End-to-end Surface Optimization for Light Control

TL;DR

This paper introduces an end-to-end differentiable optimization method for designing freeform optical surfaces that accurately control light distribution, incorporating geometric constraints for fabrication and using optimal transport to avoid local minima.

Contribution

It presents a novel differentiable rendering-based optimization framework combined with optimal transport to improve surface design accuracy and manufacturability.

Findings

Achieves close resemblance to target light distributions in simulations.

Successfully applied to physical prototypes demonstrating practical viability.

Enhances surface design robustness by integrating geometric constraints.

Abstract

Designing a freeform surface to reflect or refract light to achieve a target distribution is a challenging inverse problem. In this paper, we propose an end-to-end optimization strategy for an optical surface mesh. Our formulation leverages a novel differentiable rendering model, and is directly driven by the difference between the resulting light distribution and the target distribution. We also enforce geometric constraints related to fabrication requirements, to facilitate CNC milling and polishing of the designed surface. To address the issue of local minima, we formulate a face-based optimal transport problem between the current mesh and the target distribution, which makes effective large changes to the surface shape. The combination of our optimal transport update and rendering-guided optimization produces an optical surface design with a resulting image closely resembling the target, while the geometric constraints in our optimization help to ensure consistency between the rendering model and the final physical results. The effectiveness of our algorithm is demonstrated on a variety of target images using both simulated rendering and physical prototypes.