Figure 12
(a) The radial profile of the phase plate was measured using both single-grating interferometry and X-ray speckle tracking in differential mode by making measurements of the wavefront, with and without the phase plate inserted, and performing an azimuthal average of the resulting 2D profile [see Fig. 11(c)]. Since care was taken to process data with and without the phase plate in exactly the same way, the only fit parameter is a scaling of the radial coordinates. (b) A quantitative comparison can be made by examining the phase difference between the curves from (a). The curves labeled Δϕgs, Δϕgd and Δϕsd refer to differences between grating and speckle, grating and design, and speckle and design, respectively. The region between the solid horizontal lines corresponds to agreement within ±λ/20 and the region between the dashed horizontal lines corresponds to within ±λ/50. |