Patent Number: 
Section: claims

1. An x-ray source comprising:an electron source for generating an electron beam;an anode, at which the electron beam is directed to produce x-rays, the anode comprising a layer of a metal on a substrate, the metal layer being less than 8 micrometers thick;a monochromator for suppressing Bremsstrahlung radiation in the x-rays relative to x-ray radiation of a characteristic line of the metal; anda central stop for spatially filtering the x-rays. 2. An x-ray source as claimed in claim 1, wherein the metal layer of the anode is thin, being less than 3-5 micrometers thick. 3. An x-ray source as claimed in claim 1, wherein the metal layer comprises copper. 4. An x-ray source as claimed in claim 1, wherein the metal layer comprises chromium, tungsten, platinum, or gold. 5. An x-ray source as claimed in claim 1, wherein the substrate comprises beryllium. 6. An x-ray source as claimed in claim 1, wherein the substrate comprises carbon. 7. An x-ray source as claimed in claim 1, wherein the substrate comprises diamond. 8. An x-ray source as claimed in claim 1, further comprising a barrier layer between the metal layer and the substrate. 9. An x-ray source as claimed in claim 1, wherein a thickness of the metal layer is selected based on an acceleration voltage of the electron beam such that electrons lose only about 5-15% of their energy in the metal layer. 10. An x-ray source as claimed in claim 1, wherein an energy of the electron beam more than 8 times an atomic shell ionization energy of the metal layer. 11. An x-ray source as claimed in claim 1, wherein an energy of the electron beam about 15 times an atomic shell ionization energy of the metal layer, or more. 12. An x-ray source as claimed in claim 1, further comprising a pin hole aperture. 13. An x-ray source as claimed in claim 1, wherein the x-rays are collected at a take-off angle of 6-45 degree relative to the layer of the metal. 14. An x-ray source as claimed in claim 1, wherein a focal spot size of the electron beam on the metal layer is less than 5 micrometers. 15. A method for generating x-rays, comprising:generating an electron beam;directing the electron beam at a metal layer to generate x-rays, the metal layer being less than 8 micrometers thick;filtering the x-rays to suppress Bremsstrahlung radiation relative to x-ray radiation of a characteristic line of the metal; andspatially filtering the x-rays with a central stop. 16. A method as claimed in claim 15, wherein the metal layer is less than 3 micrometers thick. 17. A method as claimed in claim 15, wherein an energy of the electron beam is more than 8 times an atomic shell ionization energy of the metal layer. 18. A method as claimed in claim 15, wherein an energy of the electron beam is about 15 times an atomic shell ionization energy of the metal layer, or more. 19. A method as claimed in claim 15, wherein the step of filtering comprises using a monochromator. 20. A method as claimed in claim 15, further comprising spatially filtering the x-rays with a pin hole aperture. 21. A method as claimed in claim 15, further comprising collecting the x-rays at a take-off angle of 6-45 degree relative to the layer of the metal. 22. A method as claimed in claim 15, wherein a focal spot size of the electron beam on the metal layer is less than 5 micrometers.