title: A Universal Moiré Effect and Application in X-Ray Phase-Contrast Imaging.
abstract: A moiré pattern is created by superimposing two black-and-white or gray-scale patterns of regular geometry, such as two sets of evenly spaced lines. We observed an analogous effect between two transparent phase masks in a light beam which occurs at a distance. This phase moiré effect and the classic moiré effect are shown to be the two ends of a continuous spectrum. The phase moiré effect allows the detection of sub-resolution intensity or phase patterns with a transparent screen. When applied to x-ray imaging, it enables a polychromatic far-field interferometer (PFI) without absorption gratings. X-ray interferometry can non-invasively detect refractive index variations inside an object1-10. Current bench-top interferometers operate in the near field with limitations in sensitivity and x-ray dose efficiency2, 5, 7-10. The universal moiré effect helps overcome these limitations and obviates the need to make hard x-ray absorption gratings of sub-micron periods.
authors.affiliation: Biophysics and Biochemistry Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Houxun
authors.initials: H
authors.lastname: Miao
authors.affiliation: Biophysics and Biochemistry Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Alireza
authors.initials: A
authors.lastname: Panna
authors.affiliation: Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Gomella
authors.affiliation: Biophysics and Biochemistry Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Eric E
authors.initials: EE
authors.lastname: Bennett
authors.affiliation: Biophysics and Biochemistry Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Sami
authors.initials: S
authors.lastname: Znati
authors.affiliation: Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.affiliation: Biophysics and Biochemistry Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Han
authors.initials: H
authors.lastname: Wen