Dual-wavelength digital holographic imaging with phase background subtraction

Alexander Khmaladze, Rebecca L. Matz, Joshua Jasensky, Emily Seeley, Mark M. Banaszak Holl, Zhan Chen

Research output: Contribution to journalArticleResearchpeer-review

16 Citations (Scopus)


Three-dimensional digital holographic microscopic phase imaging of objects that are thicker than the wavelength of the imaging light is ambiguous and results in phase wrapping. In recent years, several unwrapping methods that employed two or more wavelengths were introduced. These methods compare the phase information obtained from each of the wavelengths and extend the range of unambiguous height measurements. A straightforward dual-wavelength phase imaging method is presented which allows for a flexible tradeoff between the maximum height of the sample and the amount of noise the method can tolerate. For highly accurate phase measurements, phase unwrapping of objects with heights higher than the beat (synthetic) wavelength (i.e. the product of the original two wavelengths divided by their difference), can be achieved. Consequently, three-dimensional measurements of a wide variety of biological systems and microstructures become technically feasible. Additionally, an effective method of removing phase background curvature based on slowly varying polynomial fitting is proposed. This method allows accurate volume measurements of several small objects with the same image frame.

Original languageEnglish
Article number055801
Number of pages8
JournalOptical Engineering
Issue number5
Publication statusPublished - 1 May 2012
Externally publishedYes


  • Background removal
  • Cell imaging
  • Curvature removal
  • Digital holography
  • Phase imaging
  • Phase unwrapping
  • Three-dimensional microscopy

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