Single-shot ptychography with highly tilted illuminations

Optical ptychography for biomedical imaging: recent progress and future directions [Invited]

Ptychography is an enabling microscopy technique for both fundamental and applied sciences. In the past decade, it has become an indispensable imaging tool in most X-ray synchrotrons and national laboratories worldwide. However, ptychography's limited resolution and throughput in the visible light regime have prevented its wide adoption in biomedical research. Recent developments in this technique have resolved these issues and offer turnkey solutions for high-throughput optical imaging with minimum hardware modifications. The demonstrated imaging throughput is now greater than that of a high-end whole slide scanner. In this review, we discuss the basic principle of ptychography and summarize the main milestones of its development. Different ptychographic implementations are categorized into four groups based on their lensless/lens-based configurations and coded-illumination/coded-detection operations. We also highlight the related biomedical applications, including digital pathology, drug screening, urinalysis, blood analysis, cytometric analysis, rare cell screening, cell culture monitoring, cell and tissue imaging in 2D and 3D, polarimetric analysis, among others. Ptychography for high-throughput optical imaging, currently in its early stages, will continue to improve in performance and expand in its applications. We conclude this review article by pointing out several directions for its future development.

Morphological variations to a ptychographic algorithm

Ptychography is a technique widely used in microscopy for achieving high-resolution imaging. This method relies on computational processing of images gathered from diffraction patterns produced by several partial illuminations of a sample. We numerically studied the effect of using different shapes for illuminating the aforementioned sample: convex shapes, such as circles and regular polygons, and unconnected shapes that resemble a QR code. Our results suggest that the use of unconnected shapes seems to outperform convex shapes in terms of convergence and, in some cases, accuracy.

3D single-shot ptychography with highly tilted illuminations

A method based on highly tilted illumination and non-paraxial iterative computation is proposed to improve the image quality of single-shot 3D ptychography. A thick sample is illuminated with a cluster of laser beams that are separated by large enough angles to record each diffraction pattern distinctly in a single exposure. 3D structure of the thick sample is accurately reconstructed from recorded diffraction patterns using a modified multi-slice algorithm to process non-paraxial illumination. Sufficient number of recorded diffraction patterns with noticeably low crosstalk enhances the fidelity of reconstruction significantly over single-shot 3D ptychography methods that are based on paraxial illumination. Experimental observations guided by the results of numerical simulations show the feasibility of the proposed method.