Effect of pixel size and lateral distortion on the accuracy of stitching interferometry for high-precision x-ray...

Stitching interferometry is essential for X-ray mirror metrology where lateral distortion and pixel size are critical factors influencing its accuracy. Simulations and experiments reveal that 1% error in pixel size causes a 2% deviation in the radius of curvature. After correcting pixel size, the stitching profile error of an elliptical mirror reduces from 2 μm to 250 nm (peak-to-valley). Lateral distortion correction can further reduce retrace errors. For stitching measurements using small sub-apertures, distortion correction can be minor if the average pixel size has been corrected and the actual distortion along the stitching direction is small.