Conical collimator for X-ray measurements
X ray apparatus includes a sample stage ( 4 ) for supporting a sample ( 6 ), an X-ray source ( 2 ) and an energy dispersive X-ray detector ( 8 ). A conical X-ray collimator ( 10 ) is provided either between the sample and the X-ray source or between the sample and the energy-dispersive X-ray detector, the conical X-ray collimator including a plurality of truncated cones arranged concentrically around a central axis, the truncated cones having a common apex defining a central measurement spot on the sample.
1. An X-ray fluorescence apparatus, comprising:
a sample stage for supporting a sample;
an X-ray source;
an energy dispersive X-ray detector;
characterised by a conical collimator provided either between the sample and the X-ray source or between the sample and the energy-dispersive X-ray detector, the conical collimator including a plurality of truncated cones arranged concentrically around a central axis, the truncated cones having a common apex defining a central measurement spot on the sample, for collimating X-rays from the X-ray source onto the central measurement spot and wherein the truncated cones are configured to absorb X-rays incident on the truncated cones.
2. The X-ray fluorescence apparatus according to claim 1 , wherein the conical collimator is of refractive metal.
3. The X-ray fluorescence apparatus according to claim 1 , wherein the conical collimator is integrally formed as a single unit.
4. The X-ray fluorescence apparatus according to claim 1 , wherein the conical X-ray collimator defines a spot at the sample stage of lateral dimension no more than 1 mm.
5. The X-ray fluorescence apparatus according to claim 1 , wherein the conical collimator subtends a solid angle of 0.1 mSr to 10 mSr.
6. The X-ray fluorescence apparatus according to claim 1 , wherein the conical collimator is placed between the sample stage and the energy-dispersive X-ray detector.
7. The X-ray fluorescence apparatus according to claim 1 , wherein the conical collimator is placed between the sample stage and the X-ray source.
8. The X-ray fluorescence apparatus according to claim 1 , wherein the conical collimator includes at least 4 concentric truncated cones supported by a plurality of radial supports.
9. The X-ray fluorescence apparatus according to claim 8 , wherein each truncated cone is formed of a sheet having a thickness of 40 μm to 200 μm.
10. The X-ray fluorescence apparatus according to claim 8 , wherein the spacing between adjacent truncated cones at the closest point is in the range 50 μm to 250 μm.
11. A method of making an X-ray fluorescence measurement, comprising:
directing X-rays from an X-ray source onto a sample;
detecting, using an energy-dispersive X-ray detector, X-rays from the sample;
wherein a conical X-ray collimator is provided either between the sample and the X-ray source or between the sample and the energy-dispersive X-ray detector, the conical X-ray collimator including a plurality of truncated cones arranged concentrically around a central axis, the truncated cones having a common apex defining a central measurement spot on the sample and wherein the truncated cones are configured to absorb X-rays incident on the truncated cones.
12. The method of making an X-ray fluorescence measurement according to claim 11 , wherein the conical collimator is of refractive metal.
13. The method of making an X-ray fluorescence measurement according to claim 11 , wherein the conical collimator is integrally formed as a single unit.