Analysis of active optics correction for a large honeycomb mirror

Solvay Blomquist, Hubert Martin, Hyukmo Kang, Rebecca Whitsitt, Kevin Derby, Heejoo Choi, Ewan S. Douglas, Daewook Kim

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


In the development of space-based large telescope systems, having the capability to perform active optics correction allows correcting wavefront aberrations caused by thermal perturbations so as to achieve diffraction-limited performance with relaxed stability requirements. We present a method of active optics correction used for current ground-based telescopes and simulate its effectiveness for a large honeycomb primary mirror in space. We use a finite-element model of the telescope to predict misalignments of the optics and primary mirror surface errors due to thermal gradients. These predicted surface error data are plugged into a Zemax ray trace analysis to produce wavefront error maps at the image plane. For our analysis, we assume that tilt, focus and coma in the wavefront error are corrected by adjusting the pointing of the telescope and moving the secondary mirror. Remaining mid- to high-order errors are corrected through physically bending the primary mirror with actuators. The influences of individual actuators are combined to form bending modes that increase in stiffness from low-order to high-order correction. The number of modes used is a variable that determines the accuracy of correction and magnitude of forces. We explore the degree of correction that can be made within limits on actuator force capacity and stress in the mirror. While remaining within these physical limits, we are able to demonstrate sub-25 nm RMS surface error over 30 hours of simulated data. The results from this simulation will be part of an end-to-end simulation of telescope optical performance that includes dynamic perturbations, wavefront sensing, and active control of alignment and mirror shape with realistic actuator performance.

Original languageEnglish (US)
Title of host publicationAstronomical Optics
Subtitle of host publicationDesign, Manufacture, and Test of Space and Ground Systems IV
EditorsTony B. Hull, Daewook Kim, Pascal Hallibert
ISBN (Electronic)9781510665682
StatePublished - 2023
EventAstronomical Optics: Design, Manufacture, and Test of Space and Ground Systems IV 2023 - San Diego, United States
Duration: Aug 21 2023Aug 24 2023

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering


ConferenceAstronomical Optics: Design, Manufacture, and Test of Space and Ground Systems IV 2023
Country/TerritoryUnited States
CitySan Diego


  • active optics
  • bending mode
  • diffraction-limited imaging
  • large optics
  • space telescope
  • telescope simulation
  • thermal gradients
  • wavefront error

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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