Fabrication and On-Machine Metrology of Precision Optics

Abstract

High-quality precision spherical, aspheric, and freeform optics are in constant demand in the fields of astronomy, ophthalmology, the automobile industry, biomedical instrumentation, and fundamental research. But due to stringent requirements on surface finish, limited choice of material that is suitable for optimal optical performance, and specific application-based demands, all of these are driving different fabrication techniques development. This dissertation investigates these fabrication techniques, including digital light process-enabled 3D printing technology, single-point diamond turning (SPDT) fabrication, and precision glass molding technology. Another focus of this dissertation addresses the critical need for on-machine metrology (OMM) in the precision optics fabrication process, especially in the SPDT tool alignment process. A unique dual-mode OMM system has been developed, integrating polarization-based phase-shift for measuring surface form and roughness with laser interferometry mode and LED microscopy mode. It employs a defocus-model-based least squares (L2) regression and a convex-hull-based L2 regression approach for robust and accurate tool deviation outputs in X and Y axes. Additionally, it utilizes Zernike high-order approximation model to relax the OMM system alignment requirements, minimizing errors from part handling, offering a novel alternative solution to meet the critical demand for SPDT tool alignment process.