Open AccessStress-induced deformation of the coating on large lightweight freeform optics
Author(s) -
Guanbo Qiao,
Haixiang Hu,
Xuejun Zhang,
Xiao Luo,
Xue Deng,
Ge Zhang,
Liqi Yi,
Yu Yang,
Wei Deng
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.414953
Subject(s) - materials science , optics , coating , finite element method , fabrication , deformation (meteorology) , optical coating , stress (linguistics) , ray tracing (physics) , composite material , structural engineering , physics , engineering , medicine , linguistics , philosophy , alternative medicine , pathology
Large aperture, lightweight optics are frequently utilized in modern optical systems. However, despite the use of advanced techniques for developing their materials, fabrication, and mechanical structure, the coatings placed on the substrates induce slight lattice mismatches and increase the thin film stress on polished surfaces. This significantly distorts nano-accuracy optical surfaces, especially on lightweight freeform surfaces. In this study, we construct a finite element model (FEM) and a ray tracing model to estimate the impact of the stress-induced deformation of the coating on a 1.5m class lightweight silicon carbine (SiC) mirror with a freeform surface. Our simulation results are within 10% deviation from the experimental results, and the deformation texture map matches these results as well. We discuss several possible strategies to overcome stress-induced deformation, including fabrication pre-compensation, lightweight structure redesign, and an inverse print-through effect.