Method and apparatus for measuring the diameter of a rod-shaped article

Abstract

An apparatus and a method for measuring the diameter of at least one rod-shaped article. A beam splitter is arranged to split a beam coming from the radiation source into several component beams and to conduct the beams from different directions onto the rod-shaped article. A detection device includes a plurality of detectors each arranged to generate a signal indicating a shading of a respective one of the component beams caused by the rod-shaped article. The rod-shaped article is positioned in or guided through the beam paths between the radiation source and the detection device and the diameter of the rod-shaped article is determined from the signals generated in the detection device.

1 . An apparatus for measuring the diameter of a rod-shaped article, comprising: 
 a radiation source for generating a beam;    a beam splitter arranged to split the beam coming from the radiation source into several component beams and to conduct the beams from different directions onto the rod-shaped article; and    a detection device including a plurality of detectors each arranged to generate a signal indicating a shading of a respective one of the component beams caused by the rod-shaped article,    wherein the rod-shaped article is positioned in or guided through the beam paths between the radiation source and the detection device and the diameter of the rod-shaped article is determined from the signals generated in the detection device.    
   
   
       2 . The apparatus according to  claim 1 , wherein the beam splitter conducts the component beams onto the rod-shaped article so that each component beam is only partially shaded by the rod-shaped article.  
   
   
       3 . The apparatus according to  claim 1 , further including an evaluation unit coupled to the detection device to determine the diameter of the rod-shaped article based on the signals generated by the detection device.  
   
   
       4 . The apparatus according to  claim 3 , wherein the evaluation unit includes an average-value former to form an average value from the signals generated by the detecting means.  
   
   
       5 . The apparatus according to  claim 1 , wherein the beam splitter includes mirrors that deflect at least some of the component beams of the main beam so such that the component beams impinge from different directions on the rod-shaped article.  
   
   
       6 . The apparatus according to  claim 1 , wherein the beam splitter comprises at least one prism that deflects at least some of the component beams of the main beam, such that the component beams impinge from different directions on the rod-shaped article.  
   
   
       7 . The apparatus according to  claim 1 , further including a beam re-combination device arranged to recombine the component beams after they impinge on the rod-shaped article into a single beam in which the component beams are substantially parallel to each other, wherein the detectors are essentially aligned side-by-side in a row.  
   
   
       8 . The apparatus according to  claim 7 , wherein the beam re-combination device comprises mirrors that redirect the component beams to the same direction.  
   
   
       9 . The apparatus according to  claim 7 , wherein the beam re-combination device comprises at least one prism that redirects the component beams to the same direction.  
   
   
       10 . The apparatus according to  claim 1 , further including an alignment device positioned between the radiation source and the beam splitter to substantially parallel align the beam coming from the radiation source.  
   
   
       11 . The apparatus according to  claim 10 , wherein the alignment device comprises a collimating lens.  
   
   
       12 . The apparatus according to  claim 10 , further including a cylindrical lens arranged downstream of the alignment device.  
   
   
       13 . The apparatus according to  claim 1 , wherein the radiation source comprises a laser.  
   
   
       14 . The apparatus according to  claim 12 , wherein the laser comprises a laser diode.  
   
   
       15 . The apparatus according to  claim 1 , wherein the detectors comprise charge-coupled device elements.  
   
   
       16 . The apparatus according to  claim 1 , wherein the beam is an optical beam.  
   
   
       17 . A method for measuring the diameter of a rod-shaped article, comprising: 
 generating a beam of radiation;    splitting the beam into several component beams that are conducted from different directions onto the rod-shaped article    generating separate signals each of which indicate a shading of a respective one of the component beams caused by the rod-shaped article; and    determining the diameter of the rod-shaped article from the signals.    
   
   
       18 . The method according to  claim 17 , wherein the splitting step includes conducting the component beams onto the rod-shaped article so that each component beam is shaded only partially by the rod-shaped article.  
   
   
       19 . The method according to  claim 17 , further including recombining the component beams, after impinging on the rod-shaped article, to form a single beam in which the component beams are aligned substantially parallel to each other.  
   
   
       20 . The method according to  claim 17 , and further including forming an average value from the signals generated by the different component beams.  
   
   
       21 . The method according to  claim 17 , further including aligning the beam to be parallel before being split into component beams.  
   
   
       22 . The method according to  claim 17 , wherein the step of generating a beam includes generating an optical beam.