1. Introduction
The performance of an optical imaging system is fundamentally constrained by its space-bandwidth product (SBP), which forces the user to make a compromise between a high-resolution image and a large field-of-view (FoV) one. To overcome this problem, Fourier ptychography (FP) [1] is recently proposed as a computational imaging technique that successfully breaks through the SBP limitation of the optical imaging system via post-processing. This method works by iteratively stitching together a sequence of low-resolution images in Fourier space to recover an accurate high-resolution, high-SBP output image. The required low-resolution images are captured under angularly varying illumination with the help of a programmable light-emitting diode (LED) matrix illumination module. As a result, this method is able to transform a conventional optical microscope into a high-resolution (0.78 half-pitch resolution, 0.5 NA), wide-FOV (120 mm2) microscope with a final SBP of 0.23 gigapixels.