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Instruments / Technical Area	Publication Details	Published
	Ptycho-endoscopy on a lensless ultrathin fiber bundle tip Pengming Song , Ruihai Wang , Lars Loetgering , Jia Liu , Peter Vouras , Yujin Lee , Shaowei Jiang , Bin Feng , Andrew Maiden , Changhuei Yang , Guoan Zheng Light: Science & Applications 13 DOI: 10.1038/s41377-024-01510-5 Open Access Show Abstract ▼ Abstract: Synthetic aperture radar (SAR) utilizes an aircraft-carried antenna to emit electromagnetic pulses and detect the returning echoes. As the aircraft travels across a designated area, it synthesizes a large virtual aperture to improve image resolution. Inspired by SAR, we introduce synthetic aperture ptycho-endoscopy (SAPE) for micro-endoscopic imaging beyond the diffraction limit. SAPE operates by hand-holding a lensless fiber bundle tip to record coherent diffraction patterns from specimens. The fiber cores at the distal tip modulate the diffracted wavefield within a confined area, emulating the role of the ‘airborne antenna’ in SAR. The handheld operation introduces positional shifts to the tip, analogous to the aircraft’s movement. These shifts facilitate the acquisition of a ptychogram and synthesize a large virtual aperture extending beyond the bundle’s physical limit. We mitigate the influences of hand motion and fiber bending through a low-rank spatiotemporal decomposition of the bundle’s modulation profile. Our tests demonstrate the ability to resolve a 548-nm linewidth on a resolution target. The achieved space-bandwidth product is ~1.1 million effective pixels, representing a 36-fold increase compared to that of the original fiber bundle. Furthermore, SAPE’s refocusing capability enables imaging over an extended depth of field exceeding 2 cm. The aperture synthesizing process in SAPE surpasses the diffraction limit set by the probe’s maximum collection angle, opening new opportunities for both fiber-based and distal-chip endoscopy in applications such as medical diagnostics and industrial inspection.	Jul 2024
	Comparing ptychographic methods for maximum low dose performance Tamazouzt Chennit , Christoph Hofer , Biao Yuan , Songge Li , Andrew Maiden , Timothy J. Pennycook Microscopy & Microanalysis 2024 DOI: 10.1093/mam/ozae044.929	Jul 2024
	Near-field multi-slice optical ptychography Andrew M. Maiden , Ziyang Hu , Yiqian Zhang Optica Imaging Congress 2024 Show Abstract ▼ Abstract: We show how near-field multi-slice ptychography can be implemented on an optical microscope to realize computational sectioning of thick samples. We use the method to section a 90 µm-thick sample into 40 slices.	Jul 2024
I13-1-Coherence	WASP: weighted average of sequential projections for ptychographic phase retrieval Andrew M. Maiden , Wenjie Mei , Peng Li Optics Express 32 DOI: 10.1364/OE.516946 Diamond Proposal Number(s): [34119] Open Access Show Abstract ▼ Abstract: We introduce the weighted average of sequential projections, or WASP, an algorithm for ptychography. Using both simulations and real-world experiments, we test this new approach and compare performance against several alternative algorithms. These tests indicate that WASP effectively combines the benefits of its competitors, with a rapid initial convergence rate, robustness to noise and poor initial conditions, a small memory footprint, easy tuning, and the ability to reach a global minimum when provided with noiseless data. We also show how WASP can be parallelised to split operation across several different computation nodes.	May 2024
	Lorentz near-field electron ptychography Shengbo You , Peng-Han Lu , Thomas Schachinger , András Kovács , Rafal E. Dunin-Borkowski , Andrew M. Maiden Applied Physics Letters 123 DOI: 10.1063/5.0169788 Open Access Show Abstract ▼ Abstract: Over the past few years, electron ptychography has drawn considerable attention for its ability to recover high contrast and ultra-high resolution images without the need for high quality electron optics. In this Letter, we focus on electron ptychography's other potential benefits: quantitatively mapping phase variations resulting from magnetic and electric fields over extended fields of view. To this end, we propose an implementation of near-field ptychography that employs an amplitude mask located in the electron microscope's condenser aperture plane. We demonstrate the capabilities of our method by imaging a magnetic Permalloy sample and compare our results with those of off-axis electron holography.	Nov 2023
	Spatial- and Fourier-domain ptychography for high-throughput bio-imaging Shaowei Jiang , Pengming Song , Tianbo Wang , Liming Yang , Ruihai Wang , Chengfei Guo , Bin Feng , Andrew Maiden , Guoan Zheng Nature Protocols 5 DOI: 10.1038/s41596-023-00829-4 Show Abstract ▼ Abstract: First envisioned for determining crystalline structures, ptychography has become a useful imaging tool for microscopists. However, ptychography remains underused by biomedical researchers due to its limited resolution and throughput in the visible light regime. Recent developments of spatial- and Fourier-domain ptychography have successfully addressed these issues and now offer the potential for high-resolution, high-throughput optical imaging with minimal hardware modifications to existing microscopy setups, often providing an excellent trade-off between resolution and field of view inherent to conventional imaging systems, giving biomedical researchers the best of both worlds. Here, we provide extensive information to enable the implementation of ptychography by biomedical researchers in the visible light regime. We first discuss the intrinsic connections between spatial-domain coded ptychography and Fourier ptychography. A step-by-step guide then provides the user instructions for developing both systems with practical examples. In the spatial-domain implementation, we explain how a large-scale, high-performance blood-cell lens can be made at negligible expense. In the Fourier-domain implementation, we explain how adding a low-cost light source to a regular microscope can improve the resolution beyond the limit of the objective lens. The turnkey operation of these setups is suitable for use by professional research laboratories, as well as citizen scientists. Users with basic experience in optics and programming can build the setups within a week. The do-it-yourself nature of the setups also allows these procedures to be implemented in laboratory courses related to Fourier optics, biomedical instrumentation, digital image processing, robotics and capstone projects.	May 2023
I13-1-Coherence	Near-field multi-slice ptychography: quantitative phase imaging of optically thick samples with visible light and X-rays Ziyang Hu , Yiqian Zhang , Peng Li , Darren Batey , Andrew Maiden Optics Express 31 DOI: 10.1364/OE.487002 Diamond Proposal Number(s): [30097] Open Access Show Abstract ▼ Abstract: Ptychography is a form of lens-free coherent diffractive imaging now used extensively in electron and synchrotron-based X-ray microscopy. In its near-field implementation, it offers a route to quantitative phase imaging at an accuracy and resolution competitive with holography, with the added advantages of extended field of view and blind deconvolution of the illumination beam profile from the sample image. In this paper we show how near-field ptychography can be combined with a multi-slice model, adding to this list of advantages the unique ability to recover high-resolution phase images of larger samples, whose thickness places them beyond the depth of field of alternative methods.	Apr 2023
I13-1-Coherence	Sampling in x-ray ptychography T. B. Edo , D. J. Batey , A. M. Maiden , C. Rau , U. Wagner , Z. D. Pesic , T. A. Waigh , J. M. Rodenburg Physical Review A 87 (5) DOI: 10.1103/PhysRevA.87.053850 Show Abstract ▼ Abstract: Coherent diffractive imaging (CDI) is a means of overcoming the resolution and image contrast limitations of electron and x-ray lenses. The central tenet of the method is that the intensity of the diffraction pattern must be measured on a sufficiently fine pixel pitch, which is inversely related to the size of the illuminated region of the object. We show here that ptychography—a form of CDI that uses many diffraction patterns—is not subject to this constraint. Using a variant of the ePIE inversion algorithm, we demonstrate experimentally that the sampling requirement in ptychography is independent of illumination size.	May 2013

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