Developing a Sagittally Focusing Double‐Multilayer Monochromator

We report the development of a sagittally focusing double multilayer monochromator to produce a spatially extended, wide‐bandpass x‐ray beam from intense synchrotron bending‐magnet source at the Advanced Photon Source for ultrafast x‐radiography and ‐tomography applications. This monochromator consists of the two W/B4C multilayers with a 25‐A periodicity coated on Si single‐crystal substrates. The second crystal is mounted on a saggitally focusing bender which can; dynamically change the bending radius of the crystal in order to focus the beam to various points along the beamline. With this new apparatus, it becomes possible to adjust the x‐ray beam size to best match the area detector size and the object size to facilitate a more efficient data collection using ultrafast x‐radiography and ‐tomography.