Amplitude correction in image deconvolution for determining crystal defects at atomic level
A method is proposed to improve the image deconvolution technique based on the weak-phase object approximation for determining the crystal defects at atomic level. Originally, both the amplitude and phase modulation caused by the contrast transfer function (CTF) was removed for all reflections in the diffractogram of the image and then the deconvoluted image was obtained by carrying out the inverse FT. In this paper after removing the CTF modulation the amplitudes of reflections are further corrected by constraining the integral amplitudes to be equal to the corresponding structure factor amplitudes of perfect crystals. [110] high-resolution electron microscope images were simulated for a structure model of Si crystal containing the 60 degrees dislocation with different thickness. A comparison between deconvoluted images with the amplitudes corrected by the present method and those uncorrected is given to show the effectiveness of the method. The amplitude-crystal thickness dependence for images simulated close to the Scherzer defocus condition has been analysed and the result serves as an empirical basis of the method. The validity and limitation of the method are discussed.