Design strategy for imaging systems containing freeform surfaces

Abstract

Motivations driven by the ever-growing system specifications, alongside the progress in optical manufacturing and metrology open widely the door for implementing freeform surfaces for imaging system performance enhancement. Meanwhile, new challenges regarding handling and analysis are posed for this surface type due to its lack of rotational symmetry. This thesis work focuses on the development of an appropriate aberration analysis tool, as well as implementation strategies of freeform surfaces in imaging systems. The Aldis theorem, which gives the surface contribution for one ray including all orders, is revisited as the foundation for freeform system analysis. With the original theorems limitations overcome, this new tool can serve as an alternative for the Seidel diagram, indicating the system sensitivity information for freeform systems. Furthermore, this thesis investigates the numerical approaches utilized for freeform implementation regarding freeform normalization radius, freeform order, optimization strategy, freeform interaction and early-stage manufacturability assessment for both one-freeform and two-freeform issues. As a consequence, the relation between the choice of the freeform location and system aberration constitutions is revealed with the assistance of the surface eccentricity parameter. A successive implementation strategy for freeform orders and freeform quantity is proposed in the form of a workflow. Diverse system examples are presented in the end as further validation of the findings.