Optical microelectromechanical systems (MEMS) are tiny microchip-sized devices that control light and communications. Separately, time-resolved X-ray probes are devices that help scientists study highly transient phenomena. These phenomena are of short duration and involve rapid structural and functional changes. Scientists have now developed X-ray optics based on specially designed and fabricated MEMS that can harness extremely short X-ray pulses. The new devices are much smaller and lighter than conventional devices used to operate X-ray probes, and they could be essential for experiments on ultrafast phenomena at synchrotron X-ray and free-electron laser sources.
The new ultra-fast optics-on-chip device will be an order of magnitude smaller and lighter than conventional devices used to handle X-ray probes. This will enable innovative X-ray research and applications. device could help scientists study rapidly changing chemical, material and biological processes. The results could aid in the development of efficient solar cells and batteries, advanced computing storage and new drugs. In this study, scientists demonstrated the device in a synchrotron facility. A fully developed version could be used with X-ray generators found in hospitals and university labs. In these settings, the devices could support rapid non-destructive diagnostics or precise dosing for radiation therapy.
The research team, consisting of scientists from the Advanced Photon Source (APS) and the Center for Nanoscale Materials (CNM), demonstrated the X-ray optics device on a chip using the X-ray source from the ‘APS. APS and CNM are user science facilities of the Department of Energy (DOE) at Argonne National Laboratory. The device, designed at the CNM, measures only 250 micrometers and weighs only 3.5 micrograms. The extremely small size and light weight of the MEMS-based shutter allows it to oscillate at speeds equivalent to about one million revolutions per minute. The researchers took advantage of this high speed and the X-ray diffraction property of the MEMS material to create an extremely fast X-ray shutter. The resulting ultra-fast X-ray optics can handle hard X-ray pulses in excess of 350 MHz, 1,000 times faster than any mechanical modulator. Additionally, the timing characteristics of the devices can be tuned for a multitude of instruments and dynamic X-ray applications not possible with traditional optics which are typically a billion times more massive. On-chip X-ray optics devices pave the way for future dynamic and miniature X-ray optics for time-domain science and accelerator diagnostics and control, including wavefront manipulation, scattering spectrum, multiplexing and pulse chopping.
The research was supported by DOE’s Office of Science, Basic Energy Sciences, Science User Facilities Division.