WO2021240711A1

WO2021240711A1 - Rotation accuracy measurement method, rotation accuracy measurement device, three-dimensional shape measurement method, three-dimensional shape measurement device, and optical device

Info

Publication number: WO2021240711A1
Application number: PCT/JP2020/021065
Authority: WO
Inventors: 智丈寺沢
Original assignee: オリンパス株式会社
Priority date: 2020-05-28
Filing date: 2020-05-28
Publication date: 2021-12-02

Abstract

This rotation accuracy measurement method is for measuring a rotation accuracy component by separating a shape error of an object to be measured and the rotation accuracy component through use of a plurality of displacement meters. In a first step (S3), a plurality of waveform signals indicating displacement are acquired by measuring, while rotating the object to be measured, displacement in distances between the displacement meters and the object to be measured by using the displacement meters. In a second step (S5), a similarity between the waveform signals is quantitatively assessed. In a third step (S6), the position of a displacement meter included in the displacement meters is adjusted so that the similarity becomes equal to or a higher than a prescribed value.

Description

Rotation accuracy measurement method, rotation accuracy measurement device, 3D shape measurement method, 3D shape measurement device and optical equipment

The present invention relates to a rotation accuracy measuring method, a rotation accuracy measuring device, a three-dimensional shape measuring method, a three-dimensional shape measuring device, an optical instrument, and the like.

In Patent Document 1 and Patent Document 2, the three-dimensional shape of the surface of the test object is measured by measuring the displacement of the surface of the test object while rotationally scanning the test object such as an optical element or an optical element molding mold. A rotary scanning type shape measuring machine is disclosed. In such a rotary scanning type shape measuring machine, a rotation error occurs due to the rotation axis being shaken during the rotary scanning, and the rotation error lowers the accuracy of the shape measurement. In Patent Document 2, a measurement object having a measurement target surface is installed on a rotary scanning axis of a shape measuring machine, the displacement of the measurement target surface during rotation is detected by a plurality of displacement meters, and measurement is performed from the detected displacement. A method is disclosed in which the rotation accuracy is measured by separating the shape error and the rotation error of the target surface, and the shape measurement result of the subject is corrected by using the measured rotation accuracy.

In such a rotation accuracy measurement method, in order to realize high-precision measurement, it is important to make the detection positions of a plurality of displacement meters more consistent on the same line of the measurement target surface. In Patent Document 3, a mark is marked on the surface to be measured, the edge of the mark is detected by a displacement meter, the detection position of the displacement meter is grasped from the detection result, and a plurality of displacements are displaced based on the grasped detection position. A method for adjusting the position of the meter is disclosed.

U.S. Patent Application Publication No. 2013/0308139 Japanese Unexamined Patent Publication No. 2005-326344 Japanese Unexamined Patent Publication No. 2007-86034

The method of adjusting the detection positions of a plurality of displacement meters using the marks as described above has a problem that there is a limit in improving the degree of coincidence of the detection positions. For example, the edge is physically formed on the surface to be measured, and the degree of coincidence of the detection positions is limited by the sharpness of the edge formation or the detection accuracy of the edge. Alternatively, since the shape of the measurement target surface and the reflected brightness change sharply at the marked portion, the S / N of the signal output by the displacement meter decreases, and the degree of coincidence of the detection positions is limited by the decrease in the signal accuracy. ..

One aspect of the present disclosure is to rotate the measurement object in a rotation accuracy measuring method for measuring the rotation accuracy component by separating the shape error and the rotation accuracy component of the measurement object by using a plurality of displacement meters. The first step of measuring the displacement of the distance between the plurality of displacement meters and the object to be measured using the plurality of displacement meters to obtain a plurality of waveform signals indicating the displacement, and the plurality of waveform signals. Rotation accuracy including a second step of quantitatively evaluating the similarity between the two steps and a third step of adjusting the positions of the displacement meters included in the plurality of displacement meters so that the similarity is equal to or higher than a predetermined value. It is related to the measurement method.

Another aspect of the present disclosure is a processing apparatus that measures the rotation accuracy component by separating the shape error and the rotation accuracy component of the object to be measured by using a plurality of displacement meters and the plurality of displacement meters. The processing apparatus measures the displacement of the distance between the plurality of displacement meters and the object to be measured using the plurality of displacement meters while rotating the object to be measured, and the processing apparatus measures the displacement of the distance between the plurality of displacement meters and the object to be measured. The first process of acquiring the waveform signal, the second process of quantitatively evaluating the similarity between the plurality of waveform signals, and the positions of the plurality of displacement meters are adjusted so that the similarity is equal to or higher than a predetermined value. The present invention relates to a rotation accuracy measuring device that performs a third process of acquiring the plurality of waveform signals at the time of the event.

Still another aspect of the present disclosure is a shape measuring step of measuring the three-dimensional shape of the subject using a displacement meter for shape measurement in a three-dimensional shape measuring method for measuring the three-dimensional shape of the subject. The present invention relates to a three-dimensional shape measuring method including a calibration step of calibrating a measurement result of the three-dimensional shape using the rotation accuracy component obtained by the rotation accuracy measuring method described above.

Further, another aspect of the present disclosure is a shape measuring displacement meter for measuring the three-dimensional shape of the test object and a processing device in the three-dimensional shape measuring device for measuring the three-dimensional shape of the test object. The processing apparatus uses the shape measuring process for measuring the three-dimensional shape using the shape measuring displacement meter and the rotational accuracy component acquired by the rotational accuracy measuring apparatus described above. The present invention relates to a three-dimensional shape measuring device that performs a calibration process for calibrating the measurement result of the three-dimensional shape.

Yet another aspect of the present disclosure relates to an optical device equipped with an optical element selected by measuring the three-dimensional shape using the three-dimensional shape measuring device described above.

A first configuration example of a rotation accuracy measuring device. The figure explaining the rotation error in a radial direction. The flowchart which shows the procedure of rotation accuracy measurement using a rotation accuracy measuring apparatus, and the procedure of processing performed by a rotation accuracy measuring apparatus. The figure explaining the installation angle of the displacement meter. Example of shape error and waveform signal of the surface to be measured. Explanatory drawing of the phase difference correction waveform acquisition process and the similarity quantitative value acquisition process. The flowchart which shows the detailed procedure of the displacement meter position adjustment process. An example of the degree of similarity obtained while changing the position of the displacement gauge. An example of a waveform signal acquired in a second waveform acquisition step after the displacement meter position is adjusted by the displacement meter position adjustment step. An example of similarity and waveform signal when using the conventional marking adjustment method. An example of similarity and waveform signal when the adjustment method of this embodiment is used. The figure explaining the relationship between the displacement caused by a shape error and the displacement caused by a rotation accuracy component. In the second configuration example, the flowchart which shows the procedure of rotation accuracy measurement using a rotation accuracy measuring apparatus, and the procedure of processing performed by a rotation accuracy measuring apparatus. A third configuration example of the rotation accuracy measuring device. A fourth configuration example of the rotation accuracy measuring device. The figure explaining the rotation error in the tilt direction and the rotation error in the axial direction. An example of the shape error of the surface to be measured. Configuration example of 3D shape measuring device. The flowchart which shows the procedure of 3D shape measurement. An example of an optical instrument.

Hereinafter, this embodiment will be described. It should be noted that the present embodiment described below does not unreasonably limit the contents described in the claims. Further, not all of the configurations described in the present embodiment are essential constituent requirements of the present disclosure.

1. 1. First Configuration Example FIG. 1 is a first configuration example of the rotation accuracy measuring device 200 according to the present embodiment. The three-dimensional shape measuring device 100 described later in FIG. 18 rotates and scans the surface shape of the object 110, while the rotation accuracy measuring device 200 rotates and scans the measurement object 210 installed coaxially with the rotation axis of the rotation scanning. By measuring the rotation accuracy, the rotation accuracy of the rotation scanning is measured.

In the first configuration example, the rotation error in the radial direction is detected as shown in FIG. The direction parallel to the ideal rotation axis 192 is the z direction, and the directions orthogonal to the z direction and orthogonal to each other are the x direction and the y direction. The radial direction is the radial direction of rotation about the ideal rotation axis 192, and the rotation error in the radial direction indicates the deviation of the rotation axis 190 with respect to the ideal rotation axis 192 in the xy plane. In the following, the direction orthogonal to the radial direction in the xy plane is referred to as a rotation direction Drot. In the following, it is assumed that the object to be measured 210 rotates clockwise when viewed from the + z side in the −z direction, but it may rotate counterclockwise.

The rotation accuracy measuring device 200 of FIG. 1 includes a stage 285, a rotating body 280, a measuring object 210, position adjusting devices 231 to 233, displacement meters 221 to 223, and a processing device 270. Hereinafter, an example in which the rotation accuracy measuring device 200 includes three displacement meters and the rotation accuracy components are separated by using the three-point displacement method will be described, but the rotation accuracy measuring device 200 may include a plurality of displacement meters. .. The three-point displacement method is a kind of multi-probe method, but an algorithm using four or more displacement meters may be adopted as the multi-probe method. In that case, the number of displacement meters corresponding to the algorithm may be installed.

The stage 285 is installed so that the flat upper surface is horizontal, and the stage 285 is provided with a rotating body 280 and position adjusting devices 231 to 233. The rotation axis 190 of the rotating body 280 is parallel to the upper surface of the stage 285 in the height direction, that is, perpendicular to the upper surface of the stage 285. This height direction corresponds to the z direction, and the upper surface of the stage 285 is parallel to the xy plane. Although only the x-direction and the z-direction are shown in FIG. 1, the y-direction is a direction perpendicular to the x-direction and the z-direction. The rotating shaft 190 does not have to be exactly perpendicular to the height direction due to the installation tolerance of the rotating body 280 or the rotation error described above. Further, the upper surface of the stage 285 is not limited to horizontal. That is, the height means the distance in the direction perpendicular to the upper surface of the stage 285, and is not limited to the distance in the vertical direction. Similarly, the top and bottom shall mean the direction perpendicular to the upper surface of the stage 285, and are not limited to the vertical direction.

The object to be measured 210 is an object that is rotationally symmetric with respect to the central axis, and is, for example, a disk, a cylinder, a donut ring, or the like. When the object to be measured 210 is a disk or a cylinder, the object to be measured 210 has an upper surface, a lower surface, and a side surface. The upper surface and the lower surface are circular planes having the same radius, and are planes perpendicular to the rotation axis 190. The side surface is a cylindrical surface such that the cross section perpendicular to the rotation axis 190 is a circle having the same radius as the upper surface. When the object to be measured 210 has a donut ring shape, the boundary between the upper surface and the side surface and the side surface and the lower surface may be arbitrary, but for example, the range visible from the side with respect to the rotation axis is the side surface and rotates. The range that can be seen from above parallel to the axis is the upper surface, and the range that can be seen from below parallel to the axis of rotation is the lower surface. The object to be measured 210 is installed on the rotating body 280 so that the central axis of the disk cylinder or the donut ring shape coincides with the rotating axis 190 of the rotating body 280. That is, the rotation of the rotating body 280 causes the measurement object 210 to rotate about the central axis. In the first configuration example, the side surface of the measurement target object 210 is the measurement target surface MSFA whose displacement is measured by the displacement meters 221 to 223. In the fourth configuration example described later, one of the upper surface and the lower surface is the measurement target surface MSFB. Measurement target surfaces The surfaces of MSFA and MSFB are mirror-polished so that the displacement meters 221 to 223 can measure the displacement with high accuracy. Specifically, the surface accuracy of the measurement target surface MSFA is about several hundred nm to 1 μm.

The position adjusting devices 231 to 233 support the displacement meters 221 to 223, and the position adjusting devices 231 to 233 move up and down in the height direction with respect to the upper surface of the stage 285 to increase the height of the displacement meters 221 to 223. Change. By changing the height of the displacement meters 221 to 223, the position where the displacement is measured by the displacement meters 221 to 223 on the measurement target surface MSFA changes in the direction Dud orthogonal to the rotation direction Drot. Various configurations of the position adjusting devices 231 to 233 can be considered. For example, each position adjusting device includes a support column that supports the displacement meter and extends in the height direction, and a mechanism for raising and lowering the support column. Further, each position adjusting device may further include an encoder for detecting the vertical position of the displacement meter. In the first configuration example, it is assumed that the user moves the displacement meter up and down by operating the mechanism for moving the support column up and down. When the mechanism for moving the column up and down is electric, or when it is automated as in the second configuration example, the mechanism for moving the column up and down is an actuator such as a stepping motor.

The displacement meters 221 to 223 measure the displacement of the measurement target surface MSFA in the radial direction, that is, the displacement of the distance between the displacement meters 221 to 223 and the measurement target surface MSFA in the radial direction. The displacement meters 221 to 223 are arranged around the measurement target surface MSFA when viewed from the + z side in the −z direction, and the measurement direction of the distance faces the radial direction. The displacement meters 221 to 223 are non-contact type displacement meters in which the probe does not contact the measurement target surface MSFA, for example, a TOF type displacement meter, a laser interference type displacement meter, an optical color confocal type displacement meter, and a capacitance type displacement. It is a meter, a vortex current type displacement meter, or the like. As an example, the TOF type displacement meter measures the distance to an object by measuring the time from the emission of light to the return of reflected light. The laser interference type displacement meter measures the distance to the object by measuring the change in the interference between the laser reflected light from the object and the laser reflected light from another fixed reflecting surface. Although contact-type displacement meters may be used as the displacement meters 221 to 223, it is desirable to use non-contact type displacement meters.

The displacement meter 221 measures the distance to one point of the measurement target surface MSFA, and when the measurement target object 210 rotates, the displacement of the measurement target surface MSFA on the line A is measured. The line A is a line that goes around the measurement target surface MSFA in the rotation direction Drot. The displacement meter 221 outputs a waveform signal SGA indicating the displacement on the line A. The waveform signal SGA is a signal in which the displacement due to the fine unevenness on the line A of the measurement target surface MSFA and the displacement due to the rotation error are mixed. Since the height of the line A changes as the displacement meter 221 moves up and down, the displacement measured by the displacement meter 221 changes, and the waveform of the waveform signal SGA changes. Similarly, the

displacement meters

222 and 223 measure the displacement of the measurement target surface MSFA on the lines B and C. The

displacement meters

222 and 223 output waveform signals SGB and SGC indicating displacements on the lines B and C. The waveform signals SGB and SGC are signals in which displacement due to fine irregularities on lines B and C of the measurement target surface MSFA and displacement due to rotation error are mixed.

The processing device 270 separates the shape error and the rotation accuracy component of the measurement object 210 based on the waveform signals SGA to SGC. The shape error is a displacement due to fine unevenness of the measurement target surface MSFA among the displacements included in the waveform signals SGA to SGC. The rotation accuracy component is the displacement of the measurement target surface MSFA due to the rotation error among the displacements included in the waveform signals SGA to SGC.

The processing device 270 includes a displacement meter waveform reading device 271, a similarity quantitative value acquisition device 272, and an error separation calculation device 273. For example, the processing device 270 includes a controller that functions as a displacement meter waveform reader 271, an information processing device that functions as a similarity quantitative value acquisition device 272 and an error separation calculation device 273. The controller is connected to the displacement meters 221 to 223 by a cable or the like, performs processing such as waveform shaping on the waveform signals SGA to SGC, and outputs the processed waveform signals SGA to SGC to the information processing apparatus. The controller and the information processing device are connected by a cable or a network. The information processing device includes a memory for storing a program in which the functions of the similarity quantitative value acquisition device 272 and the error separation calculation device 273 are described, and a processor. When the processor executes the program read from the memory, the functions of the similarity quantitative value acquisition device 272 and the error separation calculation device 273 are realized. Details of the processing performed by the processing device 270 will be described later.

FIG. 3 is a flowchart showing a procedure of rotation accuracy measurement using the rotation accuracy measuring device 200 and a procedure of processing performed by the rotation accuracy measuring device 200.

In the measurement object installation step S1, the user installs the measurement object 210 coaxially with the rotation shaft 190 of the rotating body 280. In the displacement meter installation step S2, the user installs the displacement meters 221 to 223 in the position adjusting devices 231 to 233. As shown in FIG. 4, the displacement meters 221 to 223 are installed at different positions in the rotation direction Drot. Let φ be the difference in the relative installation angles of the

displacement meters

221 and 222 in the rotation direction Drot, and let τ be the difference in the relative installation angles of the

displacement meters

221 and 223 in the rotation direction Drot.

In the first waveform acquisition step S3, the object to be measured 210 rotates together with the rotating body 280, the displacement meters 221 to 223 measure the displacement on the lines A to C, and the displacement meter waveform reader 271 outputs the waveform signals SGA to SGC. get. The rotating body 280 includes an actuator such as a motor, and the processing device 270 drives the actuator to rotate the rotating body 280. The displacement meter waveform reader 271 is a device that reads the waveform signals SGA to SGC output by the displacement meters 221 to 223. That is, the displacement meter waveform reader 271 acquires the waveform signals SGA to SGC corresponding to one round of lines A to C on the measurement target surface MSFA, and performs processing such as waveform shaping on the waveform signals SGA to SGC. ..

An example of the shape error of the measurement target surface MSFA is shown in the upper part of FIG. This figure is a developed view of the measurement target surface MSFA, and the shape error is shown by contour lines. Dotted lines with "+ 1t" and the like indicate contour lines with t as an arbitrary height interval. Lines A to C show lines on the measurement target surface MSFA where the displacement meters 221 to 223 measure the displacement as described above.

The lower part of FIG. 5 shows the waveform signals SGA to SGC corresponding to one round of lines A to C on the measurement target surface MSFA. The values of the waveform signals SGA to SGC indicate the displacement of the measurement target surface MSFA. As described with reference to FIG. 4, since the displacement meters 221 to 223 are arranged at different positions in the rotation direction Drot, the phases of the waveform signals SGA to SGC are different. That is, the phases of the waveform signals SGA and SGB are different by φ, and the phases of the waveform signals SGA and SGC are different by τ.

As shown in the upper part of FIG. 5, if the heights of the lines A to C measured by the displacement meters 221 to 223 are different, the shape error measured by the displacement meters 221 to 223 is different. That is, the shape errors included in the waveform signals SGA to SGC are different from each other. When separating the rotation accuracy component from the waveform signals SGA to SGC, it is assumed that the shape errors of the waveform signals SGA to SGC are the same except for the phase, so that the heights of the lines A to C are different. The calculation accuracy of the rotation accuracy component is lowered. In the present embodiment, the calculation accuracy of the rotation accuracy component is improved by aligning the heights of the lines A to C using the similarity of the waveform signals SGA to SGC in S4 to S6 described below.

Phase difference correction In the waveform acquisition step S4, the similarity quantitative value acquisition device 272 corrects the phase difference of the waveform signals SGA to SGC to match the phases of the waveform signals SGA to SGC. The corrected waveform signal is SGA'to SGC'. In the similarity quantitative value acquisition step S5, the similarity quantitative value acquisition device 272 acquires the similarity for all combinations of the two waveform signals of the waveform signals SGA'to SGC'.

FIG. 6 shows an explanatory diagram of the phase difference correction waveform acquisition step S4 and the similarity quantitative value acquisition step S5. Here, an example of matching the phase with the waveform signal SGA as a reference will be described. The similarity quantitative value acquisition device 272 acquires the waveform signal SGB'by shifting the phase of the waveform signal SGB by -φ degree, and shifts the phase of the waveform signal SGC by -τ degree to obtain the waveform signal SGC. 'Get. The waveform signal SGA'is the same as the waveform signal SGA. The similarity quantitative value acquisition device 272 may use known values as the phase differences φ and τ, or may obtain the phase differences φ and τ by matching processing of the waveform signals SGA to SGC.

The similarity quantitative value acquisition device 272 obtains the similarity RAB of the waveform signals SGA and SGB, the similarity RBC of the waveform signals SGB and SGC, and the similarity RCA of the waveform signals SGC and SGA. The degree of similarity is a degree indicating how similar the two waveforms are, and the higher the similarity, the larger the value. However, as an index for actually measuring the similarity, an index having a larger value as the similarity is higher and an index having a smaller value as the similarity is higher can be used. In the latter case, the smaller the index, the higher the similarity. In the first configuration example, the similarity quantitative value acquisition device 272 uses, for example, SSD (Sum of Squared Difference) or SAD (Sum of Absolute Difference) as an index indicating the similarity.

In the displacement meter position adjustment step S6, the heights of the lines A to C measured by the displacement meters 221 to 223 are aligned by adjusting the positions of the displacement meters 221 to 223 based on the similarity of the waveform signals SGA to SGC. Details of this step will be described later.

In the second waveform acquisition step S7, the object to be measured 210 rotates together with the rotating body 280, and the displacement meters 221 to 223 measure the displacement. The displacement meter waveform reader 271 acquires waveform signals SGA to SGC in which the heights of the lines A to C are aligned in the displacement meter position adjustment step S6.

In the error separation calculation step S8, the error separation calculation device 273 separates the shape error and the rotation accuracy component from the waveform signals SGA to SGC acquired in the second waveform acquisition step S7. Specifically, the waveform signals SGA to SGC are expressed by the following equations (1) to (3). θ is the rotation angle of the object to be measured 210 in the rotation direction Drot. φ and τ are the installation angles of the displacement gauge described in FIG. r (θ) is a shape error of the measurement target surface MSFA. ex (θ) and ey (θ) are the x component and the y component of the rotation error in the radial direction described with reference to FIG.

The error separation calculation device 273 obtains the shape error r (θ) and the rotation errors ex (θ) and ey (θ) by solving the simultaneous equations according to the above equations (1) to (3) by the inverse filtering method. The rotation errors ex (θ) and ey (θ) correspond to the separated rotation accuracy components. For details of the three-point displacement method, see, for example, "Nanomeasurement of rotational accuracy by separating shape error and motion error", Journal of Precision Engineering, Vol. 67, No. 7,2001, p1067-p1071.

FIG. 7 is a flowchart showing a detailed procedure of the displacement meter position adjusting step S6.

In the reference displacement meter setting step S11, one of the displacement meters 221 to 223 is set as the reference displacement meter. Specifically, the displacement meter obtained with a large degree of similarity in the similarity quantitative value acquisition step S5 is set as the reference displacement meter. For example, it is assumed that the similarity RAB, RCA, and RBC acquired in the similarity quantitative value acquisition step S5 have the largest values in this order. At this time, the displacement meter 221 that corresponds to both RAB and RCA is set as the reference displacement meter. The user may select a reference displacement meter, or the similarity quantitative value acquisition device 272 may automatically select a reference displacement meter based on the similarity. Hereinafter, it is assumed that the displacement meter 221 is set as the reference displacement meter.

In the displacement meter position information acquisition step S12, the height of the displacement meter 221 which is the reference displacement meter is fixed, and the

displacement meters

222 and 223 other than the reference displacement meter are changed in the height direction, and the object to be measured is measured at each position. Rotate 210. The displacement meter waveform reader 271 acquires the waveform signals SGB and SGC at each position, and the similarity quantitative value acquisition device 272 acquires the similarity RAB and RCA at each position.

FIG. 8 shows an example of the degree of similarity acquired while changing the position of the displacement meter. Here, it is assumed that the similarity is normalized and can take a range of 0 or more and 1 or less. Each point shown in the PTM is the similarity measured at each position. LAP is an approximate curve of the point PTM. A waveform as shown in FIG. 8 is obtained for each of the

displacement meters

222 and 223.

In the similarity maximum position estimation step S13, the position where the similarity is maximum is estimated based on the similarity obtained at each position while moving the position of the displacement meter. The user may determine the position where the similarity is maximum from the waveform of FIG. 8, or the similarity quantitative value acquisition device 272 may infer the position where the similarity is maximum from the waveform of FIG. good.

In the maximum similarity position estimation step S13, the position of the displacement meter whose similarity is equal to or higher than a predetermined value may be estimated. The predetermined value is smaller than the maximum value of the similarity, but the larger the predetermined value is, the more desirable it is from the viewpoint of improving the measurement accuracy of the rotation error. For example, there is an error between the actual maximum position and the estimated maximum position due to the measurement error of the similarity or the approximation error of the approximate curve LAP. A predetermined value is set in anticipation of this error. Alternatively, a degree of similarity that can obtain an acceptable accuracy as the measurement accuracy of the rotation error may be set as a predetermined value.

Although the example of determining the position where the similarity is maximum after acquiring the waveform has been described above, the method for determining the position where the similarity is maximum is not limited to this. For example, a method of measuring the similarity while changing the height of the displacement meter and estimating the maximum position at the position where the similarity exceeds a predetermined value can be considered.

In the displacement meter position correction step S14, the

displacement meters

222 and 223 are moved to the positions estimated in the similarity maximum position estimation step S13. The user may manually move the

displacement meters

222 and 223, or the processing device 270 may move the

displacement meters

222 and 223 by driving the actuators of the position adjusting devices 231 to 233.

In the determination step S15, it is determined whether or not the similarity in the position of the displacement meter corrected in the displacement meter position correction step S14 is equal to or higher than a predetermined value. That is, the displacement meter waveform reader 271 acquires the waveform signals SGA to SGC at the position of the displacement meter corrected in the displacement meter position correction step S14, and the similarity quantitative value acquisition device 272 between the waveform signals SGA and SGC. Obtain the similarity RAB, RBA, and RCA. The similarity quantitative value acquisition device 272 ends the displacement meter position adjustment step S6 when the similarity RAB, RBA, and RCA are all equal to or higher than a predetermined value. If any of the similarity RABs, RBAs, and RCAs is not equal to or higher than a predetermined value, S11 to S15 are repeated until all of the similarities RAB, RBA, and RCA are equal to or higher than a predetermined value.

FIG. 9 is an example of waveform signals SGA'to SGC' acquired in the second waveform acquisition step S7 after the displacement meter position is adjusted by the displacement meter position adjustment step S6. Here, the waveform signal after phase correction is shown.

The upper part of FIG. 9 shows the contour lines of the shape error of the measurement target surface MSFA as in the upper part of FIG. By adjusting the positions of the displacement meters 221 to 223, the heights of the lines A to C where the displacement meters 221 to 223 measure the displacement are almost the same, and the shape errors measured by the displacement meters 221 to 223 are almost the same. Become. As a result, as shown in the lower part of FIG. 9, since the waveforms of the waveform signals SGA'to SGC' are almost the same, the waveform signals SGA'to SGC'with very high similarity can be obtained. In the lower part of FIG. 9, the waveforms of the waveform signals SGA'to SGC' appear to match, but in reality, the rotation accuracy component differs depending on the installation angle of the displacement meters 221 to 223, and the rotation accuracy component is used. Except for this, the waveforms of the waveform signals SGA'to SGC' are almost the same.

FIG. 10 is an example of similarity and rotation error when the adjustment method by marking, which is a conventional technique, is used, and FIG. 11 is an example of similarity and rotation error when the adjustment method of the present embodiment is used. be.

As shown in the upper part of FIG. 10, in the conventional technique, the similarity RAB and RBA are lower than 0.990, and it is presumed that there is a non-negligible deviation in the measurement position on the measurement target surface MSFA. On the other hand, as shown in the upper part of FIG. 11, in the present embodiment, the similarity RAB and RBA exceed 0.990, and it can be seen that the similarity between the waveform signals can be improved. That is, the heights measured by the three displacement meters on the measurement target surface MSFA are the same, and the three displacement meters measure substantially the same shape error. The EST shown in the lower part of FIGS. 10 and 11 is a rotation error estimated by a method different from that of the present embodiment. Compared with the rotation error MESA when the adjustment method of the present embodiment is not used, the rotation error MESB when the adjustment method of the present embodiment is used is the rotation estimated by a method different from the present embodiment. It can be seen that it is close to the error waveform.

Although the mutual correlation coefficient varies depending on the rotation accuracy and the surface accuracy of the surface to be measured, it is basically desirable that the value is 0.990 or more, and the value is 0.995 or more. desirable.

As described above, in the rotation accuracy measuring method of the present embodiment, the rotation accuracy component is measured by separating the shape error and the rotation accuracy component of the object to be measured 210 by using a plurality of displacement meters 221 to 223. do. The rotation accuracy measuring method includes a first step, a second step, and a third step. In the first step, while rotating the object to be measured 210, the displacement of the distance between the plurality of displacement meters 221 to 223 and the object to be measured 210 is measured using a plurality of displacement meters 221 to 223, and the displacement is shown. Obtain a plurality of waveform signals SGA to SGC. The second step quantitatively evaluates the similarity RAB, RBA, and RCA between the plurality of waveform signals SGA to SGC. In the third step, the positions of the displacement meters included in the plurality of displacement meters 221 to 223 are adjusted so that the similarity RAB, RBA, and RCA become equal to or higher than a predetermined value. In the first configuration example, the first step corresponds to the first waveform acquisition step S3 in FIG. 3, and the second step corresponds to the phase difference correction waveform acquisition step S4 and the similarity quantitative value acquisition step S5 in FIG. The third step corresponds to the displacement meter position adjusting step S6 of FIGS. 3 and 7.

Further, the rotation accuracy measuring device 200 of the present embodiment includes a plurality of displacement meters 221 to 223 and a processing device 270. The processing device 270 measures the rotation accuracy component by separating the shape error and the rotation accuracy component of the object to be measured 210 by using a plurality of displacement meters 221 to 223. The processing device 270 performs the first processing, the second processing, and the third processing. In the first process, while rotating the object to be measured 210, the displacement of the distance between the plurality of displacement meters 221 to 223 and the object to be measured 210 is measured using a plurality of displacement meters 221 to 223, and the displacement is shown. Acquire a plurality of waveform signals SGA to SGC. The second process quantitatively evaluates the similarity RAB, RBA, and RCA between the plurality of waveform signals SGA to SGC. The third process acquires a plurality of waveform signals SGA to SGC when the positions of the plurality of displacement meters 221 to 223 are adjusted so that the similarity RAB, RBA, and RCA become equal to or higher than a predetermined value. In the first configuration example, the first process corresponds to the first waveform acquisition step S3 in FIG. 3, the second process corresponds to the similarity quantitative value acquisition step S5 in FIG. 3, and the third process corresponds to FIG. Corresponds to the second waveform acquisition step S7.

By doing so, it is possible to align the detection positions where a plurality of displacement meters measure the displacement by using the similarity of the waveform signals indicating the displacement. When marking is used, the shape of the surface to be measured and the reflected brightness change sharply, so that the measurement accuracy of the rotation error is limited. You can avoid that problem. As a result, highly accurate rotation accuracy measurement becomes possible, and the measurement accuracy of the three-dimensional shape measurement can be improved by using the rotation accuracy component. The phrase "adjusting the position of the displacement meter so that the degree of similarity is equal to or higher than a predetermined value" includes, for example, the following two. The first is to move the displacement meter and stop the displacement meter at that position when the similarity exceeds the threshold value. In this case, the threshold value corresponds to a predetermined value. The second is to search for the maximum value of similarity as in the hill climbing method, and stop the displacement meter at the position determined to be the maximum value. In this case, the maximum value cannot always be determined exactly, so there is some variation. That is, the range of error associated with the maximum value determination corresponds to a predetermined value.

Further, in the present embodiment, the rotation accuracy measuring method includes the measurement object installation process S1 and the displacement meter installation process S2. In the measurement object installation step S1, the measurement object 210 having the measurement object surface MSFA is installed coaxially with the rotation shaft 190 of the rotating body 280. In the displacement meter installation step S2, a plurality of displacement meters 221 to 223 are arranged around the object to be measured 210. In the first step, a plurality of waveform signals SGA to SGC are acquired while rotating the measurement object 210 on the rotation shaft 190. The rotation accuracy component is a component used for calibrating the rotation accuracy of the rotating body 280 on which the measurement object 210 is installed.

As described above, since the rotation accuracy component can be detected with high accuracy by using the similarity of the waveform signal, the rotation accuracy can be calibrated with high accuracy using the rotation accuracy component. For example, in the three-dimensional shape measuring method described later and the rotary scanning shape measurement in the three-dimensional shape measuring device 100, the rotational accuracy can be calibrated with high accuracy.

Further, in the present embodiment, in the displacement meter installation step S2, a plurality of displacement meters 221 to 223 are installed at different installation angles along the rotation direction Drot of the rotating body 280. In the first step, a plurality of waveform signals SGA to SGC are acquired while rotating the measurement object 210. In the second step, the phase difference between the plurality of waveform signals SGA to SGC caused by the difference in the installation angle and the quantitative value of the degree of similarity between the plurality of waveform signals SGA'to SGC' in which the phase difference is corrected are obtained. By finding it, the similarity is quantitatively evaluated.

By doing so, the rotation error can be measured by using a multi-probe method such as the displacement 3-point method. That is, by using a plurality of displacement meters having different installation angles, the displacement due to the rotation error is measured from different positions. By using the displacements measured from these different positions, the rotation accuracy component can be separated from the waveform signal.

Further, in the present embodiment, the rotation accuracy measuring method includes a fourth step of performing an error separation calculation for separating the shape error and the rotation accuracy component from the plurality of waveform signals SGA to SGC. In the fourth step, the error separation calculation is performed using the plurality of waveform signals SGA to SGC acquired at the positions of the displacement meters adjusted so that the similarity becomes equal to or higher than the predetermined value in the third step. In the first configuration example, the fourth step corresponds to the error separation calculation step of FIG.

By adjusting the position of the displacement meter so that the similarity of the waveform signals is equal to or higher than the predetermined value, the positions where the plurality of displacement meters measure the displacement can be almost matched. As a result, the shape errors included in the plurality of waveform signals are almost the same, so that the rotation accuracy components can be accurately separated.

Further, in the present embodiment, the third step of the rotation accuracy measuring method includes a reference displacement meter setting step S11, a displacement meter position information acquisition step S12, a similarity maximum position estimation step S13, and a displacement meter position correction step S14. The reference displacement meter setting step S11 determines a reference displacement meter 221 as a reference for position adjustment from a plurality of displacement meters 221 to 223. In the displacement meter position information acquisition step S12, the

displacement meters

222 and 223 different from the reference displacement meter 221 are moved to a plurality of positions in the rotation axis direction of the measurement object 210, and a plurality of waveform signals SGA to SGC are transmitted at each position. The degree of similarity RAB and RBA between the waveform signal SGA obtained by the reference displacement meter 221 and the waveform signals SGB and SGC obtained by the

displacement meters

222 and 223 are obtained at each position. The maximum similarity position estimation step S13 estimates the positions of the

displacement meters

222 and 223 that can obtain the similarity of a predetermined value or more based on the plurality of similarities obtained corresponding to the plurality of positions. The displacement meter position correction step S14 moves the

displacement meters

222 and 223 to the positions estimated in the similarity maximum position estimation step S13. The reference displacement meter may be any one of the plurality of displacement meters 221 to 223. In the fourth configuration example described later, the plurality of displacement meters are displacement meters 241 to 244, and in the displacement meter position information acquisition step S12, a displacement meter different from the reference displacement meter is used as a radial with respect to the rotation axis 190 of the measurement object 210. Move to multiple positions in the direction.

By doing so, in the displacement meter position information acquisition step S12, the similarity of the waveform signals at each position of the displacement meter can be obtained. This corresponds to the change tendency of the movement amount and the degree of similarity with respect to the movement direction due to the position adjustment of the displacement meter. Then, in the similarity maximum position estimation step S13, the position of the displacement meter that can obtain the similarity of a predetermined value or more can be estimated based on the movement amount due to the position adjustment of the displacement meter and the change tendency of the similarity with respect to the movement direction.

Further, in the present embodiment, as shown in FIG. 12, the displacement r (θ) due to the shape error of the measurement target surface MSFA is four times or more the displacement e (θ) due to the rotation accuracy component of the measurement target object 210. It is desirable that it is 200 times or less. That is, the difference Wr between the maximum value and the minimum value of the displacement r (θ) due to the shape error is the maximum value of the displacement e (θ) due to the rotation accuracy component while the object to be measured 210 rotates once. It is desirable that the difference between the value and the minimum value is 4 times or more and 200 times or less of We. The Wr / We value is preferably 4 times or more and 200 times or less, and more preferably 4 times or more and 90 times or less. Further, the range of 8 times or more and 15 times or less is most preferable.

If Wr / We is too large, the rotation error with respect to the shape error becomes too small, and the rotation error cannot be separated accurately. On the other hand, if Wr / We is too small, the rotation error with respect to the shape error becomes relatively large, so that the shape error cannot be separated accurately, and as a result, the rotation error cannot be separated accurately. Specifically, if the Wr / We value is in the range of 4 times or more and 90 times or less, it is possible to separate the shape error and the rotation error with sufficient accuracy, although the shape error is slightly large. Further, especially when it is 8 times or more and 15 times or less, it is possible to separate the rotation error and the shape error with very high accuracy.

2. 2. 2nd Configuration Example FIG. 13 is a flowchart showing a procedure of rotation accuracy measurement using the rotation accuracy measuring device 200 and a procedure of processing performed by the rotation accuracy measuring device 200 in the second configuration example. The parts different from the first configuration example will be mainly described, and the parts similar to the first configuration example such as the configuration of the rotation accuracy measuring device 200 will be appropriately omitted.

As shown in FIG. 13, in the mutual correlation coefficient calculation step S9, the similarity quantitative value acquisition device 272 obtains the mutual correlation coefficient as the similarity RAB, RBC, and RCA. The mutual correlation coefficient calculation step S9 corresponds to the phase difference correction waveform acquisition step S4 and the similarity quantitative value acquisition step S5 in FIG. 3, but the phase difference and the similarity are simultaneously obtained when the mutual correlation coefficient is obtained.

The similarity quantitative value acquisition device 272 obtains the mutual correlation coefficient RAB by the following equations (4) to (7). It is assumed that the waveform signal SGA is obtained as N discrete numerical strings. SGA (m) indicates the m-th numerical value. k is a shift amount in the correlation function, and k = 0, 1, 2, ..., N. CA (k) is the autocorrelation function of SGA, CB (k) is the autocorrelation function of SGB, and CAB (k) is the cross-correlation function of SGA and SGB. The similarity quantitative value acquisition device 272 adopts the maximum value of RAB (k) obtained for each k value as the similarity. Further, the phase difference corresponding to k at which the maximum value is obtained is the phase difference between the waveform signals SGA and SGB. Although RAB has been described as an example, RBC and RCA are also calculated by the same formula.

According to the embodiment described above, in the second step of the rotation accuracy measuring method, the first waveform signal and the second waveform are obtained by calculating the mutual correlation coefficient RAB (k) represented by the above equation (7). Obtain the quantitative value of the phase difference and similarity of the signal. The first waveform signal corresponds to the waveform signal SGA, and the second waveform signal corresponds to the waveform signal SGB. However, the first and second waveform signals may be any two of the waveform signals SGA to SGC.

Further, the processing apparatus 270 of the present embodiment calculates the mutual correlation coefficient RAB (k) represented by the above equation (7) in the second processing to obtain the phase difference between the first waveform signal and the second waveform signal. Obtain a quantitative value of similarity.

By using the mutual correlation coefficient, the phase difference and similarity of the waveform signal can be obtained at the same time, so the similarity can be calculated in one step. Further, since the phase difference is obtained in the calculation of the mutual correlation coefficient, the degree of similarity can be calculated even if the installation angle of the displacement meters 221 to 223 is unknown. As a result, the calculation of the degree of similarity can be simplified and the position adjustment can be made more efficient.

3. 3. Third Configuration Example FIG. 14 is a third configuration example of the rotation accuracy measuring device 200. In the third configuration example, the processing device 270 includes the displacement meter position automatic control device 274. It should be noted that the parts different from the first configuration example or the second configuration example will be mainly described, and the description of the parts similar to the first configuration example or the second configuration example such as the procedure for measuring the rotation accuracy will be omitted as appropriate. ..

The processing device 270 functions as, for example, a first controller that functions as a displacement meter waveform reader 271, a second controller that functions as a displacement meter position automatic control device 274, a similarity quantitative value acquisition device 272, and an error separation calculation device 273. It is composed of an information processing device and an information processing device. The second controller is connected to the position adjusting devices 231 to 233 by a cable or the like, and is connected to the information processing device by a cable or a network. The displacement meter position automatic control device 274 moves the displacement meters 221 to 223 up and down by driving the actuators of the position adjustment devices 231 to 233 based on the instruction from the similarity quantitative value acquisition device 272.

In the first configuration example, it is assumed that the user moves the displacement meters 221 to 223 up and down, but in the third configuration example, the position adjustment of the displacement meters 221 to 223 is automated. That is, in the third configuration example, the rotation accuracy measuring device 200 automatically adjusts the positions of the displacement meters 221 to 223 in the displacement meter position adjusting step S6 of FIG. Specifically, in the displacement meter position information acquisition step S12 of FIG. 7, the similarity quantitative value acquisition device 272 instructs the displacement meter position automatic control device 274 to move the positions of the displacement meters 221 to 223, and each position. The waveform signals SGA to SGC are read by the displacement meter waveform reader 271. The similarity quantitative value acquisition device 272 estimates the position of the displacement meter whose similarity is equal to or higher than the predetermined value in the similarity maximum position estimation step S13, and in the displacement meter position correction step S14, the displacement meter position automatic control device 274 is used. Instruct to move the positions of the displacement meters 221 to 223 to the estimated positions.

According to the embodiment described above, the third step of the rotation accuracy measuring method includes the maximum similarity position estimation step S13, the displacement meter position correction step S14, and the determination step S15. In the similarity maximum position estimation step S13, the displacement at which the similarity RAB, RBA, and RCA become equal to or higher than a predetermined value based on the change tendency of the similarity RAB, RBA, and RCA with respect to the movement amount and the movement direction by adjusting the position of the displacement meter. Guess the position of the meter. The displacement meter position correction step S14 corrects the position of the displacement meter based on the result of the similarity maximum position estimation step S13. The determination step S15 determines whether or not the position of the displacement meter has been adjusted so that the similarity RAB, RBA, and RCA are equal to or higher than a predetermined value. The "change tendency of the movement amount and the degree of similarity with respect to the movement direction due to the position adjustment of the displacement meter" is the degree of similarity with respect to the movement amount and the movement direction when the displacement meter is moved in the direction perpendicular to the rotation direction Drot. It means how much it changes to positive or negative. For example, the waveform showing the relationship between the displacement meter position and the degree of similarity described in FIG. 8 corresponds to the above-mentioned change tendency.

Further, in the present embodiment, the processing device 270 performs the similarity maximum position estimation process, the displacement meter position correction process, and the determination process in the third process. The similarity maximum position estimation process is based on the change tendency of the similarity RAB, RBA, and RCA with respect to the movement amount and the movement direction by the position adjustment of the displacement meters included in the plurality of displacement meters 221 to 223, and the similarity degree RAB, RBA. , Estimate the position of the displacement meter whose RCA is equal to or higher than the predetermined value. The displacement meter position correction process adjusts the positions of the displacement meters 221 to 223 based on the result of the similarity maximum position estimation process. The determination process determines whether or not the position of the displacement meter has been adjusted so that the similarity RAB, RBA, and RCA are equal to or higher than a predetermined value.

By doing so, it is determined whether or not the position of the displacement meter has been adjusted so that the similarity RAB, RBA, and RCA are equal to or higher than the predetermined values. Therefore, the similarity RAB, RBA, and RCA are equal to or higher than the predetermined values. Adjusted to the position of the displacement meter. Further, when it is determined that the similarity RAB, RBA, RCA is not equal to or higher than the predetermined value, the similarity RAB, RBA, RCA can be increased to be equal to or higher than the predetermined value by repeating the position adjustment of the displacement meter. This makes it possible to provide highly accurate rotation accuracy measurement. Further, since the rotation accuracy measuring device 200 can automatically perform the displacement meter position adjustment, the displacement meter position adjustment can be made more efficient.

4. Fourth Configuration Example FIG. 15 is a fourth configuration example of the rotation accuracy measuring device 200. The rotation accuracy measuring device 200 includes a stage 285, a rotating body 280, a measuring object 210, position adjusting devices 251 to 254, displacement meters 241 to 244, and a processing device 270. The parts different from the first to third configuration examples will be mainly described, and the parts similar to the first to third configuration examples such as the procedure for measuring the rotation accuracy will be omitted as appropriate.

In the fourth configuration example, as shown in FIG. 16, the rotation error in the tilt direction and the rotation error in the axial direction are detected. The tilt direction is the inclination of the upper surface of the object to be measured 210, that is, the inclination of the rotation axis 190 with respect to the ideal rotation axis 192. The rotation error in the tilt direction indicates the tilt angle of the rotation axis 190 with respect to the z-axis and the direction in which the tilt is oriented with respect to the x-axis and the y-axis. The axial direction is the vertical direction along the rotation axis 190. The rotational error in the axial direction indicates the deviation of the object to be measured 210 in the vertical direction along the z-axis.

In the fourth configuration example, the upper surface of the measurement target object 210 is the measurement target surface MSFB whose displacement is measured by the displacement meters 241 to 244. The surface of the measurement target surface MSFB is mirror-polished so that the displacement meters 241 to 244 can measure the displacement with high accuracy. The surface accuracy of the measurement target surface MSFB is several hundred nm to 1 μm.

The position adjusting devices 251 to 254 support the displacement meters 241 to 244, and the position adjusting devices 251 to 254 move in the radial direction with respect to the rotation axis 190 so that the positions of the displacement meters 241 to 244 in the radial direction can be changed. Change. By changing the positions of the displacement meters 241 to 244, the positions where the displacements are measured by the displacement meters 241 to 244 on the measurement target surface MSFB change in the direction orthogonal to the rotation direction Dolot. Various configurations of the position adjusting devices 251 to 254 can be considered. For example, each position adjusting device includes a support column that supports the displacement meter and extends in the radial direction, and a mechanism for moving the support column. Further, each position adjusting device may further include an encoder for detecting the position of the displacement meter in the radial direction. The user may move the stanchion as in the first configuration example, or the stanchion movement may be automated as in the second configuration example. When automated, the mechanism for raising and lowering the columns is an actuator such as a stepping motor.

The displacement meters 241 to 244 measure the displacement of the measurement target surface MSFB in the tilt direction and the axial direction, that is, the displacement of the distance between the displacement meters 241 to 244 in the tilt direction and the axial direction and the measurement target surface MSFB. The displacement meters 241 to 244 are arranged around the rotation axis 190 and on the measurement target surface MSFB when viewed from the + z side in the −z direction, and the measurement direction of the distance faces the −z direction. Although the displacement meters 241 to 244 are non-contact type displacement meters, a contact type displacement meter may be adopted. However, it is desirable to use a non-contact type displacement meter.

The displacement meter 241 measures the distance to one point of the measurement target surface MSFB, and when the measurement target object 210 rotates, the displacement of the measurement target surface MSFB on the line D is measured. The line D is a line that goes around the measurement target surface MSFB in the rotation direction Drot. The displacement meter 241 outputs a waveform signal SGD indicating the displacement on the line D. The waveform signal SGD is a signal in which the displacement due to the shape error on the line D of the measurement target surface MSFB and the displacement due to the rotation error are mixed. Since the position of the line D changes as the displacement meter 241 moves in the radial direction, the displacement measured by the displacement meter 241 changes, and the waveform of the waveform signal SGD changes. Similarly, the displacement meters 242 to 244 measure the displacement of the measurement target surface MSFB on the lines E to G. The displacement meters 242 to 244 output waveform signals SGE to SGG indicating displacements on the lines E to G. The waveform signals SGE to SGG are signals in which the displacement due to the shape error on the lines E to G of the measurement target surface MSFB and the displacement due to the rotation error are mixed.

The processing device 270 separates the shape error and the rotation accuracy component of the measurement object 210 based on the waveform signals SGD to SGG. The processing device 270 includes a displacement meter waveform reading device 271, a similarity quantitative value acquisition device 272, and an error separation calculation device 273. The procedure for measuring the rotation accuracy is the same as that of the first to third configuration examples, but the moving direction of the displacement meter is the radial direction. In the fourth configuration example, the rotation accuracy components in the tilt direction and the axial direction are separated. For the method, for example, "Study on precise measurement of axial and angular motion error of machine tool rotation spindle by multi-point method" Precision Engineering Journal, Vol. 67, No. 7,2001, p1120-p1124.

FIG. 17 shows contour lines of the shape error of the measurement target surface MSFB and lines D to G on the measurement target surface MSFB on which the displacement meters 241 to 244 measure the displacement. The left figure of FIG. 17 is before the position adjustment of the displacement meter, and the right figure is after the position adjustment of the displacement meter. By adjusting the position of the displacement meter, the positions of the lines D to G in the radial direction are substantially the same, and the shape errors measured by the displacement meters 241 to 244 are substantially the same. As a result, the waveforms of the waveform signals SGD to SGG are almost the same except for the rotation accuracy component, so that the waveform signals SGD to SGG having very high similarity can be obtained.

5. Three-dimensional shape measuring device and three-dimensional shape measuring method FIG. 18 is a configuration example of a three-dimensional shape measuring device 100 including a rotation accuracy measuring device 200. The three-dimensional shape measuring device 100 includes an object 110, a displacement meter 120 for shape measurement, a position adjusting device 130, a shape measuring data reading device 275, and a rotation accuracy measuring device 200. The rotation accuracy measuring device 200 may be any of the first to fourth configuration examples, or may be a combination of two or more of them. FIG. 18 shows an example in which the first configuration example and the fourth configuration example are combined.

The three-dimensional shape measuring device 100 is also called a rotary scanning type shape measuring machine, and measures the three-dimensional shape of the test object 110 by rotationally scanning the surface displacement of the test object 110. The test object 110 is an optical element such as a lens, or a molding die for molding the optical element. However, the test object 110 may be an object that is rotationally symmetric with respect to the central axis. The test object 110 is installed on the measurement object 210 so that its central axis is coaxial with the rotation axis 190.

The displacement meter 120 for shape measurement is a non-contact type displacement meter. A contact type displacement meter may be adopted as the shape measurement displacement meter 120, but it is desirable to adopt a non-contact type displacement meter. As the non-contact type displacement meter, various displacement meters mentioned in the first configuration example can be adopted.

The position adjusting device 130 is a device that supports the shape measuring displacement meter 120 and moves the position of the shape measuring displacement meter 120. The position adjusting device 130 includes, for example, a first strut extending in the x direction, a second strut extending in the z direction, a first actuator for moving the second strut along the first strut in the x direction, and a second strut. A second actuator for connecting the displacement meter 120 for measurement and rotating the displacement meter 120 for shape measurement on a rotation axis perpendicular to the z-axis is included. Further, the position adjusting device 130 has a first encoder that detects the position of the shape measuring displacement meter 120 in the x direction and a second encoder that detects the rotation angle of the shape measuring displacement meter 120 on the rotation axis perpendicular to the z axis. And may be included.

By rotating the rotating body 280, the subject 110 rotates around the rotating shaft 190. In this state, the position adjusting device 130 scans the displacement meter 120 for shape measurement, so that the displacement measurement points are spirally scanned on the surface of the test object 110. As a result, the three-dimensional shape of the surface of the test object 110 is measured.

The shape measurement data reading device 275 is a device that reads the waveform signal output by the displacement meter 120 for shape measurement. That is, the shape measurement data reader 275 acquires a waveform signal when the shape measurement displacement meter 120 spirally scans the surface of the test object 110, and performs processing such as waveform shaping on the waveform signal. .. FIG. 18 shows an example in which the shape measurement data reading device 275 is provided separately from the processing device 270 as a controller, and the controller is connected to the processing device 270 by a cable or the like. However, the shape measurement data reading device 275 may be included in the processing device 270.

FIG. 19 is a flowchart showing the procedure of three-dimensional shape measurement.

In the rotation accuracy measuring step S51, the rotation accuracy measuring device 200 described in the first to fourth configuration examples measures the rotation accuracy of the object to be measured 210. In the shape measuring step S52, the three-dimensional shape measuring device 100 measures the three-dimensional shape of the surface of the test object 110. The rotation accuracy measuring step S51 and the shape measuring step S52 are executed at the same time while rotating the measurement target object 210 and the test object 110. That is, the rotation accuracy measuring device 200 detects the rotation accuracy component during the measurement operation of the three-dimensional shape measuring device 100.

In the calibration step S53, the measurement error in the three-dimensional shape measurement is calibrated using the rotation accuracy component acquired in S51. Specifically, the processing device 270 converts the rotation accuracy component acquired in S51 into a rotation error in the displacement measurement of the test object 110, and corrects the three-dimensional shape measurement result so that the rotation error is canceled. do. More specifically, the processing apparatus 270 measures the base point of the inclination of the rotating shaft 190, the height from the base point to the measurement points of the displacement meters 221 to 223 and 241 to 244, and the measurement of the displacement meter 120 for shape measurement from the base point. The height to the point is detected from the output of the encoder or the like. The processing apparatus 270 uses these parameters to convert the rotation accuracy component detected by the measurement object 210 into the rotation accuracy component in the test object 110. The processing device 270 corrects the waveform signal output from the shape measuring displacement meter 120 so as to cancel the rotation accuracy component in the test object 110.

The three-dimensional shape measuring method of the present embodiment described above is described in the shape measuring step S52 for measuring the three-dimensional shape of the test object 110 using the shape measuring displacement meter 120, and the first to fourth configuration examples. It includes a calibration step S53 for calibrating the measurement result of the three-dimensional shape using the rotation accuracy component obtained by the rotation accuracy measurement method.

Further, the three-dimensional shape measuring device 100 of the present embodiment includes a displacement meter 120 for shape measurement for measuring the three-dimensional shape of the test object 110, and a processing device 270. The processing device 270 uses a shape measurement process for measuring a three-dimensional shape using a shape measurement displacement meter 120 and a rotation accuracy component acquired by the rotation accuracy measurement methods described in the first to fourth configuration examples. A calibration process for calibrating the measurement result of the three-dimensional shape is performed.

By doing so, it is possible to acquire the measurement data of the three-dimensional shape and the rotation accuracy component at the same time or in cooperation with each other. As a result, the measurement data of the three-dimensional shape obtained by the three-dimensional shape measuring device 100 can be corrected with high accuracy by using the measurement data of the rotation accuracy component obtained by the rotation accuracy measuring device 200, and as a result, the measurement data has high accuracy. The shape of the test object can be measured with.

Further, the rotation accuracy includes "repeated rotation error" that is repeatedly reproduced for each rotation and "non-repeated rotation error" that is not repeatedly reproduced. The "repeated rotation error" that is repeatedly reproduced for each rotation can be estimated by a method different from that of the present embodiment. Another method is, for example, a method of measuring a high-precision plane and a high-precision spherical surface having a known shape on a three-dimensional shape measuring device and evaluating a shape measurement error occurring in the shape measurement result. On the other hand, in the rotation accuracy measuring method or the rotation accuracy measuring device of the method using a plurality of displacement meters adopted in this embodiment, not only the "repeated rotation error" that is repeatedly reproduced for each rotation but also the "non-repetitive rotation error" that is not reproduced is not reproduced. It is possible to measure "total rotation accuracy" including "".

In general, the magnitude of the "non-repetitive rotation error" is sufficiently smaller than the "repeated rotation error", so that the "repeated rotation error" estimated from the shape measurement error and the rotation accuracy measuring method or rotation of the present embodiment are used. By comparing the "total rotation accuracy" measured by the accuracy measuring device, the effectiveness before and after the application of this embodiment can be explained. When this embodiment is not applied, the "total rotation accuracy" measured by the method using a plurality of displacement meters greatly deviates from the "repeated rotation error" estimated from the shape measurement error. On the other hand, when the present embodiment is applied, the "repeated rotation error" estimated from the shape measurement error and the "total rotation accuracy" measured by the method of the present embodiment are substantially the same, and the present embodiment Turns out to be valid. This point is as described with reference to FIGS. 10 and 11.

6. Optical equipment FIG. 20 is an example of an optical equipment equipped with an optical element selected by measuring a three-dimensional shape using a three-dimensional shape measuring device 100. FIG. 20 shows an endoscope device 300 as an example of an optical device, but the optical device may be a device equipped with an optical element, and is mounted on, for example, a steel camera, an interchangeable lens of an interchangeable lens camera, or an information terminal. It may be a camera unit, a video camera, or the like.

The endoscope device 300 includes a connector 320 connected to a control device which is a main body of the endoscope, a universal cable 340 having one end connected to the connector 320, and an operating device 330 connected to the other end of the universal cable 340. Includes an insertion unit 350, one end of which is connected to the operating device 330, and an image pickup device 310 provided at the other end of the insertion unit 350. The endoscope device 300 may be further provided with a lighting lens for irradiating the illumination light, a treatment tool such as forceps, a water supply port, or the like.

The image pickup apparatus 310 includes an objective lens that forms an image of a subject and an image sensor that captures the image formation. The objective lens includes a plurality of lenses, and one or more of them is an optical element selected by measuring a three-dimensional shape using a three-dimensional shape measuring device 100. In the present embodiment, since the rotation accuracy component can be detected with high accuracy, the three-dimensional shape of the optical element can be measured with high accuracy. By constructing an optical device using the optical element, a high-resolution image or video can be taken.

Although the present embodiment and its modifications have been described above, the present disclosure is not limited to each embodiment and its modifications as they are, and at the implementation stage, the components are modified within a range that does not deviate from the gist. Can be embodied. In addition, a plurality of components disclosed in the above-described embodiments and modifications can be appropriately combined. For example, some components may be deleted from all the components described in each embodiment or modification. Further, the components described in different embodiments and modifications may be combined as appropriate. As described above, various modifications and applications are possible without departing from the gist of the present disclosure. Also, in the specification or drawings, a term described at least once with a different term having a broader meaning or a synonym may be replaced with the different term in any part of the specification or the drawing.

100 3D shape measuring device, 110 test object, 120 shape measurement displacement meter, 130 position adjustment device, 190 rotation axis, 192 ideal rotation axis, 200 rotation accuracy measurement device, 210 measurement object, 221 to 223 displacement Total, 231 to 233 position adjustment device, 241 to 244 displacement meter, 251 to 254 position adjustment device, 270 processing device, 271 displacement meter waveform reader, 272 similarity quantitative value acquisition device, 273 error separation calculation device, 274 displacement meter Automatic position control device, 275 shape measurement data reader, 280 rotating body, 285 stage, 300 endoscope device, 310 imaging device, 320 connector, 330 operating device, 340 universal cable, 350 insertion part, Dot rotation direction, MSFA, MSFB measurement target surface, RBA, RBC, RCA similarity, SGA to SGE waveform signal

Claims

In the rotation accuracy measurement method for measuring the rotation accuracy component by separating the shape error of the object to be measured and the rotation accuracy component using a plurality of displacement meters.
The first step of measuring the displacement of the distance between the plurality of displacement meters and the object to be measured using the plurality of displacement meters while rotating the object to be measured, and obtaining a plurality of waveform signals indicating the displacement. ,
The second step of quantitatively evaluating the similarity between the plurality of waveform signals, and
The third step of adjusting the positions of the displacement meters included in the plurality of displacement meters so that the similarity becomes equal to or higher than a predetermined value, and
A method for measuring rotational accuracy, which comprises.
In claim 1,
The third step is
The maximum similarity position estimation step of estimating the position of the displacement meter whose similarity is equal to or higher than the predetermined value based on the change tendency of the similarity with respect to the movement amount and the movement direction due to the position adjustment of the displacement meter.
A displacement meter position correction step of correcting the position of the displacement meter based on the result of the similarity maximum position estimation step, and a displacement meter position correction step.
A determination step for determining whether or not the position of the displacement meter has been adjusted so that the similarity is equal to or higher than the predetermined value.
A method for measuring rotational accuracy, which comprises.
In claim 1,
In the second step,
The autocorrelation function of the first waveform signal among the plurality of waveform signals is CA (k), the autocorrelation function of the second waveform signal among the plurality of waveform signals is CB (k), and the first waveform. When the cross-correlation function of the signal and the second waveform signal is CAB (k), and k is the amount of shift in the correlation calculation,

A rotation accuracy measuring method characterized in that the phase difference between the first waveform signal and the second waveform signal and the quantitative value of the similarity are obtained by calculating the mutual correlation coefficient RAB (k) shown by. ..
In claim 1,
The measurement object installation process in which the measurement object having the measurement object surface is installed coaxially with the rotation axis of the rotating body,
A displacement meter installation process in which the plurality of displacement meters are arranged around the measurement object, and
Including
In the first step, the plurality of waveform signals are acquired while rotating the measurement object on the rotation axis.
The rotation accuracy measuring method, characterized in that the rotation accuracy component is a component used for calibrating the rotation accuracy of the rotating body on which the measurement object is installed.
In claim 4,
In the displacement meter installation process,
The plurality of displacement meters are installed at different installation angles along the rotation direction of the rotating body.
In the first step,
Acquiring the plurality of waveform signals while rotating the measurement object,
In the second step,
The degree of similarity is quantified by obtaining the phase difference between the plurality of waveform signals caused by the difference in the installation angle and the quantitative value of the degree of similarity between the plurality of waveform signals corrected for the phase difference. A rotation accuracy measuring method characterized by evaluation.
In claim 4,
A fourth step of performing an error separation calculation for separating the shape error and the rotation accuracy component from the plurality of waveform signals is included.
In the fourth step,
Rotation characterized in that the error separation calculation is performed using the plurality of waveform signals acquired at the positions of the displacement meters adjusted so that the similarity is equal to or higher than the predetermined value in the third step. Accuracy measurement method.
In claim 4,
The third step is
From the plurality of displacement meters, a reference displacement meter setting process for determining a reference displacement meter as a reference for position adjustment, and
The displacement meter different from the reference displacement meter is moved to a plurality of positions in the rotation axis direction of the measurement object or the radial direction with respect to the rotation axis, and the plurality of waveform signals are acquired at each position of the plurality of positions. , A displacement meter position information acquisition step for obtaining the similarity between the waveform signal obtained by the reference displacement meter and the waveform signal obtained by the displacement meter at each position.
A similarity maximum position estimation step of estimating the position of the displacement meter from which the similarity of the predetermined value or more is obtained based on the plurality of similarity obtained corresponding to the plurality of positions.
A displacement meter position correction step of moving the displacement meter to the position estimated in the similarity maximum position estimation step, and a displacement meter position correction step.
A method for measuring rotational accuracy, which comprises.
In claim 1,
A rotation accuracy measuring method, characterized in that the displacement caused by the shape error is 4 times or more and 200 times or less the displacement caused by the rotation accuracy component.
With multiple displacement meters,
A processing device that measures the rotation accuracy component by separating the shape error of the object to be measured and the rotation accuracy component using the plurality of displacement meters.
Including
The processing device is
The first process of measuring the displacement of the distance between the plurality of displacement meters and the object to be measured by using the plurality of displacement meters while rotating the object to be measured, and acquiring a plurality of waveform signals indicating the displacement. When,
The second process of quantitatively evaluating the similarity between the plurality of waveform signals, and
A third process of acquiring the plurality of waveform signals when the positions of the plurality of displacement meters are adjusted so that the similarity becomes equal to or higher than a predetermined value.
A rotation accuracy measuring device characterized by performing.
In claim 9.
The processing device is
In the third process,
Similarity in which the position of the displacement meter whose similarity is equal to or higher than the predetermined value is estimated based on the change tendency of the similarity with respect to the movement amount and the movement direction of the displacement gauges included in the plurality of displacement meters. Maximum position estimation process and
Displacement meter position correction processing that corrects the position of the displacement meter based on the result of the similarity maximum position estimation processing, and
Judgment processing for determining whether or not the position of the displacement meter has been adjusted so that the similarity is equal to or higher than the predetermined value.
A rotation accuracy measuring device characterized by performing.
In claim 9.
The processing device is
In the second process,
The autocorrelation function of the first waveform signal among the plurality of waveform signals is CA (k), the autocorrelation function of the second waveform signal among the plurality of waveform signals is CB (k), and the first waveform. When the cross-correlation function of the signal and the second waveform signal is CAB (k), and k is the amount of shift in the correlation calculation,

A rotation accuracy measuring device, characterized in that a quantitative value of a phase difference and a degree of similarity between the first waveform signal and the second waveform signal is obtained by calculating the mutual correlation coefficient RAB (k) shown by.
In the three-dimensional shape measuring method for measuring the three-dimensional shape of a test object,
A shape measurement step of measuring the three-dimensional shape of the test object using a displacement meter for shape measurement, and a shape measurement step.
A calibration step of calibrating the measurement result of the three-dimensional shape using the rotation accuracy component obtained by the rotation accuracy measurement method according to claim 1.
A three-dimensional shape measuring method comprising.
In a three-dimensional shape measuring device that measures the three-dimensional shape of a test object
A displacement meter for shape measurement for measuring the three-dimensional shape of the test object,
With the processing equipment
Including
The processing device is
The shape measurement process for measuring the three-dimensional shape using the shape measurement displacement meter, and
A calibration process for calibrating the measurement result of the three-dimensional shape using the rotation accuracy component acquired by the rotation accuracy measuring device according to claim 9.
A three-dimensional shape measuring device characterized by performing.
An optical device characterized by mounting an optical element selected by measuring the three-dimensional shape using the three-dimensional shape measuring device according to claim 13.