Hao Yuan: Ptychography and 4D imaging by spectro-ptycho-tomography

Coherent X-ray scattering (diffraction) methods will be key to exploiting the high coherent flux of 4th generation synchrotron sources. Ptychography is a coherent diffraction technique that allows rapid, reliable inversion of arrays of diffraction images into real space images by using overlapping spatial areas to constrain the reconstruction [1]. While ptychography is quite well developed in the hard X-ray regime and in electron and optical microscopy, the implementation of soft X-ray ptychography is in its infancy. Soft X-ray ptychography is a coherent diffraction imaging technique readily implemented in Scanning Transmission X-ray Microscopy (STXM) [2]. 4D imaging by soft X-ray ptychography – chemically specific, quantitative 3D mapping of nanostructures can provide insight into the physical and chemical properties. By measuring spectro-ptycho-tomography – 2D ptychographic images at multiple photon energies and multiple tilt angles – 3D chemical distribution can be derived [3].

References:

1. Pfeiffer F. X-ray ptychography. Nature Photonics, 2018, 12(1): 9-17. https://doi.org/10.1038/s41566-017-0072-5
   
2. Shapiro D A, Yu Y S, Tyliszczak T, et al. Chemical composition mapping with nanometre resolution by soft X-ray microscopy. Nature Photonics, 2014, 8(10): 765-769.
3. Wu J, Zhu X, Shapiro D A, et al. Four-dimensional imaging of ZnO-coated alumina aerogels by scanning transmission X-ray microscopy and ptychographic tomography. The Journal of Physical Chemistry C, 2018, 122(44): 25374-25385. https://pubs.acs.org/doi/abs/10.1021/acs.jpcc.8b07363