X-ray wavefront characterization with two-dimensional wavefront sensors: shearing interferometers and Hartmann wavefront sensors

Phase reconstructions from a two-dimensional shearing interferometer, based on two orthogonal phase gratings in a single plane, and a Hartmann sensor are compared. Design alternatives for both wavefront sensors are given, and simulated performance of both the two-dimensional x-ray shearing interferometer and Hartmann wavefront sensor are presented for two different phase profiles. The first comparison is an evaluation of metrology on deuterium-tritium (DT) ice layers in an inertial confinement fusion capsule, and the second comparison is a high frequency “asterisk” phase profile, which tests the ability of these wavefront sensors to detect spikes of ablator material seen in DT fuel capsule implosions. Both of these sensors can measure the two-dimensional wavefront gradient of an x-ray beam, as well as the x-ray absorption. These instruments measure the two-dimensional wavefront gradient in a single measurement, and the wavefront sensor is located in a single plane, making them much less sensitive to vibrations than most other wavefront sensing techniques.