A new method of image reconstruction with high resolution in x-ray coded aperture imaging

摘要

In the processing diagnosis of the inertia confinement fusion (ICF), the ring coded aperture imaging technique is applied in order to gain high space and time resolutions simultaneously. The key of acquiring high spatial resolution is how to obtain a point spread function of an imaging system. The common method is the firsthand projection method which is an approximate one. The x-ray diffraction effect is neglected in the method, so the resolution of reconstructed image is decreased. We have derived the point spread function (PSF) of the ring coded aperture from scalar diffraction theory. And the Wiener filter is fabricated on the basis of the PSF. In National Key Laboratory of Laser Fusion, at China Academy of Engineering Physics, the imaging experiment on the diagnosis of ICF is completed using the ring coded aperture plate with inner diameter d1 = 250μm and outer diameter d2 = 260μm .The obtained coded image is processed by the Wiener filter which diffractive effect is considered. The processed results have shown that resolution and modulation contrast of acquired image are evidently better than the results obtained by the firsthand projection method.