Abstract

Abstract: A new double-grating-based phase-contrast imaging technique is described. This technique differs from the conventional double-grating imaging method by the image acquisition strategy. The novelty of the proposed method is in lateral scanning of both gratings simultaneously while an image is collected. The collected image is not contaminated by a Moiré pattern and can be recorded even by using a high-spatial-resolution integrating detector (e.g. X-ray film), thus facilitating improved resolution and/or contrast in the image. A detailed theoretical analysis of image formation in the scanning-double-grating method is carried out within the rigorous wave-optical formalism. The transfer function for the scanningdouble-grating imaging system is derived. An approximate geometricaloptics solution for the image intensity distribution is derived from the exact wave-optical formula using the stationary-phase approach. Based on the present formalism, the effects of finite source size on the preferred operating conditions and of polychromaticity on the image contrast and resolution are investigated. References and links 1. U. Bonse and M. Hart, "An x-ray interferometer," Appl. Phys. Lett. 6, 155-156 (1965 A. Momose, "Demonstration of phase-contrast X-ray computed tomography using an X-ray interferometer," Nucl. Instrum. Methods A 352, 622-628 (1995). 4. K. Goetz, M. P. Kalashnikov, Yu. A. Mikhailov, G. V. Sklizkov, S. I. Fedotov, E. Foerster and P. Zaumseil, "Measurements of the parameters of shell targets for laser thermonuclear fusion using an x-ray schlieren method," Sov. J. Quantum Electron. 9, 607-610 (1979 65-115 (1971).