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Point-focusing monochromator crystal realized by hot plastic deformation of a Ge wafer.

Okuda H, Nakajima K, Fujiwara K, Morishita K, Ochiai S - J Appl Crystallogr (2008)

Bottom Line: Pre-polished Ge(111) single-crystal wafers were deformed just below the melting temperature to prepare point-focusing Johansson monochromator crystals.The (111) lattice plane had curvature 2R in the focusing plane and R perpendicular to it, with a hemispherical inner surface with a radius of R = 600 mm.By using Cu Kalpha radiation, the diverging X-ray beam was focused onto a small spot.

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ABSTRACT
Pre-polished Ge(111) single-crystal wafers were deformed just below the melting temperature to prepare point-focusing Johansson monochromator crystals. The (111) lattice plane had curvature 2R in the focusing plane and R perpendicular to it, with a hemispherical inner surface with a radius of R = 600 mm. By using Cu Kalpha radiation, the diverging X-ray beam was focused onto a small spot.

No MeSH data available.


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Focusing of (a) solar light with a diameter of 20 mm and (b) Cu Kα X-rays by the present crystal. Solar light was focused onto a spot at f = 300 mm, showing that the crystal surface was hemispherical with a radius of 600 mm. Cu Kα radiation was diffracted by the crystal at C and focused at L2.
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fig2: Focusing of (a) solar light with a diameter of 20 mm and (b) Cu Kα X-rays by the present crystal. Solar light was focused onto a spot at f = 300 mm, showing that the crystal surface was hemispherical with a radius of 600 mm. Cu Kα radiation was diffracted by the crystal at C and focused at L2.

Mentions: Another important condition for realizing a point-focusing monochromator is the curvature of the crystal surface. Under the present diffraction condition the surface must be hemispherical. Since the present process produces a mirror surface, the deformed crystal reflects visible light by acting as a curved mirror. A spherical mirror with a radius of curvature R has a focus at f = R/2, as shown in Fig. 2 ▶(a). When solar light with a beam diameter of 20 mm illuminates the present crystal, the image obtained at the focal point, L = 300 mm, is found to be a small spot, i.e. the surface of the present crystal is hemispherical, as shown in the figure. The spot size measured by full width at half-maximum (FWHM) is 3.0 mm, which agrees with the size of 2.9 mm expected from a convolution of the native divergence of solar light and the beam broadening of the X-ray diffraction discussed below.


Point-focusing monochromator crystal realized by hot plastic deformation of a Ge wafer.

Okuda H, Nakajima K, Fujiwara K, Morishita K, Ochiai S - J Appl Crystallogr (2008)

Focusing of (a) solar light with a diameter of 20 mm and (b) Cu Kα X-rays by the present crystal. Solar light was focused onto a spot at f = 300 mm, showing that the crystal surface was hemispherical with a radius of 600 mm. Cu Kα radiation was diffracted by the crystal at C and focused at L2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2483481&req=5

fig2: Focusing of (a) solar light with a diameter of 20 mm and (b) Cu Kα X-rays by the present crystal. Solar light was focused onto a spot at f = 300 mm, showing that the crystal surface was hemispherical with a radius of 600 mm. Cu Kα radiation was diffracted by the crystal at C and focused at L2.
Mentions: Another important condition for realizing a point-focusing monochromator is the curvature of the crystal surface. Under the present diffraction condition the surface must be hemispherical. Since the present process produces a mirror surface, the deformed crystal reflects visible light by acting as a curved mirror. A spherical mirror with a radius of curvature R has a focus at f = R/2, as shown in Fig. 2 ▶(a). When solar light with a beam diameter of 20 mm illuminates the present crystal, the image obtained at the focal point, L = 300 mm, is found to be a small spot, i.e. the surface of the present crystal is hemispherical, as shown in the figure. The spot size measured by full width at half-maximum (FWHM) is 3.0 mm, which agrees with the size of 2.9 mm expected from a convolution of the native divergence of solar light and the beam broadening of the X-ray diffraction discussed below.

Bottom Line: Pre-polished Ge(111) single-crystal wafers were deformed just below the melting temperature to prepare point-focusing Johansson monochromator crystals.The (111) lattice plane had curvature 2R in the focusing plane and R perpendicular to it, with a hemispherical inner surface with a radius of R = 600 mm.By using Cu Kalpha radiation, the diverging X-ray beam was focused onto a small spot.

View Article: PubMed Central - HTML - PubMed

ABSTRACT
Pre-polished Ge(111) single-crystal wafers were deformed just below the melting temperature to prepare point-focusing Johansson monochromator crystals. The (111) lattice plane had curvature 2R in the focusing plane and R perpendicular to it, with a hemispherical inner surface with a radius of R = 600 mm. By using Cu Kalpha radiation, the diverging X-ray beam was focused onto a small spot.

No MeSH data available.


Related in: MedlinePlus