X-ray interferometer

Abstract

Embodiments relate to an X-ray interferometer for imaging an object comprising: a phase grating for effecting in correspondence with the phase grating geometry a phase shift to at least a part of X-ray incident onto the phase grating; and an absorption grating for effecting in correspondence with the absorption grating geometry absorption to at least a part of X-ray incident onto the absorption grating. The grating period of the phase grating, and the grating period of the absorption grating may be dimensioned such that a detector for X-rays can be placed at a relatively large distance away from the absorption grating such the phase contrast sensitivity of the image of the object detected by the detector remains substantially unaffected.

What is claimed is: 
     
         1 . An X-ray interferometer for imaging an object by irradiating the object with X-ray emitted at a given radiation energy from an X-ray source, comprising:
 a phase grating for phase-shifting X-ray emanating from the object and which is incident onto the phase grating; and   an absorption grating for intensity modulating the phase-shifted X-ray;   wherein the grating period of at least one of the phase grating and of the absorption grating are dimensioned such that an X-ray detector for imaging the object can be placed at a relatively large distance away from the absorption grating such that for the given radiation energy, the X-ray flux incident onto the detector is substantially non-adversely affected.   
     
     
         2 . The X-ray interferometer according to  claim 1 , wherein the grating period of the phase grating and the grating period of the absorption grating are dimensioned such that the phase contrast sensitivity of the image of the object detected by the detector is non-adversely affected. 
     
     
         3 . The X-ray interferometer according to  claim 1 , implemented as a Talbot-Lau interferometer. 
     
     
         4 . The X-ray interferometer according to  claim 1 , implemented as a Talbot interferometer. 
     
     
         5 . The X-ray interferometer according to  claim 1 , operative at a fractional Talbot order of n=4. 
     
     
         6 . The X-ray interferometer according to  claim 1 , wherein the lateral extensions of the phase grating, the absorption grating and the detector are dimensioned such to cover the diverging field size respective of the X-ray emanating from the imaged object. 
     
     
         7 . The X-ray interferometer according to  claim 1 , wherein, during imaging, the distance between the object and the phase grating substantially equals zero. 
     
     
         8 . The X-ray interferometer according to  claim 1 , wherein the lateral dimensions of the phase grating and the absorption grating are such to allow for selecting the distance between the detector and the absorption grating to obtain, when imaging the object, a corresponding change in the multiplicative factor between the lateral dimensions of the image of the object and the object itself. 
     
     
         9 . The X-ray interferometer according to  claim 7 , wherein the multiplicative factor ranges from 1 to about at least 50. 
     
     
         10 . The X-ray interferometer according to  claim 1 , wherein the grating period of the phase grating is equal or less than about 5 μm. 
     
     
         11 . The X-ray interferometer according to  claim 1 , wherein the grating period of the absorption grating is equal or less than about 5 μm. 
     
     
         12 . The X-ray interferometer according to  claim 1 , wherein the distance between the absorption grating and the detector ranges from about 5 cm to about at least 2 meters. 
     
     
         13 . The X-ray interferometer according to  claim 1 , wherein the phase contrast sensitivity of the obtainable image of the object ranges from about 150 to about at least 300. 
     
     
         14 . The X-ray interferometer according to  claim 1 , wherein the gratings periods of the absorption and phase grating are dimensioned such that distance between the phase grating and absorption grating is small compared to the distance between the detector and the absorption grating and the distance between the source and the phase grating. 
     
     
         15 . The X-ray interferometer according to  claim 1 , wherein the lateral extensions of the phase grating, the absorption grating and the detector are dimensioned such to cover the diverging field size respective of the X-ray emanating from the imaged object and wherein, during imaging, the distance between the object and the phase grating substantially equals zero. 
     
     
         16 . The X-ray interferometer according to  claim 1 , wherein the phase contrast sensitivity of the obtainable image of the object ranges from about 150 to about at least 300, and wherein the gratings periods of the absorption and phase grating are dimensioned such that distance between the phase grating and absorption grating is small compared to the distance between the detector and the absorption grating and the distance between the source and the phase grating. 
     
     
         17 . The X-ray interferometer according to  claim 1 , wherein the gratings periods of the absorption and phase grating are dimensioned such that distance between the phase grating and absorption grating is small compared to the distance between the detector and the absorption grating and the distance between the source and the phase grating, and wherein, during imaging, the distance between the object and the phase grating substantially equals zero. 
     
     
         18 . A method for performing phase contrast imaging by employing an X-ray interferometer that is operative to irradiate an object with X-ray at a given radiation energy, the X-ray interferometer comprising:
 a phase grating for phase-shifting X-ray emanating from the object and incident onto the phase grating; and   an absorption grating for intensity modulating the phase-shifted X-ray;   the method comprising the following procedure:
 placing an X-ray detector at a relatively large distance away from the absorption grating. 
   
     
     
         19 . The method according to  claim 18 , wherein the method comprises positioning the object at distance from the phase grating which substantially equals zero. 
     
     
         20 . The method according to  claim 18  comprising:
 dark-field illuminating the object for obtaining a dark-field image thereof.