Design and analysis of single-layer f-θ metalens enabling wide-field-of-view, low-distortion scanning

Abstract

F-θ scanning lenses represent a critical component in laser systems for high-end intelligent manufacturing and optoelectronic applications, as they directly govern the system’s positioning accuracy, imaging resolution, and processing quality. In this work, we propose an ultra-thin (0.625 mm) single-sided monolithic f-θ metalens for 10.6μm laser scanning. Over a ± 40° field of view, the RMS spot radius is 15.8–35.4μm (average 28.39μm), the peak f-θ distortion is 0.0982%, and the Strehl ratio exceeds 0.99, indicating near-diffraction-limited performance. Using meta-atoms with a 3μm period, we systematically analyze three main error sources: fabrication defects, assembly tolerances, and wavelength drift. When the defective pixel ratio is below 8%, the Strehl ratio remains above 0.886. Radial misalignment within ±40 μm causes negligible spot shift and distortion change, while optical-axis tilt must remain within ±0.1°. The effective spectral bandwidth is 10.55–10.65μm. The single-sided monolithic design avoids multi-lens cascading, double-sided nanofabrication, and multilayer stacking, greatly simplifying fabrication and assembly. This metalens is well suited for portable laser welding and provides what appears to be a novel core device for chip-scale high-resolution imaging.