Iterative refinement of arbitrary micro-optical surfaces

We introduce an adaptive optical refinement method enabling ultra-precise micro-milling of arbitrary surfaces. Through repeated iteration, our method reduces surface error without requiring significant specific surface engineering. This remediates the long sample preparation times and lack of refinement capability that previously reported methods suffer from. The iterative refinement milling method was used to produce spherical mirrors with small radii of curvature and low surface roughness for use in micro Fabry-Perot cavities. We demonstrate the use of this adaptive process to produce a variety of arbitrary surface geometries on both optical fiber tips as well as optical flats. We additionally discuss our capability to apply iterative refinement milling adaptively to various materials, including to construct gradient index (GRIN) lenses.