A research team in Japan has succeeded in developing high precision X-ray deformable mirrors that can be configured as necessary. They are the first to have achieved the formation of three types of X-ray focused beams, which differ in focused spot size, without changing the experimental setup. This is a considerable step towards developing a multi-functional X-ray microscope, which will be able to perform a variety of microscopic analyses in one device.
So far, X-ray analysis and X-ray microscopes lack the flexibility of electron microscopes, as one device is merely capable of sending a fixed set of focused beams, thereby limiting the range of uses of the device. The research team centering around Professor Kazuto Yamauchi and Assistant Professor Satoshi Matsuyama, both at Graduate School of Engineering, Osaka University, Professor Yoshinori Nishino at Research Institute for Electronic Science, Hokkaido University, Director Dr. Tetsuya Ishikawa and Group Director Dr. Makina Yabashi at RIKEN SPring-8 Center successfully developed deformable mirrors that can be configured as necessary.
By combining four of these mirrors, a new X-ray focusing system, in which the focused spot size is controllable, was developed. This removes the necessity of having to change experiment setups, including the position of the sample.
Schematic of variable-NA focusing optical system. The two deformable mirrors are arranged perpendicular to each other (KB configuration). The variable-NA X-ray focusing system based on two sets of the mirror system were constructed (upper figure). The lower figure shows the schematic ray diagram. (Credit: Osaka University)
With the new system it is now possible to create light collection optical systems, which differ in numerical aperture, an index indicating the ability of a lens or mirror to focus light, just by changing the configuration of the deformable mirrors. Changing the numerical aperture allows for a controlling of the focused spot size close to the diffraction limit of a lens or mirror; that is, the limit of its ability to focus light because light is being diffracted. The researchers developed an X-ray wave front measuring technique with which to determine mirror configuration errors with high precision and control deformation with an accuracy of 2nm.
The research team conducted this procedure with precision for three optical systems with different numerical apertures.
