Micro-mirrors will help make ultrafast X-ray moving images

The technique, developed at the US Department of Energy’s Argonne National Laboratory, uses very small mirrors to steer, filter and pulse precise bursts of X-rays.

The Argonne team has designed a microelectromechanical system (MEMS), etched from a silicon wafer, which incorporates a diffracting mirror that is fabricated with a pair of hinges on either side that allow it to oscillate in a see-saw motion. A set of minute capacitors, designed with ‘finger’-like structures that can mesh together with one side attached to the mirror and the other to the baseplate, act as the motor to power the oscillation (this is known as a combdrive).

While such MEMS have recently found uses in several areas of optics, this is the first time they have been applied to X-rays, the Argonne team claimed. This is despite the fact that polished crystalline silicon is the material of choice for many applications of X-rays in optics; however, silicon crystal X-ray optics are typically two to five orders of magnitude larger and 6-15 orders of magnitude heavier than MEMS devices, which in this case are about 10µm thick and 500µm square.