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

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.