| Popis: |
Recently, experiments of X-ray free electron lasers (XFEL) single-particle coherent diffraction imaging (CDI) have demonstrated the potential to reconstruct the three-dimensional (3D) structure of non-crystalline biological samples with high spatial resolution. For successful reconstructions, a complete 3D Fourier transform of the particle is to be assembled by a lot of diffraction patterns from identical particles. In practice, this is difficult because the orientations of the injected particles are random. Incomplete 3D Fourier transform composed of limited projection orientations may cause lower resolution of 3D reconstruction. To get superior 3D reconstructions, equally sloped tomography (EST) may be applied to the incomplete 3D Fourier transform data set of single-particle CDI. In this paper, some challenges and corresponding approaches to CDI are briefly discussed. In principle, CDI can yield wavelength-limited resolution without any of the limitations of physical lenses. At present, CDI is deceptively simple to implement. Successful application of CDI to experimental data, however, is not universal and requires considerable mathematical physics skills and interdisciplinary experiences. Whether or not lensless microscopy can outweigh the lens-based one will depend on the competition between the computational power and the precise manufacturing technique of lens in the future, especially in the field of real time imaging. As a type of quickly developing algorithmic microscopy, researchers still should improve the precision, robustness and convergence speed of CDI reconstruction algorithms. |
