Surface profile determination by additive-subtractive phase modulated ESPI with fourier analysis

Liu Sheng Wang, Sridhar Krishnaswamy

Research output: Contribution to journalConference articlepeer-review

3 Scopus citations


An interferomeiric system for the determination of surface shape or height profiles of engineering components is presented. The system is based on additive-subtractive phase modulated electronic speckle pattern interferometry (AS-ESPI) and works successfully in harsh environmental conditions. Determination of profiles is achieved via repetitively changing the optical pathlength difference (OPD) between two interference beams in the ESPI setup. As the repetition rate is much higher than that of the video frame refreshing, one can remove random environmental noises that are normally of much lower frequency than the repetition rate by the use of speckle decorrelation and frame averaging procedures. Due to the nature that carrier fringes are automatically generated by the OPD change (namely tilting the iflumination angle of the object beam), Fourier transform approach is employed to extract the phase data. A simplified method for calculating the surface height (profile) is described and the results are compared to an exact solution. Quantitative measurement results obtained under rather noisy conditions for several components are presented.

Original languageEnglish (US)
Pages (from-to)162-174
Number of pages13
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - Jul 17 1996
EventLaser Interferometry VIII: Techniques and Analysis 1996 - Denver, United States
Duration: Aug 4 1996Aug 9 1996


  • Additive-subtractive phase modulated ESPI
  • Fourier transform
  • Shape measurement

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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