Algorithm of white-light interferometry for reconstruction of profile

  • Cheng Yu Pai*
  • , Jiunn Woei Liaw
  • , Ming Chang
  • *Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

An algorithm is proposed to process the interference signals of white-light interferometer in order to obtain the surface height/depth profile of a sample by using the maximum envelope method. Via a low-pass filter, the DC signal of the interference signal is obtained, and then a preprocessed signal which is the difference of the interference signal and its DC one is calculated. After that, the envelope of the preprocessed signal is obtained by using Hilbert transform, and then the height is estimated by the following peak detector. Based on this algorithm, the surface morphology of the sample is reconstructed. In our experiment, a step of 75 nm was set for a PZT motor, the scanning span in z-axis was 10.5 μm, and a 50-fold Mirau interferometer was used. In addition, a polynomial fitting can be used further for the peak detection of this envelope to improve the accuracy. Moreover, a spatial low-pass filter can be utilized to smooth the height profile.

Original languageEnglish
Title of host publicationSeventh International Symposium on Precision Engineering Measurements and Instrumentation
DOIs
StatePublished - 2011
Event7th International Symposium on Precision Engineering Measurements and Instrumentation - Lijiang, China
Duration: 07 08 201111 08 2011

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume8321
ISSN (Print)0277-786X

Conference

Conference7th International Symposium on Precision Engineering Measurements and Instrumentation
Country/TerritoryChina
CityLijiang
Period07/08/1111/08/11

Keywords

  • Hilbert transform
  • Mirau interferometer
  • analytic signal
  • envelope
  • notch
  • optical path difference
  • surface morphology
  • white-light interferometer

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