The phase spectrum-based measurement of the TEM parameters

Abstract The phase spectrum-based method proposed by Koster et al. (Ultramicroscopy 27 (1989) 251) has experimentally been demonstrated by a computerized 200 kV transmission electron microscope with a slow-scan CCD camera system, which has theoretical advantages compared to other methods utilizing diffractograms. Crucial for the practical implementation of the method has been the addition of a linear phase term in the mathematical model made of the phase contrast transfer function to represent image drift. Moreover, to improve the accuracy of the method for measuring the TEM parameters (defocus, astigmatism and beam tilt misalignment), the model for least squares fitting was used in its full mathematical form without approximation by the DSB imaging model, neglecting the SSB imaging as was done in the original proposal. Experimental results of the TEM parameter measurements, defocus, astigmatism and beam tilt misalignment, by the phase spectrum-based method are demonstrated.