Ultrafast beam steering with microradian tracking accuracy via feedforward tuning and real-time error compensation

Abstract

Beam steering is crucial in laser precision manufacturing, as its deflection range, response time, and accuracy of beam steering significantly affect the production scale, throughput, and quality. Recent advancements focus on integrating galvanometer scanners and acousto-optic deflectors (AODs) into a cascaded acousto-optic and galvanometric scanning (AOGS) system, which offers both large deflection ranges and ultrafast response times. However, the tracking accuracy of the AOGS system remains constrained by the mechanical inertia of galvanometers. This study addresses this limitation by utilizing AODs to compensate for the tracking error of galvanometers in real time, with the compensation effectiveness achieved through the synchronization of the AOGS system and the implementation of a novel frequency-domain iterative feedforward tuning (FD-IFFT) method. Specifically, the synchronization of the AOGS system enables the real-time compensation with the AODs. The FD-IFFT method achieves both high tracking accuracy and strong generalization to diverse trajectories, consistently maintaining the galvanometer tracking errors within the compensatory range of the AODs. Experimental results demonstrate that this approach enables beam steering with a response time below 10 $\mu$s, a tracking accuracy of single-digit microradians, and a sub-radian scanning range. Compared to existing AOGS systems, the proposed approach further enhances tracking accuracy and offers considerable potential for high-speed, high-precision, and large-scale laser direct processing.