Talbot X-ray microscope
Systems for x-ray microscopy using an array of micro-beams having a micro- or nano-scale beam intensity profile to provide selective illumination of micro- or nano-scale regions of an object. An array detector is positioned such that each pixel of the detector only detects x-rays corresponding to a single micro-or nano-beam. This allows the signal arising from each x-ray detector pixel to be identified with the specific, limited micro- or nano-scale region illuminated, allowing sampled transmission image of the object at a micro- or nano-scale to be generated while using a detector with pixels having a larger size and scale. Detectors with higher quantum efficiency may therefore be used, since the lateral resolution is provided solely by the dimensions of the micro- or nano-beams. The micro- or nano-scale beams may be generated using a arrayed x-ray source and a set of Talbot interference fringes.
1. An x-ray microscope system comprising:
an x-ray illumination beam generating system comprising:
an x-ray source; and
a beam-splitting grating, wherein said x-ray illumination beam generating system produces a plurality of x-ray micro-beams through the Talbot effect, the plurality of x-ray micro-beams having a depth-of-focus, an axis of propagation and a predetermined intensity profile normal to said axis for a predetermined x-ray energy;
a mount configured to support an object to be examined within the depth-of-focus, the mount configured to move the object relative to said plurality of x-ray micro-beams; and
at least one x-ray pixel array detector for detecting x-rays resulting from interaction of said plurality of x-ray micro-beams with said object, said detector comprising a plurality of pixels within said depth-of-focus.
2. The x-ray microscope system of claim 1 , wherein the beam-splitting grating is a π phase-shifting grating or a π/2 phase-shifting grating at said predetermined x-ray energy.
3. The x-ray microscope system of claim 1 , wherein the x-ray source comprises:
an emitter for an electron beam; and
a transmission x-ray target comprising a plurality of discrete microstructures comprising a first material having a first mass density and a substrate comprising a second material having a second mass density lower than the first mass density.
4. The x-ray microscope system of claim 3 , wherein the energy of the electron beam is greater than 1.1 times of the predetermined x-ray energy.
5. The x-ray microscope system of claim 3 , wherein the electron beam is incident upon the target at an oblique angle.
6. The x-ray microscope system of claim 1 , wherein the x-ray source is a microfocus x-ray source or an extended x-ray source used in combination with an absorption grating.
7. The x-ray microscope system of claim 1 , further comprising at least one filter so that the full width half maximum of the bandwidth of the plurality of x-ray micro-beams is 30% centered at the predetermined x-ray energy.
8. The x-ray microscope system of claim 1 , wherein the mount is configured to translate the object in two orthogonal directions.
9. The x-ray microscope system of claim 8 , wherein the mount is further configured to rotate the object about a direction perpendicular to the axis of propagation.
10. The x-ray microscope system of claim 1 , wherein the detector is a CCD-based detector and is aligned such that centers of the pixels are aligned to centers of the x-ray micro-beams.
11. The x-ray microscope system of claim 1 , further comprising an analysis system configured to display and analyze output signals from the detector.
12. The x-ray microscope system of claim 1 , further comprising a mask positioned to block a predetermined number of the x-ray micro-beams.
13. The x-ray microscope system of claim 1 , further comprising a mask positioned upstream of the detector to block a predetermined number of the x-ray micro-beams transmitted through the object.
14. The x-ray microscope system of claim 1 , in which the system achieves submicron spatial resolution.
15. The x-ray microscope system of claim 1 , wherein each pixel comprises an actively detecting area at a center of the pixel, the actively detecting area comprising less than 50% of a total area of the pixel.
16. The x-ray microscope system of claim 1 , further comprising an attenuating grating placed upstream of the detector and positioned to absorb x-rays between the x-ray micro-beams to increase the intensity ratio between x-ray micro-beams and the regions between the x-ray micro-beams.
17. A method for measuring the x-ray transmission of an object, the method comprising:
producing an x-ray Talbot interference pattern comprising a plurality of anti-nodes and having a depth-of-focus;
positioning an x-ray array detector comprising a plurality of pixels such that the plurality of pixels are within the depth-of-focus of the x-ray Talbot interference pattern; and
positioning an object to be examined within the depth-of-focus such that x-rays of at least some of the anti-nodes transmitted through the object to be examined are detected by the detector.
18. The method of claim 17 , further comprising blocking at least some of the x-rays transmitted through the object from being detected by the detector.
19. The method of claim 17 , further comprising blocking at least some x-rays of the x-ray Talbot interference pattern from reaching the object.
20. The method of claim 19 , wherein said blocking comprises positioning a mask in front of the object.
21. The method of claim 20 , wherein the mask is positioned within the depth-of-focus.