Curvature-Adoptive CNC Machining of Freeform Optics via Dynamic Tangential Toolpath Optimization

The manufacturing of freeform optical lenses, essential for advanced applications such as Earth observation and laser fusion, demands exceptional surface accuracy and lightweight designs. However, their complex, non-symmetrical geometries present significant manufacturing challenges. Conventional CNC machining strategies, which rely on fixed Cartesian step sizes, are inherently inefficient for surfaces with rapidly varying curvature. This inadequacy results in non-uniform material removal, prolonged machining times, and substandard surface quality. This study presents a novel curvature-adaptive machining strategy based on dynamic tangential toolpath optimization. The method continuously aligns the toolpath with the local surface geometry to maintain uniform cutting conditions. A dedicated computer-aided manufacturing (CAM) software environment was developed to generate the optimized toolpaths and corresponding G-code. Experimental validation on representative freeform optics demonstrated a substantial improvement in precision: a single error-compensation iteration achieved a reduction in peak-to-valley form error of up to 48.4%. The results confirm that the proposed strategy significantly outperforms conventional fixed-step methods, delivering superior surface finish, reduced machining time, and enhanced process flexibility without requiring specialized hardware. This work establishes a practical and high-precision advancement for the manufacture of high-performance freeform optical systems.