Transparent stepped phase measurement using two illuminating beams

Behnam Tayebi, Farnaz Sharif, Mohammad Reza Jafar Fard, Dug Young Kim

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

5 Citations (Scopus)


We propose a single shot and single wavelength phase imaging technique for measuring phase of the transparent objects without using unwrapping process. A grating between a laser and the object is used to make beams with different angle, which determines the measurement range of the microscope. The grating pitch and magnification of the lens system before the sample affect the angle. The angle inside the object is changed according to Snell's law; therefore, final angle is related to the refractive index of the object. Magnification of the lens system after sample will control the modulation frequency of microscope. The interference pattern is constructed at CCD plane and convey information of the sample. For a phase below the measurement range of the microscope, the reconstructed phase is not wrapped. By increasing the measurement range accuracy of the system will drop; therefore the magnification of the lenses must choose carefully to obtain optimal phase. The ability of this technique is demonstrated by reconstructing phases of two transparent step objects with 150 and 510 μm height. Their refractive indexes for red light are 1.515 and 1.508 , respectively. Therefore, total optical path length difference is 336 micrometers that is 500 times more than the laser wavelength. The phase is successfully reconstructed without using unwrapping algorithms.

Original languageEnglish
Title of host publicationInterferometry XVII
Subtitle of host publicationTechniques and Analysis
EditorsKatherine Creath, Jan Burke, Joanna Schmit
ISBN (Electronic)9781628412307
Publication statusPublished - 2014
EventInterferometry XVII: Techniques and Analysis - San Diego, United States
Duration: 2014 Aug 172014 Aug 19

Publication series

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


OtherInterferometry XVII: Techniques and Analysis
Country/TerritoryUnited States
CitySan Diego

Bibliographical note

Publisher Copyright:
© 2014 SPIE.

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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