Development of pseudo-perfect x-ray optics using refractive compensators

With progress towards diffraction limited focusing at third synchrotron sources, obtaining a distortion free wavefront for the X-rays following focusing optics becomes important to enable the exploitation of the high X-ray coherence. We describe a practical method for determining and applying a correction to the wavefront to compensate for distortions caused by fabrication errors in the optics. The method uses custom designed refractive correctors inserted in-line with the optical element. We describe a method for characterising the optics and determining the profile of the refractive corrector and show results from measurements made on real beamline optics.