JP2011185725A - Device for measurement of displacement or strain - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for measurement of displacement or strain, capable of facilitating keeping a relative position or attitude of an imaging device to a measuring object in a fixed state, or facilitating adjustment of the relative position or attitude to the measuring object. <P>SOLUTION: The device for measurement of the displacement or strain is constituted of an imaging device 2 and an image analyzer, wherein an image acquired by imaging a measuring object by the imaging device 2 is analyzed by the image analyzer, and displacement or strain of the measuring object is calculated. One fixed abutting member 13 and two micrometers 14 are mounted on the imaging device 2, and the fixed abutting member 13 and the tips of spindles 14b of the micrometers 14 are allowed to abut on the measuring object. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a displacement / strain measuring device that includes an imaging device and an image analysis device, and that analyzes an image obtained by imaging a measurement object using the image analysis device and calculates a displacement or strain of the measurement object. .

  First, the inventors of the present application invented a strain measurement method and apparatus for calculating the strain of an object by applying a digital image correlation method to two images obtained by imaging the object to be measured, and filed a patent application. (Japanese Patent Application No. 2009-204164, hereinafter referred to as “prior application”).

  The strain measuring device of the prior application is configured by an imaging device that images the surface of a measurement object and an image analysis device that analyzes an image captured by the imaging device and calculates displacement or strain. In addition, a CCD camera is used as the imaging device, and a computer in which a program describing an analysis method using a digital image correlation method is used as the image analysis device.

  The digital image correlation method is also disclosed in Patent Documents 1 to 4.

  Further, Patent Literature 5 discloses a strain gauge including an image detection device to which positioning means for adjusting the imaging target surface so as to be positioned at a predetermined height is attached.

JP 2005-099012 A JP 2006-329628 A JP 2006-330772 A JP 2007-078659 A JP-A-11-237217

  In the method and apparatus disclosed in the prior application, it is necessary to image the measurement object in the same direction and the same distance. This is because a change in the image caused by a difference in direction or distance is detected as a distortion of the measurement target. In order to obtain good measurement accuracy, it is necessary to position the imaging unit so that it always faces the measurement target, that is, so that the optical axis of the imaging unit is perpendicular to the surface of the measurement target.

  However, since the strain measurement device of the prior application lacked a means for keeping the relative position and orientation of the imaging device relative to the measurement object, it was difficult to image the measurement object in the same direction and the same distance.

  The strain gauge disclosed in Patent Document 5 also includes positioning means for adjusting the height of the imaging device, but lacks means for adjusting the attitude of the imaging device, so that the imaging device is correctly set as a measurement target. It was difficult to adjust to this.

  The present invention provides a displacement / strain measuring device that can easily keep a relative position and posture of an imaging device with respect to a measurement target constant or can easily adjust a relative position and posture with respect to the measurement target. With the goal.

  In order to solve the above-mentioned problem, the displacement / strain measuring device of the present invention includes an imaging device and an image analysis device, analyzes an image obtained by imaging a measurement object with the imaging device, and analyzes the image with the image analysis device. In the displacement / strain measuring apparatus for calculating the displacement or strain of the measurement object, the displacement / strain measurement apparatus includes a contact member attached to the imaging device and contacting the measurement object.

  The abutting member may be composed of one fixed abutting member and two advancing / retreating abutting members attached to end portions of the imaging device so as to freely advance and retract.

  The advance / retreat contact member may be a micrometer, and a tip of a spindle of the micrometer may contact the measurement object.

  The fixed abutting member may have a fitting portion that fits with a fitted member attached to the measurement object.

  A reference plate disposed in the field of view of the image pickup device and having a graphic pattern formed on a surface visible from the image pickup device; and a connection fixed to the image pickup device and swingably supporting the reference plate. The connecting member may include a pressing unit that urges the reference flat plate in a direction from the imaging device toward the measurement target and presses the reference flat plate against the measurement target.

  According to the present invention, since the contact member that contacts the measurement object is attached to the imaging apparatus, the relative position and orientation of the imaging apparatus with respect to the measurement object can be kept constant.

  Further, if the abutting member is composed of one fixed abutting member and two advancing / retracting abutting members attached to the end portion of the imaging device so as to be freely movable back and forth, the relative position of the imaging device with respect to the measurement object By adjusting the posture, the imaging apparatus can face the measurement object.

  Further, when the back surface of the reference flat plate is brought into contact with the measurement object and the image obtained by capturing the surface of the reference flat plate with the image pickup apparatus is analyzed, the inclination of the image pickup apparatus with respect to the measurement target object can be known.

  The above effects ultimately improve the accuracy of displacement / strain measurement.

It is a notional block diagram of a displacement / strain measuring device showing an example of an embodiment of the present invention. It is a block diagram of the imaging device which comprises a displacement / strain measuring device. It is a block diagram which shows the modification of a fixed contact member and a micrometer. It is a notional block diagram of the computer which comprises a displacement / strain measuring device. It is a flowchart which shows the outline of the process by a displacement / strain measurement program. It is a conceptual diagram which shows the principle of the displacement / strain measurement by a digital image correlation method. It is the external view of the specimen used for experiment. It is a figure which shows the relationship between the measured value of the axial direction strain by a displacement / strain measuring device, and the measured value by a strain gauge. It is a figure which shows the relationship between the measured value of the Poisson direction strain of the test piece by a displacement / strain measuring device, and the measured value by a strain gauge. It is a figure which shows the dispersion | variation in the measured value of the axial direction strain by a displacement / strain calculation apparatus. It is a figure which shows the dispersion | variation in the measured value of the axial direction distortion obtained by the conventional imaging device. It is a block diagram which shows the modification of an imaging device, (a) is the side view which carried out the cross section illustration, and (b) is sectional drawing cut | disconnected by the AA 'line of (a). It is an external view which shows the structure of a reference | standard flat plate and a connection member, (a) And (b) is a side view, (c) is a top view of a reference | standard flat plate. It is a perspective view which shows the structure of a reference | standard flat plate and a connection member. It is explanatory drawing explaining the effect | action of a reference | standard flat plate.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

  A displacement / strain measuring apparatus 1 shown in FIG. 1 is an example of an embodiment of the present invention. The displacement / strain measuring apparatus 1 includes an imaging device 2 and a computer 3, and an image of the measurement object 4 captured by the imaging device 2 is displayed on the computer 3. This is a device for obtaining the displacement or strain of the measurement object 4 by analyzing the above.

  Moreover, the imaging device 2 is comprised from the camera 5 and the light shielding cylinder 6, as shown in FIG.

  The camera 5 is a known so-called digital still camera, and includes a camera body 7 and a telecentric lens 8. The camera body 7 includes a CCD element, a shutter device, a storage device, an input / output interface and the like (all not shown), and an image formed on the CCD element is converted into an electrical signal (= image signal). The image signal can be converted and stored in a storage device, or an image signal can be output to an external device (for example, the computer 3) via an input / output interface.

  The telecentric lens 8 is a known lens system having an aperture stop (not shown) at the rear focal point of the lens so that the principal ray is parallel to the lens optical axis. Therefore, the angle of view is infinitely close to 0 degrees, distortion (distortion aberration) is small, and the size and position of the measurement object 4 can be accurately captured. In addition, an image having a certain size can be obtained regardless of the distance between the telecentric lens 8 and the measurement object 4.

  The light shielding cylinder 6 is a cylinder between the telecentric lens 8 and the measurement object 4, which is fixed to the camera 5 and shields external light incident on the telecentric lens 8. Here, the external light is natural light or artificial light incident on the telecentric lens 8 from other than the measurement object 4. In FIG. 2, the light shielding tube 6 is shown in a cross-sectional view for convenience of explanation.

  Further, an LED lamp 9 is provided inside the light-shielding tube 6 and is used as an illumination light source for imaging. The brightness of the LED lamp 9 is adjusted by the illumination power controller 10.

  In addition, a diffusion plate 11 is provided on the front side (left side in FIG. 2) of the LED lamp 9, that is, on the measurement object 4 side. The diffuser plate 11 is a kind of filter that diffuses the light emitted from the LED lamp 9 and illuminates the measurement object 4 evenly. In this embodiment, the transparent plate is made of transparent acrylic with roughened surface by sandpaper. A product in which a plurality of plates are stacked is used.

  In addition, an infrared radiation thermometer 12 is provided inside the light shielding tube 6. The infrared radiation thermometer 12 is a known temperature measuring unit that measures the surface temperature of the measurement object 4 in a non-contact manner, and includes an input / output interface (not shown) to output a measurement result to an external device (for example, the computer 3). be able to.

  Now, there is one fixed contact member 13 and two micrometers 14 at the end of the light shielding cylinder 6 on the measurement object 4 side, and protrudes toward the measurement object 4.

  The fixed contact member 13 is a member that contacts the measurement object 4 and positions the imaging device 2 with respect to the measurement object 4. The protruding height of the fixed abutting member 13 from the end of the light shielding tube 6 is such that when the fixed abutting member 13 abuts on the measurement object 4, the telecentric lens 8 is focused (the CCD element inside the camera body 7). Chosen to tie a statue on top). That is, a dimension is selected such that the distance between the camera 5 and the measurement object 4 is a regular distance.

  The micrometer 14 is an advancing / retreating contact member including a fixing portion 14a fixed to the light shielding cylinder 6 and a spindle 14b screwed to the fixing portion 14a. When the spindle 14b is rotated, the spindle 14b is in contact with the fixing portion 14a. Advance and retreat. Since the advance / retreat length of the spindle 14b is smaller than the rotation angle, the advance / retreat length of the spindle 14b with respect to the fixed portion 14a can be finely adjusted by rotating the spindle 14b.

  When the deformation or unevenness of the surface of the measurement object 4 is small enough to be ignored, that is, when the surface of the measurement object 4 is sufficiently flat, the end portions of the light shielding cylinder 6 of the fixed contact member 13 and the two spindles 14b If the fixed abutting member 13 and the two spindles 14 b are brought into contact with the measurement object 4, the imaging device 2 faces the measurement object 4. That is, the optical axis of the camera 5 (telecentric lens 8) is perpendicular to the surface of the measurement object 4.

  If the surface of the measuring object 4 is not flat, the spindle 14b of the micrometer 14 is rotated to adjust the protruding height of the spindle 14b from the end of the light shielding cylinder 6 (advanced / retracted length of the spindle 14b relative to the fixed portion 14a). Then, the orientation of the imaging device 2 is set so that the imaging device 2 faces the measurement object 4, that is, the optical axis of the camera 5 (telecentric lens 8) is perpendicular to the surface of the measurement object 4. Can be adjusted.

  The fixed contact member 13 and the micrometer 14 may be configured as shown in FIG. That is, the fitting portion 13 a is formed at the tip of the fixed contact member 13, and the fitting portion 13 a is fitted to the fitted member 15 fixed to the surface of the measurement object 4. Alternatively, the positioning member 16 may be fixed to the surface of the measurement object 4 so that the tip side surface of the spindle 14 b of the micrometer 14 is brought into contact with the side surface of the positioning member 16.

  In this way, the fixed member 15 and the positioning member 16 are fixed to the surface of the measurement object 4, and the fixed contact member 13 and the spindle 14b of the micrometer 14 are fitted and contacted with each other, thereby measuring. The reproducibility of the relative position of the imaging device 2 with respect to the object 4 is improved. That is, it becomes easy to repeatedly image a specific part of the measurement object 4.

  The computer 3 is configured as shown in FIG. 4, for example. That is, a central processing unit 3a, a storage device 3b, a communication interface (I / F) 3c, a keyboard 3d, a monitor 3e, and the like are provided. Further, the computer 3 is operated by the keyboard 3d, and the central processing unit 3a executes the program recorded in the storage device 3b. The central processing unit 3a reads data from the imaging device 1 through the communication interface (I / F) 3c according to the program, performs predetermined processing, displays the result on the monitor 3e, and stores the storage device. Record in 3b. In addition, the result of the processing can be output to a printer (not shown) via the communication interface (I / F) 3c. Alternatively, the result of the processing can be transmitted to another computer (not shown).

  In the storage device 3b of the computer 3, a program describing a procedure for calculating displacement / strain by the digital image correlation method is recorded. The central processing unit 3a roughly executes the processing shown in FIG. 5 according to the program. That is, first, before applying a load to the object to be measured (measurement object 4), a specific part of the object to be measured is imaged by the imaging device 2, and an initial image P1 is acquired and stored in the storage device 3b. (Step S1).

  Next, a load is applied to the object to be measured, and the specific part is imaged again by the imaging device 2 to obtain the posterior image P2 and stored in the storage device 3b (step S2).

  Next, two different points A and B on the initial image P1 are selected, and images of minute regions a and b (see FIG. 6) each including the points A and B are extracted (step S3).

  Next, the digital image correlation method is applied between the images of the minute areas a and b and the posterior image P2, and the correlation with the minute area a ′ and the minute area b where the correlation with the minute area a is maximized. A micro-region b ′ where is maximized is extracted from the posterior image P2 (step S4). Note that details of the digital image correlation method are disclosed in the prior application and Patent Documents 1 to 4, and thus the description thereof is omitted.

  Next, the point A ′ in the minute region a ′ is determined such that the relative position with respect to the minute region a ′ is equal to the relative position of the point A with respect to the minute region a. Similarly, a point B 'within the minute region point b' is determined such that the relative position with respect to the minute region b 'is equal to the relative position with respect to the minute region b (step S5). In the example shown in FIG. 6, since the micro areas a and b are determined so that the points A and B are located at the centers of the micro areas a and b, the centers of the micro areas a ′ and b ′ are determined. Points A ′ and B ′.

  Next, the length l of the line segment AB and the length l 'of the line segments A' and B 'are calculated (step S6).

  Finally, the values of l and l ′ are substituted into the following equation to determine the displacement d and strain ε (step S7).

  d = 1-l ', ε = d / l

[Example]
Since this displacement / strain measuring apparatus 1 was used to perform an experiment for measuring strain, the measurement result is shown in comparison with the measurement result according to the prior art.

  The specimen 17 used in the experiment is an H-shaped steel having a width of 150 mm, a height of 150 mm, and a length of 530 mm as shown in FIG. An irregular polka dot pattern having a diameter of about 0.1 mm to 1.0 mm (average 0.2 mm) is formed by spraying.

  The measurement target part 17a is a rectangular area of approximately 20 mm square, and the imaging target part 17a is imaged by the imaging device 2 to obtain an initial image P1 and a posterior image P2 composed of 6 million (3000 × 2000) pixels. .

  Four strain gauges 17b were attached to the periphery of the measurement target region 17a, and the measured values obtained by the strain gauge 17b and the measured values obtained by the displacement / strain measuring device 1 were compared.

  In addition, a uniaxial compressive load in the length direction of the specimen 17 was applied, and the strain was calculated while changing the magnitude of the load. Hereinafter, the strain in the load direction (that is, the length direction of the specimen 17) is referred to as “axial strain”, and the strain generated in the direction perpendicular to the load direction is referred to as “Poisson direction strain”.

  When the axial strain of the specimen 17 is measured using the displacement / strain measuring device 1, the vertical axis is taken, and the result measured using the strain gauge 17 b is taken on the horizontal axis and plotted, a diagram as shown in FIG. Is obtained. When the measured value of the displacement / strain measuring device 1 is equal to the measured value by the strain gauge 17b, the measurement result is plotted on the diagonal line indicated by the broken line in the figure. According to FIG. 8, the measurement result is the diagonal line. It is lined up near. That is, both agree well.

  Similarly to FIG. 8, the measurement result of the Poisson direction strain by the displacement / strain measuring device 1 is compared with the measurement result by the strain gauge 17b and is shown in FIG. Regarding the Poisson direction strain, the measured value of the displacement / strain measuring device 1 and the measured value of the strain gauge 17b are in good agreement.

  Since the Poisson distortion is smaller than the axial distortion, it is generally difficult to measure by the digital image correlation method. That is, although the Poisson direction strain measurement accuracy by the digital image correlation method is poor, it can be seen that the displacement / strain measuring device 1 gives the same result as the case of the axial strain.

  When the axial strain measurement of the specimen 17 by the displacement / strain measuring device 1 is performed a plurality of times and the results are summarized in the same manner as in FIG. 8, the result is as shown in FIG. It can be seen that the difference between the maximum value and the minimum value is small, that is, the variation in the measured value is small.

  On the other hand, the result of measuring the axial strain a plurality of times by applying the digital image correlation method to the image obtained by imaging the specimen 17 using a conventional imaging device having a non-telecentric lens is the measurement result by the strain gauge 17b. As compared with FIG. It can be seen that the measurement values obtained by the image pickup apparatus including the non-telecentric lens greatly deviate from the measurement values obtained by the strain gauge and have large variations. That is, comparing FIG. 10 with FIG. 11, it can be understood that the displacement / strain measuring device 1 including the imaging device 2 including the telecentric lens 8 can perform measurement with higher accuracy than the conventional device.

  The infrared radiation thermometer 12 provided in the imaging device 2 is used for subtracting a component caused by the temperature difference from the measured value. For example, the temperature T1 of the specimen 17 when the initial image P1 is imaged and the temperature T2 of the specimen 17 when the posterior image P2 is imaged are measured by the infrared radiation thermometer 10, and the temperature difference dT (= T2− T1) multiplied by the linear expansion coefficient of the specimen 17 is subtracted from the measured value, and the component due to the temperature difference is subtracted.

[Modification]
In addition to the configuration described above, if the reference flat plate 18 and the connecting member 19 are attached to the tip of the light-shielding tube 6 of the imaging device 2 as shown in FIG. The relative position and posture with respect to 4 can be easily adjusted. Hereinafter, the configuration and operation of a modification of the imaging device 2 will be described.

  FIG. 12A is a side view of the imaging apparatus 2, and FIG. 12B is a cross-sectional view of the imaging apparatus 2 taken along the line AA 'in FIG. As shown in FIG. 12A and FIG. 12B, at the tip of the light shielding tube 6 of the imaging device 2. Two reference flat plates 18 are respectively attached via connecting members 19. As is clear from FIG. 12B, one of the two reference flat plates 18 is arranged so that its longitudinal direction is parallel to the X axis, and the other of the two reference flat plates 18 is on the Y axis. They are arranged in parallel. In addition, the two reference plates 18 are arranged in the field of view (imaging range) of the imaging device 2. The reference flat plate 18 is pivotally supported by the connecting member 19 and freely swings around the swing axis P.

  Further, the reference flat plate 18 and the connecting member 19 are configured as shown in FIGS. That is, the connecting member 19 includes a fixed piece 20 and a movable piece 21, and the fixed piece 20 is fixed to the light shielding tube 6. The movable piece 21 includes rods 22 and 23, and the rods 22 and 23 freely slide with respect to the fixed piece 20. Therefore, the movable piece 21 can freely move in the Z-axis direction. A coil spring 24 is bridged between the fixed piece 20 and the movable piece 21 to urge the movable piece 21 in the direction from the light shielding cylinder 6 (imaging device 2) toward the measurement object 4. For this reason, as shown in FIG. 13B, when the movable piece 21 is pushed upward, the coil spring 24 acts in a direction to push the movable piece 21 downward (in the direction toward the measurement object 4). Further, the reference flat plate 18 is pivotally supported at the tip of the rod 22 via a bolt 25 and swings freely around the swing axis P.

  FIG. 13C is a view of the reference flat plate 18 viewed from the direction A in FIG. 13A, in other words, a plan view viewed from the imaging device 2. As shown in FIG. 13C, a random mosaic pattern is formed on the plane of the reference flat plate 18 that can be seen from the imaging device 2.

  Since it is configured in this way, when the imaging device 2 is placed on the measurement object 4, the reference flat plate 18 contacts the measurement object and tilts following the measurement object 4. When the measurement object 4 is inclined relative to the imaging device 2, the reference flat plate 4 is inclined as much as the measurement object 4. Therefore, if the inclination of the reference flat plate 18 is known, the inclination of the measurement object 4 can be known.

  Now, as described above, since a mosaic-like figure pattern (see FIG. 13C) is formed on the surface of the reference flat plate 18 on the side of the image pickup device 2, an image obtained by imaging the reference flat plate 18 with the image pickup device 2. A digital image correlation method can be applied.

  Here, a line segment fixed on the reference flat plate 18 is assumed. The “apparent length” when the line segment is viewed from the imaging device 2 changes when the reference plate 18 is inclined relative to the imaging device 2. Therefore, if a change in the “apparent length” of the line segment is known by applying a digital image correlation method to an image obtained by imaging the reference flat plate 18 with the image pickup device 2, the reference plate 18 relative to the image pickup device 2 is known. You can know the angle of inclination. That is, the relative inclination angle of the measuring object 4 with respect to the imaging device 2 can be known.

  For example, as shown in FIG. 15, the imaging apparatus is upright with respect to the measurement object, that is, is positioned so that the optical axis of the imaging apparatus 2 is perpendicular to the surface of the measurement object 4 ( In FIG. 15A, an image obtained by imaging the reference flat plate with the imaging device (hereinafter referred to as “reference image”) and a state in which the imaging device 2 is inclined with respect to the measurement object 4 by an angle θ from an upright position ( In FIG. 15B), an image (hereinafter referred to as “tilted image”) obtained by imaging the reference flat plate with the imaging device is considered. Further, when the digital image correlation method is applied to the reference image and the tilted image by virtually imagining the line segment AB fixed to the reference flat plate 18, the “apparent length” of the line segment AB changes from L to L ′. I can know that.

  As shown in FIG. 15C, the apparent lengths L and L ′ and the angle θ have the following relationship, and therefore the magnitude of the angle θ can be determined if the apparent lengths L and L ′ are known. I can know.

  cos θ = L ′ / L

  Further, as shown in FIG. 12, the imaging device 2 includes two reference flat plates 18 arranged in parallel to the X axis and the Y axis. The relative inclination angle around the axis can be known.

  The inclination angle of the measurement object 4 obtained in this way with respect to the imaging device 2 can be used for correcting the posture of the imaging device 2.

  The embodiment described above is an example of a specific embodiment of the present invention, and the technical scope of the present invention is not limited to the apparatus method shown in the above embodiment. The present invention can be freely modified, applied, or improved within the scope of the technical idea described in the claims.

  For example, in the said embodiment, although the example which uses the LED lamp 9 as a light source of an illumination means was shown, the light source of the illumination means of this invention is not limited to an LED lamp. Various kinds of light sources known or appearing in the future can be freely selected to carry out the present invention.

  Moreover, in the said embodiment, although the thing which laminated | stacked several transparent acrylic plates which roughened the surface with sandpaper and gave the fine unevenness | corrugation was shown as a specific example of the diffusion plate 11, the diffusion plate of this invention starts. The member is not limited. The diffusion plate of the present invention only needs to transmit the light emitted from the light source of the illuminating means, change the direction of the light transmitted through the diffusion plate at random, and illuminate the measurement object evenly, and its material, shape, or mechanical configuration You can choose freely.

  Moreover, in the said embodiment, although the micrometer 14 was shown as a specific example of the advance / retreat contact member, the advance / retreat contact member of this invention is not limited to a micrometer. The advancing / retreating contact member of the present invention includes a fixed portion fixed to the light shielding cylinder and a contact portion attached to the fixed portion so as to freely advance and retreat, and the end of the corresponding contact portion is configured to contact the measurement object. It is sufficient if it is made, and its material, shape, or mechanical configuration can be freely selected.

  In the above embodiment, as a specific example of the image analysis apparatus, the computer 3 in which the program describing the analysis method based on the digital image correlation method is installed is shown. However, the image analysis apparatus of the present invention is limited to such a computer. Not. For example, the image analysis apparatus can be configured by replacing all or part of the program with hardware.

DESCRIPTION OF SYMBOLS 1 Displacement / strain measuring device 2 Imaging device 3 Computer 4 Measurement object 5 Camera 6 Shading cylinder 7 Camera body 8 Telecentric lens 9 LED lamp 10 Illumination power supply controller 11 Diffuser 12 Infrared radiation thermometer 13 Fixed contact member 14 Micrometer 15 Member to be fitted 16 Positioning member 17 Specimen 18 Reference plate 19 Connecting member 20 Fixed piece 21 Movable piece 22 Rod 23 Rod 24 Coil spring 25 Bolt

Claims (5)

In the displacement / strain measuring device, which is constituted by an imaging device and an image analysis device, analyzes an image obtained by imaging the measurement object by the imaging device, and calculates a displacement or strain of the measurement object,
A displacement / strain measuring device, comprising: a contact member attached to the imaging device and contacting the measurement object. The contact member is
One fixed contact member;
The displacement / strain measuring device according to claim 1, further comprising: two advancing / retreating members attached to an end portion of the imaging device so as to freely advance and retract. The displacement / strain measuring apparatus according to claim 2, wherein the advance / retreat contact member is a micrometer, and a tip of a spindle of the micrometer contacts the measurement object. The displacement / strain measuring device according to claim 2, wherein the fixed abutting member has a fitting portion that fits with a fitting member attached to the measurement object. A reference plate that is disposed within the field of view of the imaging device and has a graphic pattern formed on the surface visible from the imaging device;
A coupling member fixed to the imaging device and supporting the reference plate so as to be swingable;
The said connection member has a press means which urges | biases the said reference flat plate in the direction which goes to the said measurement target object from the said imaging device, and presses the said reference flat plate to the said measurement target object. Displacement / strain measuring device.

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