采用Hilbert变换和非线性最小二乘回归分析相结合的方法提取白光干涉包络.Hilbert变换恢复了包络的大体形状,而非线性最小二乘回归则有效地确定了干涉光强主极大位置及幅度,从而得到耦合点位置、耦合强度、干涉条纹对比度及系统消光比等参数.对保偏光纤(PMF)的拍长测试结果表明,这种包络提取算法明显提高了测量的重复性,测量的重复性在μm量级.
Hilbert transform and nonlinear least square regression are applied to extract the envelope in the distributed polarization coupling analyzer. Hilbert transform is used to get the general shape of the envelope while the nonlinear least square regression can be used to get the accurate location and amplitude of the interference fringe. Consequently,the system can get the parameters, such as the location of the coupling point, coupling intensity, fringe visibility and the polarization extinction ratio. The beat length test results of Polarization-maintaining fiber(PMF) indicate that the envelope extraction has greatly improved the test repeatability and the test repeatability reaches to μm