Design of asymmetrically loaded end-plates with vacuum seal surfaces for the navy prototype optical interferometer

Joshua P. Walton, James H. Clark, F. Ernesto Penado

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


Engineering specifications for O-ring seal surfaces are well documented. However, when seal surfaces are located on asymmetrically loaded vacuum end-plates, consideration must be given not only to surface finish and flatness, but also to load-induced deflections. When deflections are significant, O-ring compression can relax and potentially cause vacuum leaks. Large vacuum systems, such as the 9000 cubic foot system at the Navy Prototype Optical Interferometer (NPOI), cannot afford costly vacuum leaks due to improper end-plate design. The NPOI employs vacuum end-plates that serve both as structural members, and as vacuum system entrance and exit ports for stellar light. These ports consist of vacuum components attached directly to the end-plate via static O-ring sealing techniques. Optical geometry dictates off-center port locations, which create asymmetric end-plate loading. This paper details the behavior of a 22 inch diameter, multi-port, end-plate for the NPOI Fast Delay Line subsystem. In depth CAD modeling and finite element analysis techniques were used to determine load-induced stress distributions and deflections in the end-plate. After several design iterations, an end-plate design was substantiated that maintains vacuum seal integrity under loading, exhibits a conservative factor of safety, and is readily manufacturable.

Original languageEnglish (US)
Title of host publicationNew Developments in Optomechanics
StatePublished - 2007
EventNew Developments in Optomechanics - San Diego, CA, United States
Duration: Aug 28 2007Aug 30 2007

Publication series

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


OtherNew Developments in Optomechanics
Country/TerritoryUnited States
CitySan Diego, CA


  • Deflection
  • End-plate
  • FEA
  • NPOI
  • O-ring
  • Seal surface
  • Vacuum
  • Warpage

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 asymmetrically loaded end-plates with vacuum seal surfaces for the navy prototype optical interferometer'. Together they form a unique fingerprint.

Cite this