High-resolution display screen as programmable illumination for Fourier ptychography

We introduce a new programmable illumination strategy for Fourier ptychographic microscopy (FPM), utilizing a high-resolution organic light-emitting diode (OLED) display screen at the vicinity of the sample to achieve super-resolution and quantitative phase imaging of biological samples. High-density pixels in the OLED screen allow for the angle-scanning illumination required for FP by placing the sample slide directly on the screen, where multiple images of the sample are captured while scanning the pixels on the screen. We discuss the design of the OLED-FP illumination and the corresponding image reconstruction strategies and experimentally validate the super-resolution and phase imaging capabilities of FP using a smartphone screen as illumination. Further, we extend our method to patterned illumination strategies, which multiplexes multiple illumination pixels to achieve full-field FP imaging with a reduced number of measurements, where we identify an optimal illumination pattern and density to maximize the imaging speed without sacrificing the image quality. Our approach offers a simple and compact programmable illuminator that can effectively transform any microscope into a compact FPM with resolution improvement and phase imaging capabilities.