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Figure 1
Experimental setup and data processing procedure for the 2D metrology of an X-ray mirror. The mirror was positioned to reflect horizontally to decouple the measurements from any vertical vibration and structure coming from the double-multilayer monochromator. The sandpaper speckle generator translated across the beam in the x direction. Two image stacks were acquired: (1) the reference beam image stack without the mirror being tested in the beam and (2) the reflected beam image stack with the mirror in the beam. Sub-regions of the raw images were selected for the 2D data analysis, as indicated by the white rectangles. In order to analyse the whole detecting area, the sub-regions were shifted to cover the full extent of the raw image. Column-by-column analysis was conducted in each sub-region. One column of pixels from each image in both image stacks was extracted and stitched together to form two new images, as shown on the right. The two new images were then used in a cross-correlation calculation to obtain the displacements in two directions, iy and ix. The 2D map of the displacements was generated by calculating the results for all of the columns within one sub-region and then shifting the sub-region to cover the whole raw image.

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ISSN: 1600-5775
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