Lensless quantitative microscopy based on multi-angle illumination and coded ptychographic phase retrieval

Area of Science:

• Optics and Photonics
• Microscopy
• Image Reconstruction

Background:

• Conventional coded ptychography (CP) offers high-resolution, large field-of-view (FOV) imaging but struggles with low-frequency phase recovery.
• This limitation hinders reconstruction fidelity by failing to convert slow-varying phase information into detectable intensity variations.

Purpose of the Study:

• To develop a novel lensless microscopy method integrating multi-angle illumination with coded ptychographic phase retrieval.
• To enhance quantitative phase recovery, particularly for low-frequency components, and improve reconstruction fidelity.

Main Methods:

• A new platform utilizes multi-angle illumination and lateral translation of a tube lens for phase diversity measurements.
• A coded image sensor captures diffraction patterns, with spatial modulation providing support constraints for phase recovery.
• Incident beam angles are directly recovered, and a calibration experiment characterizes the coded layer's transmission profile to address positioning accuracy and phase unwrapping.

Main Results:

• The proposed approach achieves a 5.6 mm x 7.4 mm FOV with a 0.96 μm half-pitch resolution.
• Successfully overcomes limitations in recovering low-frequency phase components and handles multiple 2π phase wraps.
• Demonstrates quantitative phase recovery with improved fidelity.

Conclusions:

• The developed lensless microscopy method offers a significant advancement over conventional coded ptychography.
• Provides large FOV, high-resolution, and quantitative on-chip imaging capabilities.
• Suitable for point-of-care diagnostics, global health, and telemedicine applications.