Abstract

The design of a new type of flat-crystal x-ray source/monochromator is discussed. This new design has many advantages over previous designs. It is extremely easy to construct, compact, and portable. It is easy to align and may be adapted to a wide variety of detectors. Its dispersion crystal is easily changed, allowing the same instrument to be used for a very wide range of wavelengths. For example, with a crystal such as LiF (422) its operating range would be in the tens of kilovolts, whereas with a phthalate crystal its range would be from ~900 eV to ~3 keV. Furthermore the same instrument can be used with a multilayer to extend its useful range almost down to the vacuum UV.

© 1996 Optical Society of America

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References

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  1. E. L. Church, H. A. Jenkinson, J. M. Zavada, “Relationship between surface scattering and microtopographic features,” Opt. Eng. 18, 125–136 (1979).
  2. F. E. Christensen, K. P. Singh, H. W. Schnopper, “Measurements of surface scattering from mirrored surfaces using a triple axis x-ray spectrometer,” in X-Ray Instrumentation in Astronomy, J. L. Culhane, ed., Proc. SPIE597, 119–127 (1985).
  3. E. P. Burtin, Principles and Practice of X-Ray Spectrometric Analysis (Plenum, New York, 1970), pp. 210–214.
  4. J. R. Pierce, Theory and Design of Electron Beams (Van Norstrand, New York, 1949), pp. 168–187.

1979 (1)

E. L. Church, H. A. Jenkinson, J. M. Zavada, “Relationship between surface scattering and microtopographic features,” Opt. Eng. 18, 125–136 (1979).

Burtin, E. P.

E. P. Burtin, Principles and Practice of X-Ray Spectrometric Analysis (Plenum, New York, 1970), pp. 210–214.

Christensen, F. E.

F. E. Christensen, K. P. Singh, H. W. Schnopper, “Measurements of surface scattering from mirrored surfaces using a triple axis x-ray spectrometer,” in X-Ray Instrumentation in Astronomy, J. L. Culhane, ed., Proc. SPIE597, 119–127 (1985).

Church, E. L.

E. L. Church, H. A. Jenkinson, J. M. Zavada, “Relationship between surface scattering and microtopographic features,” Opt. Eng. 18, 125–136 (1979).

Jenkinson, H. A.

E. L. Church, H. A. Jenkinson, J. M. Zavada, “Relationship between surface scattering and microtopographic features,” Opt. Eng. 18, 125–136 (1979).

Pierce, J. R.

J. R. Pierce, Theory and Design of Electron Beams (Van Norstrand, New York, 1949), pp. 168–187.

Schnopper, H. W.

F. E. Christensen, K. P. Singh, H. W. Schnopper, “Measurements of surface scattering from mirrored surfaces using a triple axis x-ray spectrometer,” in X-Ray Instrumentation in Astronomy, J. L. Culhane, ed., Proc. SPIE597, 119–127 (1985).

Singh, K. P.

F. E. Christensen, K. P. Singh, H. W. Schnopper, “Measurements of surface scattering from mirrored surfaces using a triple axis x-ray spectrometer,” in X-Ray Instrumentation in Astronomy, J. L. Culhane, ed., Proc. SPIE597, 119–127 (1985).

Zavada, J. M.

E. L. Church, H. A. Jenkinson, J. M. Zavada, “Relationship between surface scattering and microtopographic features,” Opt. Eng. 18, 125–136 (1979).

Opt. Eng. (1)

E. L. Church, H. A. Jenkinson, J. M. Zavada, “Relationship between surface scattering and microtopographic features,” Opt. Eng. 18, 125–136 (1979).

Other (3)

F. E. Christensen, K. P. Singh, H. W. Schnopper, “Measurements of surface scattering from mirrored surfaces using a triple axis x-ray spectrometer,” in X-Ray Instrumentation in Astronomy, J. L. Culhane, ed., Proc. SPIE597, 119–127 (1985).

E. P. Burtin, Principles and Practice of X-Ray Spectrometric Analysis (Plenum, New York, 1970), pp. 210–214.

J. R. Pierce, Theory and Design of Electron Beams (Van Norstrand, New York, 1949), pp. 168–187.

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Figures (16)

Fig. 1
Fig. 1

Simple flat-crystal monochromator. As the crystal rotates through angle Θ, the detector must rotate through angle 2Θ. The resolution of this device is determined simply by the Bragg equation and the angular width of the pair of slits.

Fig. 2
Fig. 2

Basic parallel flat-crystal monochromator. All rays striking the first crystal at the Bragg angle must necessarily strike the second crystal at the Bragg angle also. Therefore this device has zero angular dispersion. We may select different wavelengths by rotating the assembly as shown, but then it is necessary to translate at least one crystal for the beam to remain where it was initially.

Fig. 3
Fig. 3

Monochromator using a parabolically bent crystal. The wavelength may be changed by a simple translation of the slit.

Fig. 4
Fig. 4

Basic principle behind the mechanical design of this source/monochromator. When the axis of rotation is offset, the intersection of the incoming beam with the diffraction element moves in such a way that the diffracted beam strikes the detector at nearly the same position. We show 11 different crystal settings superimposed. The resolution is completely determined from the entrance slits.

Fig. 5
Fig. 5

Geometry of Fig. 4 depicting symbols X1, Y1, etc. used to calculate the width of the focusing error.

Fig. 6
Fig. 6

Deviation of the diffracted x rays as the crystal is rotated from 15 to 30 deg.

Fig. 7
Fig. 7

Monochromatic x-ray source. The source was built into a 4-in.- (10.16-cm-) diameter cross and measured 8 in. (20.3 cm) in length.

Fig. 8
Fig. 8

X-ray scattering facility. The optic to be tested was positioned in the center of the chamber. Both the optic and the slit could be remotely adjusted.

Fig. 9
Fig. 9

X-ray output as a function of x-ray energy for a pyrolitic graphite crystal.

Fig. 10
Fig. 10

X-ray output as a function of energy for a PET crystal. Copper K was detected in second order. The rapid falloff in 3.4-keV output is due to the decomposition of the crystal.

Fig. 11
Fig. 11

X-ray output for quartz (1011).

Fig. 12
Fig. 12

X-ray output for RAP. KAP and TLAP gave very similar results.

Fig. 13
Fig. 13

(a) Radiation scattered from a gold-coated replicated mirror. The surface roughness of this mirror was determined to be ~21 Å. The angular distribution of the incident beam is superimposed for comparison. (b) Radiation reflected and scattered from a superpolished reference flat. The angle of incidence for this uncoated flat was 88.75 deg. As in (a) the incident beam is superimposed for comparison.

Fig. 14
Fig. 14

Angular distribution of reflected, diffracted, and scattered 930-eV radiation from a ruled diffraction grating. The 0 through 4 orders are visible.

Fig. 15
Fig. 15

Data similar to that of Fig. 14 except the grazing angle was lowered to 0.35 deg to increase the size of the footprint of the x-ray beam on the surface of the grating. This figure demonstrates how it is possible to test the uniformity of the grating.

Fig. 16
Fig. 16

X-ray output as a function of time for 1.5-keV aluminum K radiation. The source crystal was KAP.

Equations (13)

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I s = I i 4 k 4 π 2 sin ( Θ i ) sin 2 ( Θ s ) R S ,
S = ( 1 2 L ) 2 | - L + L d x - L + L d y exp [ i ( p x + q y ) ] Z ( x , y ) | 2 ,
S = ( 1 I i ) ( π 2 k 4 Θ i Θ s 2 ) ( d I s d Ω ) d Ω .
p k ( cos Θ s - cos Θ i ) , p k [ ( 1 - Θ s 2 2 ) - ( 1 - Θ i 2 2 ) ] , p k ( 1 2 ) ( Θ i 2 - Θ s 2 ) , p k ( 1 2 ) ( Θ i + Θ i ) ( Θ i - Θ s ) , p k Θ i ( Θ i - Θ s ) ,
q k Φ s .
σ 2 = 1 ( 2 I i k 2 Θ i 2 ) - + d I s d Ω d Ω .
X 1 = X 3 - Y 1 / tan ( 2 a 1 ) ,             X 1 = Y 0 / tan ( a 1 ) - y 1 / tan ( 2 a 1 ) , X 1 = Y 0 / tan ( a 2 ) - Y 1 / tan ( 2 a 2 ) .
Y 1 = Y 0 ( cot ( a 1 ) - cot ( a 2 ) ) / [ cot ( 2 a 1 ) - cot ( 2 a 2 ) ] ,
X 1 = Y 0 / tan ( a 1 ) - Y 1 / tan ( 2 a 1 ) .
L = Y 0 [ csc ( a 1 ) - csc ( a 2 ) ] .
Δ λ = 2 d [ sin ( a 2 ) - sin ( a 1 ) ] .
Δ λ / λ = [ sin ( a 2 ) - sin ( a 1 ) ] / sin [ ( a 1 + a 2 ) / 2 ] .
d λ λ = d Θ tan Θ .

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