Electron tomography is a widely used technique for 3D structural analysis of nanomaterials, but it can cause damage to samples due to high electron doses and long exposure times. To minimize such damage, researchers often reduce beam exposure by acquiring fewer projections through tilt undersampling. However, this approach can also introduce reconstruction artifacts due to insufficient sampling. Therefore, it is important to determine the optimal number of projections that minimizes both beam exposure and undersampling artifacts for accurate reconstructions of beam-sensitive samples. Current methods for determining this optimal number of projections involve acquiring and post-processing multiple reconstructions with different numbers of projections, which can be time-consuming and requires multiple samples due to sample damage. To improve this process, we propose a protocol that combines golden ratio scanning and quasi-3D reconstruction to estimate the optimal number of projections in real-time during a single acquisition. This protocol was validated using simulated and realistic nanoparticles, and was successfully applied to reconstruct two beam-sensitive metal-organic framework complexes.

翻译：电子断层扫描是一种广泛应用于纳米材料三维结构分析的技术，但高电子剂量和长曝光时间可能对样品造成损伤。为最大限度减少这种损伤，研究人员通常通过倾斜欠采样获取更少的投影来降低光束照射。然而，这种方法也可能因采样不足而引入重建伪影。因此，确定能在光束敏感样品的精确重建中同时最小化光束暴露和欠采样伪影的最佳投影数至关重要。当前确定该最佳投影数的方法需要获取和处理多个不同投影数的重建结果，这既耗时又因样品损伤而需要多个样品。为改进这一过程，我们提出了一种结合黄金比例扫描和准三维重建的协议，可在单次采集过程中实时估算最佳投影数。该协议通过模拟和真实纳米颗粒进行了验证，并成功应用于两个光束敏感金属有机框架复合物的重建。