title: 2D and 3D X-ray phase retrieval of multi-material objects using a single defocus distance.
abstract: A method of tomographic phase retrieval is developed for multi-material objects whose components each has a distinct complex refractive index. The phase-retrieval algorithm, based on the Transport-of-Intensity equation, utilizes propagation-based X-ray phase contrast images acquired at a single defocus distance for each tomographic projection. The method requires a priori knowledge of the complex refractive index for each material present in the sample, together with the total projected thickness of the object at each orientation. The requirement of only a single defocus distance per projection simplifies the experimental setup and imposes no additional dose compared to conventional tomography. The algorithm was implemented using phase contrast data acquired at the SPring-8 Synchrotron facility in Japan. The three-dimensional (3D) complex refractive index distribution of a multi-material test object was quantitatively reconstructed using a single X-ray phase-contrast image per projection. The technique is robust in the presence of noise, compared to conventional absorption based tomography.
authors.affiliation: School of Physics, Monash University, VIC 3800, Australia. Mario.Beltran@sci.monash.edu.au
authors.forename: M A
authors.initials: MA
authors.lastname: Beltran
authors.forename: D M
authors.initials: DM
authors.lastname: Paganin
authors.forename: K
authors.initials: K
authors.lastname: Uesugi
authors.forename: M J
authors.initials: MJ
authors.lastname: Kitchen
mesh_terms: D000465:Algorithms; D004867:Equipment Design; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008858:Microscopy, Phase-Contrast / Q000295:instrumentation* / Q000379:methods; D055095:Optics and Photonics; D012031:Refractometry; D017356:Synchrotrons; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014965:X-Rays