Abstract:
A shape measuring apparatus includes: an irradiating part configured to irradiate work with a linear line laser, the irradiating part including: a light source configured to produce light; and an optical element configured to linearly spread the light from the light source and generate the line laser, the optical element being constructed rotatably around an optical axis of the line laser; and an imaging part configured to image the line laser reflected by the work.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2013-054535, filed on Mar. 18, 2013, the entire contents of which are incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a shape measuring apparatus for measuring a shape of an object to be measured by irradiating the object to be measured with light and imaging the object to be measured. 
         [0004]    2. Description of the Related Art 
         [0005]    Conventionally, a shape measuring apparatus for measuring a surface shape of work by scanning a surface of the work by a probe and capturing position coordinates etc. of each part of the work is known. 
         [0006]    Such a known shape measuring apparatus is a non-contact apparatus for making measurement without bringing a probe into contact with a surface of work as described in JP-T-2009-534969. 
         [0007]    In the non-contact surface shape measuring apparatus described in JP-T-2009-534969, a surface shape of work is measured by irradiating a surface of the work with a linear line laser by a scanning probe and imaging this surface from a predetermined angle with respect to a direction of irradiation with the line laser. According to such a non-contact surface shape measuring apparatus, there is no fear of damaging the surface of the work and also considering an influence on measurement accuracy due to abrasion of the probe. 
         [0008]    Also, it is necessary to rotate the line laser according to the shape of the work in the shape measuring apparatus described above. In this case, in JP-A-2011-110675, the whole scanning probe is rotated to thereby rotate the line laser. However, since the whole scanning probe is rotated, a measurement speed decreases. 
       SUMMARY 
       [0009]    An object of the invention is to provide a shape measuring apparatus for improving a measurement speed. 
         [0010]    A shape measuring apparatus according to the invention has an irradiating part and an imaging part. The irradiating part irradiates work with a linear line laser. The imaging part images the line laser reflected by the work. The irradiating part has a light source and an optical element. 
         [0011]    The optical element linearly spreads light from the light source and generates the line laser. The optical element is constructed rotatably around an optical axis of the line laser. 
         [0012]    According to this invention, a shape measuring apparatus for improving a measurement speed can be provided. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawing which is given by way of illustration only, and thus is not limitative of the present invention and wherein: 
           [0014]      FIG. 1  is the overall diagram of a system constructing a shape measuring apparatus according to a first embodiment of the invention; 
           [0015]      FIG. 2  is a diagram showing a configuration of an optical probe  17  according to the embodiment; 
           [0016]      FIGS. 3A and 3B  are schematic diagrams showing a line laser applied using the optical probe  17 ; 
           [0017]      FIG. 4  is a schematic diagram showing arrangement of the inside of the optical probe  17 ; 
           [0018]      FIG. 5A  is a schematic diagram showing a laser light generating part  172  according to the embodiment; 
           [0019]      FIG. 5B  is a schematic diagram showing another state of the laser light generating part  172  according to the embodiment; 
           [0020]      FIG. 6  is a pattern diagram showing a CMOS sensor  1732  according to the embodiment; 
           [0021]      FIG. 7  is a pattern diagram showing the CMOS sensor  1732  according to the embodiment; 
           [0022]      FIG. 8  is a block diagram representing a control system of the optical probe  17 ; 
           [0023]      FIG. 9  is a flowchart showing operation of the shape measuring apparatus according to the embodiment; and 
           [0024]      FIG. 10  is a flowchart showing operation of a shape measuring apparatus according to another embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    A shape measuring apparatus according to an embodiment of the invention will be described in detail with reference to the drawings.  FIG. 1  is the overall diagram of a system constructing the shape measuring apparatus according to the embodiment. This shape measuring apparatus is constructed by attaching an optical probe  17  according to the present embodiment as a measurement probe of a coordinate measuring machine  1  as shown in  FIG. 1 . This shape measuring apparatus includes a motion controller  2 , an operation panel  3 , and a host system  4 . The motion controller  2  drives and controls the coordinate measuring machine  1  and also, captures a necessary measured coordinate value from this coordinate measuring machine  1 . The operation panel  3  manually operates this coordinate measuring machine  1  through this motion controller  2 . The host system  4  edits and executes a part program for instructing a measurement procedure in the motion controller  2 . Also, the host system  4  has a function of doing calculation for fitting a geometric shape to the measured coordinate value captured through the motion controller  2 , or recording or sending the part program. 
         [0026]    The coordinate measuring machine  1  is constructed as described below. That is, a surface plate  11  is placed on an anti-vibration table  10  so that an upper surface of the surface plate  11  matches with a horizontal plane as a base surface, and an X-axis guide  13  is supported on the upper ends of arm support bodies  12   a,    12   b  erected from both side ends of this surface plate  11 . The lower end of the arm support body  12   a  is driven in a Y-axis direction by a Y-axis driving mechanism  14 , and the lower end of the arm support body  12   b  is supported on the surface plate  11  movably in the Y-axis direction by air bearings. The X-axis guide  13  drives a Z-axis guide  15  extending vertically in an X-axis direction. The Z-axis guide  15  is provided with a Z-axis arm  16  so as to be driven along the Z-axis guide  15 , and the non-contact optical probe  17  is attached to the lower end of the Z-axis arm  16 . In addition, the optical probe  17  may be rotatable in a horizontal plane or a vertical plane. 
         [0027]      FIG. 2  shows a configuration of the optical probe  17  according to the present embodiment. The optical probe  17  has a chassis  171 , a laser light generating part  172  arranged inside the chassis  171 , an imaging device  173  for imaging work, and a control circuit  174  for adjusting the laser light generating part  172  as shown in  FIG. 2 . In addition, a detailed configuration of the laser light generating part  172  and control of the configuration will be described below. 
         [0028]    The laser light generating part  172  irradiates work  5  with a linear line laser extending in a direction orthogonal to a plane formed by the optical axis (the optical axis in the center of a scanning direction) of the laser light generating part  172  and the optical axis of the imaging device  173 , and linearly illuminates a surface of the work  5 . 
         [0029]    The imaging device  173  has a band-pass filter  1731   a,  a lens  1731   b,  and a CMOS sensor  1732  for imaging an image of the work  5  through the band-pass filter and the lens. The imaging device  173  is arranged in a direction of receiving light from a direction of forming a predetermined angle with respect to a direction of irradiating the work  5  with light from a light source. That is, the surface of the work  5  is irradiated with the line laser, and light reflected along a shape of the surface of the work  5  is received from a predetermined angle by the imaging device  173 . 
         [0030]      FIGS. 3A and 3B  are schematic diagrams showing a line laser applied using the optical probe  17 . As shown in  FIG. 3A , when the work  5  is irradiated with a linear line laser L 1  by the laser light generating part  172 , reflected light L 1 ′ of the line laser is deformed along the surface of the work  5 , and a contour at the time of cutting the work  5  in a certain plane is sectioned by the reflected light L′. The imaging device  173  images the work  5  at a predetermined angle from a direction of irradiation with laser light of the laser light generating part  172 , and images an image of the reflected light L 1 ′ as shown in  FIG. 3B . 
         [0031]    Further, in the present embodiment, the laser light generating part  172  can rotate the line laser L 1  around the optical axis and generate a line laser L 2  as shown in  FIG. 3B . 
         [0032]      FIG. 4  is a schematic diagram showing arrangement of the inside of the optical probe  17 . In addition, the band-pass filter  1731   a  is omitted in  FIG. 4 . The optical probe  17  according to the present embodiment uses the Scheimpflug principle and as shown in  FIG. 4 , surfaces S 1  to S 3  respectively extending an imaging surface of the CMOS sensor  1732 , a principal plane including a principal point of the lens  1731   b,  and a surface of irradiation with the line laser with which the work  5  is irradiated intersect at one point P. By such arrangement, focus is achieved on the whole imaging surface of the CMOS sensor  1732 . 
         [0033]      FIG. 5A  is a schematic diagram showing the laser light generating part  172  according to the present embodiment. The laser light generating part  172  has a light source  1721  for applying laser light, and a rod lens  1722  for spreading the laser light and generating a line laser as shown in  FIG. 5A . The rod lens  1722  is fitted into the lower portion of an opening  1723   a  of a gear  1723 . The gear  1723  meshes with a gear  1724 , and the center of the gear  1724  is bonded to a rotating shaft of a motor  1725 . As shown in  FIG. 5A , the laser light from the light source  1721  is applied to the rod lens  1722  through the opening  1723   a  of the gear  1723 , and a line laser L 1  is generated. 
         [0034]      FIG. 5B  is a schematic diagram showing another state of the laser light generating part  172 . As shown in  FIG. 5B , the motor  1725  rotates the rod lens  1722  around the optical axis of the laser light through the gears  1724 ,  1723 . With this, the line laser L 1  is rotated to generate a line laser L 2  as shown in  FIG. 5B . 
         [0035]      FIG. 6  is a pattern diagram showing the CMOS sensor  1732  according to the present embodiment. The CMOS sensor  1732  has 2D array of pixel sensors in X and Y directions as shown in  FIG. 6 . For example, in the present embodiment, the CMOS sensor  1732  has  1024  light receiving elements E in a direction of extension of the linear line laser and  1280  light receiving elements E in a direction orthogonal to this direction of extension. 
         [0036]    Also, the CMOS sensor  1732  has an electronic shutter (rolling shutter). When the electronic shutter is driven continuously without stopping rotation of the line laser, many images can be acquired in a short time. Consequently, time of shape measurement can be shortened. Also, an increase in shutter speed of the electronic shutter can prevent degradation in measurement accuracy due to image blurring based on rotation of the line laser. In addition, in order to acquire an image capable of calculating a shape of the work  5 , the shutter speed could be controlled in the range capable of ensuring the necessary amount of light. 
         [0037]    For example, in the CMOS sensor  1732 , the light receiving elements arranged in one column in a region A in substantially the center of the Y direction first receive light simultaneously as shown in  FIG. 7 . Subsequently, the line laser is rotated by an angle θ. Then, the light receiving elements arranged in a region B in which the region A is rotated by the angle θ receive light simultaneously. Thereafter, the line laser is similarly rotated by the angle θ, and the light receiving elements arranged in a region C in which the region B is rotated by the angle θ receive light simultaneously. However, in such measurement, a misalignment of focal point on the CMOS sensor  1732  increases with rotation of the rod lens  1722 . For example, the focal point is shifted in the light receiving elements in regions Ba of both ends of the region B, and the focal point is shifted in the light receiving elements in regions Ca of both ends of the region C. Then, the region Ca becomes larger than the region Ba. Hence, as shown in  FIG. 7 , in the present embodiment, the control circuit  174  eliminates light received by the light receiving elements arranged in the regions other than an elliptic region Z on the CMOS sensor  1732 , and computes a shape of the work  5 , and reduces an influence of the misalignment of focal point. 
         [0038]      FIG. 8  is a block diagram representing a control system of the optical probe  17  according to the present embodiment. 
         [0039]    The control circuit  174  has a CPU  1741 , a program storage part  1742  connected to the CPU  1741 , a work memory  1743 , and a multi-valued image memory  1744  as shown in  FIG. 8 . Image information acquired in the CMOS sensor  1732  is inputted to the CPU  1741  through the multi-valued image memory  1744 . The CPU  1741  controls a driving state of the motor  1725 . 
         [0040]    Next, operation of the shape measuring apparatus according to the embodiment will be described with reference to  FIG. 9 .  FIG. 9  is a flowchart showing the operation of the shape measuring apparatus. As shown in  FIG. 9 , the control circuit  174  first activates (turns on) the light source  1721  (S 101 ). Accordingly, the work  5  is irradiated with a line laser. Next, the control circuit  174  acquires an image of the work  5  by the CMOS sensor  1732  (S 102 ). Subsequently, the control circuit  174  deactivates (turns off) the light source  1721  (S 103 ). 
         [0041]    Subsequently, the control circuit  174  determines whether or not an end command is accepted (S 104 ). When the end command is not accepted (S 104 , No), the control circuit  174  rotates the rod lens  1722  by a predetermined angle (S 105 ), and again executes processing of step S 101 . On the other hand, when the end command is accepted (S 104 , Yes), the control circuit  174  calculates a shape of the work  5  based on the acquired image of the work  5  (S 106 ). 
         [0042]    In the present embodiment described above, the rod lens  1722  rotates around the optical axis of the line laser as shown in  FIGS. 5A and 5B . With this, the line laser also rotates as shown in  FIGS. 3A and 3B . Consequently, the present embodiment can measure the end of the work  5  with a lens shape without moving the optical probe  17 . That is, the present embodiment can improve a measurement speed as compared with the case of rotating the whole optical probe  17 . 
       Other Embodiment  
       [0043]    One embodiment of the shape measuring apparatus according to the invention has been described above, but the invention is not limited to the embodiment described above, and various changes, additions, replacements, etc. can be made without departing from the gist of the invention. For example, a cylindrical lens may be formed instead of the rod lens  1722 . 
         [0044]    Also, as shown in  FIG. 10 , the control circuit  174  may determine whether or not an end command is accepted after step S 102  (S 103   a ). When the end command is not accepted herein (S 103   a,  No), the control circuit  174  rotates the rod lens  1722  by a predetermined angle (S 105 ), and again executes processing of step S 102 . On the other hand, when the end command is accepted (S 103   a,  Yes), the control circuit  174  deactivates (turns off) the light source  1721  (S 104   a ) and thereafter, executes step S 106 . In addition, in  FIGS. 9 and 10 , a shape of the work  5  is calculated after all the images of the work  5  are acquired by way of example. However, the shape of the work  5  may be calculated after images of respective works  5  are acquired.