Wide-field, high-resolution Fourier ptychographic microscopy

Abstract

In this article, we report an imaging method, termed Fourier ptychographic microscopy (FPM), which iteratively stitches together a number of variably illuminated, low-resolution intensity images in Fourier space to produce a wide-field, high-resolution complex sample image. By adopting a wavefront correction strategy, the FPM method can also correct for aberrations and digitally extend a microscope’s depth-of-focus beyond the physical limitations of its optics. As a demonstration, we built a microscope prototype with a resolution of 0.78 μm, a field-of-view of ~120 mm2, and a resolution-invariant depth-of-focus of 0.3 mm (characterized at 632 nm). Gigapixel colour images of histology slides verify FPM’s successful operation. The reported imaging procedure transforms the general challenge of high-throughput, high-resolution microscopy from one that is coupled to the physical limitations of the system’s optics to one that is solvable through computation.

3D intensity and phase imaging from light field measurements in an LED array microscope

“…This is possible because data with angular diversity provide both 3D information and phase contrast. 2D phase of thin samples can be computed from images taken at multiple illumination angles [20][21][22][23][24] because of asymmetry introduced in the pupil plane [25]. All of these approaches assume a thin sample; in thick samples, angle-dependent data usually represent tomographic information.…”

A record-breaking microscope

“…Over the past ten years, ptychography has been widely used for microscopy in the X-ray 4 , extreme ultraviolet 6 and visible-light 7,8 regions of the electromagnetic spectrum. It has also been used with some success with electrons, but Jiang and colleagues are the first to show that it can surpass the resolution obtained by the best electron lenses.…”

Software: The computer will see you now

“…Yang's solution is to increase the field of view and resolution of conventional microscopes. In July 2013, Yang hacked a low-resolution light microscope to create a high-resolution microscope with a wide field of view that can create whole-slide images with cheap hardware 4 . In conventional microscopes, low-power lenses provide a wide field of view at the expense of resolution; high resolution only occurs in small fields of view, hence the need for mechanical scanning.…”