Measurement of optical flatness using electronic levels

Julius Yellowhair, James H. Burge

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Conventional measurement methods for large flat mirrors are generally difficult and expensive. In most cases, comparison with a master or a reference flat similar in size is required. Using gravity, as in modern pendulum-type electronic levels, takes advantage of a free reference to precisely measure inclination or surface slopes. We describe using two electronic levels to measure flatness of large mirrors. We provide measurement results on a 1.6-m-diameter flat mirror to an accuracy of 50 nm rms of low-order Zernike aberrations.

Original languageEnglish (US)
Article number023604
JournalOptical Engineering
Issue number2
StatePublished - Feb 1 2008


  • Electronic levels
  • Large flat mirrors
  • Metrology
  • Optical manufacturing
  • Slope testing

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Engineering(all)


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