In-Situ Shearing Interferometry Of National Synchrotron Light Source Mirrors

In situ mirror distortion measurements were made with a lateral shearing interferometer on three mirrors in beam line X17T at the National Synchrotron Light Source. Lateral shearing interference is insensitive to vibrational motion in five of the six degrees of freedom, so it is well-suited for investigations in the synchrotron radiation (SR) environment. No distortion was seen in an uncooled silicon carbide mirror and in a cooled copper alloy mirror on X17TB, but a change in the radius of an uncooled electroless nickel-plated aluminum cylinder mirror of about 6.2% was observed on X17TA. Angular vibrations in the 2-3 arc second range were easily observed on one of the beam lines, as was an overall mirror rotation in the arc second range.