Biophotonics Laboratory
California Institute of Technology


Fourier Ptychographic Microscopy (FPM)
Wide Field of View Microscopy (WFOV)
Time-reversal Wavefront Engineering



Introduction to Fourier Ptychographic Microscopy (FPM)

Motivation: Increase the space–bandwidth product (SBP) of a conventional microscope system

  • Wide field-of-view: 12mm diameter (~120mm2)
  • High resolution: ~0.78 µm resolution
  • Large depth of focus: 0.3 mm resolution-invariant depth of focus
  • Complete information of the sample: both intensity and phase
  • No mechanical scanning
  • Compatible with most conventional microscopes

Principle of Operation:

  • Acquire multiple images: each image illuminated with a unique LED
  • Angularly varying illumination: Light from angularly offset LED's carry high-resolution sample information to the camera
  • Phase retrieval algorithm: Multiple images are fused together for both resolution enhancement and complex image recovery

Optical Setup:

Demonstration of resolution enhancement

Imaging biological samples with FPM

Digital Pathology

The figure above shows a gigapixel color imaging of a pathology slide. Insets demonstrate detail with comparison to a conventional microscope image

Extending image depth-of-focus with digital refocusing

  • FPM digitally corrects for slide positioning and tilt errors


  • FPM enhances resolution: Extends resolution beyond the conventional limit defined by a microscope's optics
  • FPM acquires phase: Reveals new sample information and allows for digital refocusing
  • Connections: Shares properties with ptychography, synthetic aperture imaging, phase retrieval and light-field microscopy
  • Future work: Application to 3D imaging and fluorescence


[1] Guoan Zheng, Roarke Horstmeyer and Changhuei Yang, "Wide-field, high-resolution Fourier ptychographic microscopy;" Nature Photonics, doi:10.1038/nphoton.2013.187

[2] Xiaoze Ou, Roarke Horstmeyer, Changhuei Yang, and Guoan Zheng, "Quantitative phase imaging via Fourier ptychographic microscopy (FPM);" submitted.


This work is supported by National Institutes of Health (grant no.1DP2OD007307-01).