调制函数对偏振调制激光测距精度影响分析

为减小传统激光测距方法中复杂电路系统对脉冲计时或相位比较引起的测距误差，针对偏振调制激光测距技术，利用电光调制器中晶体折射率随施加电场线性变化的特性，将待测物体反射的光脉冲调制成时间的函数，通过所得偏振光两个垂直方向上的光强比值求解待测距离。在研究其测距原理、距离方程及误差分析的基础上，推得文中测距方法所能达到理论测距精度的表达式，并分析调制过程中正弦、锯齿、指数三种调制函数对测距精度的影响，在相同距离范围内，锯齿函数具有更好的适用性，正弦函数与指数函数的组合函数具有更高的测距精度。进一步分析正弦函数不同波段对测距精度的影响可知，采用-/6~/6波段调制时其适用性及测距精度都有很大提高。研究结果对提高偏振调制激光测距精度具有重要意义。

Influence of modulation function on precision of laser ranging based on polarization modulation

In order to reduce the ranging error caused by the pulse timing or phase comparison of the complex circuit system in the traditional laser ranging method, the laser ranging based on polarization modulation was demonstrated. Using the characteristic that the crystal refractive index of the electro-optical modulator changed with the linear change of the applied electric field, the laser pulse reflected by the object to be measured was made into a function of time, and the distance was solved by the ratio of the light intensity in the two vertical directions. Based on the principle of distance measurement, distance equation and error analysis, the accuracy expression of theory ranging that was obtained by the ranging method in the paper, the influence of three kinds of modulation functions of sine, sawtooth and exponential on the accuracy of ranging was analyzed by simulation. In the same distance range, the sawtooth function had better applicability, and the combination of sine and exponential had higher accuracy of ranging. By analyzing the influence of different modulation bands of sine function on the accuracy of ranging, the applicability and the accuracy were greatly improved by using -/6-/6 band. The results will be helpful to improve the accuracy of laser ranging based on polarization modulation.