Micro beam collimator for high resolution xrd investigations with conventional diffractometers

Abstract

A micro collimator for compressing X-ray beams for use in a X-ray diffractometer is described, wherein said collimator has a channel means for providing a channel guiding said X-ray beams, said channel having a channel entrance portion and a channel exit portion. The object of the invention is to provide a micro beam collimator capable of being used in a conventional X-ray diffractometer with the Bragg-Brentano geometry, so as to enable the characterisation of very small sample regions without need of very large radiation sources (synchrotron). For solving this technical problem it is proposed to form the channel means by two opposite, polished, oblong plate means made of or coated with a material selected from the group consisting of the heavyweight metals and materials having total reflection properties comparable to those of the heavyweight metals.

1 . A micro beam collimator for compressing X-ray beams for use in a X-ray diffractometer, wherein said collimator ( 1 ) has a channel means for providing a channel guiding said X-ray beams, said channel having a channel entrance portion ( 38 ) and a channel exit portion ( 39 ),  
       characterized in that 
 said channel means is formed by two opposite, polished, oblong plate means ( 10 ,  11 ) made of or coated with a material selected from the group consisting of the heavyweight metals and materials having total reflection, properties comparable to those of the heavyweight metals.  
 
     
     
         2 . A micro beam collimator according to  claim 1 ,  
       characterized in that 
 said group consists of Nickel, Wolfram and Platinum.  
 
     
     
         3 . A micro beam collimator according to  claim 1  or  2 ,  
       characterized in that 
 said plate means ( 10 ,  11 ) are flexible and that adjustment means ( 19 ,  20 ,  21 ,  22 ) for adjusting the longitudinal profile of said channel and/or the opening width of said channel entrance portion ( 38 ) by bending said plate means ( 10 ,  11 ) are provided.  
 
     
     
         4 . A micro beam collimator according to one of the preceding claims,  
       characterized in that 
 said channel has a constant cross-section in a said channel exit portion ( 39 ) so that a quasi-parallel output X-ray beam is produced.  
 
     
     
         5 . A micro beam collimator according to  claim 4 ,  
       characterized in that 
 said channel exit portion ( 39 ) has a length of less than 50% of the total length (L) of said channel.  
 
     
     
         6 . A micro beam collimator according to  claim 4 ,  
       characterized in that 
 said channel exit portion ( 39 ) has a length of less than 30% of the total length (L) of said channel.  
 
     
     
         7 . A-micro beam collimator according to one of  claims 4  to  6 ,  
       characterized in that 
 spacer means ( 16 ) are sandwiched in said channel exit portion ( 39 ) between said plate means ( 10 ,  11 ) for spacing the same.  
 
     
     
         8 . A micro beam collimator according to  claim 7 ,  
       characterized in that 
 said spacer means are two noble metal strip foils ( 16 ).  
 
     
     
         9 . A micro beam collimator according to one of the preceding claims,  
       characterized in that 
 said plate means ( 10 ,  11 ) are received in a holding means ( 12 ) having a receiving cavity ( 26 ).  
 
     
     
         10 . A micro beam collimator according to  claim 9 ,  
       characterized in that 
 said receiving cavity ( 26 ) has a width increasing in the direction from said channel exit portion ( 39 ) to said channel entrance portion ( 38 ).  
 
     
     
         11 . A micro beam collimator according to  claim 9  or  10  in combination with  claim 3 ,  
       characterized in that 
 said adjustment means are comprising two block means ( 21 ,  22 ) each of which being fixed in said channel entrance portion ( 38 ) to the outside of each of said plate means ( 10 ,  11 ) and a plurality of adjustment screws ( 19 ,  20 ) mounted in said holding means ( 12 ) and interacting with said block means ( 21 ,  22 ).  
 
     
     
         12 . A micro beam collimator according to one of the preceding claims,  
       characterized in that 
 an anti-divergence means ( 28 ) is located at the channel exit for stopping oblique radiation.  
 
     
     
         13 . A micro beam collimator according to one of the preceding claims in combination with  claim 9 ,  
       characterized in that 
 an outer housing means ( 13 ) connectable to said holding means ( 12 ) is provided for at least partially enclosing said plate means ( 10 ,  11 ) and said holding means ( 12 ).  
 
     
     
         14 . A micro beam collimator according to  claim 13  and  12 ,  
       characterized in that 
 said anti divergence means ( 28 ) is mounted in an end portion ( 32 ) of said outer housing means ( 12 ).  
 
     
     
         15 . A micro beam collimator according to  claim 14 ,  
       characterized in that 
 said end portion is formed by an end cap ( 32 ) detachably connectable to the remaining part ( 33 ) said outer housing means ( 13 ).  
 
     
     
         16 . A micro beam collimator according to one of  claim 12 ,  14  or  15 ,  
       characterized in that 
 said anti-divergence means ( 28 ) comprises two diaphragm blocks ( 29 ,  30 ) forming a slit between each other.  
 
     
     
         17 . A micro beam collimator according to  claim 16 ,  
       characterized in that 
 further spacer means are arranged between said diaphragm blocks ( 29 ,  30 ) for adjusting the width of said slit.  
 
     
     
         18 . A micro beam collimator according to  claim 16  or  17 ,  
       characterized in that 
 an aligning means ( 35 ,  36 ,  37 ) for aligning said slit with said channel exit portion ( 39 ) is provided.  
 
     
     
         19 . A method of carrying out high resolution XRD studies  
       characterized by 
 using a micro beam collimator ( 1 ) according to one of the preceding claims with a diffractometer equipped with a micropositioning means ( 3 ) for positioning a sample (S) to be scanned.