Phase estimation from digital holograms without unwrapping.

Area of Science:

• Optical Metrology
• Holographic Imaging
• Microscopy

Background:

• Digital holography is a powerful tool for quantitative phase imaging of transparent objects.
• Phase unwrapping algorithms are typically required for phase maps exceeding 2π, but are sensitive to noise.
• Existing methods for phase retrieval in noisy environments remain challenging.

Purpose of the Study:

• To develop a novel procedure for phase determination in digital holography that avoids the need for phase unwrapping.
• To provide a robust method for analyzing phase shifts in transparent samples, even with significant noise.
• To demonstrate the applicability of the proposed technique to microscopic samples.

Main Methods:

• Phase gradient is directly computed from the reconstructed holographic field.
• Phase is estimated by integrating the computed phase gradient.
• The method is applied to digital holograms of microscopic specimens.

Main Results:

• The proposed procedure successfully estimates phase without unwrapping, even for phase changes greater than 2π.
• The method demonstrates robustness in the presence of noise, a common issue in digital holography.
• Effective application to microscopic samples validates the technique's practical utility.

Conclusions:

• The developed method offers a viable alternative to traditional phase unwrapping in digital holography.
• This approach simplifies quantitative phase imaging, particularly for noisy data and complex samples.
• The technique holds promise for advanced applications in optical metrology and microscopy.