Measurement of a large deformable aspherical mirror using SCOTS (software configurable optical test system)

Run Huang, Peng Su, Todd Horne, Guido Brusa Zappellini, Jim H. Burge

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

17 Scopus citations


The software configurable optical test system (SCOTS) is an efficient metrology technology based on reflection deflectometry that uses only an LCD screen and a camera to measure surface slope. The surface slope is determined by triangulations using the coordinates of the display screen, camera and test mirror. We present our recent SCOTS test results concentrated on high dynamic range measurements of low order aberrations. The varying astigmatism in the 91 cm diameter aspheric deformable secondary mirror for the Large Binocular Telescope (LBT) was measured with SCOTS, requiring no null corrector. The SCOTS system was designed on axis with camera and screen aligned on the optical axis of the test mirror with the help of a 6 inch pellicle beam splitter. The on-axis design gives better control of the astigmatism in the test. The high dynamic range of slope provided a measurement of astigmatism with 0.2 μm rms accuracy in the presence of 231 μm peak-to-valley (PV) aspheric departure. The simplicity of the test allowed the measurements to be performed at multiple elevation angles.

Original languageEnglish (US)
Title of host publicationOptical Manufacturing and Testing X
StatePublished - 2013
EventOptical Manufacturing and Testing X - San Diego, CA, United States
Duration: Aug 26 2013Aug 27 2013

Publication series

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


OtherOptical Manufacturing and Testing X
Country/TerritoryUnited States
CitySan Diego, CA


  • Aspheric
  • Deflectometry
  • Optical metrology

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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