High-Precision Metrology of Lens Mold Asphericity with High Dynamic Range Using Iterative Reverse Optimization in Radial Shearing Interferometry

We present a high-precision measurement procedure for lens mold asphericity with high dynamic range, incorporating a novel calibration strategy based on radial shearing interferometry (RSI). The RSI system was first modeled using ZEMAX^® ray-tracing software with a bulk-optics configuration and experimentally validated. A numerical approach, referred to as iterative reverse optimization, was introduced to adapt the initial lens design model to measured wavefront data. In this study, RSI was employed to rapidly minimize measurement departures, enabling calibration with a spherical target using multiple axial displacements at non-confocal positions combined with reverse optimization. The ZEMAX^® model was optimized to simultaneously fit all non-confocal experimental wavefront departures, thereby revealing complete system parameters, including assembly deviations and misalignments. The calibrated system was subsequently applied to measure the asphericity of a lens mold, with the aspheric surface parameters retrieved through the proposed reverse optimization procedure. The extracted asphericity showed excellent agreement with independent measurements performed by the Form Talysurf contact method. This approach demonstrates a flexible and practical route for measuring asphericities of varying degrees in non-null testing conditions.