方波调制消除Wollaston棱镜非线性系数对空间测角的影响

Square wave modulation to eliminate the influence of Wollaston prism nonlinear coefficients on spatial angle measurement

建立了一种基于Wollaston棱镜偏振分束的空间测角模型。对于Wollaston棱镜出射光强对系统测角精度带来的影响做了简要的理论分析和仿真,仿真结果表明出射光强偏离马吕斯定律,出现了一定的非线性偏差,且Wollaston棱镜的非线性偏差对空间测角装置的测角精度影响很大,降低了装置的实用价值。提出了一种采用方波磁光调制提高测角精度的方法,该方法有效消除了Wollaston棱镜的非线性系数、磁光玻璃的调制度波动、电路增益差异及光强波动的影响,且该方法相对正弦磁光调制方法更容易实现。最后通过相关的对比实验,采用该方法系统在-8°^+8°范围内能够达到15″的测角精度。

A spatial angle measurement model was established based on polarizing beam splitting principle of Wollaston prism. The influence of exit light intensity from Wollaston prism on the system angle measurement accuracy was made by theoretical analysis and simulation briefly. The simulation results show that the exit light intensity deviates from the Malus′ law, a certain nonlinear deviation is presented, and there is a great influence of the nonlinear deviation of Wollaston prism on the angle measurement accuracy of spatial angle measurement, the practical value of the device is reduced. Furthermor, a method of square wave magneto-optical modulation was presented to improve the angle measurement accuracy, which effectively eliminated the influence of nonlinear coefficients of Wollaston prism, fluctuations of magneto-optical glass modulation, differences of circuit gain and fluctuations of the light intensity. Finally, by doing relevant experiments, the system angle measurement accuracy can reach 15″in the range of-8＆#176; to＋8＆#176; by using this method.