Three-dimensional nano-coherent diffraction imaging technology based on high order harmonic X-ray sources

Coherent diffractive imaging (CDI) using ultra-short wavelength light source has become an three-dimensional(3D) nanoimaging technique. In CDI, a target sample is first illuminated by a coherent EUV and soft X-ray light, then the diffraction pattern is recorded by using a charge coupled device (CCD), and finally the image of the sample is obtained based on the pattern by using a phase retrieval algorithm. Of the many currently available coherent EUV and soft X-ray light sources, the high-order harmonic generation (HHG) is the simplest in structure, the lowest in cost, and most compact in size. Therefore, it has become the most promising light source for CDI. Through years of development, HHG based CDI technique(HHG-CDI) has become an outstanding 3D nano-imaging technique with the advantages of no aberration, no damage, and no contact either, and it also possesses the extra-capabilities of probing the dynamics, chemical composition and quantum information in various semiconductor and quantum devices. We believe that the HHG-CDI will soon become a generic nano-imaging tool that can complement or even replace the matured nanoimaging techniques, such as atomic force, near field, X-ray, electron, or scanning tunneling microscopes.