Ronchi lateral shearing interferometry (LSI) is widely used in wavefront measurements for advanced lithography tools. However, its accuracy is limited by interference from higher-order diffraction beams. This paper proposes a novel, to the best of our knowledge, hybrid optimization algorithm (HOA) to achieve robust and accurate Ronchi LSI measurements. A robust error function is constructed, which flexibly incorporates at least two interferograms. The proposed HOA employs particle swarm optimization (PSO) to perform a global search and generate effective initial value estimates. Subsequently, an advanced nonlinear optimizer iteratively refines these estimates to obtain the final demodulation results. Extensive validation demonstrates that the proposed algorithm outperforms existing methods, achieving superior accuracy and robustness.
Zhu et al. (Fri,) studied this question.