Patent Publication Number: US-10323933-B2

Title: Optical three-dimensional shape measuring device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims foreign priority based on Japanese Patent Application No. 2016-127054, filed Jun. 27, 2016, the contents of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a measuring device that measures a measuring object. 
     2. Description of Related Art 
     In a measuring device of a triangular distance measuring method, a light projecting unit irradiates a surface of a measuring object with light, and a light receiving unit including pixels arrayed one-dimensionally or two-dimensionally receives the light reflected from the surface. A height of the surface of the measuring object can be measured based on a peak position of a light reception amount distribution obtained by the light receiving unit. 
     Measurement of the triangular distance measuring method in which coded light and a phase shift method are combined is proposed in Toni F. Schenk, “Remote Sensing and Reconstruction for Three-Dimensional Objects and Scenes”, Proceedings of SPIE, Volume 2572, pp. 1-9 (1995). 
     Measurement of the triangular distance measuring method in which coded light and stripe light are combined is proposed in Sabry F. El-Hakim and Armin Gruen, “Videometrics and Optical Methods for 3D Shape Measurement”, Proceedings of SPIE, Volume 4309, pp. 219-231 (2001). In these methods, measurement accuracy of the measuring object can be improved. 
     In the above triangular distance measuring method, it is necessary that the measuring object be placed such that a portion to be measured is included in a specific region defined by a positional relationship between the light projecting unit and the light receiving unit, an imaging visual field of the light receiving unit and the like. However, because measuring objects have various sizes, it is difficult for an unskilled user to place the measuring object at an appropriate position according to the size of the measuring object. Even for a skilled user, it is troublesome to perform operation to place the measuring object at the appropriate position according to each size of the measuring object. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a measuring device having improved operability. 
     (1) A measuring device according to the present invention includes: a stage holding unit; a stage held by the stage holding unit and on which a measuring object is placed; a head unit including a light projecting unit and first and second light receiving units, the light projecting unit irradiating the measuring object placed on the stage with measurement light having a pattern, the first and second light receiving units receiving the measurement light reflected by the measuring object and outputting a light reception signal representing a light reception amount; a coupling part that fixedly couples the head unit and the stage holding unit such that the measurement light is guided obliquely downward from the light projecting unit to the measuring object, and such that optical axes of the first and second light receiving units extend obliquely downward; a selection section that receives selection of one of the first and second light receiving units; a point cloud data generating section that generates point cloud data representing a three-dimensional shape of the measuring object based on the light reception signal output from the selected first or second light receiving unit; and a measuring section that receives designation of a point to be measured in the measuring object and calculates a measurement value of the designated point based on the point cloud data generated by the point cloud data generating section. The first light receiving unit has a first imaging visual field, the second light receiving unit has a second imaging visual field smaller than the first imaging visual field, and in a space on the stage, the second imaging visual field is included in the first imaging visual field, and the optical axis of the second light receiving unit is located below the optical axis of the first light receiving unit. 
     In the measuring device, the head unit including the light projecting unit and the first and second light receiving units is fixedly coupled to the stage holding unit using the coupling part. The measuring object is placed on the stage held by the stage holding unit. The measuring object is irradiated obliquely downward with the measurement light having the pattern from the light projecting unit. The measurement light reflected obliquely upward by the measuring object is received by a selected one of the first and second light receiving units, and the light reception signal representing the light reception amount is output. The point cloud data representing the three-dimensional shape of the measuring object is generated based on the light reception signal. The measurement value at the designated point is calculated based on the generated point cloud data. 
     In the above configuration, an irradiation range of the measurement light to the space on the stage and the positional relationship between the first and second imaging visual fields are uniquely fixed because the head unit and the stage holding unit are fixedly coupled together. Therefore, it is not necessary for a user to previously adjust the positional relationship among the light projecting unit, the first and second light receiving units, and the stage. 
     The second imaging visual field of the second light receiving unit is smaller than the first imaging visual field of the first light receiving unit, and included in the first imaging visual field. In this case, the measuring object having a relatively larger size can appropriately be located within the first imaging visual field by the selection of the first light receiving unit. By the selection of the second light receiving unit, the measuring object having a relatively smaller size can appropriately be located within the second imaging visual field while an unnecessary surrounding portion is not located within the second imaging visual field. Because the optical axis of the second light receiving unit is located below the optical axis of the first light receiving unit, it is not necessary to move the stage or the measuring object upward so as to locate the measuring object within the second imaging visual field. Therefore, operability of the measuring device can be improved. 
     (2) The optical axis of the second light receiving unit may be located between the head unit and the space on the stage and below the optical axis of the first light receiving unit. In this case, the optical axes of the first and second light receiving units come close to a parallel state. Therefore, the image of the measuring object can be captured in the substantially same direction using the first and second light receiving units. 
     (3) The light projecting unit may include first and second light projecting units, and the first and second light projecting units may be disposed on an opposite side with respect to the first and second light receiving units. In this case, the first and second light projecting units irradiate the wide range of the measuring object with the measurement light from a plurality of directions. Therefore, the point cloud data can be generated in the wide range of the measuring object. 
     (4) The first and second light receiving units may include first and second light reception lenses, respectively, and magnification of the second light reception lens may be higher than magnification of the first light reception lens. In this case, the second imaging visual field can easily be made smaller than the first imaging visual field. The selection of the second light reception lens enables the relatively small measuring object to be observed with high magnification. 
     (5) The first and second light receiving units may be fixed so as to be adjacent to each other, the head unit may further include an illumination unit that illuminates the measuring object placed on the stage with illumination light having no pattern, and the illumination unit may include an illumination light output port surrounding the first and second light receiving units. 
     In this case, the irradiation of the measuring object with the illumination light allows the user to observe a live image of the measuring object obtained in real time with the first or second light receiving unit. The illumination light output port surrounds the first and second light receiving units, so that the live image having a small shadow portion can be observed even when any one of the first and second light receiving units is used. 
     (6) The stage may be provided in the stage holding unit so as to be rotatable about a rotation axis in a vertical direction, and the measuring device may further include a rotation control section that controls rotation of the stage, and the point cloud data generating section may generate first three-dimensional shape data as the point cloud data based on a light reception signal output from the light receiving unit when the stage is located at a first rotation position, and may generate second three-dimensional shape data as the point cloud data based on a light reception signal output from the light receiving unit when the stage is located at a second rotation position, to synthesize the first three-dimensional shape data and the second three-dimensional shape data. 
     In this case, because the rotation axis of the stage is not parallel to the optical axis of the light receiving unit, the rotation of the stage changes the point of the measuring object oriented toward the light receiving unit. The measuring object is irradiated with the measurement light while the rotation position of the stage varies, whereby the light receiving unit receives the light reflected at different points of the measuring object. Accordingly, the point cloud data can be generated in the wide range of the measuring object based on the light reception signal output from the light receiving unit. 
     (7) The head unit may be configured to be detachably attached to the coupling part, and the measuring device may further include: a calculating section that calculates a positional relationship between the rotation axis of the stage and the light receiving unit in a state where the head unit is attached to the coupling part; and a storage section in which the positional relationship calculated by the calculating section is stored, and the point cloud data generating section synthesizes the first three-dimensional shape data and the second three-dimensional shape data based on the positional relationship stored in the storage section. 
     In this case, when the head unit is detached from the coupling part, the measuring object that cannot be placed on the stage can be measured in another place different from the stage. On the other hand, the head unit is attached to the coupling part, and the first three-dimensional shape data and the second three-dimensional shape data are generated while the stage is rotated. Therefore, the point cloud data can be generated in the wide range of the measuring object. At this time, the first three-dimensional shape data and the second three-dimensional shape data cannot accurately be synthesized when the positional relationship between the rotation axis of the stage and the light receiving unit is displaced before and after the operation to detach and attach the head unit from and to the coupling part. 
     According to the above configuration, the positional relationship between the rotation axis of the stage and the light receiving unit is calculated after the operation to detach and attach the head unit from and to the coupling part. Therefore, the first three-dimensional shape data and the second three-dimensional shape data are accurately synthesized based on the calculated positional relationship. 
     (8) The measuring device may further include a positioning mechanism that determines a position of the head unit with respect to the coupling part. In this case, the user can easily position the head unit with respect to the coupling part when attaching the head unit to the coupling part. 
     (9) The head unit may further include a holding tool that holds the first second light receiving units and a plurality of coupling members, and the plurality of coupling members may couple the holding tool and the light projecting unit while being separated from each other. 
     In this case, the light projecting unit and the first and second light receiving units are coupled together with the plurality of coupling members. Here, the plurality of coupling members are separated from each other, so that heat generated from the light projecting unit and the first and second light receiving units can easily be diffused. Additionally, cooling air can easily be introduced in order to cool the light projecting unit and the first and second light receiving units. Therefore, the change of the positional relationship among the light projecting unit, the first light receiving unit, and the second light receiving unit can be prevented from occurring due to a temperature change. Therefore, measurement accuracy can be improved. 
     It is not necessary to add a device such as a temperature sensor to the measuring device for the purpose of temperature compensation of a measurement result. Because heat dissipation increases between the coupling members, degrees of deformation of the plurality of coupling members and the holding tool are reduced. Accordingly, it is not necessary that the plurality of coupling members and the holding tool be made of an expensive material having a small linear expansion coefficient. As a result, cost of the measuring device can be reduced. 
     (10) The point cloud data generating section may generate point cloud data by a triangular distance measuring method, and each of the plurality of coupling members may include one end to be brought into contact with the holding tool and the other end to be brought into contact with the light projecting unit. 
     In the triangular distance measuring method, the measurement accuracy degrades when an angle between the light projecting unit and the first and second light receiving units changes. According to the above configuration, a contact portion between each coupling member and the holding tool is kept minimum. A contact portion between each coupling member and the light projecting unit is also kept minimum. Even if the holding tool and the plurality of coupling members are slightly deformed due to the temperature change, the holding tool and the plurality of coupling members have a small variation in deformation degree, and the angle between the light projecting unit and the first and second light receiving units does not change. Therefore, degradation of the measurement accuracy of the point cloud data can be prevented. 
     (11) Each of the holding tool and the plurality of coupling members may have a predetermined linear expansion coefficient within a certain range. In this case, because of a small difference in linear expansion coefficient between the holding tool and the plurality of coupling members, the variation in deformation degree of the holding tool and the plurality of coupling members decreases even if the holding tool and the plurality of coupling members are slightly deformed due to the temperature change. Therefore, the degradation of the measurement accuracy of the point cloud data can be prevented. 
     According to the present invention, the shape of the measuring object can easily and accurately be measured. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating a configuration of a measuring device according to one embodiment of the present invention; 
         FIG. 2  is a schematic diagram illustrating a configuration of a measuring unit of the measuring device in  FIG. 1 ; 
         FIG. 3  is a functional block diagram illustrating a function implemented by a CPU in  FIG. 1 ; 
         FIG. 4  is a perspective view illustrating a schematic appearance of the measuring unit; 
         FIG. 5  is a schematic side view of the measuring unit illustrating details of a positional relationship between two light receiving units and a stage; 
         FIG. 6  is a view illustrating a principle of a triangular distance measuring method; 
         FIGS. 7A and 7B  are views illustrating a first pattern of measurement light; 
         FIGS. 8A to 8D  are views illustrating a second pattern of the measurement light; 
         FIGS. 9A to 9C  are views illustrating a third pattern of the measurement light; 
         FIG. 10  is a view illustrating a relationship between timing at which an image of a specific portion of a measuring object is captured and intensity of received light; 
         FIGS. 11A to 11D  are views illustrating a fourth pattern of the measurement light; 
         FIGS. 12A and 12B  are views illustrating comparison between an offset optical system and a non-offset optical system; 
         FIGS. 13A to 13F  are views illustrating an example in which a plurality of pieces of three-dimensional shape data are generated by capturing the image of the measuring object from a plurality of directions; 
         FIG. 14  is a flowchart illustrating a procedure for preparing shape measurement; 
         FIG. 15  is a flowchart illustrating details of first adjustment in the procedure for preparing the shape measurement; 
         FIG. 16  is a flowchart illustrating details of the first adjustment in the procedure for preparing the shape measurement; 
         FIG. 17  is a flowchart illustrating details of second adjustment in the procedure for preparing the shape measurement; 
         FIG. 18  is a flowchart illustrating data generation processing; 
         FIG. 19  is a perspective view illustrating an appearance example of the measuring object; 
         FIG. 20  is a view illustrating an example of a textured three-dimensional shape image obtained through data generation processing performed on the measuring object in  FIG. 19 ; 
         FIG. 21  is a view illustrating an example of a synthesized image representing only a portion corresponding to an effective region in the textured three-dimensional shape image in  FIG. 20 ; 
         FIG. 22  is a view illustrating an example of a method for designating a region to be removed; 
         FIG. 23  is a view illustrating an example of the textured three-dimensional shape image in which a portion corresponding to the designated region is removed from the textured three-dimensional shape image in  FIG. 22 ; 
         FIG. 24  is a view illustrating a setting example of a measurement condition in measuring a distance between a top surface of a board and a top surface of an element in  FIG. 19 ; 
         FIG. 25  is a view illustrating a setting example of the measurement condition in measuring the distance between the top surface of the board and the top surface of the element in  FIG. 19 ; 
         FIG. 26  is a view illustrating a setting example of the measurement condition in measuring the distance between the top surface of the board and the top surface of the element in  FIG. 19 ; 
         FIG. 27  is a flowchart illustrating measurement processing; 
         FIG. 28  is a flowchart illustrating measurement data generation processing performed in step S 52  of  FIG. 27 ; 
         FIG. 29  is a view illustrating a setting example of a measurement condition that uses a first function; 
         FIG. 30  is a view illustrating a setting example of the measurement condition that uses the first function; 
         FIG. 31  is a view illustrating a setting example of the measurement condition that uses the first function; 
         FIG. 32  is a view illustrating another display example of a reference surface image; 
         FIG. 33  is a view illustrating a setting example of a measurement condition that uses a second function; 
         FIG. 34  is a view illustrating a setting example of the measurement condition that uses the second function; 
         FIG. 35  is a view illustrating a setting example of the measurement condition that uses the second function; 
         FIG. 36  is a perspective view illustrating a measurement optical unit before a light projecting unit and a light receiving unit are coupled; 
         FIG. 37  is a perspective view illustrating the measurement optical unit after the light projecting unit and the light receiving unit are coupled; 
         FIG. 38  is a perspective view illustrating a configuration of a mount; 
         FIGS. 39A and 39B  are views illustrating comparison between effects of presence and absence of a diffuser on an optical path; 
         FIG. 40  is a perspective view illustrating a head unit when the head unit is seen from the front; 
         FIG. 41  is a perspective view illustrating the head unit when the head unit is seen from the back; 
         FIG. 42  is a view illustrating one passage route of cooling air; 
         FIG. 43  is a view illustrating another passage route of the cooling air; 
         FIGS. 44A to 44C  are schematic diagrams illustrating an example of a positioning mechanism; 
         FIG. 45  is a schematic diagram illustrating an example of the positioning mechanism; 
         FIG. 46  is a flowchart illustrating an example of rotation axis calibration processing; 
         FIG. 47  is a perspective view illustrating an appearance of the measuring unit to which a light shielding mechanism is attached; 
         FIG. 48  is a perspective view of an appearance of the measuring unit, illustrating an example of a rear light shielding member attached to a rear cover member; 
         FIG. 49  is a perspective view of an appearance of the measuring unit, illustrating an example of a front and side light shielding member attached to a front cover member; 
         FIGS. 50A and 50B  are views illustrating a configuration example of a stage plate; and 
         FIG. 51  is a schematic side view illustrating an example in which the measuring unit captures the image of the measuring object while an inclination part is in an inclination attitude. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     Hereinafter, a measuring device according to one embodiment of the present invention will be described with reference to the drawings. 
     [1] Configuration of Measuring Device 
       FIG. 1  is a block diagram illustrating a configuration of a measuring device according to one embodiment of the present invention.  FIG. 2  is a schematic diagram illustrating a configuration of a measuring unit of a measuring device  500  in  FIG. 1 . Hereinafter, the measuring device  500  according to the present embodiment will be described with reference to  FIGS. 1 and 2 . As illustrated in  FIG. 1 , the measuring device  500  includes a measuring unit  100 , a PC (Personal Computer)  200 , a control unit  300 , and a display unit  400 . For example, the measuring unit  100  is an imaging device in which a light projecting unit and a light receiving unit are integrated. The measuring unit  100  includes a light projecting unit  110 , a light receiving unit  120 , an illumination light output unit  130 , a stage  140 , and a control board  150 . 
     The measuring unit  100  may include a plurality of light projecting units  110 . The measuring unit  100  may include a plurality of light receiving units  120 . In the present embodiment, the measuring unit  100  includes two light projecting units  110  and two light receiving units  120 . Hereinafter, in the case where the two light projecting units  110  are distinguished from each other, one of the light projecting units  110  is referred to as a light projecting unit  110 A, and the other light projecting unit  110  is referred to as a light projecting unit  110 B. In the case where the two light receiving units  120  are distinguished from each other, one of the light receiving units  120  is referred to as a light receiving unit  120 A, and the other light receiving unit  120  is referred to as a light receiving unit  120 B. 
     Referring to  FIG. 2 , two light projecting units  110  and one light receiving unit  120  are illustrated in the two light projecting units  110  and the two light receiving units  120 . The light projecting units  110  and the light receiving units  120  are each disposed in one direction at a position obliquely above the stage  140 . Details of the dispositions of the light projecting unit  110  and the light receiving unit  120  will be described later. 
     As illustrated in  FIG. 2 , each light projecting unit  110  includes a measurement light source  111 , a pattern generating unit  112 , and a plurality of lenses  113 ,  114 . Each light projecting unit  110  also includes a light projection control board  115  (see  FIG. 36 ) that controls operation of the pattern generating unit  112  based on an instruction from the PC  200 . Each light receiving unit  120  includes a camera  121  and a lens  122 . Each light receiving unit  120  also includes a light reception control board  123  (see  FIG. 36  to be described later) that controls operation of the camera  121  based on an instruction from the PC  200 . A measuring object S is placed on the stage  140 . 
     For example, the measurement light source  111  of each of the light projecting units  110 A,  110 B is a blue LED (Light Emitting Diode). The measurement light source  111  may be other light sources such as a halogen lamp. Light (hereinafter, referred to as measurement light) emitted from the measurement light source  111  is appropriately collected by the lens  113 , and then enters the pattern generating unit  112 . 
     For example, the pattern generating unit  112  is a DMD (Digital Micro-mirror Device). The pattern generating unit  112  may be an LCD (Liquid Crystal Display), an LCOS (Liquid Crystal on Silicon), or a mask. The measurement light incident on the pattern generating unit  112  is output after being converted into the measurement light having a previously-set pattern and previously-set intensity (brightness). The measurement light output from the pattern generating unit  112  is converted into the measurement light having a diameter larger than a size of the measuring object S by using the lens  114 , and the measuring object S on the stage  140  is irradiated with the measurement light. 
     The measurement light source  111 , lens  113 , and pattern generating unit  112  of the light projecting unit  110 A are disposed substantially parallel to an optical axis of the light receiving unit  120 . Similarly, the measurement light source  111 , lens  113 , and pattern generating unit  112  of the light projecting unit  110 B are disposed substantially parallel to an optical axis of the light receiving unit  120 . On the other hand, the lens  114  of each of the light projecting units  110 A,  110 B is disposed so as to be offset from the measurement light source  111 , the lens  113 , and the pattern generating unit  112 . Therefore, the optical axes of the light projecting units  110 A,  110 B are inclined with respect to the optical axis of the light receiving unit  120 , and the measurement light is output toward the measuring object S from both sides of the light receiving unit  120 . 
     In this example, to make an irradiation range of the measurement light wide, the light projecting units  110 A,  110 B are configured to have a given angle of view. For example, the angles of view of the light projecting units  110 A,  110 B are defined by a size of the pattern generating unit  112  and a focal distance of the lens  114 . In the case where the irradiation range of the measurement light does not need to be widened, a telecentric optical system in which the angle of view becomes substantially 0 degrees may be used in each of the light projecting units  110 A,  110 B. 
     The measurement light reflected toward above the stage  140  by the measuring object S is focused through the lens  122  of the light receiving unit  120  to form an image, and received by using an imaging element  121   a  of the camera  121 . 
     In this example, to make an imaging visual field of the light receiving unit  120  wide, the light receiving unit  120  is configured to have a given angle of view. As used herein, the imaging visual field of the light receiving unit  120  means a spatial region where the light receiving unit  120  can capture an image. For example, the angle of view of the light receiving unit  120  is defined by the size of the imaging element  121   a  and the focal distance of the lens  122 . When the wide visual field is unnecessary, the telecentric optical system may be used for the light receiving unit  120 . Here, magnifications of the lenses  122  of the two light receiving units  120  provided in the measuring unit  100  differ from each other. Therefore, selective use of the two light receiving units  120  enables the image of the measuring object S to be captured with two different magnifications. Preferably, the two light receiving units  120  are disposed such that the optical axes of the two light receiving units  120  are parallel to each other. In this case, the image of the measuring object S can be captured in the substantially same direction by using the two light receiving units  120 . 
     For example, the camera  121  is a CCD (Charge Coupled Device) camera. For example, the imaging element  121   a  is a monochrome CCD (Charge Coupled Device). The imaging element  121   a  may be other imaging elements such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor. Each pixel of the imaging element  121   a  outputs, to the control board  150 , an analog electric signal (hereinafter, referred to as a light reception signal) corresponding to a light reception amount. 
     In the monochrome CCD, unlike a color CCD, it is not necessary to provide a pixel receiving light having a red wavelength, a pixel receiving light having a green wavelength, and a pixel receiving light having a blue wavelength. In the case where a specific wavelength such as the blue wavelength is adopted as the measurement light, only the pixel receiving the light having the specific wavelength can be used during the measurement in the color CCD, while the monochrome CCD is free from such restriction. Therefore, measurement resolution of the monochrome CCD is higher than resolution of the color CCD. In the monochrome CCD, unlike the color CCD, it is not necessary to provide a color filter in each pixel. Therefore, sensitivity of the monochrome CCD is higher than sensitivity of the color CCD. For these reasons, the monochrome CCD is provided in the camera  121  in this example. 
     In this example, the illumination light output unit  130  outputs the light having the red wavelength, the light having the green wavelength, and the light having the blue wavelength to the measuring object S in a time division manner. According to this configuration, the light receiving unit  120  provided with the monochrome CCD can capture a color image of the measuring object S. 
     On the other hand, in the case where the color CCD has the sufficient resolution and sensitivity, the imaging element  121   a  may be the color CCD. In this case, the illumination light output unit  130  does not need to irradiate the measuring object S with the light having the red wavelength, the light having the green wavelength, and the light having the blue wavelength in the time division manner, but irradiates the measuring object S with white light. Therefore, a configuration of an illumination light source  320  (to be described later) can be simplified. 
     An A/D converter (Analog/Digital Converter) (not illustrated) and a FIFO (First In First Out) memory (not illustrated) are mounted on the control board  150 . Under the control of the control unit  300 , the A/D converter of the control board  150  converts a light reception signal output from the camera  121  into a digital signal while sampling the light reception signal in a given sampling period. The digital signal output from the A/D converter is sequentially accumulated in the FIFO memory. The digital signals accumulated in the FIFO memory are sequentially transferred to the PC  200  as pixel data. Here, the A/D converter is not necessarily provided when the camera  121  is the monochrome CMOS camera, and the digital electric signal corresponding to the light reception amount is output from each pixel of the imaging element  121   a  to the control board  150 . 
     As illustrated in  FIG. 1 , the PC  200  includes a CPU (Central Processing Unit)  210 , a ROM (Read Only Memory)  220 , a working memory  230 , a storage device  240 , and an operation unit  250 . The operation unit  250  includes a keyboard and a pointing device. For example, a mouse or a joystick is used as the pointing device. 
     A system program is stored in the ROM  220 . The working memory  230  is configured by a RAM (Random Access Memory), and is used to process various pieces of data. For example, the storage device  240  is configured by a hard disk drive. For example, a data generation program, a measurement program, and a rotation axis calibration program are stored in the storage device  240 . The storage device  240  is also used to store various pieces of data such as pixel data supplied from the control board  150 . 
     The CPU  210  generates image data based on the pixel data supplied from the control board  150 . The CPU  210  also performs various pieces of processing on the generated image data using the working memory  230 , and displays the image on the display unit  400  based on the image data. The CPU  210  also applies a drive signal to a stage drive unit  146 , to be described later, through the control board  150 . For example, the display unit  400  is configured by an LCD panel or an organic EL (Electro-Luminescence) panel. For example, an image (hereinafter, referred to as a live image) is displayed on the display unit  400  based on the image data, which is obtained in real time with the camera  121  of the light receiving unit  120 . 
     An image of the measuring object S irradiated with the measurement light from the one light projecting unit  110 A and an image of the measuring object S irradiated with the measurement light from the other light projecting unit  110 B may be displayed side by side on the display unit  400  (dual screen display). An image of the measuring object S irradiated with the measurement light from the one light projecting unit  110 A and an image of the measuring object S irradiated with the measurement light from the other light projecting unit  110 B may be displayed on the display unit  400  so as to overlap each other (synthesized display). 
     In the case of the dual screen display, the light projecting units  110 A,  110 B alternately irradiate the measuring object S with the measurement light at, for example, a constant period (several Hz), and the image that is obtained when the light projecting unit  110 A irradiates the measuring object S with the measurement light and the image that is obtained when the light projecting unit  110 B irradiates the measuring object S with the measurement light are separately displayed on the display unit  400 . While viewing the displayed image, a user can adjust the light reception amount of the light receiving unit  120  when the light projecting unit  110 A outputs the measurement light, and adjust the light reception amount of the light receiving unit  120  when the light projecting unit  110 B outputs the measurement light. The light reception amount of the light receiving unit  120  can be adjusted by changing brightness of the light reception amount output from the light projecting units  110 A,  110 B or changing exposure time of the light receiving unit  120 . 
     In the case of the synthesized display, similarly to the dual screen display, while viewing the displayed image, the user can adjust the light reception amount of the light receiving unit  120  when the light projecting unit  110 A outputs the measurement light, and adjust the light reception amount of the light receiving unit  120  when the light projecting unit  110 B outputs the measurement light. In this case, in addition to the synthesized-display image, the image of the measuring object S irradiated with the measurement light from the one light projecting unit  110 A and the image of the measuring object S irradiated with the measurement light from the other light projecting unit  110 B may be displayed side by side on the display unit  400 . The image of the dual screen display and the image of the synthesized display may be displayed on the display unit  400  in a switching manner. Alternatively, the image of the synthesized display, the image of the measuring object S irradiated with the measurement light from the one light projecting unit  110 A, and the image of the measuring object S irradiated with the measurement light from the other light projecting unit  110 B may be displayed on the display unit  400  in a switching manner. 
     As illustrated in  FIG. 2 , the stage  140  includes a stage base  141  and a stage plate  142 . The stage plate  142  is disposed on the stage base  141 . The stage plate  142  includes a placement surface on which the measuring object S is placed. An attaching part (for example, a screw hole) to which a clamp or a jig is attached may be provided in the stage plate  142 . The stage plate  142  according to the present embodiment has a disc shape. 
     A substantially columnar effective region MR is set in a space on the stage plate  142 . The effective region MR can be irradiated with the measurement light from the light projecting units  110 A,  110 B, and the image of the effective region MR can be captured by the light receiving unit  120 . For example, the imaging visual field of the light receiving unit  120  is defined by a magnification, a focal depth, and an angle of view of the lens  122  included in the light receiving unit  120 . Details of a setting content of the effective region MR will be described later. 
     The stage  140  is attached to a rotation mechanism  143 . The rotation mechanism  143  is fixed to an installation part  161  (see  FIG. 4 ) to be described later. For example, the rotation mechanism  143  includes an encoder and a stepping motor. The rotation mechanism  143  is driven by a stage operation unit  145  or the stage drive unit  146  in  FIG. 1 , and rotated about a rotation axis Ax, which passes through a center of the stage  140  and extend in a vertical direction. The user can manually operate the stage operation unit  145  to rotate the stage  140 . Based on the drive signal supplied from the PC  200  through the control board  150 , the stage drive unit  146  supplies current to the rotation mechanism  143 , which allows the placement surface of the stage plate  142  to rotate relative to the light receiving unit  120 . 
     During the rotation of the stage  140 , a signal output from the encoder of the rotation mechanism  143  is transmitted to the PC  200  through the control board  150 . The signal enables the CPU  210  in  FIG. 1  to detect a rotation amount (rotation position) of the stage plate  142  from a predetermined reference angle. 
     In the present embodiment, the stage  140  can be driven with the stepping motor of the rotation mechanism  143 , and can be manually operated. However, the present invention is not limited thereto. Alternatively, the stage  140  may be driven only with the stepping motor of the rotation mechanism  143 , or can only be manually operated. 
     The control unit  300  includes a control board  310  and an illumination light source  320 . A CPU (not illustrated) is mounted on the control board  310 . Based on an instruction from the CPU  210  of the PC  200 , the CPU of the control board  310  controls the light projection control board  115  (see  FIG. 36 ), the light reception control board  123  (see  FIG. 36 ), and the control board  150 . The control board  310  and the illumination light source  320  are provided separately from the measuring unit  100 . In this case, a thermal noise and an electric noise, which are caused by the control board  310  and illumination light source  320  to the measuring unit  100 , are blocked. Therefore, measurement accuracy of the measuring unit  100  can be improved. 
     The measurement light source  111  or the control board  150  may be provided in the control unit  300 . Therefore, the thermal noise and the electric noise, which are caused by the measurement light source  111  or control board  150  to the measuring unit  100 , are blocked, and measurement accuracy of the measuring unit  100  can be further improved. On the other hand, in the case where the measurement accuracy of the measuring unit  100  is not degraded because of the small thermal noise and electric noise from the control board  310  or the illumination light source  320 , the control board  310  or the illumination light source  320  may be mounted on the measuring unit  100 . 
     For example, the illumination light source  320  includes three LEDs that emit red light, green light, and blue light. The light having any color can be generated from the illumination light source  320  by control of luminance of the light emitted from each LED. The light (hereinafter, referred to as illumination light) generated from the illumination light source  320  is output from the measuring unit  100  of the illumination light output unit  130  through a light guide  330 . The illumination light source  320  may not be provided in the control unit  300 , but may be provided in the measuring unit  100 . In this case, the necessity of the light guide  330  is eliminated. 
       FIG. 3  is a functional block diagram illustrating a function implemented by the CPU  210  in  FIG. 1 . As illustrated in  FIG. 3 , the CPU  210  includes a point cloud data generating unit  501 , a measurement data obtaining unit  502 , a measurement data correcting unit  503 , a measurement unit  504 , a receiving unit  505 , a rotation control unit  506 , and a positional relationship calculating unit  507 . 
     The point cloud data generating unit  501  generates point cloud data representing a three-dimensional shape of the measuring object S based on the light reception signal output from the light receiving unit  120 . When selection is made that the point cloud data corresponding to the effective region MR should be set to the measurement data, the measurement data obtaining unit  502  obtains the point cloud data corresponding to the effective region MR as the measurement data with respect to the space on the stage  140  based on region information (to be described later) stored in the storage device  240 . When selection is made that the point cloud data corresponding to the effective region MR and other regions should be set to the measurement data, the measurement data obtaining unit  502  obtains all the pieces of point cloud data generated by the point cloud data generating unit  501 . 
     In the case where a region to be removed is designated in the region corresponding to the obtained measurement data, the measurement data correcting unit  503  removes the point cloud data corresponding to the designated region from the obtained measurement data. 
     The measurement unit  504  receives the designation of a point to be measured in the measuring object S, and calculates a measurement value at the designated point based on the measurement data obtained by the measurement data obtaining unit  502  or the measurement data corrected with the measurement data correcting unit  503 . 
     Based on the user operation of the operation unit  250 , the receiving unit  505  receives the selection as to whether the measurement data is set to the point cloud data corresponding to the effective region MR or the point cloud data corresponding to the effective region MR and other regions. Based on the user operation of the operation unit  250 , the receiving unit  505  also receives the designation of the region to be removed in the region corresponding to the obtained measurement data. Based on the user operation of the operation unit  250 , the receiving unit  505  also receives the light receiving unit  120  to be used in the light receiving units  120 A,  120 B. 
     The rotation control unit  506  controls the stage drive unit  146 , thereby controlling the rotation of the stage  140 . The positional relationship calculating unit  507  calculates a positional relationship between the rotation axis Ax of the stage  140 , the rotation axis, and the light receiving unit  120  in rotation axis calibration processing (to be described later). Details of the functions will be described later. 
     The CPU  210  executes one of a system program, a data generation program, a measurement program, and a rotation axis calibration program, which are stored in the ROM  220  and the storage device  240 , thereby implementing the point cloud data generating unit  501 , the measurement data obtaining unit  502 , the measurement data correcting unit  503 , the measurement unit  504 , the receiving unit  505 , the rotation control unit  506 , and the positional relationship calculating unit  507 . A part or all the functional sections may be implemented by hardware such as an electronic circuit. 
     The plurality of light projecting units  110 , the plurality of light receiving units  120 , the illumination light output unit  130 , and the stage  140  are coupled to one another in the measuring unit  100  such that a positional relationship among these components is kept constant. 
       FIG. 4  is a perspective view illustrating a schematic appearance of a measuring unit  100 . In  FIG. 4 , the appearance of the measuring unit  100  is indicated by a bold solid line, and some components provided in the measuring unit  100  are indicated by a dotted line. As illustrated in  FIG. 4 , the measuring unit  100  includes a mount  170 . The two light projecting units  110 , the two light receiving units  120 , the illumination light output unit  130 , and the control board  150  are attached to the mount  170 . In this state, the positional relationship among the two light projecting units  110 , the two light receiving units  120 , and the illumination light output unit  130  is fixed using the mount  170 . The two light receiving units  120  are vertically arranged. The illumination light output unit  130  has an elliptically cylindrical shape, and is disposed so as to surround the two light receiving units  120 . An elliptical illumination light output port  131  is formed at one end of the illumination light output unit  130 . The two light projecting units  110  are arranged such that the two light receiving units  120  and the illumination light output unit  130  are interposed therebetween. 
     The light projecting units  110 A,  110 B are disposed at the same height as the light receiving unit  120 A. This enables maximization of an imaging visual field TR 1  of the light receiving unit  120 A. The light receiving unit  120 B can capture the image using part of the measurement light from the light projecting units  110 A,  110 B. 
     A head casing  180  is attached to the mount  170 . The two light projecting units  110 , the two light receiving units  120 , the illumination light output unit  130 , and a part of the control board  150  are accommodated in the head casing  180 . The two light projecting units  110 , the two light receiving units  120 , the illumination light output unit  130 , the control board  150 , the mount  170 , and the head casing  180  constitute a head unit  190 . 
     The measuring unit  100  also includes an installation part  161  and a stand  162 . The installation part  161  has a flat bottom, and is formed with a substantially constant width so as to extend in one direction. The installation part  161  is installed on a horizontal installation surface such as a top surface of a table. 
     The stand  162  is formed so as to be connected to one of ends of the installation part  161 , and so as to extend upward from the one end of the installation part  161 . The rotation mechanism  143  in  FIG. 2  is fixed to a position near the other end of the installation part  161 . The rotation mechanism  143  rotatably holds the stage  140 . A driver circuit (not illustrated) is mounted on the installation part  161  or the stand  162  in order to control the stage  140 . In this case, the driver circuit is separated from the head unit  190 , and the thermal noise and electric noise, which are caused by the driver circuit to the head unit  190 , are blocked. Therefore, measurement accuracy of the head unit  190  can be improved. 
     In the present embodiment, the installation part  161  and the stand  162  may be configured so as to be detachable from each other. In this case, the large-size measuring object S, which cannot be placed on the installation part  161 , can be measured by detaching the installation part  161  from the stand  162 . 
     A pair of grips  179  is provided on both sides of the mount  170  so as to be able to be gripped by the user. Only one of the pair of grips  279  is illustrated in  FIG. 4 . The mount  170  of the head unit  190  is configured to be detachably attached to the top of the stand  162 . As illustrated by outline arrows in  FIG. 4 , the user can attach and detach the mount  170  to and from the stand  162  by gripping the pair of grips  179  of the mount  170 . 
     The mount  170  of the head unit  190  is attached to the stand  162 , whereby the head unit  190  and the installation part  161  are fixedly coupled together using the stand  162 . At this time, the control board  150  is electrically connected to the driver circuit (not illustrated) of the stage  140  while the head unit  190  is mechanically connected to the stand  162 . The control board  150  issues an electric control instruction to the driver circuit through an electric wiring and a connector (not illustrated), which are provided in a coupling member  160 . The driver circuit controls operation of the stage  140  based on the electric control instruction issued from the control board  150 . 
     The mount  170  of the head unit  190  is attached to the stand  162 , whereby the positional relationship among the stage  140 , the two light projecting units  110 , and the light receiving units  120  is kept constant. Each light projecting unit  110  is positioned such that the irradiation region irradiated with the measurement light includes the stage  140  and a space above the stage  140 . The measurement light is guided obliquely downward with respect to the measuring object S of the light projecting unit  110 . Each light receiving unit  120  is positioned such that the optical axis extends obliquely downward, and such that the imaging visual field of the camera  121  in  FIG. 2  includes the stage  140  and the space above the stage  140 . In  FIG. 4 , an irradiation region IR of each light projecting unit  110  is indicated by an alternate long and two short dashes line, and the imaging visual field TR 1  of the one light receiving unit  120 A is indicated by an alternate long and short dash line. Each of the light receiving units  120 A,  120 B is fixed in a state where a predetermined angle (for example, 45 degrees) is formed between the optical axis (the optical axis of the lens  122  in  FIG. 2 ) of the optical system thereof and the placement surface of the stage plate  142 . 
     As illustrated in  FIG. 4 , the irradiation regions IR of the two light projecting units  110 A,  110 B and the imaging visual field TR 1  of the light receiving unit  120 A partially overlap each other in the space above the stage  140 . An effective region MR 1  corresponding to the light receiving unit  120 A is set to the position where the irradiation regions IR of the light projecting units  110 A,  110 B and the imaging visual field TR 1  of the light receiving unit  120 A overlap each other. 
     The two light receiving units  120 A,  120 B provided in the measuring unit  100  in this example differ from each other in the magnification, focal depth, and angle of view of the lens  122 . Specifically, the magnification of the lens  122  of the light receiving unit  120 B is higher than the magnification of the lens  122  of the light receiving unit  120 A. The focal depth of the lens  122  of the light receiving unit  120 B is shallower than the focal depth of the lens  122  of the light receiving unit  120 A. The angle of view of the lens  122  of the light receiving unit  120 B is smaller than the angle of view of the lens  122  of the light receiving unit  120 A. In this case, the imaging visual field of the light receiving unit  120 B is smaller than the imaging visual field TR 1  of the light receiving unit  120 A. Therefore, the effective region MR 1  corresponding to the one light receiving unit  120 A is set in a relatively wide range on the stage  140 . On the other hand, the effective region corresponding to the other light receiving unit  120 B is set on the stage  140  in a range narrower than the effective region MR 1  corresponding to the light receiving unit  120 A. 
       FIG. 5  is a schematic side view illustrating details of a positional relationship between the two light receiving units  120 A,  120 B and the stage  140  in the measuring unit  100 . In  FIG. 5 , an optical axis A 1  of the optical system of the light receiving unit  120 A is indicated by a bold alternate long and short dash line, and the imaging visual field TR 1  and the effective region MR 1  of the light receiving unit  120 A is indicated by a bold dotted line. An optical axis A 2  of the optical system of the light receiving unit  120 B is indicated by an alternate long and short dash line, and an imaging visual field TR 2  and an effective region MR 2  of the light receiving unit  120 B is indicated by a dotted line. 
     When the two optical axes A 1 , A 2  are on the same straight line while the imaging visual field TR 1  is set to the wide range including the stage  140 , there is a possibility that the imaging visual field TR 2  is displaced from the position near the placement surface of the stage  140 . In this case, when the measuring object S with a low height is placed on the placement surface of the stage  140 , the measuring object S cannot be measured with the high-magnification light receiving unit  120 B. On the other hand, in the measuring unit  100  according to the present embodiment, the optical axis A 2  is positioned below the optical axis A 1  as illustrated in  FIG. 5 . Therefore, irrespective of the position of the imaging visual field TR 1 , the imaging visual field TR 2  can be set to the position near the placement surface of the stage  140 . 
     As described above, in the space on the stage  140 , the imaging visual field TR 2  of the light receiving unit  120 B includes the imaging visual field TR 1  of the light receiving unit  120 A. In this case, for example, the live image obtained by the light receiving unit  120 A includes the region of the live image that can be obtained by the light receiving unit  120 B. Accordingly, the light receiving units  120 A,  120 B used in the imaging can easily be switched. 
     For example, the effective region MR 1  corresponding to the light receiving unit  120 A is set around an intersection F 1  between the rotation axis Ax of the stage  140  and a focal surface of the optical system of the light receiving unit  120 A. For example, the effective region MR 2  corresponding to the light receiving unit  120 B is set around an intersection F 2  between the rotation axis Ax of the stage  140  and a focal surface of the optical system of the light receiving unit  120 B. In the present embodiment, a focal position F 1  is positioned at the intersection between the optical axis A 1  and the rotation axis Ax. Below the focal position F 1 , a focal position F 2  is positioned at the intersection between the optical axis A 2  and the rotation axis Ax. 
     In these cases, the measuring object S is placed in the center of the stage plate  142 , which allows the measuring object S to be easily placed in the effective regions MR 1 , MR 2 . The light receiving units  120 A,  120 B used in the imaging are switched without moving the measuring object S. Therefore, a surface state of the measuring object S can accurately be observed while the magnification of the live image of the measuring object S is changed. Specifically, the relatively large measuring object S can be observed or imaged with the low-magnification light receiving unit  120 A, and the relatively small measuring object S can be observed or imaged with the high-magnification light receiving unit  120 B. 
     Preferably, a height of the intersection between the rotation axis Ax of the stage  140  and the optical axes A 1 , A 2  is positioned at 40% of a maximum height of the measuring object S that can be measured at each magnification. In this case, the measuring object S can be prevented from protruding from the effective regions MR 1 , MR 2  (visual field missing), when the measuring object S is observed or imaged while the stage plate  142  is rotated as described later. 
     Indexes (for example, circles) indicating bottom ranges of the effective regions MR 1 , MR 2  corresponding to the light receiving units  120 A,  120 B may be marked on the placement surface of the stage plate  142 . In this case, the user can easily recognize the positions and sizes of the effective regions MR 1 , MR 2  set onto the stage  140 . 
     The light receiving units  120 A,  120 B are disposed while being offset from each other in a direction of the optical axis A 1  or optical axis A 2 . Therefore, interference between the light receiving units  120 A,  120 B can be prevented, and a vertical distance between the optical axes A 1 , A 2  can flexibly be adjusted. An optical path length corresponding to the high-magnification light receiving unit  120 A is easily shortened compared with an optical path length corresponding to the low-magnification light receiving unit  120 B. Therefore, in the present embodiment, the light receiving unit  120 A is disposed closer to the rotation axis Ax compared with the light receiving unit  120 B. 
     Hereinafter, a region other than the effective region MR 1  in the imaging visual field TR 1  of the light receiving unit  120 A and a region other than the effective region MR 2  in the imaging visual field TR 2  of the light receiving unit  120 B are referred to as an ineffective region. For example, information distinguishing the effective regions MR 1 , MR 2  from the ineffective region is previously stored in the storage device  240  of  FIG. 1  as region information at a point of factory shipment of the measuring device  500 . 
     In the measuring unit  100  illustrated in  FIGS. 4 and 5 , a three-dimensional coordinate system (hereinafter, referred to as a device coordinate system) unique to the measuring unit  100  is defined in the space on the stage  140  including the effective regions MR 1 , MR 2 . The device coordinate system in this example includes an X-axis, a Y-axis, and a Z-axis, which are orthogonal to an origin. Hereinafter, a direction parallel to the X-axis of the device coordinate system is referred to as an X-direction, a direction parallel to the Y-axis is referred to as a Y-direction, and a direction parallel to the Z-axis is referred to as a Z-direction. A direction rotating about an axis parallel to the Z-axis is referred to as a θ-direction. The X-direction and the Y-direction are orthogonal to each other in a plane parallel to the placement surface of the stage plate  142 . The Z-direction is orthogonal to a plane parallel to the placement surface of the stage plate  142 . In  FIGS. 4 and 5 , the X-direction, the Y-direction, the Z-direction, and the θ-direction are indicated by arrows. 
     [2] Three-Dimensional Shape Data Indicating Three-Dimensional Shape of Measuring Object 
     (1) Measurement by Triangular Distance Measuring Method 
     The measuring unit  100  measures the shape of the measuring object S by the triangular distance measuring method.  FIG. 6  is a view illustrating a principle of the triangular distance measuring method. The X-direction, the Y-direction, the Z-direction, and the θ-direction, which are defined along with the device coordinate system, are indicated by arrows in  FIG. 6  and each of  FIGS. 7A and 7B ,  FIGS. 8A to 8D ,  FIGS. 9A to 9C , and  FIGS. 11A to 11D  to be described later. 
     An angle α between the optical axis of the measurement light output from the light projecting unit  110  and the optical axis (the optical axis of the light receiving unit  120 ) of the measurement light incident on the light receiving unit  120  is previously set as illustrated in  FIG. 6 . The angle α is larger than 0 degrees and smaller than 90 degrees. 
     In the case where the measuring object S is not placed on the stage  140 , the measurement light output from the light projecting unit  110  is reflected from a point O on the placement surface of the stage  140 , and is incident on the light receiving unit  120 . On the other hand, in the case where the measuring object S is placed on the stage  140 , the measurement light output from the light projecting unit  110  is reflected from a point A on the surface of the measuring object S, and is incident on the light receiving unit  120 . 
     Assuming that d is a distance between the point O and the point A in the X-direction, a height h of the point A of the measuring object S with respect to the placement surface of the stage  140  is given by h=d÷tan(α). The CPU  210  of the PC  200  in  FIG. 1  measures the distance d between the point O and the point A in the X-direction based on the pixel data of the measuring object S, the pixel data being supplied from the control board  150 . Based on the measured distance d, the CPU  210  calculates the height h at the point A on the surface of the measuring object S. The heights at all the points on the surface of the measuring object S are calculated, which allows a coordinate represented by the device coordinate system to be specified with respect to all the points irradiated with the measurement light. This enables the measurement of the three-dimensional shape of the measuring object S. 
     In order to irradiate all the points on the surface of the measuring object S with the measurement light, the light projecting unit  110  in  FIG. 2  outputs pieces of measurement light having various patterns. The pattern generating unit  112  in  FIG. 2  controls the pattern of the measurement light. Patterns of the measurement light will be described below. 
     (2) First Pattern of Measurement Light 
       FIGS. 7A and 7B  are views illustrating a first pattern of the measurement light.  FIG. 7A  illustrates a state in which the light projecting unit  110  irradiates the measuring object S on the stage  140  with the measurement light.  FIG. 7B  is a plan view illustrating the measuring object S irradiated with the measurement light. As illustrated in  FIG. 7A , measurement light (hereinafter, referred to as linear measurement light) having a linear section parallel to the Y-direction is output from the light projecting unit  110  as the first pattern. In this case, as illustrated in  FIG. 7B , a portion of the linear measurement light with which the stage  140  is irradiated and a portion of the linear measurement light with which the surface of the measuring object S is irradiated is displaced from each other in the X-direction by the distance d corresponding to the height h of the surface of the measuring object S. Accordingly, the height h of the measuring object S can be calculated by the measurement of the distance d. 
     In the case where a plurality of portions on the surface of the measuring object S along the Y-direction have different heights, the heights h of the plurality of portions along the Y-direction can be calculated by the measurement of the distance d in each portion. 
     After measuring the distance d with respect to the plurality of portions along the Y-direction at one position in the X-direction, the CPU  210  in  FIG. 1  performs scan in the X-direction with the linear measurement light parallel to the Y-direction, thereby measuring the distance d with respect to the plurality of portions along the Y-direction at another position in the X-direction. Therefore, the heights h of the plurality of portions of the measuring object S along the Y-direction are calculated at the plurality of positions in the X-direction. The scan is performed with the linear measurement light in the X-direction in the range wider than the size of the measuring object S in the X-direction, which allows the height h to be calculated at all the points on the surface of the measuring object S. This enables the measurement of the three-dimensional shape of the measuring object S. 
     (3) Second Pattern of Measurement Light 
       FIGS. 8A to 8D  are views illustrating a second pattern of the measurement light. As illustrated in  FIGS. 8A to 8D , measurement light (hereinafter, referred to as sinusoidal measurement light), which has the linear section parallel to the Y-direction and in which the intensity changes sinusoidally in the X-direction, is output from the light projecting unit  110  a plurality of times (in this example, four times) as the second pattern. 
       FIG. 8A  illustrates the sinusoidal measurement light output at a first time. The intensity of the sinusoidal measurement light output at the first time has an initial phase ϕ in any portion P 0  on the surface of the measuring object S. When the sinusoidal measurement light is output, the light receiving unit  120  receives the light reflected by the surface of the measuring object S. The intensity of the received light is measured based on the pixel data of the measuring object S. It is assumed that I 1  is the intensity of the light reflected by a portion P 0  on the surface of the measuring object S. 
       FIG. 8B  illustrates the sinusoidal measurement light output at a second time. The intensity of the sinusoidal measurement light output at the second time has a phase (ϕ+π/2) in the portion P 0  on the surface of the measuring object S. When the sinusoidal measurement light is output, the light receiving unit  120  receives the light reflected by the surface of the measuring object S. The intensity of the received light is measured based on the pixel data of the measuring object S. It is assumed that I 2  is the intensity of the light reflected by the portion P 0  on the surface of the measuring object S. 
       FIG. 8C  illustrates the sinusoidal measurement light output at a third time. The intensity of the sinusoidal measurement light output at the third time has a phase (ϕ+π) in the portion P 0  on the surface of the measuring object S. When the sinusoidal measurement light is output, the light receiving unit  120  receives the light reflected by the surface of the measuring object S. The intensity of the received light is measured based on the pixel data of the measuring object S. It is assumed that I 3  is the intensity of the light reflected by the portion P 0  on the surface of the measuring object S. 
       FIG. 8D  illustrates the sinusoidal measurement light output at a fourth time. The intensity of the sinusoidal measurement light output at the fourth time has a phase (ϕ+3π/2) in the portion P 0  on the surface of the measuring object S. When the sinusoidal measurement light is output, the light receiving unit  120  receives the light reflected by the surface of the measuring object S. The intensity of the received light is measured based on the pixel data of the measuring object S. It is assumed that I 4  is the intensity of the light reflected by the portion P 0  on the surface of the measuring object S. 
     The initial phase ϕ is given by ϕ=tan −1 [(I 1 −I 3 )/(I 2 −I 4 )]. The height h in any portion of the measuring object S is calculated from the initial phase ϕ. According to the method, the initial phase ϕ can easily be calculated at high speed in all the portions of the measuring object S by the four-time measurement of the light intensity. Pieces of measurement light having different phases are output at least three times to measure the intensity of the received light, which allows the calculation of the initial phase ϕ. The height h is calculated in all the portions on the surface of the measuring object S, which allows the measurement of the three-dimensional shape of the measuring object S. 
     (4) Third Pattern of Measurement Light 
       FIGS. 9A to 9C  are views illustrating a third pattern of the measurement light. As illustrated in  FIGS. 9A to 9C , measurement light (hereinafter, referred to as stripe measurement light) having the linear sections, which are parallel to the Y-direction and arranged in the X-direction, is output from the light projecting unit  110  a plurality of times (in this example, 16 times) as the third pattern. That is, linearly bright portions parallel to the Y-direction and linearly dark portions parallel to the Y-direction are periodically arrayed in the X-direction in the stripe measurement light. 
     When the first-time stripe measurement light is output, the light receiving unit  120  receives the light reflected by the surface of the measuring object S. The intensity of the received light is measured based on the pixel data of the first captured image of the measuring object S.  FIG. 9A  illustrates the first-time captured image of the measuring object S corresponding to the first stripe measurement light. 
     The second-time stripe measurement light has a pattern in which the bright and dark portions are moved from the first-time stripe measurement light by one unit in the X-direction. When the second-time stripe measurement light is output, the light receiving unit  120  receives the light reflected by the surface of the measuring object S. The intensity of the received light is measured based on the pixel data of the second captured image of the measuring object S. 
     The third-time stripe measurement light has a pattern in which the bright and dark portions are moved from the second-time stripe measurement light by one unit in the X-direction. When the third-time stripe measurement light is output, the light receiving unit  120  receives the light reflected by the surface of the measuring object S. The intensity of the received light is measured based on the pixel data of the third captured image of the measuring object S. 
     Through repetition of similar operations, the light intensities corresponding to fourth-time striped measurement light to sixteenth-time striped measurement light are measured based on the pixel data of the fourth to sixteenth captured images of the measuring object S. All the portions of the surface of the measuring object S are irradiated with the striped measurement light when the striped measurement light, in which the period in the X direction is 16 units, is output sixteen times.  FIG. 9B  illustrates the seventh captured image of the measuring object S corresponding to the seventh-time stripe measurement light.  FIG. 9C  illustrates the thirteenth-time captured image of the measuring object S corresponding to the thirteenth-time stripe measurement light. 
       FIG. 10  is a view illustrating a relationship between timing (order) at which the image of a specific portion of the measuring object S is captured and the intensity of received light. In  FIG. 10 , a horizontal axis indicates order of the image and a vertical axis indicates the intensity of the received light. As described above, first to sixteenth captured images are generated for each portion of the measuring object S. The intensity of the light corresponding to each pixel of the generated first to sixteenth photographed images is measured. 
     The intensity of the light of each pixel of the captured image corresponding to the number of the captured image is illustrated, thereby obtaining a scatter diagram as illustrated in  FIG. 10 . The number (order) of the captured image at the maximum intensity of the light can be estimated with accuracy smaller than 1 by fitting, for example, a Gaussian curve, a spline curve or a parabola to the obtained scatter diagram. In the example of  FIG. 10 , the intensity of light is estimated to be the maximum in a virtual 9.38th captured image located between the ninth and the tenth captured images using the curve indicated by a fitted dotted line. 
     The maximum intensity of the light can be estimated from the fitted curve. The height h in each portion of the measuring object S can be calculated based on the number of the captured image in which the intensity of the light estimated in each portion of the measuring object S becomes the maximum. According to this method, the three-dimensional shape of the measuring object S is measured based on the intensity of the light having a sufficiently large S/N (Signal/Noise) ratio. Therefore, shape measurement accuracy of the measuring object S can be improved. 
     A relative height (a relative value of the height) in each portion on the surface of the measuring object S is measured in the shape measurement of the measuring object S using the measurement light having a periodic pattern shape such as the sinusoidal measurement light, the striped measurement light and the like. This is attributed to the following fact. Each of a plurality of straight lines (stripes), which constitute the pattern while being parallel to the Y-direction, cannot be identified, and uncertainty corresponding to an integral multiple of one period (2π) of the plurality of straight lines exists. Therefore, an absolute phase cannot be obtained. For this reason, known unwrapping processing may be performed on data of the measured height on the assumption that a height in one portion of the measuring object S and a height in an adjacent portion change-continuously. 
     (5) Fourth Pattern of Measurement Light 
       FIGS. 11A to 11D  are views illustrating a fourth pattern of the measurement light. As illustrated in  FIGS. 11A to 11D , measurement light (hereinafter, referred to as code-like measurement light), which has the linear sections parallel to the Y-direction and in which the bright and dark portions are arrayed in the X-direction, is output from the light projecting unit  110  a plurality of times (in this example, four times) as the fourth pattern. Each of proportions of the bright and dark portions is 50% in the code-like measurement light. 
     The surface of the measuring object S is divided into a plurality of regions (in the example of  FIGS. 11A to 11D , 16 regions) in the X direction. Hereinafter, the plurality of divided regions of the measuring object S in the X direction are referred to as first to sixteenth regions. 
       FIG. 11A  illustrates the code-like measurement light output at the first time. The code-like measurement light output at the first time includes the bright portion with which the first to eighth regions of the measuring object S are irradiated. The coded measurement light output at the first time includes the dark portion with which the ninth to sixteenth regions of the measuring object S are irradiated. Therefore, in the code-like measurement light output at the first time, the bright and dark portions are parallel in the Y direction and are arrayed in the X direction. Each of the proportions of the bright and dark portions is 50% in the code-like measurement light output at the first time. 
       FIG. 11B  illustrates the code-like measurement light output at the second time. The code-like measurement light output at the second time includes the bright portion with which the fifth to twelfth regions of the measuring object S are irradiated. The code-like measurement light output at the second time includes the dark portions with which the first to fourth, and thirteenth to sixteenth regions of the measuring object S are irradiated. Therefore, in the code-like measurement light output at the second time, the bright and dark portions are parallel in the Y direction and are arrayed in the X direction. Each of the proportions of the bright and dark portions is 50% in the code-like measurement light output at the second time. 
       FIG. 11C  illustrates the code-like measurement light output at the third time. The code-like measurement light output at the third time includes the bright portions with which the first, second, seventh to tenth, fifteenth and sixteenth regions of the measuring object S are irradiated. The code-like measurement light output at the third time includes the dark portions with which the third to sixth, and eleventh to fourteenth regions of the measuring object S are irradiated. Thus, in the code-like measurement light output at the third time, the bright and dark portions are parallel in the Y direction and are arrayed in the X direction. Each of the proportions of the bright and dark portions is 50% in the code-like measurement light output at the third time. 
       FIG. 11D  illustrates the code-like measurement light output at the fourth time. The code-like measurement light output at the fourth time includes the bright portions with which the first, fourth, fifth, eighth, ninth, twelfth, thirteenth, and sixteenth regions of the measuring object S are irradiated. The code-like measurement light output at the fourth time includes the dark portions with which the second, third, sixth, seventh, tenth, eleventh, fourteenth, and fifteenth regions of the measuring object S are irradiated. Therefore, in the code-like measurement light output at the fourth time, the bright and dark portions are parallel in the Y direction and are arrayed in the X direction. Each of the proportions of the bright and dark portions is 50% in the code-like measurement light output at the fourth time. 
     A logic “1” is assigned to the bright portion of the code-like measurement light, and a logic “0” is assigned to the dark portion of the code-like measurement light. An alignment of the logics of the first- to fourth-time code-like measurement light with which each region of the measuring object S is irradiated is referred to as a code. In this case, the first region of the measuring object S is irradiated with the code-like measurement light of a code “1011”. Therefore, the first region of the measuring object S is coded into the code “1011”. 
     The second region of the measuring object S is irradiated with the code-like measurement light of a code “1010”. Therefore, the second region of the measuring object S is coded into the code “1010”. The third region of the measuring object S is irradiated with the code-like measurement light of a code “1000”. Therefore, the third region of the measuring object S is coded into the code “1000”. Similarly, the sixteenth region of the measuring object S is irradiated with the code-like measurement light of a code “0011”. Therefore, the sixteenth region of the measuring object S is coded into the code “0011”. 
     Thus, the measuring object S is irradiated with the code-like measurement light a plurality of times such that any one of digits of the code varies only by “1” between the adjacent regions of the measuring object S. That is, the measuring object S is irradiated with the coded measurement light a plurality of times such that the bright and dark portions change into a gray code-like pattern. 
     The light receiving unit  120  receives the light reflected by each region on the surface of the measuring object S. The code that changes due to the presence of the measuring object S is obtained in each region of the measuring object S by the measurement of the code of the received light. A difference between the obtained code and the code during the absence of the measuring object S is obtained in each region to calculate the distance corresponding to the distance d in  FIG. 6 . The absolute value of the distance d is calculated by the measurement method using the code-like measurement light, the measurement method using the code-like measurement light having a characteristic that the code appears only once in the X-axis direction of the image. Therefore, the absolute height (the absolute value of the height) of the region of the measuring object S is calculated. The three-dimensional shape of the measuring object S can be measured by the calculation of the heights of all the regions on the surface of the measuring object S. 
     In the above description, the surface of the measuring object S is divided into the 16 regions in the X direction, and the code-like measurement light is output from the light projecting unit  110  four times. However, the present invention is not limited thereto. Alternatively, the surface of the measuring object S may be divided into 2 N  regions (N is a natural number) in the X direction, and the code-like measurement light may be output from the light projecting unit  110  N times. In the above description, N is set to 4 for the sake of easy understanding. In the later-described data generation processing, for example, N is set to 8 in data generation processing. Accordingly, the surface of the measuring object S is divided into 256 regions in the X direction. 
     In the shape measurement of the measuring object S using the code-like measurement light, the distance in which the code-like measurement light can be separated and identified, that is, the distance corresponding to one pixel is the minimum resolution. Accordingly, when the light receiving unit  120  has the 1024-pixel visual field in the X direction, the measuring object S having the height of 10 mm can be measured with the resolution of 10 mm÷1024≈10 μm. By combining the shape measurement using the low-resolution code-like measurement light in which the absolute value can be calculated and the shape measurement using the high-resolution sinusoidal measurement light or stripe measurement light in which the absolute value cannot be calculated, the absolute value of the height of the measuring object S can be calculated with higher resolution. 
     Particularly, the resolution of 1/100 pixel can be attained in the shape measurement of the measuring object S using the stripe measurement light of  FIGS. 9A to 9C . The resolution of 1/100 pixel corresponds to the division of the surface of the measuring object S into about 100000 regions in the X direction (that is, N≈17) when the light receiving unit  120  has the 1024-pixel visual field in the X direction. Therefore, the absolute value of the height of the measuring object S can be calculated with higher resolution by the combination of the shape measurement using the code-like measurement light and the shape measurement using the stripe measurement light. 
     The method for scanning the measuring object S with the linear measurement light is generally referred to as a light section method. On the other hand, the method for irradiating the measuring object S with the sinusoidal measurement light, the stripe measurement light, or the code-like measurement light is classified into a pattern projection method. Among the pattern projection methods, the method for irradiating the measuring object S with the sinusoidal measurement light or the stripe measurement light is classified into the phase shift method, and the method for irradiating the measuring object S with the coded measurement light is classified into a space coding method. 
     In the phase shift, method, during the sinusoidal measurement light or stripe measurement light that is a periodic projection pattern, the height of the measuring object S is obtained from a phase difference between the phase, which is calculated based on the light reception amount reflected from a reference height position when the measuring object S is absent, and the phase, which is calculated based on the light reception amount reflected from the surface of the measuring object S when the measuring object S is present. In the phase shift method, the individual periodic stripes cannot be distinguished from each other, but the uncertainty corresponding to the integral multiple of one period of stripe (2π) exists. Therefore, there is a disadvantage that the absolute phase cannot be obtained. However, because fewer images are obtained compared to the light section method, there are advantages that the measurement time is relatively short and that the measurement resolution is high. 
     On the other hand, in the space coding method, the code changed due to the presence of the measuring object S is obtained in every region of the measuring object S. The absolute height of the measuring object S can be obtained by obtaining the difference between the obtained code and the code during the absence of the measuring object S in each region. In the space coding method, there is an advantage that the measurement can be performed using relatively few images to obtain the absolute height. However, there is a limitation to the measurement resolution compared to the phase shift method. 
     Although each of the projection methods has advantages and disadvantages, the projection methods are common in the use of the principle of triangular distance measuring method. The point cloud data representing the three-dimensional shape of the measuring object S is generated based on image data (hereinafter, referred to as pattern image data) of the measuring object S to which the measurement light having the above pattern is projected. 
     Hereinafter, the point cloud data representing the three-dimensional shape of the measuring object S is referred to as three-dimensional shape data. The three-dimensional shape data includes pieces of positional data at a plurality of points on the surface of the measuring object S. For example, the positional data represents coordinates in the X-direction, the Y-direction, and the Z-direction. Assuming that Pn (n is a natural number) is data at any point in the three-dimensional shape data, for example, Pn can be represented by (Xn,Yn,Zn) using a coordinate value of the device coordinate system. The three-dimensional shape data may be configured by surface information data generated based on the point cloud data, or include data in another format such as polygon mesh. An image (hereinafter, referred to as a three-dimensional shape image) representing the three-dimensional shape of the measuring object S can be displayed based on the three-dimensional shape data. 
     In the present embodiment, the three-dimensional shape image is an image indicating a state in which the three-dimensional shape data is projected onto any plane, in which a two-dimensional coordinate system is defined, and an image used to receive the user designation of the measurement point. The user can designate the plane onto which the three-dimensional shape data is projected as a direction (the position of the light receiving unit  120  with respect to the measuring object S) in which the user views the measuring object S. This enables the change in orientation of the measuring object S represented by the three-dimensional shape image. 
     (6) Offset Optical System 
     In the present embodiment, the telecentric optical system is used in the light projecting unit  110 , and the offset optical system is also used in the light projecting unit  110 .  FIGS. 12A and 12B  are views illustrating comparison between the offset optical system and a non-offset optical system. As used herein, the offset optical system means an optical system in which the center of the pattern generating unit  112  is offset from the optical axis of the lens  114 . The non-offset optical system means an optical system in which the center of the pattern generating unit  112  is disposed on the optical axis of the lens  114 . 
     The light projecting unit  110  having the offset optical system and the light receiving unit  120  are illustrated in an upper part of  FIG. 12A . An image, which is obtained when the light projecting unit  110  having the offset optical system outputs the stripe measurement light, is illustrated in a lower part of  FIG. 12A . The light projecting unit  110  having the non-offset optical system and the light receiving unit  120  are illustrated in the upper part of  FIG. 12B . An image, which is obtained when the light projecting unit  110  having the non-offset optical system outputs the stripe measurement light, is illustrated in the lower part of  FIG. 12B . 
     In the offset optical system, as illustrated in the upper part of  FIG. 12A , the light projecting unit  110  can irradiate the whole effective region MR 1  with the measurement light while an optical axis A 3  of the lens  114  is disposed in parallel to the optical axis A 1  of the light receiving unit  120 . Here, a projection plane of the measurement light is parallel to an observation plane perpendicular to the optical axis A 1  of the light receiving unit  120 . Therefore, as illustrated in the lower part of  FIG. 12A , the pattern of the measurement light becomes substantially uniform in the effective region MR 1 . Specifically, widths (an interval between the dark portions) of the plurality of bright portions of the measurement light become uniform, and widths (an interval between the bright portions) of the plurality of dark portions of the measurement light become uniform. 
     With this disposition, the irradiation region of the measurement light is easily matched with the effective region MR 1 . Therefore, the effective region MR 1  can easily be enlarged. Additionally, the whole light projecting unit  110  is disposed in parallel to the light receiving unit  120 , so that the head unit  190  can be miniaturized. 
     On the other hand, in the non-offset optical system, as illustrated in the upper part of  FIG. 12B , it is necessary that the optical axis A 3  of the lens  114  be disposed oblique to the optical axis A 1  of the light receiving unit  120  in order that the light projecting unit  110  irradiates the whole effective region MR 1  with the measurement light. In this case, the projection plane of the measurement light is oblique to the observation plane perpendicular to the optical axis A 1  of the light receiving unit  120 . Therefore, as illustrated in the lower part of  FIG. 12A , the pattern of the measurement light becomes nonuniform in the effective region MR 1 . Specifically, on the observation plane of the light receiving unit  120 , with increasing distance from the light projecting unit  110 , the width (the interval between the dark portions) of the bright portion of the measurement light increases, and the width (the interval between the bright portions) of the dark portion of measurement light increases. The irradiation region of the measurement light increases excessively relative to the effective region MR 1 . For these reasons, preferably, the offset optical system is used in the light projecting unit  110 . 
     (7) Synthesis of a Plurality of Pieces of Three-Dimensional Shape Data 
     When the position and attitude of the measuring object S are kept constant with respect to the light projecting unit  110  and the light receiving unit  120 , only a part of the measuring object S is irradiated with the measurement light. Only the light reflected partially by the measuring object S is incident on the light receiving unit  120 . Therefore, the three-dimensional shape data cannot be obtained in the wide range of the surface of the measuring object S. The image of the measuring object S is captured from a plurality of directions different from each other while the position and attitude of the measuring object S are changed, a plurality of pieces of three-dimensional shape data corresponding to the plurality of imaging directions are obtained, and the obtained plurality of pieces of three-dimensional shape data may be synthesized. 
       FIGS. 13A to 13F  are views illustrating an example in which the plurality of pieces of three-dimensional shape data are generated by capturing the image of the measuring object S from a plurality of directions. For example, as illustrated in  FIG. 13A , after the user adjusts the position and attitude of the measuring object S on the stage  140 , the image of the measuring object S is captured using the measurement light, whereby the initial three-dimensional shape data is generated.  FIG. 13D  illustrates an example of the obtained three-dimensional shape image. The three-dimensional shape data is generated based on the measurement light, which is incident on the light receiving unit  120  after being reflected by the surface of the measuring object S. Therefore, on the surface of the measuring object S, the three-dimensional shape data is generated in a portion, which is visible from the position of the light receiving unit  120 , but the three-dimensional shape data cannot be generated in a portion, which is invisible from the position of the light receiving unit  120 . 
     As illustrated in  FIG. 13B , after the rotation mechanism  143  in  FIG. 2  rotates the stage  140  by a given angle, the image of the measuring object S is captured using the measurement light, whereby the second three-dimensional shape data is generated. In the example of  FIG. 13B , the stage  140  is rotated counterclockwise by about 45 degrees from the state in  FIG. 13A  when seen from above.  FIG. 13E  illustrates an example of the obtained three-dimensional shape image. When the stage  140  is rotated as described above, the portion visible from the position of the light receiving unit  120  and the portion invisible from the position of the light receiving unit  120  on the surface of the measuring object S also change according to the rotation of the stage  140 . As a result, the three-dimensional shape data including a portion that is not obtained during the initial imaging is generated. 
     As illustrated in  FIG. 13C , after the rotation mechanism  143  in  FIG. 2  rotates the stage  140  by a given angle, the image of the measuring object S is captured using the measurement light, whereby the third three-dimensional shape data is generated. In the example of  FIG. 13C , the stage  140  is rotated counterclockwise by about 45 degrees from the state in  FIG. 13B  when the stage  140  is seen from above.  FIG. 13F  illustrates an example of the obtained three-dimensional shape image. 
     The plurality of pieces of three-dimensional shape data corresponding to the plurality of imaging directions are generated by the repetition of the rotation of the stage  140  and the imaging of the measuring object S. 
     During the plurality of times of imaging, the CPU  210  in  FIG. 1  detects a rotation position (rotation angle) of the stage  140 . The positional relationship among the two light projecting units  110 , the two light receiving units  120 , and the rotation axis Ax of the stage  140  is kept constant. For example, a parameter (hereinafter, referred to as a device parameter) representing the relative position is stored in the storage device  240  of  FIG. 1 . For example, the device parameter is represented by the device coordinate system. 
     In this case, based on the device parameter and the rotation position of the stage  140 , each of the plurality of pieces of three-dimensional shape data can be coordinate-transformed such that the positional data included in each piece of three-dimensional shape data is represented by a virtually common three-dimensional coordinate system based on a part of the stage  140 . 
     In this example, as described above, the plurality of pieces of three-dimensional shape data are coordinate-transformed so as to be represented by the common three-dimensional coordinate system, and the coordinate-transformed plurality of pieces of three-dimensional shape data are synthesized by pattern matching performed on the overlapping portion. Therefore, the three-dimensional shape data is generated in the wide range of the outer surface of the measuring object S. 
     [3] Texture Image Data Representing Appearance of Measuring Object 
     In the measuring unit  100 , image data (hereinafter, referred to as texture image data) representing an appearance (surface state) of the measuring object S is generated while the illumination light output unit  130  irradiates the measuring object S with the illumination light or while the light projecting units  110 A,  110 B irradiate the measuring object S with uniform measurement light. The uniform measurement light means measurement light having no pattern, and can be used instead of the illumination light. Hereinafter, such measurement light is referred to as uniform measurement light. For example, the surface state of the measuring object S includes a pattern and a hue. Hereinafter, an image represented by the texture image data is referred to as a texture image. 
     Various examples of the texture image data will be described below. For example, the plurality of pieces of texture image data may be obtained while a focal position of the light receiving unit  120  is changed with respect to the measuring object S. In this case, the texture image data (hereinafter referred to as all-focus texture image data) focused on the whole surface of the measuring object S is generated by the synthesis of the plurality of pieces of texture image data. In the case where the all-focus texture image data is generated, it is necessary to provide a focus moving mechanism that moves the focal position of the light receiving unit  120  in the measuring unit  100 . 
     The plurality of pieces of texture image data may be obtained on a plurality of different imaging conditions. For example, the imaging conditions include the exposure time of the light receiving unit  120 , the intensity (brightness) of the illumination light from the illumination light output unit  130 , and the intensity (brightness) of the uniform measurement light from the light projecting unit  110 . In this case, by performing known High-Dynamic Range (HDR) synthesis using the obtained plurality of pieces of texture image data, the texture image data (hereinafter, referred to as HDR texture image data) in which underexposure and overexposure are suppressed is generated. 
     The imaging condition may be changed while the focal position is changed. Specifically, the texture image data is obtained on the plurality of different imaging conditions at each position while the focus of the light receiving unit  120  is changed to a plurality of positions with respect to the measuring object S. The texture image data, which is focused on the whole surface of the measuring object S and in which the underexposure and the overexposure are suppressed, is generated by the synthesis of the obtained plurality of pieces of texture image data. 
     Each piece of texture image data includes texture information (information representing optical surface state) representing color or luminance at each point of the measuring object S. On the other hand, the three-dimensional shape data does not include the information about the optical surface state of the measuring object S. Therefore, textured three-dimensional shape data in which texture information is provided to the three-dimensional shape data is generated by the synthesis of the three-dimensional shape data and any one of the pieces of texture image data. 
     The textured three-dimensional shape data includes both positional data at each of a plurality of points on the surface of the measuring object S and data indicating the color or luminance of the point correlated with the positional data at each point. In this case, assuming that TPn (n is a natural number) is data indicating any point in the textured three-dimensional shape data, for example, TPn can be represented by (Xn,Yn,Zn,Rn,Gn,Bn) using a coordinate value of the device coordinate system and red, green, and blue components (R,G,B) of three primary colors. Alternatively, for example, TPn can be represented by (Xn,Yn,Zn,In) using a coordinate value of the device coordinate system and luminance value (I). The textured three-dimensional shape data may be configured by surface information data that is generated based on the point cloud data. 
     Hereinafter, the texture image represented by the texture image data obtained by the constant focal position and imaging condition is referred to as a normal texture image, an image represented by the all-focus texture image data is referred to as an all-focus texture image, and an image represented by the HDR texture image data is referred to as an HDR texture image. The image represented by the textured three-dimensional shape data is referred to as a textured three-dimensional shape image. 
     In the present embodiment, the textured three-dimensional shape image is an image indicating the state in which the textured three-dimensional shape data is projected onto any plane, in which the two-dimensional coordinate system is defined, and an image used to receive the user designation of the measurement point. The user can designate the plane onto which the textured three-dimensional shape data is projected as a direction (the position of the light receiving unit  120  with respect to the measuring object S) in which the user views the measuring object S. This enables the change in orientation of the measuring object S represented by the textured three-dimensional shape image. 
     As described above, the image of the measuring object S is captured using the illumination light or the uniform measurement light in order to generate the texture image data. Here, as described above, the illumination light output unit  130  includes the illumination light output port  131  that is formed into the elliptical shape so as to surround the two light receiving units  120 . With such a configuration, the measuring object S is irradiated with at least part of the illumination light output from the output port  131  in a state where the illumination light is substantially parallel to the optical axis of the light receiving unit  120 . Even if the imaging is performed with any one of the light receiving units  120 , a shadow component is hardly generated in the generated texture image data when the illumination light is used. Preferably, the illumination light is used during the generation of the texture image data. 
     As illustrated in the example of  FIGS. 13A to 13F , in the case where the plurality of pieces of three-dimensional shape data are generated by the imaging of the measuring object S from the plurality of directions, the imaging may be performed using the illumination light or uniform measurement light together with the imaging performed using the measurement light. In this case, the plurality of pieces of texture image data corresponding to the plurality of pieces of three-dimensional shape data can be generated. Accordingly, the textured three-dimensional shape data representing the three-dimensional shape and surface state can be generated in the wide range of the outer surface of the measuring object S by the synthesis of the plurality of pieces of three-dimensional shape data and the plurality of pieces of texture image data. 
     [4] Shape Measurement 
     (1) Preparation for Shape Measurement 
     The user prepares the shape measurement before measuring the measuring object S.  FIG. 14  is a flowchart illustrating a procedure for preparing the shape measurement. The procedure for preparing the shape measurement will be described below with reference to  FIGS. 1, 2, and 14 . The user firstly places the measuring object S on the stage  140  (step S 1 ). Then, the user irradiates the measuring object S with the measurement light using the light projecting unit  110  (step S 2 ). At this time, the live image of the measuring object S is displayed on the display unit  400 . Subsequently, the user adjusts the brightness of the obtained live image and the position and attitude of the measuring object S (hereinafter, referred to as first adjustment) while viewing the live image displayed on the display unit  400  (step S 3 ). 
     The live image brightness obtained in step S 3  can be adjusted by the change of at least one of the measurement light amount and the exposure time of the light receiving unit  120 . In the present embodiment, one of the measurement light amount and the exposure time of the light receiving unit  120  is adjusted in order to set the brightness of the live image obtained using the measurement light to the brightness suitable for the observation. Preferably, the brightness of the obtained live image is adjusted by the exposure time of the light receiving unit  120  while the measurement light amount is kept constant. This enables the suppression of measurement accuracy degradation, which is caused by a temperature change of the measurement light source  111  in association with the change of the measurement light amount. 
     In step S 2 , the measuring object S may be irradiated with the measurement light having any one of the first to fourth patterns, or the measuring object S may be irradiated with the uniform measurement light. In step S 3 , when the shadow is not generated at the point to be measured (hereinafter, referred to as a measurement point) in the measuring object S, the user does not need to adjust the position and attitude of the measuring object S, but only needs to adjust the measurement light amount or the exposure time of the light receiving unit  120 . 
     The user then stops the irradiation of the measurement light, and irradiates the measuring object S with the illumination light from the illumination light output unit  130  (step S 4 ). Here, the live image of the measuring object S is displayed on the display unit  400 . Subsequently, the user adjusts the brightness of the obtained live image (hereinafter, referred to as second adjustment) while viewing the live image displayed on the display unit  400  (step S 5 ). 
     Basically, similarly to the example in step S 3 , the live image brightness obtained in step S 5  can be adjusted by the change of at least one of the illumination light amount and the exposure time of the light receiving unit  120 . In the present embodiment, one of the illumination light amount and the exposure time of the light receiving unit  120  is adjusted in order to set the brightness of the live image obtained using the illumination light to the brightness suitable for the observation. 
     The user then checks the live image displayed on the display unit  400 , and determines whether the light amount, the exposure time of the light receiving unit  120 , and the position and attitude of the measuring object S (hereinafter referred to as an observation state) are appropriate (step S 6 ). In step S 6 , the measuring object S may be irradiated with the measurement light or the illumination light, or sequentially be irradiated with the measurement light and the illumination light. 
     When the observation state is determined to be inappropriate in step S 6 , the user returns to the processing in step S 2 . On the other hand, when the observation state is determined to be appropriate in step S 6 , the user ends the preparation for the shape measurement. 
     In the above description, the second adjustment is performed after the first adjustment. However, the present invention is not limited thereto. Alternatively, the first adjustment may be performed after the second adjustment. In this case, the user may adjust the position and attitude of the measuring object S in the second adjustment, and check whether the desired portion of the measuring object S is irradiated with the measurement light during the first adjustment. When the desired portion of the measuring object S is not irradiated with the measurement light, the position and attitude of the measuring object S may be adjusted again, and the illumination light amount or the exposure time of the light receiving unit  120  may be adjusted again as the second adjustment. 
     (2) First Adjustment 
       FIGS. 15 and 16  are flowcharts illustrating details of the first adjustment in the procedure for preparing the shape measurement. The details of the first adjustment in the procedure for preparing the shape measurement will be described below with reference to  FIGS. 1, 2, 15, and 16 . Hereinafter, the measurement light output from one of the light projecting units  110 A,  110 B is referred to as one piece of measurement light, and the measurement light output from the other of the light projecting units  110 A,  110 B is referred to as the other piece of measurement light. In the measuring unit  100 , amounts of one and the other pieces of measurement light can independently be set. The exposure time of the light receiving unit  120  when the image of the measuring object S is captured using one piece of measurement light, and the exposure time of the light receiving unit  120  when the image of the measuring object S is captured using the other piece of measurement light can independently be set. 
     First, the user temporarily adjusts the amount of one piece of measurement light and the exposure time of the light receiving unit  120  in order to set the brightness of the obtained live image to the brightness suitable for the observation (step S 11 ). The user then adjusts the magnification (hereinafter, referred to as a visual field size) of the live image of the measuring object S displayed on the display unit  400  (step S 12 ). Specifically, the user selects one of the light receiving unit  120 A having the low-magnification lens  122  and the light receiving unit  120 B having the high-magnification lens  122  as the light receiving unit  120  used in the measurement of the measuring object S. Therefore, the live image obtained by the selected light receiving unit is displayed on the display unit  400 . The visual field size in the selection of the low-magnification light receiving unit  120 A is larger than the visual field size in the selection of the high-magnification light receiving unit  120 B. The measuring unit  100  may have a digital zoom function. In this case, the user can select one of the two light receiving units  120 A,  120 B, and adjust display magnification of the live image obtained by the selected light receiving unit  120 . 
     The user then determines whether the position and attitude of the measuring object S are appropriate based on the live image of the measuring object S displayed on the display unit  400  (step S 13 ). When the shadow is not generated at the measurement point of the measuring object S, the user determines that the position and attitude of the measuring object S are appropriate. On the other hand, when the shadow is generated at the measurement point of the measuring object S, the user determines that the position and the attitude of the measuring object S are inappropriate. 
     When the position and attitude of the measuring object S are determined to be inappropriate in step S 13 , the user adjusts the position and attitude of the measuring object S (step S 14 ). Specifically, the user adjusts the position and attitude of the measuring object S by rotating the stage  140  with the rotation mechanism  143  or manually moving the measuring object S. Then, the user returns to the processing in step S 13 . 
     On the other hand, when the position and attitude of the measuring object S are determined to be appropriate in step S 13 , the user determines whether the brightness of the obtained live image is the brightness suitable for the observation, that is, whether the amount of one piece of measurement light with which the measuring object S is irradiated or the exposure time of the light receiving unit  120  is appropriate based on the live image of the measuring object S displayed on the display unit  400  (step S 15 ). 
     When the amount of one piece of measurement light is determined to be inappropriate in step S 15 , the user adjusts the amount of one piece of measurement light or the exposure time of the light receiving unit  120  (step S 16 ). Then, the user returns to the processing in step S 15 . 
     On the other hand, when the amount of one piece of measurement light or the exposure time of the light receiving unit  120  is determined to be appropriate in step S 15 , the user determines whether the observation state is appropriate from the live image of the measuring object S displayed on the display unit  400  (step S 17 ). When the observation state is determined to be inappropriate in step S 17 , the user returns to the processing in step S 14  or S 16 . Specifically, the user returns to the processing in step S 14  when the position and attitude of the measuring object S are determined to be inappropriate in the observation state. The user returns to the processing in step S 16  when the amount of light (one piece of measurement light) or the exposure light of the light receiving unit  120  is determined to be inappropriate in the observation state. 
     On the other hand, when the observation state is determined to be appropriate in step S 17 , the user stops the irradiation of one piece of measurement light and irradiates the measuring object S with the measurement light from the other light projecting unit  110 B (step S 18 ). Therefore, the live image of the measuring object S is displayed on the display unit  400 . Subsequently, in order to set the brightness of the obtained live image to the brightness suitable for the observation, the user adjusts the amount of the other piece of measurement light or the exposure time of the light receiving unit  120  while viewing the live image of the measuring object S displayed on the display unit  400  (step S 19 ). 
     Then, based on the live image of the measuring object S displayed on the display unit  400 , the user determines whether the brightness of the obtained live image is suitable for the observation, that is, whether the amount of the other piece of measurement light or the exposure time of the light receiving unit  120  is appropriate (step S 20 ). The user returns to the processing in step S 19  when the amount of the other piece of measurement light or the exposure time of the light receiving unit  120  is determined to be inappropriate in step S 20 . On the other hand, when the amount of the other piece of measurement light or the exposure time of the light receiving unit  120  is determined to be appropriate in step S 20 , the user ends the first adjustment. The light amount condition of one and the other pieces of measurement light optimal for the generation of the three-dimensional shape data or the exposure time condition of the light receiving unit  120  corresponding to each of one and the other pieces of measurement light is set by performing the first adjustment. In the case where the other light projecting unit  110 B is not used, the user may omit the procedure in steps S 18  to S 20  and end the first adjustment after the processing in step S 17 . 
     (3) Second Adjustment 
       FIG. 17  is a flowchart illustrating details of the second adjustment in the procedure for preparing the shape measurement. The details of the second adjustment in the procedure for preparing the shape measurement will be described below with reference to  FIGS. 1, 2, and 17 . In the measuring unit  100  according to the present embodiment, the illumination light amount can be set independently of the amounts of one and the other pieces of measurement light. The exposure time of the light receiving unit  120  in capturing the image of the measuring object S using the illumination light can beset independently of the exposure time of the light receiving unit  120  in capturing the image of the measuring object S using one and the other pieces of measurement light. 
     The user firstly adjusts the illumination light amount or the exposure time of the light receiving unit  120  in order to set the brightness of the obtained live image to the brightness suitable for the observation (step S 31 ). Based on the live image of the measuring object S displayed on the display unit  400 , the user then determines whether the brightness of the obtained live image is suitable for the observation, that is, whether the illumination light amount with which the measuring object S is irradiated or the exposure time of the light receiving unit  120  is appropriate (step S 32 ). 
     The user returns to the processing in step S 31  when the illumination light amount or the exposure time of the light receiving unit  120  is determined to be inappropriate in step S 32 . On the other hand, when the illumination light amount or the exposure time of the light receiving unit  120  is determined to be appropriate in step S 32 , the user selects a type of the texture image to be obtained (step S 33 ), and ends the second adjustment. For example, the type of the texture image includes the normal texture image, the all-focus texture image, and the HDR texture image. The light amount condition of the illumination light optimal for the generation of the texture image data or the exposure time of the light receiving unit  120  corresponding to the illumination light is set by performing the second adjustment. 
     When the all-focus textured image or the HDR texture image is selected in step S 33 , another setting may be performed in order to appropriately obtain the all-focus texture image data or the HDR texture image data. For example, a change range of the focal position may be set when the all-focus texture image is selected. For example, a change range of the imaging condition may be set when the HDR texture image data is selected. Based on these settings, the all-focus texture image or the HDR texture image may be displayed on the display unit  400  for the purpose of pre-view. 
     (4) Data Generation Processing 
     After the user prepares the shape measurement in  FIG. 14 , the data generation processing is performed in order to generate the three-dimensional shape data and textured three-dimensional shape data of the measuring object S. The data generation processing is performed based on a data generating condition set previously by the user. The data generating condition is previously stored in the storage device  240  in  FIG. 1  before the data generation processing is performed. The data generating condition includes information about the three-dimensional shape data that should be generated through the data generation processing. 
     For example, as illustrated in the example of  FIGS. 13A to 13F , in the case where one piece of three-dimensional shape data is generated by the synthesis of the plurality of pieces of three-dimensional shape data obtained by the imaging from the plurality of directions, it is necessary to rotate the stage  140  (see  FIG. 2 ) in order to generate the plurality of pieces of three-dimensional shape data. Therefore, the user sets the rotation position of the stage  140  at each imaging time, the rotation direction of the stage  140 , and the number of imaging times as the generating condition. 
     More specifically, in planar view, the user rotates the stage plate  142  clockwise by each 120 degrees in the range of 0 degrees to 360 degrees to perform the imaging at positions of 0 degrees, 120 degrees, and 240 degrees. Alternatively, in planar view, the user rotates the stage plate  142  counterclockwise by each 60 degrees in the range of 120 degrees to 300 degrees to perform the imaging at positions of 120 degrees, 180 degrees, 240 degrees, and 300 degrees. 
     During the setting of the generating condition, a user interface may be displayed on a screen of the display unit  400 , for example, in order to input or designate a rotation start position, a rotation end position, a rotation direction, and rotation pitch angle of the stage plate  142 . In the user interface, a user interface may be displayed in order to input or designate a rotation passing position in addition to or instead of the rotation direction. Therefore, the user can easily set the generating condition by operating the user interface using the operation unit  250  in  FIG. 1 . 
       FIG. 18  is a flowchart illustrating data generation processing. The CPU  210  in  FIG. 1  performs the data generating program stored in the storage device  240  of  FIG. 1  in response to the instruction to start the data generation processing from the user. 
     The CPU  210  firstly irradiates the measuring object S with the measurement light from the light projecting unit  110  according to the light amount condition set in the first adjustment, and obtains image data (pattern image data) of the measuring object S in which the pattern of the measurement light is projected onto the measuring object S (step S 41 ). The obtained pattern image data is stored in the working memory  230 . 
     The CPU  210  then processes the obtained pattern image data using a predetermined algorithm to generate the three-dimensional shape data indicating the three-dimensional shape of the measuring object S (step S 42 ). The generated three-dimensional shape data is stored in the working memory  230 . 
     The CPU  210  then obtains the texture image data corresponding to the type of the texture image selected in step S 33  of  FIG. 17  (step S 43 ). The obtained texture image data is stored in the working memory  230 . 
     The CPU  210  then generates the textured three-dimensional shape data by the synthesis of the three-dimensional shape data generated in step S 42  and the texture image data obtained in step S 43  (step S 44 ). 
     Based on the previously-set generating condition, the CPU  210  then determines whether the imaging is performed on the whole measuring object S (step S 45 ). When the imaging is not performed on the whole measuring object S, the CPU  210  rotates the stage  140  (see  FIG. 2 ) by a predetermined pitch based on the generating condition (step S 46 ), and returns to the processing in step S 41 . 
     When the imaging is performed on the whole measuring object S in step S 45 , the CPU  210  performs synthesis of the plurality of pieces of three-dimensional shape data generated by the plural repetition of the processing in step S 42 , and performs synthesis of the plurality of pieces of textured three-dimensional shape data generated by the plural repetition of the processing in step S 44  (step S 47 ). In the case where the pieces of processing in steps S 41  to S 45  are performed only once, the processing in step S 47  is omitted. Thus, the three-dimensional shape data and textured three-dimensional shape data, which are used to measure the measuring object S, are generated. 
     Then, based on the generated three-dimensional shape data or textured three-dimensional shape data, the CPU  210  displays the three-dimensional shape image or textured three-dimensional shape image of the measuring object S on the display unit  400  (step S 48 ). 
     In step S 48 , the user can appropriately select one of the three-dimensional shape image and the textured three-dimensional shape image as the image to be displayed on the display unit  400 . When the measurement point of the measuring object S is not appropriately displayed in step S 45 , the user may perform the first adjustment in  FIGS. 15 and 16  again. 
     In the data generation processing, the point cloud data generating unit  501  in  FIG. 3  mainly performs the pieces of processing in steps S 41  to S 45 , S 47 , and S 48 , and the rotation control unit  506  in  FIG. 3  mainly performs the processing in step S 46 . 
     (5) Measurement of Measuring Object 
     Various types of measurement are performed on the measuring object S based on the three-dimensional shape data or textured three-dimensional shape data, which is generated through the data generation processing in  FIG. 18 , and a measurement condition set by the user. The measurement condition includes a measurement point and a measurement item. Details of the measurement point and measurement item will be described later. 
     During the setting of the measurement condition, for example, the textured three-dimensional shape image is displayed on the display unit  400  based on the textured three-dimensional shape data generated through the previous data generation processing. The user can operate the operation unit  250  in  FIG. 1  to designate the direction (the position of the light receiving unit  120  with respect to the measuring object  5 ) in which the user views the measuring object S. 
     In response to the user designation of the direction, the CPU  210  in  FIG. 1  displays the textured three-dimensional shape image in which the orientation of the observation object S on the display unit  400  is adjusted such that the state in which the measuring object S is seen from the designated direction is reproduced. In this state, the user operates the operation unit  250  in  FIG. 1  while visually recognizing the textured three-dimensional shape image, thereby setting the measurement condition on the screen of the display unit  400 . 
       FIG. 19  is a perspective view illustrating an example of the measuring object S, and  FIG. 20  is a view illustrating an example of the textured three-dimensional shape image obtained through the data generation processing performed on the measuring object S in  FIG. 19 . As illustrated in  FIG. 19 , the measuring object S in this example includes a board B 1  and elements B 2 , B 3  mounted on the board B 1 . 
     As illustrated in  FIGS. 4 and 5 , the light receiving unit  120 A that captures the image of the measuring object S is positioned such that the imaging visual field TR 1  includes at least the placement surface of the stage  140  and a space surrounding the placement surface. Therefore, in the data generation processing, the measurement light reflected at a position other than the measuring object S is incident on the light receiving unit  120 A. In this case, as illustrated in  FIG. 20 , the textured three-dimensional shape image obtained through the data generation processing includes an image illustrating many members existing in the imaging visual field TR 1  (see  FIGS. 4 and 5 ) of the light receiving unit  120 A. 
     Specifically, the textured three-dimensional shape image of  FIG. 20  includes an image  1401  of the stage  140  in  FIG. 2 , an image  1601  of the coupling member  160  in  FIG. 3 , an image TI of a table on which the measuring unit  100  in  FIG. 3  is placed, and an image PI of a pencil placed on the table together with an image SI of the measuring object S. The point cloud data representing the images  1401 ,  1601 , TI, and PI corresponds to the ineffective region displaced from the effective regions MR 1 , MR 2  (see  FIG. 5 ), and is basically unnecessary for the measurement of the measuring object S. 
     When many unnecessary pieces of point cloud data are present in the measurement of the measuring object S, there is a possibility that the user mistakenly sets the measurement condition. There is also a possibility that an unnecessarily large load is applied during calculation processing or display processing in the measurement. Therefore, in the measuring device  500  according to the present embodiment, the user can select the obtainment of only the point cloud data corresponding to the effective region from the three-dimensional shape data generated through the data generation processing or the obtainment of the point cloud data corresponding to the effective region and the point cloud data corresponding to the ineffective region as the measurement data. In this case, the CPU  210  in  FIG. 1  obtains the measurement data from the three-dimensional shape data generated through the data generation processing according to the user selection. 
     The user can also designate the region to be removed from the region corresponding to the obtained measurement data. In this case, the CPU  210  in  FIG. 1  removes the point cloud data corresponding to the designated region in the obtained measurement data in response to the user designation, thereby correcting the measurement data. 
       FIG. 21  is a view illustrating an example of the textured three-dimensional shape image representing only a portion corresponding to the effective region in the textured three-dimensional shape image in  FIG. 20 . For example, the user selects the obtainment of the point cloud data corresponding to the effective region as the measurement data in the state where the textured three-dimensional shape image in  FIG. 20  is displayed on the display unit  400 . Therefore, the CPU  210  in  FIG. 1  removes the point cloud data corresponding to the ineffective region from the three-dimensional shape data corresponding to the example in  FIG. 19 , and uses the remaining point cloud data as the measurement data. 
     In the textured three-dimensional shape image of  FIG. 21 , the portion other than the placement surface in the image  1401  of the stage  140 , the image  1601  of the coupling member  160 , the image TI of the table, and the image PI of the pencil are removed from the textured three-dimensional shape image in  FIG. 20 . 
     In the case where the user considers that the image  1401  of the stage  140  is also unnecessary in the textured three-dimensional shape image of  FIG. 21 , the user designates the unnecessary portion on the screen of the display unit  400 , thereby designating the region to be removed from the region corresponding to the measurement data. 
       FIG. 22  is a view illustrating an example of a method for designating the region to be removed. As illustrated in  FIG. 22 , for example, in the state where the textured three-dimensional shape image including the measuring object S and the placement surface of the stage  140  are displayed on the display unit  400 , the user designates the plurality of portions on the textured three-dimensional shape image while moving a pointer P displayed together with the textured three-dimensional shape image, which allows the user to designate the region to be removed. In the example of  FIG. 22 , the region corresponding to the portion surrounded by an alternate long and dash line by the pointer P in the textured three-dimensional shape image is designated as the region to be removed. Therefore, the point cloud data corresponding to the designated region is removed from the three-dimensional shape data corresponding to the textured three-dimensional shape image in  FIG. 22 . 
       FIG. 23  is a view illustrating an example of the textured three-dimensional shape image in which the portion corresponding to the designated region is removed from the textured three-dimensional shape image in  FIG. 22 . The user checks the textured three-dimensional shape image displayed on the display unit  400  to determine that the region to be removed does not exist, and then sets the measurement condition. At this time, the three-dimensional shape data corresponding to the textured three-dimensional shape image displayed on the display unit  400  becomes the measurement data. 
     In the textured three-dimensional shape image of  FIG. 23 , the user can clearly distinguish the images B 1 I, B 2 I, B 3 I of the board B 1 , element B 2 , and element B 3  from one another in the image SI of the measuring object S. 
     The user designates the measurement point on the textured three-dimensional shape image while roughly recognizing the shape of each portion of the measuring object S. At this time, in order to specify the measurement point, the user can designate a geometric shape (such as a point, a straight line, a circle, a surface, a sphere, a cylinder, and a cone) including the measurement point. The user can designate the measurement item with respect to the designated geometric shape. The measurement item is the type of the parameter to be measured at the measurement point designated by the user in the measuring object S, and includes a distance, a height, a diameter, an area and the like. 
       FIGS. 24 to 26  are views illustrating a setting example of the measurement condition in measuring the distance between the top surface of the board B 1  and the top surface of the element B 2  in  FIG. 19 . For example, as illustrated in  FIG. 24 , the user operates the pointer P displayed on the screen of the display unit  400  to designate the portion, in the image B 2 I, corresponding to the top surface of the element B 2  as the measurement point. Then, as illustrated in  FIG. 25 , the user operates the pointer P to designate the portion, in the image B 1 I, corresponding to the top surface of the board B 1  as the measurement point. 
     Preferably, during the setting of the measurement condition, the measurement point designated by the user is displayed in a mode different from other portions. The measurement point designated by the user is hatched in the examples of  FIGS. 24 and 25 . Therefore, the user can easily identify the measurement point designated by the user. 
     Subsequently, the user designates a distance between the two measurement points (plane) designated as the measurement item. Therefore, the distance between the top surface of the board B 1  and the top surface of the element B 2  is calculated based on the point cloud data corresponding to the top surface of the board B 1  and the point cloud data corresponding to the top surface of the element B 2 . As a result, as illustrated in  FIG. 26 , a calculation result is displayed on the textured three-dimensional shape image as a measurement result. In the example of  FIG. 26 , “zz (mm)” is displayed as the distance between the top surface of the board B 1  and the top surface of the element B 2 . 
       FIG. 27  is a flowchart illustrating measurement processing. The CPU  210  in  FIG. 1  performs the measurement program stored in the storage device  240  in  FIG. 1  in response to the instruction to start the setting of the measurement condition from the user. 
     The CPU  210  firstly reads the three-dimensional shape data of the measuring object S from the storage device  240  (step S 51 ). At this time, the user may designate the desired three-dimensional shape data as a reading target from one or a plurality of pieces of three-dimensional shape data stored in the storage device  240 . In this case, the CPU  210  reads the three-dimensional shape data designated by the user from the storage device  240 . 
     The CPU  210  then performs measurement data generation processing of generating the measurement data based on the user operation of the operation unit  250  in  FIG. 1  and the region information previously stored in the storage device  240  (step S 52 ). Details of the measurement data generation processing will be described later. 
     The CPU  210  then displays the three-dimensional shape image of the measuring object S corresponding to the measurement data generated through the measurement data generation processing on the display unit  400  (step S 53 ). At this time, the CPU  210  adjusts the orientation, size, or attitude of the three-dimensional shape image of the measuring object S according to the user designation of the direction. 
     The CPU  210  then receives the user setting of the measurement condition (step S 54 ). Specifically, when the user operates the operation unit  250  in  FIG. 1 , the CPU  210  receives the information about the measurement point and measurement item, which are designated as illustrated in  FIG. 24  to  FIG. 26 , and stores the received information in the storage device  240  in  FIG. 1 . 
     The CPU  210  then calculates the measurement value corresponding to the set measurement condition based on the measurement data, and displays the calculated measurement value on the display unit  400  (step S 55 ). 
     In the present embodiment, the user operates the operation unit  250  in  FIG. 1  to be able to issue an instruction to the CPU  210  to complete the measurement. After the processing in step S 55 , the CPU  210  determines whether the user issues the instruction to complete the measurement (step S 56 ). When the user does not issue the instruction to complete the measurement, the CPU  210  returns to the processing in step S 54 . On the other hand, when the user issues the instruction to complete the measurement, the measurement processing is ended. 
     After the end of the measurement processing, the CPU  210  may store one or a plurality of measurement values obtained through the previously-performed measurement processing in the storage device  240  in FIG.  1  as a data file with a predetermined format. At this time, the CPU  210  may decide a name of the data file stored in the storage device  240  in response to the user designation of a file name. In the case where a printing device is connected to the PC  200  as an external device of the measuring device  500 , the CPU  210  may control the printing device to print on paper the obtained one or a plurality of measurement values in a report format. 
     In step S 51 , the CPU  210  may read the textured three-dimensional shape data of the measuring object S instead of the three-dimensional shape data of the measuring object S. In this case, the CPU  210  displays the textured three-dimensional shape image of the measuring object S corresponding to the measurement data on the display unit  400  in step S 53 . In the measuring device  500 , the user can select the type of the data to be read during the measurement processing. In this case, one of the three-dimensional shape data and the textured three-dimensional shape data, which is selected by the user, is read in step S 51 . 
     Details of the measurement data generation processing will be described below.  FIG. 28  is a flowchart illustrating the measurement data generation processing performed in step S 52  of  FIG. 27 . As illustrated in  FIG. 28 , the CPU  210  displays the three-dimensional shape image on the display unit  400  based on the three-dimensional shape data read in step S 51  of  FIG. 27  (step S 61 ). 
     Then, based on the user operation of the operation unit  250 , the CPU  210  determines whether the obtainment of the point cloud data corresponding to the effective region from the three-dimensional shape data generated through the data generation processing or the obtainment of the point cloud data corresponding to the effective region and the point cloud data corresponding to the ineffective region as the measurement data has been selected (step S 62 ). That is, the CPU  210  determines whether the point cloud data corresponding to the ineffective region should be removed from the three-dimensional shape data. 
     Upon receiving the selection (the selection to remove the ineffective region) to obtain the point cloud data corresponding to the effective region as the measurement data, the CPU  210  generates the measurement data corresponding to the effective region by removing the point cloud data corresponding to the ineffective region from the three-dimensional shape data read in step S 51  of  FIG. 27 , based on the region information previously stored in the storage device  240  in  FIG. 1  (step S 63 ). 
     On the other hand, upon receiving the selection (the selection that does not remove the ineffective region) to obtain the point cloud data corresponding to the effective region and the point cloud data corresponding to the ineffective region as the measurement data, the CPU  210  sets the three-dimensional shape data read in step S 51  of  FIG. 27  to the measurement data (step S 64 ). This measurement data corresponds to the effective region and the ineffective region. 
     Subsequently, the CPU  210  displays the three-dimensional shape image corresponding to the measurement data obtained through the processing in step S 63  or S 64  on the display unit  400  (step S 65 ). 
     The CPU  210  then determines whether the designation of the region to be removed is received based on the user operation of the operation unit  250  in  FIG. 1  (step S 66 ). At this time, as illustrated in the example of  FIG. 22 , by operating the operation unit  250  in  FIG. 1 , the user can designate the portion corresponding to the region to be removed while moving the pointer P on the three-dimensional shape image displayed on the display unit  400 . 
     When the region to be removed is not designated (for example, when the user does not designate the region to be removed for at least a given period), the CPU  210  ends the measurement data generation processing, and proceeds to the processing in step S 53  of  FIG. 27 . On the other hand, when the region to be removed is designated, the CPU  210  removes the point cloud data corresponding to the designated region from the measurement data obtained through the processing in step S 63  or S 64  (step S 67 ), ends the measurement data generation processing, and proceeds to the processing in step S 53  of  FIG. 27 . 
     In the case where the textured three-dimensional shape data is read in step S 51  of  FIG. 27 , the CPU  210  displays the textured three-dimensional shape image on the display unit  400  in steps S 61  and S 65 . 
     In the measurement data generation processing according to the present embodiment, the pieces of processing in steps S 62  and S 64  may be omitted. In this case, in the measurement data generation processing, the positional data corresponding to the ineffective region is automatically removed from the three-dimensional shape data generated through the data generation processing in  FIG. 18 , and the measurement data is generated. 
     In the measurement data generation processing, the pieces of processing in steps S 65  to S 67  may be omitted. In this case, a generation error of the measurement data due to erroneous operation is prevented because the point cloud data is not removed based on the user designation. 
     In the measurement processing, the measurement data obtaining unit  502  in  FIG. 3  mainly performs the pieces of processing in steps S 61  and S 63  to S 65  of the measurement data generation processing, and the measurement data correcting unit  503  in  FIG. 3  mainly performs the processing in step S 67  of the measurement data generation processing. The receiving unit  505  in  FIG. 3  mainly performs the pieces of processing in steps S 62  to S 66  of the measurement data generation processing, and the measurement unit  504  in  FIG. 3  mainly performs the pieces of processing in steps S 51  and S 53  to S 56 . 
     (6) First Function Usable During Setting of Measurement Condition 
     As described above, during the setting of the measurement condition, the user designates the direction in which the measuring object S is viewed, which allows the user to easily change the orientation of the measuring object S on the three-dimensional shape image displayed on the display unit  400 . 
     A display mode suitable for the setting exists depending on a setting content of the measurement condition. For example, in the case where the distance between the two straight lines is measured in any plane of the measuring object S, preferably, the three-dimensional shape image of the measuring object S is displayed such that the plane is viewed in the direction orthogonal to the plane. Therefore, the user can easily and accurately designate the two straight lines on the plane. The measuring device  500  according to the present embodiment has a first function usable during the setting of the measurement condition. 
     The first function is a function of, during the setting of the measurement condition, causing the user to designate any surface of the measuring object S, and of adjusting and fixing the orientation of the measuring object S on the three-dimensional shape image such that the reference surface that is the designated surface is viewed in the direction orthogonal to the reference surface. 
       FIGS. 29 to 31  are views illustrating a setting example of the measurement condition that uses the first function. For example, as illustrated in  FIG. 24 , it is considered that the user designates the top surface of the element B 2  of the measuring object S in  FIG. 19 . In this state, the user can issue an instruction to use the first function with the designated surface as a reference surface by operating the operation unit  250  in  FIG. 1 . 
     In this case, as illustrated in  FIG. 29 , the orientation of the measuring object S on the three-dimensional shape image is adjusted and fixed such that the designated reference surface is viewed in the direction orthogonal to the reference surface. Thus, the planar image is displayed, in which the measuring object S is viewed in the direction orthogonal to the reference surface. Hereinafter, the planar three-dimensional shape image, which is fixed while the measuring object S is viewed in the direction orthogonal to the reference surface, is referred to as a reference surface image. 
     Then, as illustrated in  FIG. 30  for example, the user designates two sides parallel to each other in the element B 2  as the measurement point on the designated reference surface, and designates the distance between the two sides as the measurement item. At this time, in the element B 2 , images L 1 , L 2  of the two sides designated by the user are highlighted compared with other portions. The measurement value corresponding to the measurement condition designated based on the measurement data is calculated by the setting of the measurement condition. The calculated measurement value is displayed on the reference surface image as illustrated in  FIG. 31 . In the example of  FIG. 31 , “xx (mm)” is displayed as the distance between the two sides of the element B 2  in  FIG. 19 . 
     As described above, according to the first function, the use of the reference surface image allows the user to intuitively set the measurement condition without being conscious of the three-dimensional shape of the measuring object S. 
     The reference surface image may be displayed as follows.  FIG. 32  is a view illustrating another display example of the reference surface image. In the reference surface image of  FIG. 32 , the portion of the measuring object S other than the reference surface is colored according to a height difference relative to the reference surface. As used herein, the height means the distance from the reference surface in the direction orthogonal to the reference surface. In  FIG. 32 , a color difference is represented by a difference of a dot pattern. In this case, the user can easily recognize a difference in height between the reference surface and other portions. As described above, the reference surface image serves as the height image in which the three-dimensional shape data or the textured three-dimensional shape data is represented by the height from a predetermined reference surface. 
     (7) Second Function Usable During Setting of Measurement Condition 
     As described above, the display mode suitable for the setting exists depending on the setting content of the measurement condition. For example, in the case where an angle between two surfaces intersecting each other is measured in the measuring object S, preferably, an image (hereinafter, referred to as a profile image) representing a profile (sectional shape) of the measuring object S is displayed. In this case, the two straight lines included in each of the two target surfaces can easily and accurately be designated on the profile image. The measuring device  500  according to the present embodiment has the second function usable during the setting of the measurement condition. 
     The second function is a function of, during the setting of the measurement condition, causing the user to designate any section in the measuring object S, and of displaying the profile image of the designated section. 
       FIGS. 33 to 35  are views illustrating a setting example of the measurement condition that uses the second function. For example, the user can issue an instruction to use the second function by operating the operation unit  250  in  FIG. 1 . In this case, the designation of the sectional position where the profile image is to be displayed is received. In this example, as illustrated in  FIG. 33 , the sectional position of the measuring object S in which the profile image is to be displayed is designated by a line segment LS on the reference surface image displayed by the first function. 
     In this case, based on the measurement data, profile data representing the profile of the measuring object S is generated on the surface, which passes through the line segment LS and is orthogonal to the reference surface. The profile image in  FIG. 34  is displayed based on the generated profile data. The profile image includes a profile line PL representing the profile of the measuring object S. At this time, the reference surface image in  FIG. 33  may be displayed on the screen of the display unit  400  together with the profile image. 
     Then, as illustrated in  FIG. 35  for example, the user designates the angle between the straight line corresponding to the top surface of the element B 2  in  FIG. 19  and the straight line corresponding to one end face of the board B 1  in  FIG. 19  as the measurement item on the displayed profile line PL. At this time, an image L 12  of the top surface of the element B 2  and an image L 11  of one end face of the board B 1 , which are designated by the user, are highlighted compared with other portions as illustrated in  FIG. 35 . The measurement value corresponding to the measurement condition designated based on the measurement data is calculated by the setting of the measurement condition. The calculated measurement value is displayed on the profile image. In the example of  FIG. 35 , “yy (degree)” is displayed as the angle between the top surface of the element B 2  and one end face of the board B 1 . 
     As described above, according to the second function, the use of the profile image improves convenience in setting of the measurement condition. 
     [5] Head Unit 
     (1) Measurement Optical Unit 
     Hereinafter, in the Y-direction, a direction from the stand  162  toward the stage  140  of the coupling member  160  is referred to as front, and an opposite direction to the front is referred to as rear. In the present embodiment, the two light projecting units  110 A,  110 B and the two light receiving units  120 A,  120 B are integrally coupled to form a measurement optical unit.  FIG. 36  is a perspective view illustrating the measurement optical unit before the light projecting units  110 A,  110 B and the light receiving units  120 A,  120 B are coupled.  FIG. 37  is a perspective view illustrating the measurement optical unit after the light projecting units  110 A,  110 B and the light receiving units  120 A,  120 B are coupled. 
     As illustrated in  FIG. 36 , a measurement optical unit  10  includes a flat horizontal support plate  11  and two flat vertical support plates  12 ,  13  in addition to the two light projecting units  110 A,  110 B and the two light receiving units  120 A,  120 B. The measurement optical unit  10  also includes a plurality of (in this example, four) rod-like coupling members  14 , a plurality of (in this example, four) rod-like coupling members  15 , and a plurality of (in this example, four) rod-like coupling members  16 . 
     The two vertical support plates  12 ,  13  are disposed with surfaces of the vertical support plates  12 ,  13  facing each other. In the vertical support plates  12 ,  13 , each of the surfaces facing each other is referred to as an inner surface, and a surface opposite to the inner surface is referred to as an outer surface. The plurality of coupling members  14  are disposed between the vertical support plates  12 ,  13 . In this state, a plurality of (in this example, four) fixing members  14   a  such as screws are inserted from the outer surface into the inner surface of the vertical support plate  12 , and screwed to end faces of the plurality of coupling members  14 . Other plurality of (in this example, four) fixing members  14   a  are inserted from the outer surface into the inner surface of the vertical support plate  13 , and screwed to end faces of the plurality of coupling members  14 . Therefore, the vertical support plates  12 ,  13  are coupled while being separated from each other. The light receiving units  120 A,  120 B are fixed to the inner surface of one of the vertical support plates  13  using a fixing member (not illustrated). 
     The light projecting unit  110 A is disposed adjacent to the outer surface of the vertical support plate  12 . The plurality of coupling members  15  are disposed between the vertical support plate  12  and the light projecting unit  110 A. In this state, a plurality of (in this example, four) fixing members  15   a  such as screws are inserted from the inner surface into the outer surface of the vertical support plate  12 , and screwed to end faces of the plurality of coupling members  15 . Other plurality of (in this example, four) fixing members  15   a  are inserted in a plurality of attachment pieces  110   a  formed in the light projecting unit  110 A, and screwed to end faces of the plurality of coupling members  15 . Therefore, the light projecting unit  110 A is coupled to the vertical support plate  12 . 
     The light projecting unit  110 B is disposed adjacent to the outer surface of the vertical support plate  13 . The plurality of coupling members  16  are disposed between the vertical support plate  13  and the light projecting unit  110 B. In this state, a plurality of (in this example, four) fixing members  16   a  such as screws are inserted from the inner surface into the outer surface of the vertical support plate  13 , and screwed to end faces of the plurality of coupling members  16 . Other plurality of (in this example, four) fixing members  16   a  are inserted in a plurality of attachment pieces  110   a  formed in the light projecting unit  110 B, and screwed to end faces of the plurality of coupling members  16 . Therefore, the light projecting unit  110 B is coupled to the vertical support plate  13 . 
     The two vertical support plates  12 ,  13  are fixed to the top surface of the horizontal support plate  11  so as to protrude upward. Therefore; the measurement optical unit  10  is completed as illustrated in  FIG. 37 . In this configuration, as compared with the case where the light projecting unit  110  and the light receiving unit  120  are coupled using a single rigid body, a weight of the measurement optical unit  10  can be reduced while the rigidity is maintained. Additionally, the degradation of the measurement accuracy of the measuring unit  100  can be prevented. The reason will be described below. 
     In the triangular distance measuring method, the measurement is performed based on the predetermined angle between the optical axis of the light projecting unit  110  and the optical axis of the light receiving unit  120 . Therefore, when expansion or contraction of the support members of the light projecting unit  110  and the light receiving unit  120  are generated due to a temperature change, the angle between the optical axis of the light projecting unit  110  and the optical axis of the light receiving unit  120  changes and the measurement accuracy degrades. The configuration of the measurement optical unit  10  facilitates active passage of cooling air between the plurality of coupling members  14 , between the plurality of coupling members  15 , and between the plurality of coupling members  16 . Therefore, nonuniformity of a temperature distribution among the plurality of coupling members  14  to  16  is reduced and deformations of the plurality of coupling members  14  to  16  can be minimized. As a result, the angle between the optical axis of the light projecting unit  110  and the optical axis of the light receiving unit  120  is maintained and the degradation of the measurement accuracy can be prevented. 
     In order to maintain the measurement accuracy, it is necessary to stabilize the temperature of the optical system such as the light projecting unit  110  and the light receiving unit  120 . However, immediately after the measuring device  500  is powered on, the temperature of the optical system increases gradually due to heat generation, and it takes a long time to stabilize the optical system. According to the above configuration, since the cooling air is actively passed among the plurality of coupling members  14  to  16 , time required for the stabilization of the temperature of the optical system can be shortened. Moreover, the temperature increase caused by the heat generation is minimized in the optical system, and the degradation of the measurement accuracy can be prevented. 
     Each coupling member  14  is coupled to the vertical support plate  12  at one point with the single fixing member  14   a , and coupled to the vertical support plate  13  at one point with another fixing member  14   a . Each coupling member  15  is coupled to the vertical support plate  12  at one point with the single fixing member  15   a , and coupled to the light projecting unit  110 A at one point with another fixing member  15   a . Each coupling member  16  is coupled to the vertical support plate  13  at one point with the single fixing member  16   a , and coupled to the light projecting unit  110 B at one point with another fixing member  16   a.    
     That is, each of the coupling members  14 ,  15 ,  16  makes contact with the same support member at one point. With this configuration, a hysteresis caused by a difference in linear expansion coefficient between the coupling member and the support member is reduced even if the coupling member and the support member are made of different materials. Therefore, the angle between the optical axis of the light projecting unit  110  and the optical axis of the light receiving unit  120  is maintained, and the degradation of the measurement accuracy can be prevented. 
     Particularly, in the present embodiment, the offset optical system is used in the light projecting unit  110 , and the whole light projecting unit  110  is disposed in parallel to the light receiving unit  120 . Because holding lengths of the plurality of coupling members  15 ,  16  between the light projecting unit  110  and the light receiving unit  120  can equally be set, the angle between the optical axis of the light projecting unit  110  and the optical axis of the light receiving unit  120  can easily be maintained when an expansion amount or a contraction amount is uniform. 
     In the above configuration, the horizontal support plate  11 , the vertical support plates  12 ,  13 , and the coupling members  14  to  16  are preferably made of a material having a linear expansion coefficient within a certain range, and more preferably made of a material having the same linear expansion coefficient. In this case, the expansion and contraction of the horizontal support plate  11 , the vertical support plates  12 ,  13 , and the coupling members  14  to  16  due to the temperature change are uniformly generated in all directions. Therefore, robustness of the measurement accuracy against the temperature change can be improved. 
     Preferably, various components of the light projecting unit  110  and the light receiving unit  120  are made of a material having a linear expansion coefficient within a certain range. Similarly to various components of the light projecting unit  110  and the light receiving unit  120 , preferably, the horizontal support plate  11 , the vertical support plates  12 ,  13 , and the coupling members  14  to  16  are made of a material having a linear expansion coefficient within a certain range. In this case, the robustness of the measurement accuracy against the temperature change can be further improved. 
     On the other hand, when the robustness of the measurement accuracy against the temperature change is sufficiently high, the horizontal support plate  11 , the vertical support plates  12 ,  13 , and the coupling members  14  to  16  may be made of any material. In this case, because the horizontal support plate  11 , the vertical support plates  12 ,  13 , and the coupling members  14  to  16  have a degree of freedom in the material, the rigidity of the measurement optical unit  10  is further improved, and the weight of the measurement optical unit  10  can easily be reduced. 
     (2) Mount 
       FIG. 38  is a perspective view illustrating a configuration of the mount  170 . As illustrated in  FIG. 38 , the mount  170  includes a bottom surface part  171 , a lower casing  172 , an inclination table  173 , a plurality of support columns  174 , a top surface part  175 , a fan unit  176 , and a diffuser unit  177  in addition to the pair of grips  179 . The bottom surface part  171  has a substantially rectangular shape. A guide rail  171   a  extending in the X-direction is provided in a front end face of the bottom surface part  171 . The lower casing  172  is provided so as to cover both sides and a rear side in the X-direction of the bottom surface part  171 . The pair of grips  179  is provided in outer side surfaces in the X-direction of the lower casing  172 . 
     For example, the inclination table  173  is made of a sheet metal, and provided on the top surface of the bottom surface part  171 . The inclination table  173  includes a placement surface  173   a  that is inclined obliquely upward from the front to the rear. In the present embodiment, the placement surface  173   a  has an angle of 45 degrees with respect to the surface perpendicular to the Z-axis. The horizontal support plate  11  of the measurement optical unit  10  in  FIG. 37  is attached onto the placement surface  173   a . The illumination light output unit  130  is attached onto the placement surface  173   a  while the output port  131  in  FIG. 4  surrounds the two light receiving units  120  in  FIG. 37 . Therefore, the measurement optical unit  10  and the illumination light output unit  130  are fixed to the mount  170 . The control board  150  is attached to the rear end of the inclination table  173 . 
     The plurality of support columns  174  are provided so as to extend vertically from the top surface of the inclination table  173  or the inner surface of the lower casing  172 . The top surface part  175  is attached to the upper end of the support column  174 . Therefore, the top surface part  175  is disposed above the measurement optical unit  10  in  FIG. 37 . The top surface part  175  is formed into a lattice shape, and has a ventilation property. 
     The fan unit  176  is attached onto the top surface part  175 . The fan unit  176  includes three fans  176 A,  176 B,  176 C. The fan  176 A is disposed in a substantially central portion in the X-direction. The fans  176 B and  176 C are disposed in one end and the other end in the X-direction. The fans  176 A to  176 C send air upward from the lower side. Details will be described later. 
     The diffuser unit  177  includes two diffusers  177 A,  177 B. For example, the diffusers  177 A,  177 B have isotropic diffusion performance, and isotropically diffuse the light transmitted through the diffusers  177 A,  177 B in a plane orthogonal to a traveling direction of the light. The diffusers  177 A,  177 B are attached to the guide rail  171   a  of the bottom surface part  171  so as to be movable in the X-direction. During the shape measurement of the measuring object S, for example, the diffusers  177 A,  177 B moves to the substantially central portion in the X-direction so as not to intersect the optical axes of the light projecting units  110 A,  110 B in  FIG. 37 . 
     On the other hand, during rotation axis calibration processing (to be described later), the diffuser  177 A moves to the front of the light projecting unit  110 A so as to intersect the optical axis of the light projecting unit  110 A, and the diffuser  177 B moves to the front of the light projecting unit  110 B so as to intersect the optical axis of the light projecting unit  110 B. Therefore, the diffusers  177 A,  177 B are inserted in the optical paths of the light output from the light projecting units  110 A,  110 B, respectively. An effect of the diffusers  177 A,  177 B will be described below. 
     A white sheet is placed on the stage plate  142  in  FIG. 2  as the measuring object S, and the light projecting unit  110 A irradiates the measuring object S with the uniform measurement light to obtain the image.  FIGS. 39A and 39B  are views illustrating comparison between effects of presence and absence of the diffuser  177 A on the optical path.  FIG. 39A  illustrates the image when the diffuser  177 A is not inserted in the optical path, and  FIG. 39B  illustrates the image when the diffuser  177 A is inserted in the optical path. 
     When the diffuser  177 A is not inserted in the optical path, in the measuring object S, the portion corresponding to a non-light guide portion between modulation elements of the pattern generating unit  112  in  FIG. 2  is not irradiated with the bright portion of the uniform measurement light. Therefore, as illustrated in  FIG. 39A , a lattice-like shadow pattern is reflected in the obtained image. 
     On the other hand, when the diffuser  177 A is inserted in the optical path, the light transmitted through the diffuser  177 A is diffused, and the light goes around even in the portion, in the measuring object S, corresponding to the non-light guide portion between the modulation elements of the pattern generating unit  112 . Therefore, as illustrated in  FIG. 39B , the lattice-like shadow pattern is not reflected in the obtained image. This enables the device parameter to be accurately calibrated in the later-described rotation axis calibration processing. 
     When a main power supply of the measuring device  500  is turned off, the diffusers  177 A,  177 B move to the front of the light projecting units  110 A,  110 B, respectively. Therefore, leading ends of the light projecting units  110 A,  110 B are covered with the diffusers  177 A,  177 B. A foreign matter such as dust is prevented from adhering to the leading ends of the light projecting unit  110 A,  110 B while the leading ends of the light projecting units  110 A,  110 B are protected. 
     In the above configuration, the fan unit  176 , the diffuser unit  177 , and the control board  150  are fastened to the inclination table  173 , and mechanically separated from the measurement optical unit  10 . Therefore, a disturbance such as a vibration of the fan unit  176 , heat of the diffuser unit  177 , and heat of the control board  150  is not directly applied to the measurement optical unit  10 . Similarly, a mounting component (not illustrated) and a protective member (not illustrated) are fastened to the inclination table  173 , and mechanically separated from the measurement optical unit  10 . As a result, a disturbance such as a dropping impact is not directly applied to the measurement optical unit  10 . Therefore, the robustness of the measurement optical unit  10  against the disturbance is improved. 
     (3) Cooling Mechanism 
     The head casing  180  in  FIG. 4  is attached to the mount  170  so as to cover the upper portion of the measurement optical unit  10 , whereby the head unit  190  is configured. In the present embodiment, because heat sources such as the measurement light source  111 , the light projection control board  115 , the light reception control board  123 , and the control board  150  are provided in the head casing  180 , preferably, a cooling mechanism is provided in order to efficiently cool the heat sources. 
       FIG. 40  is a perspective view illustrating the head unit  190  when the head unit  190  is seen from the front.  FIG. 41  is a perspective view illustrating the head unit  190  when the head unit  190  is seen from the back. In  FIG. 40 , for easy understanding of an internal configuration of the head casing  180 , the head casing  180  is illustrated with the upper portion of the head casing  180  being cut out, and components other than the fans  176 A to  176 C are omitted. 
     As illustrated in  FIG. 40 , a plurality of intake holes  181  and a plurality of intake holes  182  are formed in a front surface of the head casing  180 . The plurality of intake holes  181  are disposed at one end in the X-direction so as to be vertically arranged. The plurality of intake holes  182  are disposed at the other end in the X-direction so as to be vertically arranged. 
     As illustrated in  FIG. 41 , a plurality of intake holes  172   a  and a plurality of intake holes  172   b  are formed in a rear surface of the lower casing  172  of the mount  170 . The plurality of intake holes  172   a  are disposed at one end in the X-direction so as to be vertically arranged. The plurality of intake holes  172   b  are disposed at the other end in the X-direction so as to be vertically arranged. 
     A plurality of exhaust holes  183 , a plurality of exhaust holes  184 , and a plurality of exhaust holes  185  are formed in the top surface of the head casing  180 . The plurality of exhaust holes  183  are disposed in the substantially central portion in the X-direction so as to be arranged in a front-back direction. The plurality of exhaust holes  184  are disposed at one end in the X-direction so as to be arranged in the front-back direction. The plurality of exhaust holes  185  are disposed at the other end in the X-direction so as to be arranged in the front-back direction. In this disposition, the plurality of exhaust holes  183  face the fan  176 A in  FIG. 40 , the plurality of exhaust holes  184  face the fan  176 B in  FIG. 40 , and the plurality of exhaust holes  185  face the fan  176 C in  FIG. 40 . 
       FIG. 42  is a view illustrating one passage route of the cooling air. As illustrated in  FIG. 42 , when the fan  176 A is operated, the cooling air is introduced into the head casing  180  through the intake hole  172   a , passes through the light projection control board  115  of the light projecting unit  110 A, and is discharged to the outside of the head casing  180  through the exhaust hole  183 . When the fan  176 B is operated, the cooling air is introduced into the head casing  180  through the intake hole  181 , passes through the measurement light source  111  of the light projecting unit  110 A, and is discharged to the outside of the head casing  180  through the exhaust hole  184 . Therefore, the measurement light source  111  and the light projection control board  115  of the light projecting unit  110 A are cooled. 
     Similarly, when the fan  176 A is operated, the cooling air is introduced into the head casing  180  through the intake hole  172   b  (see  FIG. 41 ), passes through the light projection control board  115  of the light projecting unit  110 B, and is discharged to the outside of the head casing  180  through the exhaust hole  183 . When the fan  176 C (see  FIG. 40 ) is operated, the cooling air is introduced into the head casing  180  through the intake hole  182  (see  FIG. 40 ), passes through the measurement light source  111  of the light projecting unit  110 B, and is discharged to the outside of the head casing  180  through the exhaust hole  184 . Therefore, the measurement light source  111  and the light projection control board  115  of the light projecting unit  110 B are cooled. 
       FIG. 43  is a view illustrating another passage route of the cooling air. When the fan  176 A is operated, the cooling air is introduced into the head casing  180  through the intake holes  172   a ,  172   b , passes through the control board  150 , and is discharged to the outside of the head casing  180  through the exhaust hole  183 . When the fan  176 A is operated, the cooling air is introduced into the head casing  180  through the intake holes  181 ,  182 , passes through the light reception control board  123  of the light receiving unit  120 A and the light reception control board  123  of the light receiving unit  120 B, and is discharged to the outside of the head casing  180  through the exhaust hole  183 . Therefore, the control board  150 , the light reception control board  123  of the light receiving unit  120 A, and the light reception control board  123  of the light receiving unit  120 B are cooled. 
     According to the above configuration, the route of the cooling air used to cool the measurement light source  111  is separated from the route of the cooling air used to cool the light projection control board  115 , the light reception control board  123  and the control board  150 , and the heat generated from the measurement light source  111  can efficiently be discharged to the outside without being transferred to the inside of the measurement optical unit  10 . Accordingly, a temperature drift is reduced in the measurement optical unit  10 , and the temperature can easily be stabilized. The intake holes  172   a ,  172   b ,  181 ,  182  and the exhaust holes  183  to  185  are provided such that the route of the cooling air does not interfere with the optical paths of the measurement light and illumination light. Therefore, the air in the optical path does not fluctuate even if the cooling air is introduced into the head casing  180 . Therefore, the degradation of the measurement accuracy can be improved. 
     (4) Positioning Mechanism 
     In the present embodiment, a positioning mechanism is provided in the measuring unit  100  in order to keep the positional relationship between the coupling member  160  and the head unit  190  constant.  FIGS. 44A to 44C  and  FIG. 45  are schematic diagrams illustrating an example of the positioning mechanism.  FIG. 44A  is a plan view schematically illustrating the stand  162 . As illustrated in  FIG. 44A , two protrusions  163 , separated from each other in the X-direction and protruding upward, are formed in an upper end face of the stand  162 . A fall prevention member  164 , extending in the X-direction and protruding upward, is formed in the front surface at the upper end of the stand  162 . 
       FIG. 44B  is a bottom view schematically illustrating the mount  170 . As illustrated in  FIG. 44B , two grooves  171   b  separated from each other in the X-direction are formed in a front portion of the bottom surface of the bottom surface part  171  of the mount  170 . Each groove  171   b  has a V-shape, and the distance between two sides of the groove  171   b  in the X-direction increases gradually from the rear toward the front. The two grooves  171   b  correspond to the two protrusions  163 . A depth of each groove  171   b  is substantially equal to a thickness of each protrusion  163 , or larger than the thickness of each protrusion  163 . 
       FIG. 44C  is a plan view schematically illustrating the stand  162  and the mount  170 . In  FIG. 44C , perspective views of the upper end face of the stand  162  and the two protrusions  163  are illustrated by a dotted line, and perspective views of the two grooves  171   b  in the bottom surface of the mount  170  are illustrated by a dotted line. When attaching the head unit  190  to the stand  162 , the user grasps the grip  179  to place the front portion of the bottom surface of the mount  170  on the rear portion of the upper end face of the stand  162  as illustrated by a solid line in  FIG. 45 . In this state, the user slides the head unit  190  toward the front as indicated by an outline arrow in  FIG. 45 . 
     In this case, as illustrated in  FIG. 44C , the protrusions  163  of the stand  162  abut on two sides of the groove  171   b  corresponding to the mount  170 . The front surface of the mount  170  abuts on the fall prevention member  164  of the stand  162 . Therefore, the head unit  190  stops sliding, and the coupling member  160  and the head unit  190  are positioned while a given positional relationship is maintained. In  FIG. 45 , the positioned head unit  190  is indicated by an alternate long and short dash line. 
     Thus, the two protrusions  163  and the two grooves  171   b  constitute the positioning mechanism. This enables the user to position the mount  170  and the head unit  190  by simple operation. The fall prevention member  164  can prevent the head unit  190  from falling from the stand  162 . 
     In the examples of  FIGS. 44A to 44C  and  FIG. 45 , the upper end face of the stand  162  and the bottom surface of the mount  170  are horizontally formed. However, the present invention is not limited thereto. The upper end face of the stand  162  and the bottom surface of the mount  170  may be formed so as to be inclined upward from the front toward the rear. In this case, the user can easily introduce the mount  170  to a predetermined position of the stand  162  using gravity. Therefore, the mount  170  and the head unit  190  can more easily be positioned. 
     [6] Calibration 
     The user can detach the head unit  190  from the stand  162  by grasping the grips  179  provided on both the sides of the mount  170  of the head unit  190  in  FIG. 4 . In this case, the head unit  190  is attached to a support body different from the stand  162  or placed on an installation surface. Therefore, the shape of the measuring object S that cannot be placed on the stage  140  can be measured. 
     However, in the case where the head unit  190  detached once is attached to the stand  162  again, the head unit  190  is not always attached to the same position as that before the head unit  190  is detached. In this case, there is a possibility that displacement occurs in the positional relationship between the head unit  190  and the rotation axis Ax of the stage  140  before and after the attachment and detachment of the head unit  190 . 
     As described above, the device parameter previously stored in the storage device  240  of  FIG. 1  is used to generate the three-dimensional shape data. When the device parameter stored in the storage device  240  differs from the actual positional relationship between the head unit  190  and the stage  140 , the plurality of pieces of three-dimensional shape data, which are generated while the stage  140  is rotated, cannot accurately be synthesized in the data generation processing. 
     Because the effective regions MR 1 , MR 2  are set based on the positions of the light receiving units  120 A,  120 B of the head unit  190 , when the above positional displacement occurs every time the head unit  190  is attached and detached, a positional displacement also occurs between the effective regions MR 1 , MR 2  and the stage  140 . 
     For this reason, it is necessary to calibrate the device parameter when the head unit  190  is attached to the stand  162  again after the head unit  190  is detached from the stand  162 . 
     In the present embodiment, the rotation axis calibration processing is performed in order to calibrate the device parameter. For example, the rotation axis calibration processing is performed based on the user instruction when the head unit  190  is attached to the stand  162  again after the head unit  190  is detached from the stand  162 . 
       FIG. 46  is a flowchart illustrating an example of the rotation axis calibration processing. The CPU  210  in  FIG. 1  performs the rotation axis calibration processing stored in the storage device  240  in  FIG. 1  in response to the instruction to start the rotation axis calibration processing from the user. 
     Before the rotation axis calibration processing is performed, the user previously disposes a flat-plate calibration board on the stage  140  such that the calibration board is inclined with respect to the placement surface of the stage  140 . A calibration index is provided in the calibration board. The index may be formed by engraving, or marking using paint. 
     In response to the instruction to start the rotation axis calibration processing, the CPU  210  firstly generates a plurality of pieces of three-dimensional shape data corresponding to a plurality of (for example, three) predetermined rotation positions of the stage  140  (step S 101 ). Specifically, when the stage  140  is rotated in a stepwise manner, the rotation position of the stage  140  is changed to a plurality of predetermined angle positions in the stepwise manner. When the stage  140  is located at each rotation position, the light projecting unit  110  irradiates the calibration board with the measurement light, and the light receiving unit  120  obtains the pattern image data. The three-dimensional shape data is generated based on each pattern image data. Therefore, the plurality of pieces of three-dimensional shape data corresponding to the plurality of rotation positions are generated. 
     Then, the CPU  210  calculates a relative positional relationship between the light receiving units  120 A,  120 B and the rotation axis Ax of the stage  140  in the device coordinate system based on the plurality of predetermined rotation positions and the point cloud data corresponding to the calibration index in the plurality of pieces of three-dimensional shape data (step S 102 ). The CPU  210  then updates the device parameter stored in the storage device  240  based on the calculated positional relationship (step S 103 ). Therefore, the rotation axis calibration processing is ended. 
     The relative positional relationship between the light receiving units  120 A,  120 B and the rotation axis Ax of the stage  140  is accurately calculated through the rotation axis calibration processing. Therefore, the plurality of pieces of three-dimensional shape data generated through the data generation processing can accurately be synthesized based on the device parameter including the calculated positional relationship. Additionally, the effective regions MR 1 , MR 2  are prevented from being displaced from the position to be located on the stage  140 . As a result, the degradation of the measurement accuracy of the observation object S is suppressed. In the rotation axis calibration processing, the positional relationship calculating unit  507  in  FIG. 3  mainly performs the processing in step S 102 . 
     The shape of the calibration board is known, and the position of the calibration index in the calibration board is also known. In the case where the plurality of pieces of three-dimensional shape data are generated at the plurality of rotation positions through the rotation axis calibration processing, the calibration can be performed in order to secure the accuracy of the generated three-dimensional shape data based on the pieces of three-dimensional shape data, the shape of the calibration board, and the position of the calibration index. That is, the three-dimensional shape data generation processing can be calibrated such that the shape of the calibration board is more accurately reproduced from the obtained plurality of pieces of three-dimensional shape data. The accuracy of the generated three-dimensional shape data is secured by the calibration even if the positional relationship between the light projecting unit  110  and the light receiving unit  120  is displaced in the head unit  190 . Thus, in the rotation axis calibration processing according to the present embodiment, the relative positional relationship between the light receiving units  120 A,  120 B and the rotation axis Ax of the stage  140  can accurately be calculated, and at the same time, the three-dimensional shape data generation processing can be calibrated. 
     [7] Light Shielding Mechanism 
     When ambient light reflected by the measuring object S is incident on the light receiving units  120 A,  120 B, a noise component caused by the ambient light is included in the light reception signal output from the light receiving units  120 A,  120 B. In this case, the accuracy of the point cloud data generated through the data generation processing degrades when the ambient light incident on the light receiving units  120 A,  120 B increases. 
     A light shielding mechanism is attached to the measuring unit  100  according to the present embodiment in order to prevent the ambient light around the measuring unit  100  from entering the space including the effective regions MR 1 , MR 2  on the stage  140 .  FIG. 47  is a perspective view illustrating an appearance of the measuring unit  100  to which the light shielding mechanism is attached. As illustrated in  FIG. 47 , a light shielding mechanism  600  includes a rear cover member  610 , a front cover member  620 , a front-cover support member  630 , and a hinge  640 . 
     The rear cover member  610  is detachably attached to the upper end of the coupling member  160 . The rear cover member  610  extends in the X-direction while being bent at the position between the imaging visual fields TR 1 , TR 2  of the light receiving units  120 A,  120 B and the stand  162 . Only the imaging visual field TR 1  of the light receiving unit  120 A in the light receiving units  120 A,  120 B is illustrated in  FIG. 47 . 
     The front-cover support member  630  is connected to both the sides of the rear cover member  610  so as to cover the space above the rear cover member  610 . The rear end of the front-cover support member  630  is connected to the front end of the head casing  180  while the rear cover member  610  is attached to the stand  162 . The front cover member  620  is connected to the front end of the front-cover support member  630  via the hinge  640 . The front cover member  620  is formed so as to extend forward from the front end of the front-cover support member  630  toward the space on the stage  140 . 
     The front cover member  620  is provided such that the space on the stage  140  can be opened and closed by the hinge  640  as illustrated by a bold dotted line in  FIG. 47 . The front cover member  620  is formed so as to face the whole placement surface of the stage  140  in the closed state, and covers the space on the stage  140  from above. At this time, the front-cover support member  630  and the front cover member  620  do not block the measurement light with which the measuring object S is irradiated from the light projecting units  110 A,  110 B. On the other hand, the front cover member  620  does not cover the space on the stage  140  in the open state. 
     According to the above configuration, in the measuring unit  100 , the light shielding mechanism  600  blocks the ambient light from above the effective regions MR 1 , MR 2  on the stage  140  when the front cover member  620  is in the closed state while the light shielding mechanism  600  is attached to the measuring unit  100 . The front cover member  620  and the front-cover support member  630  do not block the measurement light with which the effective regions MR 1 , MR 2  are irradiated. Therefore, the noise component caused by the ambient light is reduced because the ambient light incident on the light receiving units  120 A,  120 B is reduced. As a result, the degradation of the accuracy of the point cloud data is suppressed. 
     According to the above configuration, the rear cover member  610  in the light shielding mechanism  600  blocks part of the ambient light from the rear of the space on the stage  140 . The rear cover member  610  does not block the measurement light with which the effective regions MR 1 , MR 2  are irradiated. Therefore, the noise component caused by the ambient light is further reduced because the ambient light incident on the light receiving units  120 A,  120 B is further reduced. As a result, the degradation of the accuracy of the point cloud data is further suppressed. 
     According to the above configuration, the operation to place the measuring object S on the stage  140  and the operation to position the measuring object S can easily be performed when the front cover member  620  is put into the open state. The operation to measure the measuring object S is easily performed because the front cover member  620  can open and close the space on the stage  140 . Moreover, because the light shielding mechanism  600  is connected to not the head unit  190  but the coupling member  160 , a stress caused by the weight of the light shielding mechanism  600  is applied to the coupling member  160  and not applied to the head unit  190 . Because the coupling member  160  has the high rigidity, the coupling member  160  is hardly deformed even if the light shielding mechanism  600  is attached. Therefore, the positional relationship between the coupling member  160  and the head unit  190  does not substantially change before and after the attachment of the light shielding mechanism  600 . As a result, the measurement accuracy can be maintained. 
     The following light shielding member may be attached to the light shielding mechanism  600  in order to further block the ambient light from the rear of the space on the stage  140 .  FIG. 48  is a perspective view of the measuring unit  100  illustrating an example of the rear light shielding member attached to the rear cover member  610 . In the example of  FIG. 48 , a black curtain-like rear light shielding member  650  is attached to the rear cover member  610  so as to extend from the lower end of the rear cover member  610  to the top surface of the installation part  161 . 
     Further, the following light shielding member may be attached to the light shielding mechanism  600  in order to block the ambient light from the front, the right, and the left of the space on the stage  140 .  FIG. 49  is a perspective view of the measuring unit  100  illustrating an example of the front and side light shielding member attached to the front cover member  620 . In the example of  FIG. 49 , a black curtain-like front and side light shielding member  660  is attached to the front cover member  620  so as to extend from an outer edge at the lower end of the front cover member  620  having a substantially U-shape to a periphery of the installation part  161 . 
     As illustrated in  FIG. 49 , the rear light shielding member  650  and the front and side light shielding member  660  are attached to the light shielding mechanism  600 , whereby an entire circumference of the space on the stage  140  is surrounded by the rear light shielding member  650  and the front and side light shielding member  660 . Therefore, the space on the stage plate  142  is blocked from an external environment, and the rear light shielding member  650  and the front and side light shielding member  660  block the ambient light from all sides including the front, the rear, the right, and the left of the space on the stage  140 . Accordingly, the noise component caused by the ambient light is further reduced because the ambient light incident on the light receiving units  120 A,  120 B is further reduced. Additionally, an influence of the temperature change of the ambient temperature and an influence of the air fluctuation are reduced. As a result, the degradation of the accuracy of the point cloud data is further suppressed. 
     The rear light shielding member  650  and the front and side light shielding member  660  may be made of resin or metal, or may be made of cloth or rubber. Preferably, the rear light shielding member  650  and the front and side light shielding member  660  are made of a soft material such as cloth and rubber. In this case, damage of the rear light shielding member  650 , the front and side light shielding member  660 , and the measuring object S is prevented even if the rear light shielding member  650  or the front and side light shielding member  660  makes contact with the measuring object S. Preferably, the rear light shielding member  650  and the front and side light shielding member  660  are detachable. Therefore, the maintenance is improved, and the rear light shielding member  650  or the front and side light shielding member  660  can easily be exchanged even if the rear light shielding member  650  or the front and side light shielding member  660  is degraded or damaged. 
     The front and side light shielding member  660  in  FIG. 49  includes nylon cloth and a plurality of metallic frame members, and is formed into a bellows shape extendable in the vertical direction. In this case, the user can vertically expand and contract the front and side light shielding member  660  to easily perform the operation to place the measuring object S on the stage  140  and the operation to position the measuring object S. 
     In the configurations of  FIGS. 47 to 49 , preferably, the portions facing the space on the stage  140  in the light shielding mechanism  600 , the rear light shielding member  650 , and the front and side light shielding member  660  are configured in a color (for example, black) that absorbs the light. Therefore, in the space on the stage  140 , the measurement light or the illumination light is prevented from being reflected by the inner surfaces of the light shielding mechanism  600 , rear light shielding member  650 , and front and side light shielding member  660 . As a result, the noise component caused by diffused measurement light or illumination light is reduced. 
     [8] Stage Plate 
     The stage plate  142  in  FIG. 2  may have the following configuration.  FIGS. 50A and 50B  are views illustrating a configuration example of the stage plate  142 . Referring to  FIGS. 50A and 50B , the stage plate  142  includes a fixed part  401  and an inclination part  402 . The fixed part  401  includes a flat fixed placement surface  401   a , and the inclination part  402  includes a flat inclination placement surface  402   a . A plurality of attaching parts (for example, screw holes) are formed in the fixed placement surface  401   a  and the inclination placement surface  402   a  in order to fix the measuring object S, the clamp, or the jig. 
     The fixed part  401  is fixed to the stage base  141 , and the fixed placement surface  401   a  is kept horizontal. On the other hand, the inclination part  402  can be switched between a horizontal attitude in which the inclination placement surface  402   a  is kept horizontal and an inclination attitude in which the inclination placement surface  402   a  is inclined with respect to the fixed placement surface  401   a . The inclination part  402  is in the horizontal attitude in  FIG. 50A , and the inclination part  402  is in the inclination attitude in  FIG. 50B . When the inclination part  402  is in the inclination attitude, the bottom surface of the inclination part  402  is supported by a support member  403 . 
     An inclination angle (an inclination angle of the inclination placement surface  402   a  with respect to the horizontal surface) D 2  of the inclination placement surface  402   a  may be set to an angle, at which the inclination placement surface  402   a  is orthogonal to the optical axes A 1 , A 2  of the light receiving units  120 A,  120 B, or may be set to another angle, or may be set so as to be changeable to a plurality of angles. 
       FIG. 51  is a schematic side view of the measuring unit  100  illustrating an example in which the image of the measuring object S is captured while the inclination part  402  is in the inclination attitude. In this example, it is assumed that the inclination angle D 2  (see  FIG. 50B ) of the inclination placement surface  402   a  is set such that the inclination placement surface  402   a  is orthogonal to the optical axes A 1 , A 2  of the light receiving units  120 A,  120 B. For example, the measuring object S having the top surface and bottom surface, which are parallel to each other, is placed on the inclination placement surface  402   a  such that the bottom surface of the measuring object S makes contact with the inclination placement surface  402   a . At this time, the top surface of the measuring object S is orthogonal to the optical axes A 1 , A 2  of the light receiving units  120 A,  120 B. 
     When the image of the measuring object S is captured in the state of  FIG. 51 , the live image is displayed on the display unit  400  as the image of the measuring object S when the top surface of the measuring object S is seen from immediately above. Therefore, the user can observe the measuring object S with a feeling similar to when using a general microscope. 
     The user can operate operation unit  250  in  FIG. 1  to easily switch between single-shot measurement and entire-circumference measurement. In the single-shot measurement, the top surface of the measuring object S when seen from immediately above is measured. In the entire-circumference measurement, the entire circumference of the measuring object S is measured while the stage plate  142  is rotated. 
     As described above, in the stage plate  142  of this example, the angle between the inclination placement surface  402   a  and the fixed placement surface  401   a  can be changed such that the inclination placement surface  402   a  is inclined with respect to the fixed placement surface  401   a . This enables the user to selectively place the measuring object S on one of the inclination placement surface  402   a  and the fixed placement surface  401   a . Accordingly, the attitude of the measuring object S can easily be changed. Additionally, the angle of the inclination placement surface  402   a  can appropriately be changed according to the measuring object S and the measurement point of the measuring object S. For example, the angle of the placement surface for the measuring object S can arbitrarily be set such that halation caused by regular reflection of the measurement light or illumination light does not occur at the measurement point. Accordingly, the convenience of the measurement of the measuring object S is improved. 
     [9] Region Information 
     As described above, in the measuring device  500  according to the present embodiment, the effective regions MR 1 , MR 2  are the regions, which can be irradiated with the measurement light using the light projecting units  110 A,  110 B and in which the image of the region can be captured using the light receiving unit  120 . Additionally, the effective region of the light receiving unit  120  may be set in consideration of the following points. 
     The effective region may be set such that the placement surface of the stage plate  142  of the stage  140  is removed. In this case, the effective region may be set according to the state of the inclination part  402  of the stage plate  142  in the configuration in which the inclination part  402  of the stage plate  142  can be switched between the horizontal attitude and the inclination attitude as illustrated in the examples of  FIGS. 40 and 51 . In these cases, the user can measure the measuring object S without considering the presence of the stage plate  142 . 
     As illustrated in the example of  FIG. 49 , it is assumed that while the light shielding mechanism  600  is attached to the measuring unit  100 , the rear light shielding member  650  and the front and side light shielding member  660  are attached to the rear cover member  610  and the front cover member  620 , respectively. In this case, when the imaging visual field of the light receiving unit  120  is large, the image of the inner surface of the front and side light shielding member  660  is partially captured together with the measuring object S during the imaging of the measuring object S using the light receiving unit  120 . Therefore, the effective region may be set so as to be located on the inner side of the front and side light shielding member  660 , and such that the outer edge of the effective region comes close to the front and side light shielding member  660 . This enables the effective region to be widely ensured on the inner side of the front and side light shielding member  660 . 
     [10] Effects 
     In the measuring device  500  according to the present embodiment, the head unit  190  and the installation part  161  are fixedly coupled together using the stand  162 . Accordingly, the range where the space on the stage  140  is irradiated with the measurement light using the light projecting units  110 A,  110 B and the positional relationship between the imaging visual fields TR 1 , TR 2  of the light receiving units  120 A,  120 B is uniquely fixed. Therefore, it is not necessary for the user to previously adjust the positional relationship among the light projecting units  110 A,  110 B, the light receiving units  120 A,  120 B, and the stage  140 . 
     The imaging visual field TR 2  of the light receiving unit  120 B is smaller than the imaging visual field TR 1  of the light receiving unit  120 A, and included in the imaging visual field TR 1 . In this case, the measuring object S having the relatively larger size can appropriately be located within the imaging visual field TR 1  by the selection of the light receiving unit  120 A. By the selection of the light receiving unit  120 B, the measuring object S having the relatively smaller size can appropriately be located within the imaging visual field TR 2  while an unnecessary surrounding portion is not located within the imaging visual field TR 2 . Because the optical axis A 2  of the light receiving unit  120 B is located below the optical axis A 1  of the light receiving unit  120 A, it is not necessary to move the stage  140  or the measuring object S upward so as to locate the measuring object S within the imaging visual field TR 2 . Therefore, the operability of the measuring device  500  can be improved. 
     In the measurement optical unit  10 , the light projecting unit  110 A and the light receiving units  120 A,  120 B are coupled together using the plurality of coupling members  15 , and the light projecting unit  110 B and the light receiving units  120 A,  120 B are coupled together using the plurality of coupling members  16 . The plurality of coupling members  15  are separated from the plurality of coupling members  16 , so that the heat generated from the light projecting units  110 A,  110 B and the light receiving units  120 A,  120 B can easily be diffused. Additionally, the cooling air can easily be introduced in order to cool the light projecting units  110 A,  110 B and the light receiving units  120 A,  120 B. Therefore, the change of the positional relationship between the light projecting units  110 A,  110 B and the light receiving units  120 A,  120 B can be prevented from occurring due to a temperature change. Therefore, measurement accuracy can be improved. 
     It is not necessary to add a device such as a temperature sensor to the measuring device  500  for the purpose of temperature compensation of the measurement result. Because of the high heat dissipation between the coupling members  14 , between the coupling members  15 , and between the coupling members  16 , the horizontal support plate  11 , the vertical support plates  12 ,  13 , and the deformation of the coupling members  14  to  16  is reduced to a low level. Accordingly, it is not necessary that the horizontal support plate  11 , the vertical support plates  12 ,  13 , and the coupling members  14  to  16  be made of an expensive material having a small linear expansion coefficient. As a result, the cost of the measuring device  500  can be reduced. 
     In the present embodiment, contact regions of the coupling members  14  to  16  with the vertical support plates  12 ,  13  or light projecting units  110 A,  110 B can be maintained at the minimum. Even if the vertical support plates  12 ,  13  and the coupling members  14  to  16  are slightly deformed due to the temperature change, the vertical support plates  12 ,  13  and the coupling members  14  to  16  have the small variation in deformation degree, and the angle between the light projecting units  110 A,  110 B and the light receiving units  120 A,  120 B does not change. Therefore, degradation of the measurement accuracy of the point cloud data can be prevented. 
     [11] Other Embodiments 
     (1) In the above embodiment, the effective region is set in each light receiving unit  120 . However, the present invention is not limited thereto. A plurality of effective regions having different sizes may be set to one light receiving unit  120 . In this case, the CPU  210  may receive the user selection of the effective region, and generate the measurement data based on the effective region selected by the user. 
     (2) In the above embodiment, the information indicating the effective region is previously stored in the drive unit  240  as the region information at the time of shipment of the measuring device  500 . However, the present invention is not limited thereto. For example, the region information may be edited by the user before the measurement of the measuring object S. In this case, the user can set the more appropriate region information according to the measurement content of the measuring object S. Therefore, the convenience of the measuring device  500  is improved. 
     (3) In the above embodiment, in the measuring unit  100  of the measuring device  500 , the two light receiving units  120 A,  120 B that differ from each other in the magnification of the optical system is provided in order to capture the image of the measuring object S. However, the present invention is not limited thereto. In the measuring device  500 , only one light receiving unit  120  may be provided as the configuration that captures the image of the measuring object S. In this case, the configuration of the measuring device  500  is further simplified. 
     (4) In the above embodiment, the magnification of the optical system does not change in the light receiving units  120 A,  120 B. However, the present invention is not limited thereto. A zoom lens may be provided as the optical system for each of the light receiving units  120 A,  120 B. In this case, the sizes of the effective regions MR 1 , MR 2  corresponding to the light receiving units  120 A,  120 B may be changed according to the magnification of the zoom lens. 
     (5) In the above embodiment, the monocular camera is used as the light receiving units  120 A,  120 B. A compound-eye camera may be used instead of or in addition to the monocular camera. Alternatively, a plurality of light receiving units  120 A and a plurality of light receiving units  120 B may be used to generate the three-dimensional shape data by a stereo method. In the above embodiment, the two light projecting units  110  are used. Alternatively, as long as the three-dimensional shape data can be generated, only one light projecting unit  110  may be used or at least three light projecting units  110  may be used. 
     In the case where the texture image data is obtained using the uniform measurement light from the light projecting unit  110 , the illumination light output unit  130  and the illumination light source  320  do not need to be provided. The texture image data can be generated by the synthesis of the pieces of pattern image data. In this case, the illumination light output unit  130  and the illumination light source  320  do not need to be provided. 
     In the above embodiment, the pattern image data and the texture image data are obtained using the common light receiving units  120 A,  120 B. Alternatively, a light receiving unit that obtains the three-dimensional shape data and a light receiving unit that obtains the live image data and the texture image data may separately be provided. 
     In the above embodiment, the point cloud data is generated by the triangular distance measuring method. Alternatively, the point cloud data may be generated by other methods such as TOF (Time Of Flight). 
     (6) In the above embodiment, the stage  140  is rotatable about the rotation axis Ax using the stage drive unit  146 , and is not moved in other directions. However, the present invention is not limited thereto. 
     For example, the stage  140  may be movable in at least one of the X-direction, the Y-direction, and the Z-direction while being rotatable about the rotation axis Ax. In this case, the rotation position and position of the stage  140  can freely be changed while the measuring object S is placed on the stage  140  in the constant attitude. Accordingly, during the data generation processing, the image of the measuring object S can be captured from various directions. As a result, the three-dimensional shape data can be obtained in the wider range of the surface of the measuring object S. 
     [12] Correspondence Relationship Between Each Component of the Claims and Each Section of the Embodiment 
     An example of a correspondence between each component of the claims and each section of the embodiment will be described below, but the present invention is not limited to the following examples. 
     In the above embodiment, the installation part  161  is an example of the stage holding unit, the measuring object S is an example of the measuring object, the stage  140  is an example of the stage, and the light projecting unit  110  is an example of the light projecting unit. The light projecting units  110 A,  110 B are examples of the first and second light projecting units, respectively, the light receiving units  120 A,  120 B are examples of the first and second light receiving units, respectively, and the head unit  190  is an example of the head unit. The optical axes A 1 , A 2  are examples of the optical axis, the stand  162  is an example of the coupling part, the receiving unit  505  is an example of the selection section, the point cloud data generating unit  501  is an example of the point cloud data generating section, and the measurement unit  504  is an example of the measuring section. 
     The imaging visual fields TR 1 , TR 2  are examples of the first and second imaging visual fields, respectively, the measuring device  500  is an example of the measuring device, the lens  122  is an example of the first and second light reception lens, and the illumination light output unit  130  is an example of the illumination unit. The output port  131  is an example of the illumination light output port, the rotation axis Ax is an example of the rotation axis, the rotation control unit  506  is an example of the rotation control section, and the positional relationship calculating unit  507  is an example of the calculating section. The storage device  240  is an example of the storage section, the protrusion  163  and the groove  171   b  are examples of the positioning mechanism, the vertical support plates  12 ,  13  are examples of the holding tool, and the coupling members  15 ,  16  are examples of the coupling member. 
     Various components having the configuration or function described in the claims may be used as the components of the claims. 
     The present invention can be applied to various measuring devices that measure the measuring object.