Precision measurement of high-aspect-ratio micro-hole aperture based on far-field diffraction FWHM analysis of Gaussian beams

Addressing the limitations of the traditional thin-aperture Airy model—which neglects waveguide confinement, edge truncation, and inner-wall scattering—a hybrid light-field reconstruction (HLFR) model is established and propagated using angular spectrum theory.

Comparative analysis shows that the main spot FWHM exhibits superior robustness against wavefront non-uniformity and non-ideal scattering compared to conventional Airy pattern features. By applying a dual-parameter adaptive correction combining aperture and hole length across 25 simulated samples, the relative FWHM inversion error is significantly reduced from 8.72% to within 1.20%. Experimental validation on four physical thick pinholes demonstrates strong consistency across propagation distances, with a blind-test deviation of approximately 0.5%.