The development of coherent modes decoupling method for partially coherent light transport system

Abstract

Accurate simulation of partially coherent light transport system is critical for the design and optimization of fourth-generation Diffraction-Limited Storage Rings (DLSR) beamlines and advanced lithographic systems. However, traditional wave-optics approaches based on Coherent Mode Decomposition (CMD) suffer from prohibitive computational costs due to the necessity of propagating massive sets of two-dimensional (2D) modes. In this paper, we propose a Coherent Mode Decoupling (CMDC) algorithm designed to accelerate these simulations without compromising accuracy. The CMDC method utilizes Singular Value Decomposition (SVD) to factorize complex 2D coherent modes into efficient, separable one-dimensional (1D) components in either Cartesian or Polar coordinates. Crucially, the algorithm incorporates a robust residual correction mechanism that captures non-separable coupling effects—induced by source intrinsic asymmetry or optical aberrations—via a compressed subspace of 2D residual modes. We validated the method using the Hard X-ray Coherent Scattering (HXCS) beamline at the High Energy Photon Source (HEPS). The results demonstrate that CMDC achieves excellent R2 even under significant optical aberrations (Strehl Ratio = 0.7). For a complete optical system simulation, the computational time is reduced by two orders of magnitude compared to full 2D propagation. The proposed framework offers a flexible balance between speed and precision, making it a powerful tool for partially coherent optical transport systems.

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