Autonomous closed-loop control for multi-segmented optic aligning and assembly

Heejoo Choi, Marcos A. Esparza, Ryan Luu, Tom Milster, Daniel Apai, Daewook Kim

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

2 Scopus citations


To meet the scientific requirements demanded for futuristic space exploration, the Nautilus space mission has adopted the newly developed multi-order diffractive optical elements (MODE) design. Primary optics with large aperture diameters, like those used commonly in observatories, are frequently the design most employed and demanded by astronomers. However, this is limited by the difficult challenges that comes with fabrication, alignment, and launch of said optics. The proposed primary optics fabrication breaks through these challenges by using molded segments as its primary optics. With the main advantage of requiring a relatively simplified assembly process and having a compressed volume, the compact form factor will allow for multiple telescope units to be sent together in a single launch. Additionally, the molding and segmented manufacturing creates a fine structure on the diffractive lens surface that is not easy to obtain via traditional surface removal fabrication processes for an identical optical surface piece. The feasibility of this assembly in respect to its accuracy and labor are the key factors of this approach. Therefore, we developed an in-Progress Metrology Control (iPMC) technique that was combined with a motorized mounting system to give us full autonomous closed-loop control during the UV curing of multiple segments. The iPMC monitors and guides the aligning of the adhesion process of the multi-segment MODE, while the metrology system measures the position of the multi-segments so that an individual actuator can automatically adjust the segment’s orientation during the UV curing process. This is happening simultaneously as the influence matrix of each actuator receives feedback from the metrology system. The validity of the iPMC is then checked using the mock-up MODE lens assembly.

Original languageEnglish (US)
Title of host publicationOptical Manufacturing and Testing XIV
EditorsDaewook Kim, Heejoo Choi, Heidi Ottevaere, Rolf Rascher
ISBN (Electronic)9781510654266
StatePublished - 2022
EventOptical Manufacturing and Testing XIV 2022 - San Diego, United States
Duration: Aug 22 2022Aug 24 2022

Publication series

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


ConferenceOptical Manufacturing and Testing XIV 2022
Country/TerritoryUnited States
CitySan Diego


  • Close-loop alignment
  • Metrology
  • automatic alignment
  • in-process metrology
  • multi-segmented optics

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 'Autonomous closed-loop control for multi-segmented optic aligning and assembly'. Together they form a unique fingerprint.

Cite this