JP6080389B2 - Shape measuring device - Google Patents

Description

  The present invention relates to a shape measuring apparatus for measuring the shape of a lens, a mold or the like with high accuracy.

  The conventional shape measuring apparatus is configured to contact the surface of the object to be measured, which is the surface to be measured, and scan along the surface, so that the probe follows the surface while the probe follows the surface. Driven in the direction (see Patent Document 1). The laser length measurement optical system is fixedly provided on the moving body together with a measurement probe and the like, and measures the distance of the Z coordinate of the probe based on the Z reference mirror by a known optical interference method. Similarly, the laser measuring optical system measures the distance between the X coordinate and the Y coordinate of the probe based on the X reference mirror and the Y reference mirror, respectively.

  Said X reference mirror, Y reference mirror, and Z reference mirror are being fixed on the stone surface plate via the support part. The X stage and the Y stage move the moving body in the X axis direction and the Y axis direction, respectively. With the above configuration, the probe is scanned in the X and Y axis directions while following the shape of the surface of the object to be measured. Then, a column of Z coordinate data at the scanning position of the XY coordinates of the probe is obtained, and the shape of the surface of the object to be measured is measured based on the column of Z coordinate data.

Japanese Patent No. 3827496

  However, although the conventional example described in Patent Document 1 describes the measurement of the coordinates with reference to the reference mirror, feedback control is performed to position the probe with reference to a reference structure such as a reference mirror. is not. This makes it difficult to scan the target position with a probe with high accuracy in a small object to be measured such as a pickup lens for a DVD or Blu-ray disc.

  Further, the coordinate system based on the X reference mirror, the Y reference mirror, and the Z reference mirror includes an orthogonality error of the reference mirror, and is not an ideal XYZ orthogonal coordinate system. In other words, when the probe position coordinates are obtained based on the measurement results of the probe distance to the reference structure, the probe position coordinates are not based on the ideal coordinate system, but are based on the reference structure coordinate system. It becomes that. For this reason, it is difficult to scan the position aimed by the probe in an ideal XYZ orthogonal coordinate system only by positioning based on the reference structure.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a shape measuring apparatus that improves the measurement accuracy of the surface shape of an object to be measured by scanning a probe at a target position with high accuracy.

The present invention relates to a shape measuring apparatus for measuring the shape of the surface of an object to be measured, a probe that scans the surface of the object to be measured, a first stage that supports the object to be measured, and a first stage that supports the probe. a two-stage unit, and driving at least one of the first stage portion and the second stage unit, a driving unit for relatively scanning the probe relative to the surface of the object to be measured, the drive unit an encoder for detecting a rotational position, is supported by the first stage portion, and the criteria structure having a reference surface, a measuring section for measuring the distance in the scanning direction of the probe relative to the reference surface of the reference structure, the A target coordinate setting unit for setting a target position coordinate in the scanning direction of the probe with reference to a two-coordinate system; and a target coordinate with respect to the second coordinate system set by the target coordinate setting unit. A coordinate conversion unit that performs orthogonality correction for correcting an orthogonality error of the reference structure, performs coordinate conversion so as to be based on the first coordinate system defined by the reference structure, and the measurement A position coordinate calculation unit that performs pitching correction for correcting an inclination amount of the probe with respect to the reference plane based on a measurement result of the unit, and obtains a position coordinate of the probe with reference to the first coordinate system; and the coordinate conversion unit A first subtraction unit that subtracts the output of the position coordinate calculation unit from the output of the output, and a first position control unit that generates and outputs a first command value based on the output of the first subtraction unit; Generating a second command value for driving the drive unit based on the output of the second subtracting unit, and a second subtracting unit that subtracts the output of the encoder from the first command value a second position control unit to and outputs, with a And wherein the door. Further, the present invention provides a shape measuring apparatus for measuring the shape of the surface of the object to be measured, a probe that scans the surface of the object to be measured, a first stage unit that supports the object to be measured, and the probe that supports the probe. A second stage unit that drives, at least one of the first stage unit and the second stage unit to drive the probe relative to the surface of the object to be measured, and the drive An encoder that detects the rotational position of the unit, a reference structure that is supported by the first stage unit and has a reference surface, and a measurement unit that measures the distance in the scanning direction of the probe with respect to the reference surface of the reference structure; A target coordinate setting unit that sets a target position coordinate in the scanning direction of the probe with reference to a second coordinate system, and an inclination amount of the probe with respect to the reference plane based on a measurement result of the measurement unit For the output of the position coordinate calculation unit, the position coordinate calculation unit that performs pitching correction to be corrected and obtains and outputs the position coordinates of the probe with reference to the first coordinate system defined by the reference structure, A coordinate conversion unit that performs orthogonality correction for correcting an orthogonality error of the reference structure, converts the coordinates so that the second coordinate system is used as a reference, and outputs the coordinates from the output of the target coordinate setting unit A first subtracting unit that subtracts and outputs the output of the conversion unit; a first position control unit that generates and outputs a first command value based on the output of the first subtracting unit; and the first command A second subtracting unit that subtracts the output of the encoder from the value and outputs the second subtracting unit, and generates and outputs a second command value for driving the driving unit based on the output of the second subtracting unit And a position control unit.

  According to the present invention, since the probe can be scanned with high accuracy to the target position of the device under test, the surface shape of the device under test can be measured with high accuracy.

It is explanatory drawing which shows schematic structure of the shape measuring apparatus which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows arrangement | positioning of each reference mirror. It is a control block diagram of a shape measuring apparatus. It is a functional block diagram which shows the function of NC controller of the shape measuring apparatus which concerns on 1st Embodiment of this invention. It is a functional block diagram which shows the function of NC controller of the shape measuring apparatus which concerns on 2nd Embodiment of this invention. It is a functional block diagram which shows the function of NC controller of the shape measuring apparatus which concerns on 3rd Embodiment of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is an explanatory diagram showing a schematic configuration of a shape measuring apparatus according to the first embodiment of the present invention. The shape measuring apparatus 100 includes a contact-type probe 21, and scans the probe 21 relative to the surface of the workpiece W while the tip of the probe 21 is in contact with the surface of the workpiece (measurement object) W. The shape of the surface of the workpiece W is measured. In FIG. 1, the X-axis direction in the orthogonal coordinate system (XYZ orthogonal coordinate system) and the Y-axis direction orthogonal to the X-axis direction indicate the scanning direction, and the Z-axis orthogonal to these X-axis direction and Y-axis direction. The direction indicates a direction orthogonal to the scanning direction.

  The shape measuring apparatus 100 includes vibration isolation tables 10a, 10b, and 10c that constitute a base. On the vibration isolation tables 10a, 10b, and 10c, a bed 11 serving as a base of the entire apparatus is disposed. These vibration isolation tables 10a, 10b and 10c are supported at three locations. The bed 11 has a support surface 26 for supporting the base surface plate 1, and supports the base surface plate 1 at three places on the support surface 26. The first support point has a substantially conical recess 27 provided on both the bottom surface of the base surface plate 1 and the support surface 26, and the recesses 27, 27 sandwich a sphere 29 a. The second support point is located on a straight line passing through the first support point and parallel to the Y axis, and the ridgeline direction is made to coincide with both the bottom surface of the base surface plate 1 and the support surface 26 in the Y axis direction. A substantially triangular prism-shaped recess 28 is provided, and the recesses 28, 28 are configured to sandwich a sphere 29 b. The third support point is located at a predetermined distance in the X-axis direction from the first and second support points, and a sphere 29c is sandwiched between both the bottom surface of the base surface plate 1 and the support surface 26. It consists of

  The base surface plate 1 is a fixed stage portion (first stage portion) that supports the workpiece W. A workpiece W is fixed to the upper surface of the base surface plate 1.

  Further, three support columns 5a, 5b, and 5c are fixed to the upper surface of the base surface plate 1, and the metrology frame 25 is supported at three positions on the support columns 5a, 5b, and 5c. A metrology frame 25 is firmly fixed to the first support point 22 on the first support column 5a. The second support point 24 on the second support column 5b is on a straight line passing through the first support point 22 and parallel to the Y axis, and the cross section is long in the X axis direction and thin in the Y axis direction (thin plate shape). ). The third support point 23 is located at a position separated from the first support point 22 by a predetermined distance in the X-axis direction, and is formed in a cylindrical shape having a small diameter.

  In the metrology frame 25, an X reference mirror 7, a Y reference mirror 8, and a Z reference mirror 9 are fixed as standard structures. That is, the X reference mirror 7, the Y reference mirror 8, and the Z reference mirror 9 are supported on the base surface plate 1 via the metrology frame 25 and the three support columns 5a, 5b, and 5c.

  An X-axis slide guide 12 is fixed on the bed 11, and an X-slide 3 is supported on the X-axis slide guide 12 so as to be slidable in the X-axis direction. The X slide 3 is slide-driven by an X-axis slide drive motor 13 and a ball screw 14 as a drive unit. A Y-axis slide guide 15 is fixed to the X slide 3 along the Y-axis direction, and the Y-slide 2 is supported by the Y-axis slide guide 15 so as to be slidable in the Y-axis direction. The Y slide 2 is slide-driven by a Y-axis slide drive motor 16 and a ball screw 17 as a drive unit. Further, a Z-axis slide guide 18 is fixed to the Y slide 2 along the Z-axis direction, and the Z-slide 4 is supported by the Z-axis slide guide 18 so as to be slidable in the Z-axis direction. The Z slide 4 is slide driven by a Z axis slide drive motor 19 and a ball screw 20. A probe 21 is fixed to the Z slide 4.

  With the above configuration, the probe 21 can be moved three-dimensionally in the XYZ axial directions with respect to the bed 11. That is, the X slide 3 is a moving stage unit that supports the probe 21 via the Z slide 4 and the Y slide 2, and the Y slide 2 is a moving stage unit that supports the probe 21 via the Z slide 4. The X-axis slide drive motor 13 drives the X slide 3 to scan the probe 21 in the X-axis direction relative to the surface of the workpiece W. The Y-axis slide drive motor 16 drives the Y slide 2 to scan the probe 21 in the Y-axis direction relative to the surface of the workpiece W.

  FIG. 2 is an explanatory diagram showing the arrangement of the reference mirrors. Each X reference mirror 7, Y reference mirror 8, and Z reference mirror 9 have reflection surfaces 7a, 8a, 9a, and these reflection surfaces 7a, 8a, 9a are formed in a planar shape.

  The reflection surface 7a of the X reference mirror 7 and the reflection surface 8a of the Y reference mirror 8 are attached to the metrology frame 25 so as to be substantially orthogonal to each other. The reflecting surface 9a of the Z reference mirror 9, the reflecting surface 7a of the X reference mirror 7, and the reflecting surface 8a of the Y reference mirror 8 are attached to the metrology frame 25 so as to be substantially orthogonal to each other. The reflection surfaces 7a, 8a, 9a of the X reference mirror 7, the Y reference mirror 8, and the Z reference mirror 9 are used as measurement reference surfaces.

FIG. 3 is a control block diagram of the shape measuring apparatus. As shown in FIG. 3, the shape measuring apparatus 100 includes an electrical unit 200 and five optical interferometers 201 _X1 , 201 _X2 , 201 _Y1 , 201 _Y2 , 201 _Z (201). In addition, the shape measuring apparatus 100 includes three encoders 205, 206, and 207 provided in the motors 13, 16, and 19.

As shown in FIG. 3, the tip of the Z slide 4 shown in FIG. 1 is used for measuring the distances X1 and X2 in the X-axis direction (scanning direction) of the probe 21 with respect to the reflecting surface 7a (FIG. 2) of the X reference mirror 7. Two optical interferometers 201 _X1 and 201 _X2 are provided. Further, at the tip of the Z slide 4, the two shown in FIG. 3 are used for measuring the distances Y 1 and Y 2 in the Y-axis direction (scanning direction) of the probe 21 with respect to the reflecting surface 8 a (FIG. 2) of the Y reference mirror 8. Optical interferometers 201 _Y1 and 201 _Y2 are provided. Further, the distal end of the Z slide 4, the optical interferometer 201 _Z shown in FIG. 3 used in the measurement of the distance Z in the Z-axis direction of the probe 21 relative to the reflecting surface 9a (Fig. 2) of the Z reference mirror 9 is provided ing.

The electrical unit 200 is equipped with five laser length measurement boards 202 _X1 , 202 _X2 , 202 _Y1 , 202 _Y2 , 202 _Z (202) for capturing the interference signals of the respective optical interferometers 201. The laser length measurement board 202 obtains the distances X1, X2, Y1, Y2, and Z based on the interference signal obtained from the optical interferometer 201.

In the first embodiment, the optical interferometer 201 _X1 and the laser length measurement board 202 _X1 constitute a first laser length measurement device 203 _X1 as a first length measurement device. The optical interferometer 201 _X2 and the laser length measurement board 202 _X2 constitute a second laser length measurement device 203 _X2 as a second length measurement device. The optical interferometer 201 _Y1 and the laser length measuring board 202 _Y1 constitute a first laser length measuring device 203 _Y1 as a first length measuring device. The optical interferometer 201 _Y2 and the laser length measuring board 202 _Y2 constitute a second laser length measuring device 203 _Y2 as a second length measuring device. The optical interferometer 201 _Z and the laser length measurement board 202 _Z constitute a laser length measurement device 203 _Z as a length measurement device.

The first laser length measuring device 203 _X1 measures the first distance X1 in the X-axis direction that is the scanning direction of the probe 21 with respect to the first point P _X1 on the reflection surface 7a of the X reference mirror 7 that is on the reference plane. The second laser length measuring device 203 _X2 is a second distance in the X-axis direction of the probe 21 with respect to the second point P _X2 on the reflecting surface 7a of the X reference mirror 7 that is shifted in the Z-axis direction with respect to the first point P _X1 . Measure X2.

The first laser measurement device 203 _Y1 is measured first distance Y1 in the Y axis direction is the scanning direction of the probe 21 relative to the first point P _Y1 on the reflecting surface 8a of the Y reference mirror 8 is on the reference plane To do. Second laser length measuring machine _{203 Y2} is a second distance in the Y-axis direction of the probe 21 relative to the second point _{P Y2} on the reflecting surface 8a of the Y reference mirror 8 which is shifted in the Z axis direction with respect to the first point _{P Y1} Measure Y2.

Further, the laser length measuring device 203 _Z measures a distance Z in the Z-axis direction that is a direction orthogonal to the scanning direction of the probe 21 with respect to the point P _Z on the reflection surface 9 a of the Z reference mirror 9.

  The distance data measured by each laser length measuring device 203 is output to the measurement computer 204 and processed. The distance data measured by each laser length measuring device 203 is also output to the NC controller 208 that controls the X slide 3, the Y slide 2, and the Z slide 4.

  Further, the position data of each encoder 205, 206, 207 is also output to the NC controller 208. The encoder 205 is an encoder that detects the rotational position of the X-axis slide drive motor 13. The encoder 206 is an encoder that detects the rotational position of the Y-axis slide drive motor 16, and the encoder 207 is an encoder that detects the rotational position of the Z-axis slide drive motor 19.

  The drive signals output from the NC controller 208 are input to the motor drivers 209, 210, and 211, and the motors 13, 16, and 19 are driven by the motor drivers 209, 210, and 211.

  The motor driver 209 is an X-axis slide drive motor 13, the motor driver 210 is a Y-axis slide drive motor 16, and the motor driver 211 is a drive control unit that controls the drive of the Z-axis slide drive motor 19.

In the first embodiment, the measurement unit 221 that measures the distance in the scanning direction of the probe 21 with respect to the reflection surface 7a of the X reference mirror 7 is configured by the first laser length measuring device 203 _X1 and the second laser length measuring device 203 _X2. Has been. The first laser length measuring device 203 _Y1 and the second laser length measuring device 203 _Y2 constitute a measuring unit 222 that measures the distance in the scanning direction of the probe 21 with respect to the reflecting surface 8a of the Y reference mirror 8.

  In FIG. 2, the length L1 is a distance from the Z reference mirror 9 to the height of the measurement axis at distances X1 and Y1. The length L2 is the difference in height between the measurement axis at the distances X1 and Y1 and the measurement axis at the distances X2 and Y2. The length L3 is a distance from the height of the measurement axis of the distances X2 and Y2 to the reference mirror 21b attached to the shaft 21a of the probe 21. The length L4 is a distance from the reference mirror 21b of the probe 21 to the tip 21c of the probe 21.

  FIG. 4 is a functional block diagram showing functions of the NC controller of the shape measuring apparatus according to the first embodiment of the present invention. The control block shown in FIG. 4 is configured by an NC controller 208. Here, the control of the X-axis slide drive motor 13 that drives the X-slide 3 (second stage unit) moved in the X-axis direction will be mainly described.

  The NC controller 208 includes a target coordinate setting unit 301, an orthogonality correction unit 302 as a coordinate conversion unit, a subtraction unit 303, a position control unit 304, a subtraction unit 305, a position control unit 306, and a pitching correction unit as a position coordinate calculation unit. 307 functions. In the first embodiment, a feedback control unit 309 is configured by the subtraction unit 303, the position control unit 304, the subtraction unit 305, and the position control unit 306. The feedback control unit 309 forms a minor loop that feedback-controls the position of the encoder 205, and further forms a major loop that feedback-controls the position based on the reference mirror.

On the basis of the measurement result from the measurement unit 221, the pitching correction unit 307 uses the coordinate system (first coordinate system) defined by the X reference mirror 7, the Y reference mirror 8, and the Z reference mirror 9 as a reference. obtaining the position coordinates _{X p} of the X-axis direction. This first coordinate system is an actual coordinate system including orthogonality errors based on the reference mirrors 7, 8, and 9, which are determined by the mounting state of the reference mirrors 7, 8, and 9. In the present first embodiment, the pitching compensation unit 307, based on the measurement result from the measuring unit 222 obtains the position coordinates Y _p in the Y-axis direction of the probe 21 relative to the first coordinate system. Further, in the first embodiment, the probe pitching correction unit 307, although not shown in Figure 4, based on the laser measurement device 203 _Z of the measurement results of the measuring portion, with reference to the first coordinate system obtaining the position coordinates _{Z p} in the Z-axis direction of 21. That is, the pitching correction unit 307 obtains the three-dimensional position coordinates P (X _p , Y _p , Z _p ).

On the other hand, the target coordinate setting unit 301 has a target position coordinate X0 _p ^{* in} the X-axis direction of the probe 21 with reference to a predetermined three-dimensional orthogonal coordinate system (second coordinate system), specifically, three-dimensional. target position coordinates ^P0 * of ^{_{(X0 p *, Y0 p *}} , Z0 p *) to set a. This coordinate system is an ideal coordinate system that does not include orthogonality errors. That is, the first coordinate system and the second coordinate system are different from each other.

Therefore, orthogonality correction unit 302, the target location coordinates set by the target coordinate setting unit _{^{301 P0 * (X0 p *,}} Y0 p *, Z0 p *) the, X reference mirror 7, Y reference mirror 8 and Z reference Coordinate conversion is performed so that the coordinate system (first coordinate system) defined by the mirror 9 is used as a reference.

Specifically, orthogonality correction unit 302, using the coordinate transformation matrix H, the target position coordinates relative to the first coordinate system _{^{P0 * (X0 p *, Y0}} p *, Z0 p *) , and the second The target position coordinates P ^* (X _p ^* , Y _p ^* , Z _p ^* ) are converted with reference to the coordinate system. That is, the orthogonality correction unit 302 calculates P ^* = H · P0 ^* .

The target position coordinates _{^{P0 * (X0 p *, Y0}} p *, Z0 p *) and the target position coordinate _{^{P * (X p *, Y}} p *, Z p *) between the following equations (1 ).

Here, θxy, θzx, and θzy in the coordinate transformation matrix H are relative tilt errors of the X reference mirror 7, the Y reference mirror 8, and the Z reference mirror 9. Target location coordinates the correction amount in orthogonality correction unit _{^{302 P0 * (X0 p *,}} Y0 p *, Z0 p *) performs quadrature degree correction by calculating the outputs the result to subtraction unit 303. The mathematical formula used for orthogonality correction may be a mathematical formula other than the formula (1).

  The relative tilt errors of the X reference mirror 7, the Y reference mirror 8, and the Z reference mirror 9 are, for example, literature (Masato Negishi, research on free-form surface creation by modified polishing, doctoral dissertation, University of Tokyo, 2004, Chapter 5). It is obtained by the method described in. According to the method described in the literature, the relative values of the X reference mirror 7, the Y reference mirror 8, and the Z reference mirror 9 that are not affected by the sphericity error of the spherical prototype are obtained from the measurement result of the convex or concave spherical prototype. Tilt error can be obtained.

Subtraction unit 303, the position coordinates X _p of the X-axis direction of the probe 21 relative to the first coordinate system determined by the pitching compensation unit 307, a reference to the first coordinate system determined by the orthogonality correction unit 302 The difference from the target position coordinate X _p ^{* of} the probe 21 in the X-axis direction is obtained. The position control unit 304 generates a command value by performing, for example, a PID calculation based on the difference obtained by the subtraction unit 303. As described above, the command value generated by the position control loop based on the reference mirrors 7, 8, and 9 is output to the subtraction unit 305 in the next stage.

  The subtraction unit 305 obtains a difference between the command value obtained from the position control unit 304 and the rotational position from the encoder 205. The position control unit 306 generates a command value indicating the rotational position of the motor 13 by performing, for example, PID calculation based on the difference obtained by the subtraction unit 305. The command value generated by the encoder position control loop is output to the motor driver 209, and the motor 13 is driven.

In other words, the feedback control unit 309, the position coordinates X _p relative to the first coordinate system is a feedback control of the motor 13 so as to follow the target position coordinates X _p ^* relative to the first coordinate system.

  The control of the Y-axis slide drive motor 16 that drives the Y slide 2 (second stage unit) moved in the Y-axis direction is the same, and the description thereof is omitted. Although illustration in FIG. 4 is omitted, the control of the Z-axis slide drive motor 19 that drives the Z-slide 4 moved in the Z-axis direction is the same.

As described above, in the first embodiment, the target position coordinate P0 ^* based on the ideal coordinate system is corrected to the target position coordinate P ^* based on the reference mirror coordinate system, and the reference mirror coordinate system is used as a reference. Feedback control is performed so that the position coordinate P of the probe 21 follows the target position coordinate P ^* . Therefore, the probe 21 can be scanned with high accuracy at the target position of the workpiece W, and the surface shape of the workpiece W can be measured with high accuracy.

  Here, the X slide 3 and the Y slide 2 are inclined with respect to the base surface plate 1 due to their weight, and pitching occurs.

In the first embodiment, the pitching correction unit 307 uses the measurement data of the first laser length measuring device 203 _{X1 and} the length measurement of the second laser length measuring device 203 _X2 as the position coordinates X _p of the probe 21 in the X-axis direction. It is obtained by correcting pitching using data. Similarly, the pitching correction unit 307 uses the length measurement data of the first laser length measuring device 203 _{Y1 and} the length measurement data of the second laser length measuring device 203 _Y2 as the position coordinates Y _p of the probe 21 in the Y-axis direction. This is obtained by correcting the pitching.

More specifically, the pitching correction unit 307 includes a first distance X1 that is measurement data of the first laser length measuring device 203 _X1 and a second distance that is measurement data of the second laser length measurement device 203 _X2. from X2 Prefecture, the position coordinates _{X p} of the X-axis direction of the probe 21 is calculated using equation (2). Coordinates _{Y p} likewise in the Y-axis direction of the probe 21, the first distance Y1 is a length measurement data of the first laser length measuring machine _{203 Y1} is a length measurement data of the second laser length measuring machine _{203 Y2} 2 From the distance Y2, it is calculated using equation (2).

That is, the pitching correction unit 307 that is a position coordinate calculation unit has an inclination amount (X2-X1) of the probe 21 with respect to the X reference mirror 7 according to a difference (X2-X1) obtained by subtracting the first distance X1 from the second distance X2. Calculate (L2 + L3 + L4) / L2. Then, the pitching correction unit 307 uses the value obtained by correcting the first distance X1 by the tilt amount, that is, the value obtained by adding the tilt amount to the first distance X1, the position coordinate X _{p of} the probe 21 with respect to the first coordinate system. Asking. Although determined similarly coordinates Y _p, the relation between the coordinate reference, minus sign are given.

  As described above, in the first embodiment, the position coordinate P of the probe 21 is corrected based on the pitching (inclination) of the X slide 3 and the Y slide 2, so the probe 21 is highly accurately determined by the target position of the workpiece W. Can be scanned. Therefore, the surface shape of the workpiece W can be measured with higher accuracy.

[Second Embodiment]
Next, a shape measuring apparatus according to the second embodiment of the present invention will be described. FIG. 5 is a functional block diagram showing functions of the NC controller of the shape measuring apparatus according to the second embodiment of the present invention. In addition, about the structure similar to the said 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the first embodiment, the minor loop that feedback-controls the position of the encoder 205 (206) is provided. However, the present invention is not limited to this.

  In the second embodiment, as shown in FIG. 5, only the position feedback control based on the reference mirror is used without having a minor loop for feedback control of the position of the encoder 205 (206). That is, the feedback control unit 309A includes the subtraction unit 303 and the position control unit 304 described in the first embodiment.

  Even in this case, the probe can be scanned to the target position of the object to be measured with high accuracy, and the surface shape of the object to be measured can be measured with high accuracy.

[Third Embodiment]
Next, a shape measuring apparatus according to the third embodiment of the present invention will be described. FIG. 6 is a functional block diagram showing functions of the NC controller of the shape measuring apparatus according to the third embodiment of the present invention. In addition, about the structure similar to the said 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

In the first embodiment, the orthogonality correction unit 302, which is a coordinate conversion unit, sets the target position coordinate P ^{* so} that the target position coordinate P0 ^* set by the target coordinate setting unit 301 is based on the first coordinate system ^. The case where the coordinate conversion is performed has been described. The feedback control unit 309 performs feedback control on the motor 13 (16) so that the position coordinate P based on the first coordinate system follows the target position coordinate P ^* based on the first coordinate system. did.

In the third embodiment, the orthogonality correction unit 302B, which is a coordinate conversion unit, uses the position coordinates P (X _p , Y _p , X _p ) obtained by the pitching correction unit 307, which is a position coordinate calculation unit, as a second value. position coordinates _P0 relative to the coordinate system _{(X0 p, Y0 p, Z0} p) to coordinate transformation. In this case, the orthogonality correction unit 302B may perform coordinate transformation using an inverse matrix H ⁻¹ of the coordinate transformation matrix H of the first embodiment shown in the following formula (3).

Then, the feedback control unit 309 feedback-controls the motor 13 (16) so that the position coordinate P0 based on the second coordinate system follows the target position coordinate P0 ^* based on the second coordinate system.

  That is, the orthogonality correction units 302 and 302B set the position coordinates or the target coordinate obtained by the pitching correction unit 307 so that one of the first coordinate system and the second coordinate system is used as a reference. The target position coordinates set in the unit 301 may be converted. Then, the feedback control unit 309 may perform feedback control of the motor 13 (16) so that the position coordinates based on one coordinate system follow the target position coordinates based on one coordinate system.

  Thus, by adding the orthogonality correction amount measured in advance to the control system and further adding the pitching correction, it is possible to realize highly accurate probe positioning in the ideal orthogonal coordinate system.

  The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the art within the technical idea of the present invention.

  Although the case where the feedback control unit 309 has the minor feedback loop of the encoder 205 (206) has been described in the third embodiment, the feedback control unit 309A having no minor loop may be used as in the second embodiment.

  Moreover, in the said 1st-3rd embodiment, the base surface plate 1 which supports the workpiece | work W which is a to-be-measured object is fixed, the X slide 3 and the Y slide 2 are moved, and the probe 21 is made relative to the workpiece | work W. However, the present invention is not limited to this. The probe 21 may be scanned relative to the workpiece W by fixing the probe 21 to the fixed stage portion and moving the base surface plate 1 in the X and Y axis directions. Further, the base surface plate 1, the X slide 3 and the Y slide 2 may be moved in the XY axis direction so that the probe 21 is scanned relative to the workpiece W.

  Moreover, although the case where the contact type probe was used was demonstrated in the said 1st-3rd embodiment, this invention is applicable even if it is a non-contact type probe. When a non-contact type probe is used, for example, a laser beam is irradiated from the probe toward the surface of the object to be measured, and the distance of the surface of the object to be measured with respect to the probe is measured by reflected light from the surface of the object to be measured. The Z slide may be moved in the Z-axis direction so that this measurement distance is constant. The scanning of the probe with respect to the surface of the object to be measured may be performed by moving the X slide and Y slide holding the probe in the XY axis direction, moving the base surface plate in the XY axis direction, The surface plate, the X slide, and the Y slide may be moved in the XY axis direction.

DESCRIPTION OF SYMBOLS 1 ... Base surface plate (1st stage part), 2 ... Y slide (2nd stage part), 3 ... X slide (2nd stage part), 7 ... X reference mirror (reference | standard structure), 7a ... Reflecting surface ( Reference surface), 8 ... Y reference mirror (reference structure), 8a ... Reflecting surface (reference surface), 13 ... X-axis slide drive motor (drive unit), 16 ... Y-axis slide drive motor (drive unit), DESCRIPTION OF SYMBOLS 21 ... Probe, 100 ... Shape measuring apparatus, 203 _X1 ... 1st laser length measuring device, 203 _X2 ... 2nd laser length measuring device, 203 _Y1 ... 1st laser length measuring device, 203 _Y2 ... 2nd laser length measuring device, 221 ... Measurement unit, 222 ... Measurement unit, 301 ... Target coordinate setting unit, 302 ... Orthogonality correction unit (coordinate conversion unit), 307 ... Pitching correction unit (position coordinate calculation unit), 309 ... Feedback control unit

Claims (4)

In the shape measuring device that measures the shape of the surface of the object to be measured,
A probe that scans the surface of the object to be measured;
A first stage portion for supporting the object to be measured;
A second stage portion for supporting the probe;
A driving unit that drives at least one of the first stage unit and the second stage unit to scan the probe relative to the surface of the object to be measured;
An encoder for detecting a rotational position of the drive unit;
Is supported by the first stage portion, and the criteria structure having a reference surface,
A measurement unit for measuring a distance in a scanning direction of the probe with respect to a reference surface of the reference structure;
A target coordinate setting unit for setting a target position coordinate in the scanning direction of the probe with reference to a second coordinate system;
Defined by the reference structure by performing orthogonality correction for correcting the orthogonality error of the reference structure with respect to the target position coordinates based on the second coordinate system set by the target coordinate setting unit. A coordinate conversion unit that performs coordinate conversion so as to be based on the first coordinate system.
Based on the measurement result of the measurement unit, a position coordinate calculation unit that performs a pitching correction that corrects an inclination amount of the probe with respect to the reference surface, and obtains a position coordinate of the probe with reference to the first coordinate system;
A first subtraction unit that subtracts and outputs the output of the position coordinate calculation unit from the output of the coordinate conversion unit;
A first position controller that generates and outputs a first command value based on the output of the first subtractor;
A second subtracting unit that subtracts and outputs the output of the encoder from the first command value;
A second position control unit that generates and outputs a second command value for driving the driving unit based on the output of the second subtracting unit;
A shape measuring apparatus comprising: In the shape measuring device that measures the shape of the surface of the object to be measured,
A probe that scans the surface of the object to be measured;
A first stage portion for supporting the object to be measured;
A second stage portion for supporting the probe;
A driving unit that drives at least one of the first stage unit and the second stage unit to scan the probe relative to the surface of the object to be measured;
An encoder for detecting a rotational position of the drive unit;
A reference structure supported by the first stage portion and having a reference surface;
A measurement unit for measuring a distance in a scanning direction of the probe with respect to a reference surface of the reference structure;
A target coordinate setting unit for setting a target position coordinate in the scanning direction of the probe with reference to a second coordinate system;
Based on the measurement result of the measurement unit, pitching correction is performed to correct the amount of inclination of the probe with respect to the reference surface, and the position coordinates of the probe are obtained with reference to the first coordinate system defined by the reference structure. An output position coordinate calculation unit;
A coordinate conversion unit that performs orthogonality correction for correcting an orthogonality error of the reference structure with respect to the output of the position coordinate calculation unit, and performs coordinate conversion so as to be based on the second coordinate system; ,
A first subtraction unit that subtracts and outputs the output of the coordinate conversion unit from the output of the target coordinate setting unit;
A first position controller that generates and outputs a first command value based on the output of the first subtractor;
A second subtracting unit that subtracts and outputs the output of the encoder from the first command value;
A second position control unit that generates and outputs a second command value for driving the driving unit based on the output of the second subtracting unit;
A shape measuring apparatus comprising: The measurement unit includes a first length measuring device that measures a first distance in the scanning direction of the probe with respect to a first point on a reference plane of the reference structure, and a perpendicular to the scanning direction with respect to the first point. A second length measuring device for measuring a second distance in the scanning direction of the probe with respect to a second point on the reference plane of the reference structure shifted in the direction of
The position coordinate calculation unit obtains an inclination amount of the probe with respect to the reference structure according to a difference obtained by subtracting the first distance from the second distance, and uses a value obtained by correcting the first distance by the inclination amount. The shape measuring apparatus according to claim 1, wherein a position coordinate of the probe is obtained with reference to a coordinate system of the reference structure. The reference structure is a reference mirror having a planar reflecting surface;
The shape measuring apparatus according to claim 3, wherein the first length measuring device and the second length measuring device are laser length measuring devices that measure a distance in the scanning direction with respect to a reflecting surface of the reference mirror. .

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