Patent Number: 
Section: claims

1. An x-ray optical device comprising:an x-ray source generating an x-ray beam; anda reflective element for receiving the x-ray beam and having variable focal points such that the convergence of an x-ray output beam varies across a surface of the reflective element according to a pre-defined function the convergence varying from a near end of the reflective element to a far end of the reflective element, the near end and the far end being defined by the respective positions of the ends relative to the x-ray source. 2. The optical device of claim 1 wherein the reflective element has a curved surface and wherein the portion of the x-ray output beam with the lowest convergence is delivered from the far end of the reflective element. 3. The optical device of claim 1 wherein the reflective element has a curved surface and wherein the portion of the x-ray output beam with the lowest convergence is delivered from the near end of the reflective element. 4. The optical device of claim 1 wherein the optical device delivers a uniform x-ray output beam of x-rays toward a sample or a detector. 5. The optical device of claim 1 further comprising an adjustable aperture for selecting a portion of the x-ray output beam which optimizes the convergence and flux of the x-ray output beam. 6. The optical device of claim 5 wherein the aperture is made of four individual blades. 7. The optical device of claim 5 wherein the aperture is made of two angled blades. 8. The adjustable aperture in claim 5 wherein the aperture is a round pinhole, the portion of the x-ray output beam being selected by changing the size of the pinhole. 9. The optical device of claim 1 wherein a portion of the beam is occluded, the non-occluded portion of the x-ray output beam having a desired convergence. 10. The optical device of claim 1 wherein the surface of the reflective element varies according to a pre-defined function to provide the varying convergence. 11. The optical device of claim 10 wherein the convergence varies according to a linear function. 12. The optical device of claim 10 wherein the reflective element provides a uniform x-ray output beam at a certain location. 13. The optical device of claim 1 further comprising a second reflective element arranged relative to the first reflective element to provide a two-dimensional conditioned x-ray output beam. 14. The optical device of claim 1 wherein the reflective element is a two-dimensional curved surface, which provides a two-dimensional conditioned x-ray output beam. 15. The optical device of claim 1 wherein the varying convergence across the x-ray output beam produces the varying focal points simultaneously.