Patent Publication Number: US-2013242178-A1

Title: Optical module for image measuring apparatus

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to optical systems, and more particularly, to an optical module used for an image measuring apparatus. 
     2. Description of related art 
     Image measuring apparatus usually includes an optical module for imaging a tested workpiece. However, when the workpiece has a high smoothness (e.g. a glass), the optical module has difficulty focusing the workpiece and cannot accurately finish the measuring requirement. 
     Therefore, there is room for improvement within the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the disclosed optical module can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present optical module. 
         FIG. 1  is a schematic view of an optical module according to an exemplary embodiment. 
         FIG. 2  is a cross sectional view of the optical module in  FIG. 1  for imaging an workpiece. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosed optical module  100  is used in an image measuring apparatus, although the disclosure is not limited thereto. 
     Referring to  FIGS. 1 and 2 , the optical module  100  includes a first sleeve  12 , a second sleeve  14 , a connecting member  15 , a lens barrel  16 , a main light source  18 , an image sensor  20  and a camera  30 . The connecting member  15  is connected to one side of the lens barrel  16 . The first sleeve  12  and the second sleeve  14  are connected to the connecting member  15 . 
     The first sleeve  12  defines a first hollow cavity  120 . A plurality of heat dissipating fins  122  are positioned parallel to each other and positioned along an outside peripheral wall of the first sleeve  12 . A first light source  124 , a first lens  126 , and a pattern plate  128  are orderly positioned in the first hollow cavity  120 . The first light source  124  is positioned at one end of the first sleeve  12  for illuminating the pattern plate  128 . When the first light source  124  emits light, the first lens  126  allows light emitted by the first light source  124  to uniformly pass. The pattern plate  128  is used for imaging the pattern of the pattern plate  128  on a tested workpiece. 
     The second sleeve  14  includes a second hollow cavity  140 . A second light source  144  and a second lens  146  are positioned in the hollow second cavity  140 . A plurality of heat dissipating fins  142  and  143  are respectively positioned along an outside peripheral wall of the second sleeve  14  and one end of the second light source  144 . When the second light source  144  emits light, the second lens  146  allows light emitting by the second light source  144  to uniformly pass. In the exemplary embodiment, the first light source  124  and the second light source  144  are LEDs. 
     The connecting member  15  is configured for connecting the first sleeve  12 , the second sleeve  14  and the lens barrel  16 . The connecting member  15  includes a main body  151 , a first connecting portion  152 , a second connecting portion  153 , and a third connecting portion  154  integrally formed together. The first connecting portion  152  and the third connecting portion  154  are co-axial, and the first connecting portion  152  is connected to the first sleeve  12 . The second connecting portion  153  is connected to the second sleeve  14 . The third connecting portion  154  is connected to the lens barrel  16 . A third lens  158  is positioned in the third connecting portion  154 . A beam splitter  156  is positioned at the main body  151 . The light emitted by the second light source  144  can be perpendicularly refracted by the beam splitter  156  and pass the third lens  158  to enter the lens barrel  16 . The light emitted by the first light source  124  can pass the beam splitter  156  and the third lens  158  to enter the lens barrel  16 . 
     The lens barrel  16  defines an opening  160  communicating with the third connecting portion  154 . At least one image lens  162  and a prism  164  are positioned in the lens barrel  16 . One end of the lens barrel  16  is connected to the image sensor  20 , and another end of the lens barrel  16  is connected to the main light source  18 . In the exemplary embodiment, the image sensor  20  is a charge coupled device. 
     The main light source  18  is an annular light source for illuminating the workpiece  200 . The camera  30  is positioned on the main light source  18 , and can image the workpiece  200 . A plurality of ribs  182  are located on a peripheral wall of the main light source  18 , and a plurality of arcuate heat dissipating sheets  184  are located on a top wall of the main light source  18 . 
     In use, when the tested workpiece has a high smoothness, the first light source  124  is firstly turned on. The light emitted by the first light source  124  passes the first lens  126 , and illuminates the pattern plate  128 . Then, the light passes the beam splitter  156 , and the third lens  158  to enter the lens barrel  16 . The prism  164  refracts the pattern light on the workpiece  200  for conveniently focusing the workpiece. After the workpiece  200  is focused, the first light source  124  is turned off, and the second light source  144  and the main light source  18  are turned on. The main light source  18  illuminates the workpiece  200 . The light emitted by the second light source  144  passes the second lens  146  and the beam splitter  156 , and perpendicularly refracts into the lens barrel  16 . The prism  164  refracts the light emitted by the second light source  144  on the workpiece  200 . The image of the workpiece  200  is caught by the image lens  162  and the image sensor  20 , for providing the image measuring apparatus. 
     When the tested workpiece has a low smoothness, the first light source  124  does not need to be turned on, and only the second light source  144  and the main light source  18  are opened for finishing the image process. The optical module  100  has a first light path, in which, the light from the first light source  124  passes through the first lens  126 , the pattern plate  128 , the beam splitter  156  and the prism  164 , and is refracted to the tested workpiece  200 . A second light path is defined, in which, the light from the second light source  144  passes through the second lens  146  and the beam splitter  156 , the beam splitter  156  refracts the light from the second light source  144  to the third lens  158  and the prism  164 , the prism  164  refracts the light to the tested workpiece  200 . The optical module  100  in the present disclosure can image the patter on the pattern plate  128  on a smooth workpiece for conveniently focusing the smooth workpiece, and can have a more accurate test result. 
     It is to be understood, however, that even through numerous characteristics and advantages of the present disclosure have been set forth in the foregoing description, together with details of assembly and function, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.