Design of layered sapphire composites with ablation-tunable coefficient of thermal expansion

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Composites with high elastic modulus, high specific stiffness, and ultra-low coefficient of thermal expansion (ppb/K-level) will likely be necessary for future ultra-stable optomechanical systems, such as space telescopes for high-contrast imaging. Carbon fiber reinforced polymers (CFRP) offer many favorable properties but suffer from instability due to moisture absorption and creep, and currently cannot cost-effectively achieve the 1-5 ppb/K coefficient of thermal expansion (CTE) required. New materials are desired with high elastic modulus, high specific stiffness, and ppb/K-level CTE. This paper presents three composite designs whose CTE is tunable by ablating material from one or more layers after fabrication and CTE metrology. Each composite design contains sapphire facesheets and a core material of fused silica, silicon carbide or Allvar® to achieve zero- and tunable-CTE. Finite element models reveal that each composite design exhibits CTE tunability of 200-800 ppb/K. The specific stiffness of the Sapphire-Allvar® composite design is around 60 GPa/(g/cc), whereas the others have lower specific stiffness < 20 GPa/(g/cc). These designs demonstrate the principle of tunable low-CTE materials that may have promise for future ultra-stable telescopes.

Original languageEnglish (US)
Title of host publicationOptomechanical Engineering 2023
EditorsKeith B. Doyle, Brandon D. Chalifoux, Kenneth R. Castle, Jose M. Sasian
ISBN (Electronic)9781510665521
StatePublished - 2023
EventOptomechanical Engineering 2023 - San Diego, United States
Duration: Aug 23 2023 → …

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceOptomechanical Engineering 2023
Country/TerritoryUnited States
CitySan Diego
Period8/23/23 → …


  • coefficient of thermal expansion
  • composite materials
  • ultrafast laser material processing
  • ultrastable structures

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


Dive into the research topics of 'Design of layered sapphire composites with ablation-tunable coefficient of thermal expansion'. Together they form a unique fingerprint.

Cite this