Non-contact lens metrology from optical flow and differentiable ray tracing

Abstract

Accurate lens surface metrology is essential to determine the manufactured geometry of refractive optical elements and their deviation from the specified design. We demonstrate a transmission metrology method that reconstructs refractive lens surfaces from the displacement of a wavelet-noise-patterned mask. Lens-induced distortion is represented by a dense displacement field. A differentiable ray tracer fits the lens geometry using a calibrated near-telecentric camera model with an effective finite ray origin. We validate the method on commercial lenses. The recovered geometries agree with nominal specifications, and the plano-aspheric reconstruction is compared with chromatic confocal profilometry.

arXiv comment40 pages, 25 figures, including supplementary material. Main manuscript: 11 pages, 5 figures; supplement: 29 pages, 20 figures