Non-linear solution for 2D phase shifting

- 46 NON-LINEAR SOLUTION FOR 2D PHASE SHIFTING Disclosed is a method (100) of reconstructing a representative detailed phase image from a set of fringe pattern interferogram images of an object. The images are captured by an x ray interferometer (1399) having a crossed diffraction grating (410,430). A set of captured fringe pattern interferogram images from the x-ray interferometer are provided, the set comprising no more than eight captured fringe pattern interferogram images. The method determines (120,220) an estimate of an absorption parameter (a), two-dimensional amplitude modulation parameters (ms, my), and two-dimensional phase modulation parameters (fx and fy) from an appropriate closed-form solution (Examples 1 to 5) using the received set of captured fringe pattern interferogram images, and reconstructs (130) the representative detailed phase image using the parameter estimates. 6988290 1 P053251 soeci lodoed Start Capture the fringe pattern 110 interferogram images Determine an estimate of the parameters from a closed form solution Reconstruct the phase image using estimated parameters End Fig. 1