New method for probe position correction for Ptychography

Abstract

For high resolution imaging, X-rays and electron beams are being used. However, for such a short wavelength, imaging with lenses becomes difficult as lenses absorb a part of radiation and lenses with very low aberrations must be used. Ptychography is a lens-less imaging technique which uses intensity information of the multiple diffraction patterns in the far field. These multiple far field diffraction patterns are generated by an unknown object which is scanned by a localized illuminated spot (probe). Accurate knowledge of initial parameters is important for a good reconstruction of the object. Robustness of the Ptychography Iterative Engine (PIE) has already been studied for inaccurately known initial parameters, where the success of the algorithm was found to be sensitive to the accuracy of the estimate of lateral positions of the probe.:; We present here a new method to correct the lateral position of the probe with respect to the object. This method is more straightforward to implement than other existing algorithms while comparable accuracy for the lateral position is achieved. Being able to correct the probe positions has positive implication in experiments, in particular at the short wavelength cases. It relaxes the requirement for the experimental set-up.