A stitching figure profiler of large X-ray mirrors using RADSI for subaperture data acquisition

In the third- and coming fourth-generation synchrotron radiation facilities, X-rays having both high brightness and high coherency can be utilized. Such X-rays require high accuracy in the reflective optics. In this study, we developed an ultra-precise measurement instrumentation for tangentially long X-ray mirrors using a Fizeau interferometer. In the system, the mirror figure is measured by stitching the subaperture profiles measured by the relative-angle determinable stitching interferometry, which we developed previously. High measurement accuracy of approximately 2 nm (peak to valley) was achieved in the measurement of a 400 mm-long aspherical surface.