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针对频率扫描激光干涉测距系统的参考干涉仪中存在的大量光学元件会产生非线性误差,本文基于偏振分光镜(PBS)的非理想分光性能分析了非线性误差的产生机制,推导出PBS非理想分光性能条件下的非线性误差模型,并提出了消除非线性误差的改进方法。利用MATLAB进行建模仿真表明,PBS非理想透射率和反射率对非线性误差的影响为二次谐波,透射率和反射率相差越大,非线性误差越大,当二者值相等时非线性误差大幅减小。当PBS反射率为0.90且透射率为0.97时,用传统的正交检测方法产生最大为383.3 kHz的非线性误差,而采用本文提出的方法只存在5.3 kHz的线性误差。
A large number of optical components exist in the reference interferometer for frequency-scanning laser interferometry ranging system, which will lead to nonlinear error. Based on the non-ideal spectral performance of polarization beam splitter (PBS), the mechanism of nonlinear error is analyzed, The nonlinear error model under the ideal spectral performance condition is proposed and an improved method to eliminate the nonlinear error is proposed. Modeling and simulation using MATLAB shows that the influence of non-ideal PBS transmittance and reflectivity on the nonlinear error is second harmonic, the greater the difference between the transmittance and the reflectivity, the greater the nonlinear error, and when the two values are equal The linearity error is greatly reduced. When the PBS reflectivity was 0.90 and the transmissivity was 0.97, the conventional quadrature method was used to generate nonlinear errors up to 383.3 kHz, whereas the proposed method presented only 5.3 kHz linearity errors.