Towards Single-Shot Coherent Imaging via Overlap-Free Ptychography
Summary: arXiv:2602.21361v2 Announce Type: replace-cross
Abstract
Ptychographic imaging at synchrotron and XFEL sources necessitates dense overlapping scans, which can limit throughput and increase the radiation dose received by samples. The challenge of extending coherent diffractive imaging to operate without overlap on larger samples remains unresolved. In this study, we advance the capabilities of PtychoPINN (O. Hoidn et al., Scientific Reports 13, 22789, 2023) to enable overlap-free, single-shot reconstructions in a Fresnel coherent diffraction imaging (CDI) setup, while also accelerating traditional multi-shot ptychography.
Key Contributions
- Development of a differentiable forward model for coherent scattering.
- Incorporation of a Poisson photon-counting likelihood to enhance reconstruction accuracy.
- Introduction of real-space overlap as a tunable parameter through coordinate-based grouping rather than a strict requirement.
Performance and Validation
Our framework demonstrates robust performance on synthetic benchmarks, maintaining accurate reconstructions even at low photon counts (approximately 104 photons/frame). Notably, the overlap-free single-shot reconstruction achieved an amplitude structural similarity index (SSIM) of 0.904, in contrast to 0.968 for the overlap-constrained reconstruction. This indicates a significant advantage in reconstruction quality under overlap-free conditions.
Comparative Analysis
When compared to a data-saturated supervised model utilizing the same network backbone, which was trained on 16,384 images, PtychoPINN outperformed it by achieving a higher SSIM with only 1,024 training images. Furthermore, the model showcased a remarkable ability to generalize to unseen illumination profiles, enhancing its applicability in real-world scenarios.
Efficiency and Throughput
In terms of computational efficiency, the per-graphics processing unit (GPU) throughput of the PtychoPINN framework is approximately 40 times that of the least-squares maximum-likelihood (LSQ-ML) reconstruction, while maintaining a matched resolution of 128×128 pixels. This remarkable increase in throughput is crucial for high-throughput imaging applications at contemporary light sources.
Experimental Validation
The findings have been validated on experimental data sourced from the Advanced Photon Source and the Linac Coherent Light Source. This successful validation underscores the potential of unifying single-exposure Fresnel CDI and overlapped ptychography within a single framework, paving the way for dose-efficient and high-throughput imaging techniques at modern synchrotron facilities.
Conclusion
The ability to achieve overlap-free, single-shot imaging marks a significant advancement in the field of coherent imaging. With enhanced throughput and reduced sample dose, this technique holds promise for a wide range of applications in materials science, biology, and nanotechnology.