Patent Number: 
Section: claims

1. An optical device for treating an incident X-ray beam, said device comprising:a monochromator; andan optical element for conditioning the incident X-ray beam, the optical element including an X-ray reflective surface having a multilayer structure to produce a two-dimensional optical effect in order to adapt a beam directed towards the monochromator;wherein said reflective surface consists of a single surface, said reflective surface being shaped according to two curvatures corresponding to two different directions in order to produce respective one-dimensional effects, wherein one of the one-dimensional effects is a collimation for limiting the divergence in the diffraction plane of the monochromator, and the other one-dimensional effect is a focusing. 2. The optical device according to claim 1, wherein said single reflective surface is of a multilayer type with a lateral gradient. 3. The optical device according to claim 1, wherein the single reflective surface comprises a depth gradient. 4. The optical device according to claim 1, wherein said reflective surface has a geometry which is substantially circular in a first direction and substantially parabolic in a second direction. 5. The optical device according to claim 4, wherein said first direction is a saggital direction of the optical element and the second direction is a meridional direction of the optical element. 6. The optical device according to claim 1, wherein said reflective surface has a substantially toroidal geometry. 7. The optical device according to claim 1, wherein said reflective surface has a substantially paraboloidal geometry. 8. The optical device according to claim 1, wherein said reflective surface has a substantially ellipsoidal geometry. 9. The optical device according to claim 1, wherein said reflective surface is able to reflect rays of lines Cu—K or Mo—K. 10. The optical device according to claim 1, wherein the monochromator comprises a germanium crystal, and the optical element comprises a W/Si multilayer coating with a lateral gradient. 11. The optical device according to claim 1, wherein the optical element of the optical device has a length of around 2 cm, said optical device being usable with a source of X-rays having a size of around 40 microns by 40 microns in order to produce a sample spot of around 300*300 microns. 12. The optical device according to claim 1, wherein said reflective surface has a geometry defined by an open or closed curve different from a circle in a first one of the directions and substantially parabolic in a second one of the directions. 13. The optical device according to claim 1, wherein said reflective surface has a geometry substantially elliptical in a first one of the directions and substantially parabolic in a second one of the directions. 14. The optical device according to claim 1, wherein said reflecting surface has a geometry substantially parabolic in the two different directions. 15. The optical device according to claim 1, wherein the reflective surface has a radius of curvature lower than 20 mm along the saggital direction of the optical element.