Numerical refocusing in digital holographic microscopy with extended-sources illumination

Area of Science:

• Optics and Photonics
• Microscopy Techniques
• Computational Imaging

Background:

• Numerical refocusing in digital holographic microscopy (DHM) typically relies on coherent light sources.
• Existing methods using inverse filtering are well-established for point and monochromatic illumination.
• The application of these methods to spatially incoherent sources remains underexplored.

Purpose of the Study:

• To extend numerical refocusing theory to quasi-monochromatic extended (spatially incoherent) light sources.
• To derive and validate new refocusing methods suitable for incoherent illumination in DHM.
• To demonstrate the advantages of using spatially incoherent sources for refocusing.

Main Methods:

• Theoretical derivation of numerical refocusing algorithms for spatially incoherent illumination.
• Experimental validation using digital holographic microscopy with an extended light source.
• Comparative analysis of results from coherent-based and newly derived refocusing methods.

Main Results:

• Coherent-based numerical refocusing yields incorrect results with extended-source illumination.
• The newly derived methods for spatially incoherent illumination provide accurate refocusing.
• Theoretical and experimental evidence confirms the efficacy of the new approach.

Conclusions:

• Numerical refocusing in DHM can be successfully applied to spatially incoherent light sources.
• The developed methods overcome limitations of traditional techniques for extended illumination.
• Spatially incoherent illumination offers benefits for numerical refocusing in DHM.