Partially coherent digital in-line holographic microscopy in characterization of a microscopic target

Area of Science:

• Microscopy
• Optical Imaging
• Particle Characterization

Background:

• Digital holographic microscopy (DHM) captures large 3D volumes.
• Partially coherent light sources (e.g., LEDs) offer advantages over lasers, producing speckle-free holograms.
• Reconstructed phase is unreliable for overlapping objects, necessitating intensity-based depth extraction.

Purpose of the Study:

• To introduce a novel depth extraction algorithm for DHM capable of handling multiple overlapping objects at different depths.
• To enhance the characterization of micrometer-sized particles using intensity-based methods.
• To develop an optimized, two-stage algorithm for improved accuracy and efficiency.

Main Methods:

• Utilized digital holographic microscopy with partially coherent illumination.
• Developed a novel depth extraction algorithm applying the Tamura coefficient to reconstructed intensity.
• Implemented a two-stage optimized algorithm: coarse localization followed by high-precision characterization.

Main Results:

• The novel algorithm effectively extracts depth information from reconstructed intensity, even with overlapping objects.
• The Tamura coefficient was successfully applied for focus-based depth determination.
• The two-stage optimization improved the precision of object characterization in 3D volumes.
• Experimental validation demonstrated the method's effectiveness on real microscopic samples.

Conclusions:

• The proposed depth extraction algorithm provides a robust solution for analyzing complex 3D microscopic samples.
• This method advances particle characterization capabilities in digital holographic microscopy.
• The optimized two-stage approach offers a practical and accurate tool for 3D imaging applications.