Ptychographic coherent diffractive imaging with orthogonal probe relaxation

Ptychography is a scanning coherent diffractive imaging (CDI) technique that relies upon a high level of stability of the illumination during the course of an experiment. This is particularly an issue for coherent sources where the beam intensity is usually tightly focused on the sample in order to maximize the photon flux density on the illuminated region of the sample. We present a method that includes limited stability of the illumination probe into the ptychography reconstruction. We have tested our reconstruction method in a proof of concept experiment, where the beam instability of a visible light source was emulated using a piezo driven mirror, and also in a short wavelength microscopy setup using a high harmonic generation source in the extreme ultraviolet range. Our work is showing a natural extension of the ptychography method that paves the way to use ptychographic imaging with any limited pointing stability coherent source such as free electron or soft X-ray lasers.