Hybrid reflective interferometric system combining wide-field and single-point phase measurements

Reut Friedman, Natan T. Shaked*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We present a hybrid scan-free reflective interferometric system, which combines a wide-field phase measurement, together with a single-point phase measurement, for optical inspection of thin reflective elements. The wide-field interferometric system is composed of a compact portable off-axis interferometer and is illuminated by either a highly coherence source or a narrowband low-coherence source. This is a free-space time-domain self-phase-referenced interferometric setup that can be attached to the output port of an existing reflection microscope. It records a spatial off-axis interferogram, which yields the wide-field phase map of the reflective sample. The other part of the hybrid system is a fiber-based phase-sensitive spectral-domain optical coherence tomography setup, which is illuminated by a boarder-band low-coherence source. It records an on-axis common-path spectral interferogram, which yields a single-point phase measurement of the reflective sample. In this case, since the reference beam does not interact with the sample, the phase is not self-referenced, and slow phase variations are measured as well. None of the setups contains scanning elements. The combination of these systems allows simultaneous wide-field and single-point phase measurements without co-calibration problems. By measuring thin reflective models with these external interferometers, we experimentally illustrate the ability to discriminate between refractive index changes from height changes in the sample.

Original languageEnglish
Article number7089168
JournalIEEE Photonics Journal
Issue number3
StatePublished - 1 Jun 2015


  • Digital holography
  • Holographic interferometry
  • Optical inspection
  • Phase measurement


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