CEAS Space Journal

, Volume 11, Issue 4, pp 533–541 | Cite as

Thin glass shells for active optics for future space telescopes

  • G. VecchiEmail author
  • S. Basso
  • M. Civitani
  • M. Ghigo
  • G. Pareschi
  • B. Salmaso
Original Paper


We present a method for the manufacturing of thin shells of glass, which appears promising for the development of active optics for future space telescopes. The method exploits the synergy of different mature technologies, and leverages the commercial availability of large, high-quality sheets of glass, with thickness up to few millimeters. The first step of the method foresees the pre-shaping of flat substrates of glass by replicating the accurate shape of a mold via direct hot slumping technology. The replication concept is advantageous for making large optics composed of many identical or similar segments. After the hot slumping, the shape error residual on the optical surface is addressed by applying a deterministic sub-aperture technology as computer-controlled bonnet polishing and/or ion beam figuring. Here we focus on the bonnet polishing case, during which the thin, deformable substrate of glass is temporarily stiffened by a removable holder. In this paper, we report on the results so far achieved on a 130 mm glass shell case study.


Active optics Adaptive optics Glass slumping Lightweight mirrors Space telescopes Sub-aperture polishing Thin glass shells 



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Copyright information

© CEAS 2019

Authors and Affiliations

  1. 1.INAF-Brera Astronomical ObservatoryMerateItaly

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