Differential Vortex Beam Interferometry for Nanometric Asymmetric Shaft Misalignment

This paper proposes a Misalignment Differential Vortex Beam Interferometer (MD-VBI) integrated with DenseNet-169 for high-precision asymmetric shaft alignment. The system employs a polarization-multiplexed differential configuration to linearly map nanometric displacement to interference-fringe rotations. Building upon the optical architecture’s intrinsic suppression of common-mode thermal drift, the DenseNet-169 model serves as a robust demodulation backend, further mitigating inherent system-level optical noise to precisely decode misalignment signatures in interferograms. Experimental results demonstrate a Mean Absolute Error (MAE) of 0.382 nm within a 0–500 nm range. By decoupling true asymmetric shaft misalignment from intrinsic system noise and common-mode drift, the system provides a robust, non-contact solution for nanometric metrology under realistic conditions.