Stress mitigation of replicated composite mirrors via multi-layer replication

Geena Ferrelli; Hyun Kim; Rafael Zaldivar

doi:10.1117/12.2675487

4 October 2023 Stress mitigation of replicated composite mirrors via multi-layer replication

Geena Ferrelli, Hyun Kim, Rafael Zaldivar

Proceedings Volume 12677, Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems IV; 1267702 (2023) https://doi.org/10.1117/12.2675487
Event: SPIE Optical Engineering + Applications, 2023, San Diego, California, United States

Abstract

Replicated composite optics offer a route to manufacture precision mirrors for satellite applications in a fraction of time and with substantial cost and weight savings over conventional glass mirrors. However, the dimensional stability is a critical barrier to entry for utilizing these mirrors in UV/Vis space applications due to the organic nature of the optical surface and its susceptibly to environmentally-induced distortions that can cause deviations greater than SFE λ/20 (~32nm). Recently, advances in this technology have been achieved at The Aerospace Corporation by using UV cured replicating epoxy resins to produce replicated mirrors with relatively zero residual stress and high hygroscopic stability with RT processing. Elevated thermal stability, though, remains a critical issue as CTE mismatch between the composite and resin lead to residual stress formation which immediately degrades the optical quality and then causes further optical drift over time as stress relaxation occurs. In this paper, we demonstrate improved thermal stability of replicated mirrors by utilizing multiple replication layers where buried compliant layers accumulate residual stress and the top layer is an optimized high modulus resin that achieves a high-quality replication. As a result, thermal stresses incurred by elevated temperatures were reduced by more than 60% when measured via laser interferometry. Additionally, due to faster stress relaxation rates of the compliant layers, the CTE mismatch stress was removed in a matter of days versus years of a conventional single layer replication. This stack-up provides a route to mitigate stress and enhance replication stability.

Conference Presentation

(2023) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Geena Ferrelli, Hyun Kim, and Rafael Zaldivar "Stress mitigation of replicated composite mirrors via multi-layer replication", Proc. SPIE 12677, Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems IV, 1267702 (4 October 2023); https://doi.org/10.1117/12.2675487

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