Three-stage group-by-group physicalization method for automatic zoom lens design based on principal-plane matching

Automatic initial-structure design for zoom lenses is challenging because an ideal layout must be converted into real lens groups without disrupting the coupled ray states and principal-plane separations across zoom positions. We propose a three-stage group-by-group physicalization method. It generates first-order zoom layouts, sequentially physicalizes the groups by inheriting upstream ray states and matching principal-plane separations, and then assembles and refines complete systems. Differentiable surface-intersection and total-internal-reflection losses estimated from paraxial rays screen infeasible structures before full-system real-ray tracing. Tests on 3 × and 40 × visible zoom lenses and a 30 × infrared zoom lens produced thousands of constraint-satisfying structures within tens of minutes. Ablation studies further show that the sequential strategy and ray-feasibility constraints substantially increase both the number and rate of ray-traceable candidates. The method therefore provides an efficient route to practical zoom-lens initial structures.