Experimental verification of compliant mirror wavefront correction using a single actuator

James H. Clark, F. Ernesto Penado, Micha Heilman, Wyatt E. Clark

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

5 Scopus citations


The concavity of an initially flat wavefront typically increases after each reflection of the ten-reflection beam transport system at the Navy Precision Optical Interferometer (NPOI). Ideally, the exiting wavefront contour from the beam transport system preserves the original contour that enters. The beam transport system is common to and separate from the front-end, which includes primary light collectors such as siderostats or telescopes, and the back-end which includes major subsystems such as the optical delay lines, beam combiners and detectors. The beam transport system should have minimal influence on the interferometer. However, manufacturing tolerances and mount-induced deformations of each mirror collude to alter each reflected wavefront. All beam transport mirrors at the NPOI are slightly concave and each reflection adds to the concavity in the resultant wavefront. To improve the flatness of the resultant wavefront, we counter-deform a single mirror in the ten-reflection transport system. Previous analytical work using finite element analysis demonstrated the feasibility of this approach. In the present work, we have undertaken the task of verifying this approach experimentally. We set up a nine-reflection system of NPOI transport mirrors and measured the resultant beam wavefront contour. We applied a single actuator to the backside of one of the mirrors in the system and measured the contour of the exiting wavefront. Additionally, we compared the reduced concavity of the exiting wavefront to our finite element method results from the previous work, and excellent agreement was observed. In this paper, we describe our wavefront improvement approach, experimental method and results, and recommendations.

Original languageEnglish (US)
Title of host publicationOptical System Alignment, Tolerancing, and Verification XII
EditorsJose Sasian, Richard N. Youngworth
ISBN (Electronic)9781510620650
StatePublished - 2018
EventOptical System Alignment, Tolerancing, and Verification XII 2018 - San Diego, United States
Duration: Aug 19 2018Aug 20 2018

Publication series

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


OtherOptical System Alignment, Tolerancing, and Verification XII 2018
Country/TerritoryUnited States
CitySan Diego


  • Compliant mirror
  • Deformable mirror
  • Long baseline optical interferometry
  • NPOI
  • Navy Precision Optical Interferometer
  • Wavefront correction
  • Wavefront flatness

ASJC Scopus subject areas

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


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