Real-time feedback for x-ray adaptive optics with an interferometric absolute distance sensor array

The need for smaller focal spot sizes to meet the demands for higher resolution imaging is driving the adoption of adaptive optics in x-ray beamlines. Closed-loop control of the mirror shape, position, and orientation can greatly enhance the performance of these optics by allowing for rejection of perturbations. We demonstrate the performance of an array of interferometric absolute position sensors as a means of providing real-time feedback on shape changes of the reflecting surface of a bimorph mirror by comparison to a Fizeau interferometer.