US Patent 8942449 Calibration of a probe in ptychography

A method of providing image data for constructing an image of a region of a target object, comprising providing a reference diffraction pattern of a reference target object; determining an initial guess for a probe function based upon the reference diffraction pattern; and determining, by an iterative process based on the initial guess for the probe function and an initial guess for an object function, image data for a target object responsive to an intensity of radiation detected by at least one detector.