Optimization of dynamic structured illumination for surface slope measurements

Guillaume P. Butel, Greg A. Smith, James H. Burge

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

5 Scopus citations


We present a fast and ambiguity-free method for slope measurement of reflective optical elements based on reflectometry. This novel reflectometric method applies triangulation to compute the slope based off projected patterns from an LCD screen, which are recorded by a camera. Accurate, ambiguity-free measurements can be obtained by displaying one pixel at a time on the screen and retrieving its unique image. This process is typically accelerated by scanning lines of pixels or encoding the information with phase using sinusoidal waves. Various measurement techniques exist, centroiding and phase-shifting being the most accepted, but their sensitivities vary with experimental conditions. This paper demonstrates solutions based on various parameters such as uncertainty or efficiency. The results are presented in a decision matrix and merit function. Additionally, we propose a new measurement technique - Binary squares screens - in an attempt to address system limitations and compare current systems to our solutions using the decision matrix. Several test conditions are proposed along with the best suited solution.

Original languageEnglish (US)
Title of host publicationInterferometry XVI
Subtitle of host publicationTechniques and Analysis
StatePublished - 2012
EventInterferometry XVI: Techniques and Analysis - San Diego, CA, United States
Duration: Aug 13 2012Aug 15 2012

Publication series

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


OtherInterferometry XVI: Techniques and Analysis
Country/TerritoryUnited States
CitySan Diego, CA


  • Centroiding
  • Optimization
  • Phase-shifting
  • Reflectometry
  • Sensitivity
  • Slopes
  • Structured illumination

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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