level of noise b eing induced. Both simulated and experimental results show that the se nsitivity and the signal-to-noise ratio of an optical current measurem ent system varies with the changing of the detection scheme and the cr oss-polarisation angle between the polariser and analyser. The highest sensitivity and the largest signal-to-noise ratio are obtained when u sing differential detection and a 45 degrees cross-polarisation angle. These positive results suggest that such systems may find wider appli cation in current sensing.