Active microstructured x-ray optical arrays
Michette AG., Pfauntscha SJ., Sahraeia S., Shanda M., Morrisona GR., Hart D., Vojnovicab B., Stevensonc T., Parkesc W., Dunarec C., Willingale R., Feldmand CH., Buttone TW., Zhange D., Rodriguez-Sanmartine D., Wang H., Smithg AD.
The UK Smart X-Ray Optics consortium is developing novel reflective adaptive/active x-ray optics for small-scale laboratory applications, including studies of radiation-induced damage to biological material. The optics work on the same principle as polycapillaries, using configured arrays of channels etched into thin silicon, such that each x-ray photon reflects at most once off a channel wall. Using two arrays in succession provides two reflections and thus the Abbe sine condition can be approximately satisfied, reducing aberrations. Adaptivity is achieved by flexing one or both arrays using piezo actuation, which can provide further reduction of aberrations as well as controllable focal lengths. Modelling of such arrays for used on an x-ray microprobe, based on a microfocus source with an emitting region approximately 1μ m in diameter, shows that a focused flux approximately two orders of magnitude greater than possible with a zone plate of comparable focal length is possible, assuming that the channel wall roughness is less than about 2nm. ©2009 SPIE.