Mirror Kirkpatrick-Baez

Figure 4.9. Kirkpatrick-Baez mirrors for the generation of primary beams with nanometer size cross-section. Source ESRF Newsletter (2005), 42(12), 14-15...

Yang, B.X., Rivers, M., Schildkamp, W., Eng, P.J. 1995. GeoCARS microfocussing Kirkpatrick-Baez mirror bender development. Review of Scientific Instruments, 66, 2278. 

To produce micrometer sized focused beams, one employs highly demagnifying optics to image the source onto the sample. Such optics can include Kirkpatrick-Baez mirrors, Fresnel zone plates, tapered capillaries, and compound refractive lenses, all of which have been used to produce submicron focal spots at third generation storage rings. 

For imaging with X-rays, the X-ray beam can be focused on a small spot using zone plates, Kirkpatrick-Baez mirrors, or tapered capillaries (Attwood 2000 Bertsch and Hunter... 

For imaging at the P, S, and Cl -absorption edges and for other heavy element absorption edges, researchers use pinholes (at several synchrotrons), tapered capillaries (GN George, personal communication Steve Heald and colleagues at the APS Bilderback et al. 1994), Kirkpatrick-Baez mirrors (at several synchrotrons), and also zone... 

The XRF intensity maps were obtained at beamline 20-ID-B (PNC-CAT) of the Advanced Photon Source (Argoime National Laboratory) at room temperature. The beamline had a chaimel cut Si(lll) crystal monochromator (3-27 keV) and a pair of Kirkpatrick-Baez mirrors, which focused the beam to 4 pm square at the sample. A 13-element Ge detector at 90° of the incident beam was employed to capture the emiPed fluorescence. A step size of 4 pm was used for an image of 324 X 504 pm at an energy of 10 or 7 keV. 

Another important new direction is improving the spatial resolution of APXPS, in particular, for the investigation of inhomogeneous samples, such as industrial catalysts and electrochemical devices. This can be achieved by focusing the incident X-rays using either Kirkpatrick-Baez mirror pairs (for hard X-rays, beam spots of 100 run have been achieved [79]) or Fresnel zone plates, for which a spatial resolution of 10 nm was demonstrated in the soft X-ray regime [80]. 

T. Ishikawa, K. Yamauchi, 2005, Hard X-ray Diffraction-Limited Nanofocus-ing with Kirkpatrick—Baez Mirrors ,... 

Nanobeam optics with beam diameters of several nanometers are presently developed at the ESRF. Using a Kirkpatrick-Baez optical system (cf. Fig. 4.9) beam diameters of 80 nm have been achieved. The Kirkpatrick-Baez system is made from two successively reflecting, orthogonal mirrors that are bent into elliptical shape by mechanical benders. The focused flux is strongly increased by deposition of a graded multilayer structure similar to that used with the parabolic Gobel mirror. 

In SR-scattering, a focus of 10 40 pm2 has been realized for a microprobe instrument, using two cylindrical mirrors (Kirkpatrick-Baez geometry [38]) as substrates. Such an optic appears to be suitable to reach focal spot sizes of 1 1 pm2 [39]. 

These issues lead to an approximate statement of ideal conditions for a GI experiment vertical beam divergence less than 10% of the critical angle, and beam size 100 pm or less in the vertical direction, with near 100% polarization. Focusing should be, if possible, arranged to preserve the separate identities of vertical and horizontal divergence. The latter is accomplished by using bent flat mirrors, either separately of in Kirkpatrick-Baez pairs. 

Figure 1. Schematic showing the components of an X-ray microprobe based on Kirkpatrick-Baez microfocusing mirrors.

Techniques for hard X-ray reflection include, among others, the reflection from multilayer structures with graded d-spacing. The present status of multilayer coating development allows to fabricate high quality flat mirrors, for which a large body of experience exists at the OSMIc Inc., Troy, MI, USA (Joensen et al., 1994). With flat mirrors these authors have demonstrated the feasibility of Kirkpatrick-Baez multilayer hard X-ray telescopes. 

There has also been a tremendous development of designing and manufacturing X-ray focusing lenses such as compound refractive lenses. Highly efficient in terms of flux are mirrors aligned in Kirkpatrick-Baez geometry. Ref. [30] includes a detailed review on the recent developments of X-ray optics for microscopy. 

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