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DIAMOND REFRACTIVE LENSES FOR DIFFRACTION-LIMITED X-RAY SOURCES

Name
Maxim
Surname
Polikarpov
Scientific organization
Immanuel Kant Baltic Federal University
Academic degree
PhD student
Position
PhD student
Scientific discipline
Physics & Astronomy
Topic
DIAMOND REFRACTIVE LENSES FOR DIFFRACTION-LIMITED X-RAY SOURCES
Abstract
In view of the global switch to the diffraction-limited fourth generation X-ray sources, there is a growing need for X-ray optical elements fabricated from materials that can withstand extreme heat and radiation loads. Diamond can satisfy all the requirements and in our research, for the first time single-crystal diamond planar and 2D refractive lenses were fabricated by laser micromachining in up to 1.2 mm thick diamond plates. Various lenses with apertures up to 1mm and radii of the parabola apex up to 500µm were tested in the focusing and imaging modes.
Keywords
X-ray optics, X-ray refractive lenses, diamond machining, X-ray sources
Summary

DIAMOND REFRACTIVE LENSES FOR DIFFRACTION-LIMITED X-RAY SOURCES

 M.V. Polikarpov a, S.A. Terentiev b,  V.A. Yunkin c,  I.I. Snigireva d, V.D. Blankb, T.V. Kononenkoe,f, V.G. Ralchenkoe,f and A.A. Snigirev a

a Immanuel Kant Baltic Federal University (Kaliningrad, Russia)

b FSBI TISNCM  (Troitsk, Moscow, Russia)

 cInstitute of Microelectronics Technology RAS (Chernogolovka, Russia)

d ESRF (Grenoble, France)

e General Physics Institute of Russian Academy of Sciences,

Vavilov str. 38, Moscow, Russian Federation 119991

f National Research Nuclear University ‘‘MEPhI’’, Kashirskoye shosse 31, Moscow, Russian Federation 115409

 

The intensive development of X-ray refractive optics’ instrumentation and tools has given birth to X-ray refractive lenses [1] which are now the standard elements at third-generation synchrotron radiation sources. In view of the global switch to the fourth generation of synchrotron sources and X-ray Free Electron Lasers, there is a growing need for x-ray optical elements fabricated from materials that can withstand extreme heat and radiation loads while still providing effective focusing and imaging. Diamond can satisfy all the requirements provided that a suitable lens manufacturing technology is available.

In our research [2], for the first time diamond planar refractive lenses were fabricated by laser micromachining in up to 1.2 mm thick diamond plates (both mono- and polycrystalline) which were grown by CVD and HPHT. Various linear lenses with apertures up to 1mm (fig.1) and radii of the parabola apex up to 500 µm were manufactured and analyzed with SEM, AFM, Raman spectroscopy and, of course, X-ray tests at the European Synchrotron Radiation Facility (ID06 beamline). A uniform intensity of the image of the focused X-ray beam showed the high quality of the lens’s side walls and profile allowing to focus the X-radiation in accordance with the lens’ demagnification factor. Planar lenses were followed by 2D parabolic X-ray refractive half lenses (fig. 2), which were also manufactured by laser micro-machining of single-crystal diamond. A single 2D lens had an aperture of 1 mm and parabola apex radii of 200 μm. Forming a compound refractive lens with 24 single lenses within, it has been successfully tested in the focusing and imaging modes both at the APS source [3] and at the laboratory setups using Cu K X-radiation from the rotating anode generator and microfocus MetalJet X-ray tube with a liquid-gallium jet as the anode using Ga Ka line. The lens has successfully reproduced the triangular object with the theoretical demagnification while the focusing of the 20 μm source was performed with the small deviation from the theoretical value.

The present study demonstrated that laser micro-fabrication technology provides a straight forward method for the fabrication of single-crystal diamond refractive lenses with large acceptance and high shape and surface (peak-to-valley roughness ~ 1µm) quality. Unique optical properties of diamond single-crystal lenses coupled with its excellent thermal qualities allows them to be applied as focusing, imaging and beam-conditioning elements at high-heat flux beams of today and future X-ray sources.

Figure 1. Planar refractive lenses from mono- (a,c,d) and polycrystalline (b) diamond

Figure 2. 2D parabolic single-crystal diamond refractive half lens (a) and its cross-section (b).

 

 

References

1.             Snigirev, A., et al., A compound refractive lens for focusing high-energy X-rays. Nature, 1996. 384(6604): p. 49-51.

2.             Polikarpov, M., et al., Large-acceptance diamond planar refractive lenses manufactured by laser cutting. Journal of Synchrotron Radiation, 2015. 22(1).

3.             Terentyev, S., et al., Parabolic single-crystal diamond lenses for coherent x-ray imaging. Applied Physics Letters, 2015. 107(11): p. 111108.