Providing image data

Abstract

Embodiments of the present invention provide a method of providing image data for constructing an image of a region of a target object (40) comprising providing incident radiation from a radiation source at a target object (40);detecting, by at least one detector (50), a portion of radiation scattered by the target object; and providing image data via an iterative process responsive to the detected radiation (340), wherein said iterative process comprises estimating a wave front of scattered radiation at a plane of the detector, updating a portion of the wave front based on the detected radiation, leaving a portion of the estimated wave front substantially unchanged, setting a portion of the wave front, corresponding to a portion of radiation scattered by the target object and not detected by the detector, to one or more values, and providing image data based upon the updated wave front.

Dependencies are inferred from the claim text.