Three-dimensional particle localization techniques based on phase modulation and digital vortex imaging.

Area of Science:

• Optics and Photonics
• Biophysics
• Materials Science

Background:

• Accurate three-dimensional (3D) particle localization is essential for understanding dynamic processes in complex systems.
• In-line digital holography offers a compact solution for 3D particle tracking but suffers from axial localization inaccuracies due to twin image artifacts and computationally intensive reconstruction methods.

Purpose of the Study:

• To develop a novel framework for accurate and efficient 3D particle localization.
• To overcome the limitations of twin image artifacts and iterative reconstruction in holographic imaging.
• To enable precise axial localization and robust tracking of dynamic particles.

Main Methods:

• Proposed a defocus-encoded coherent framework that simultaneously encodes defocus direction and distance.
• Introduced a vortex phase (topological charge l=1) in the frequency domain during holographic recording to encode defocus direction.
• Utilized digital vortex interferometry during numerical reconstruction to map defocus distance to vortex pattern rotation for axial offset retrieval.

Main Results:

• Demonstrated precise axial resolution in volumetric imaging within a 10 mm³ field.
• Achieved single-shot and non-iterative holographic reconstruction.
• Validated the method through experiments and simulations.

Conclusions:

• The proposed defocus-encoded coherent framework effectively addresses twin image artifacts and computational complexity in 3D particle localization.
• This single-shot, non-iterative method provides robust and efficient tracking of dynamic particles with high axial resolution.
• The technique has significant potential for applications requiring precise 3D particle position and trajectory analysis.