X-ray analyzer having multiple excitation energy bands produced using multi-material x-ray tube anodes and monochromating optics

1. An x-ray analysis apparatus for analyzing a sample spot, comprising:

an x-ray tube comprising a target on which electrons impinge to form a diverging x-ray beam, the target having a surface formed from first and second target materials, each target material tailored to emit a respective energy profile upon impingement by the electrons;

a first x-ray optic for receiving the diverging x-ray beam and directing the beam toward the sample spot, the first x-ray optic monochromating the beam to a first energy from the energy profile emitted by the first target material;

a second x-ray optic for receiving the diverging x-ray beam and directing the beam toward the sample spot, the second x-ray optic monochromating the beam to a second energy from the energy profile emitted by the second target material; and

a detector to receive fluorescence from the sample spot induced by the first and second monochromated energies and indicative of a concentration of at least one element in the sample.

2. The apparatus of claim 1 , further comprising:

the target of the x-ray tube having a surface formed from a third target material, the third target material tailored to emit a respective energy profile upon impingement by the electrons; and

a third x-ray optic for receiving the diverging x-ray beam and directing the beam toward the sample spot, the third x-ray optic monochromating the beam to a third energy from the energy profile emitted by the third target material.

3. The apparatus of claim 2 , wherein the first x-ray optic monochromates characteristic energy from the target and the second and/or third x-ray optic monochromates bremsstrahlung energy from the target.

4. The apparatus of claim 1 , wherein the x-ray optics are curved diffracting optics, for receiving the diverging x-ray beam from the x-ray tube and focusing the beam at the sample spot.

5. The apparatus of claim 4 , wherein the x-ray optics are focusing monochromating optics.

6. The apparatus of claim 5 , wherein the x-ray optics are doubly-curved crystal optics, or HOPG optics, or multi-layer optics.

7. The apparatus of claim 1 , wherein the first and/or second optic comprises a curved crystal diffracting optic comprising multiple layers, each layer having its own diffractive effect on the incident x-ray beam.

8. The apparatus of claim 7 , wherein the layers of the first and/or second optic comprise LiF.

9. The apparatus of claim 8 , wherein the first and/or second optic comprising LiF layers further comprises at least one segment bent into a curved shape.

10. The apparatus of claim 9 , wherein the first and/or second optic comprising LiF layers further comprises multiple segments, each segment bent into a curved shape, and arranged into a curved pattern.

11. The apparatus of claim 6 , wherein the curved pattern comprises a fully rotated, 360 degree pattern.

12. The apparatus of claim 1 , wherein the first x-ray optic monochromates characteristic energy from the target and the second x-ray optic monochromates bremsstrahlung energy from the target.

13. The apparatus of claim 1 , wherein fluorescence from the sample spot induced by the first and second monochromated energies is used to measure the concentration of at least one element separately in a coating and a substrate of the sample.

14. The apparatus of claim 1 , wherein each target material of the first and second target materials is formed in a separate layer on the target.

15. The apparatus of claim 1 , wherein each target material of the first and second target materials is combined into a single alloy layer on the target.

16. The apparatus of claim 1 , wherein:

one of the first and second target materials is formed in a first layer on the target; and

at least two target materials are combined into a second, alloy layer on the target.