Maskless and on-chip LED-array microscope with spatially varying angle calibration for centimeter-scale phase imaging

Area of Science:

• Biomedical Optics
• Computational Imaging
• Microscopy

Background:

• Conventional microscopes face a resolution-field-of-view trade-off, limiting imaging throughput.
• On-chip phase imaging with LED arrays offers cost-effective large field-of-view imaging but faces challenges with twin-image ambiguity and illumination angle variations.
• Existing mask-based modulation for phase reconstruction adds system complexity.

Purpose of the Study:

• To develop a computational framework for mask-free, on-chip phase imaging.
• To enable adaptive calibration of spatially varying illumination angles in LED-array-based systems.
• To achieve centimeter-scale, high-resolution, label-free phase imaging.

Main Methods:

• A computational framework divides the sensor field-of-view into subregions, approximating LED illumination as planar within each.
• LED illumination angles are geometrically initialized and refined during phase retrieval using a soft optical transparency prior.
• Reconstructed phase maps from subregions are merged to create a high-quality, large field-of-view image.

Main Results:

• Demonstrated centimeter-scale on-chip phase imaging (up to 2.7 x 1.7 cm²) with micron-scale resolution.
• Successfully imaged various biological tissue sections using the developed computational framework.
• Achieved mask-free phase imaging without complex fabrication or alignment procedures.

Conclusions:

• The presented computational framework offers a simple, low-cost, and scalable solution for large field-of-view, label-free phase imaging.
• This method overcomes limitations of traditional microscopy and existing on-chip imaging techniques.
• Enables high-quality phase reconstruction and adaptive calibration for diverse biological applications.