基于差分进化算法的微秒级超高速椭偏测量研究

Microsecond ultra-high speed ellipsometry measurement technology based on differential evolutionary algorithm

  • 摘要: 针对传统机械旋转补偿器型椭偏测量时间分辨率低、稳定性较差等问题,提出一种基于差分进化算法的穆勒矩阵求解系统模型,在此基础上结合超高速弹光调制实现了全穆勒矩阵微秒级测量。首先,通过对双驱动弹光调制器(photoelastic modulator,PEM)的工作模式展开研究,证明了在纯行波模式下,能够实现快轴方向的快速且周期性的旋转;然后,设计并加工了驱动频率分别为60 kHz和100 kHz的PEMs,构建了基于双驱动PEM的超高速椭偏测量模型,通过差分进化算法进行光强拟合,建立了穆勒矩阵求解系统模型,求解得到其光学周期在微秒级,对样品穆勒矩阵所有元素拟合的均方误差均小于0.001。

     

    Abstract: Aiming at the problems of low time resolution and poor stability of traditional mechanical rotary compensator ellipsometry, a system model for solving Muller matrix based on differential evolution algorithm was proposed. On this basis, the microsecond-level measurement of full Mueller matrix was achieved by combining ultra-high speed photoelastic modulation. Firstly, by studying the working mode of the double driven photoelastic modulator (PEM), it was proved that in the pure traveling wave mode, fast and periodic rotation in the fast axis direction could be achieved. Then, the PEMs with driving frequencies of 60 kHz and 100 kHz were designed and fabricated, and a ultra-high speed ellipsometry model based on dual driving PEM was constructed. The light intensity was fitted through differential evolution algorithm, and a system model for solving Muller matrix was established. The optical period was found to be in microseconds, and the mean square error of fitting all elements of the sample Muller matrix was less than 0.001.

     

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