JP2018162996A - Relation identifying method, relation identifying device, relation identifying program, correction method, correction device, and correction program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow an interference waveform to be corrected.SOLUTION: A computer 2 obtains interference waveforms corresponding to respective inclination angles in the case of changing an inclination angle, i.e. an angle of a work W placed on a three-dimensional measuring device 1 to an optical path of white light radiated by a white interferometer 12 at the three-dimensional measuring device 1 including the white interferometer 12, identifies a plurality of phase offsets between each of the plurality of interference waveforms obtained at the plurality of inclination angles and a reference interference waveform, and identifies relation between the inclination angle and the phase offset on the basis of the inclination angles and the phase offsets.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a relationship identification method, a relationship identification device, a relationship identification program, a correction method, a correction device, and a correction program for correcting an interference waveform in a white interferometer.

  Conventionally, equipped with a white interferometer, irradiates the workpiece and the reference surface with white light, and measures the three-dimensional shape and height of the workpiece based on the white light reflected from the workpiece and the white light reflected from the reference surface A three-dimensional measurement system is known (see, for example, Patent Document 1).

  The objective lens of the white interferometer is composed of a Milo interferometer or a Michelson interferometer. FIG. 9 is a diagram showing a configuration example of the objective lens 100 of the Milo interferometer type. As shown in FIG. 9, the objective lens 100 includes a lens group 101 that emits white light, a glass substrate 102 that transmits white light emitted from the lens group, and a portion of white light that has passed through the glass substrate 102. It includes a beam splitter 103 that reflects and transmits another part, and a reference mirror 104 that is placed on the glass substrate 102 and reflects white light reflected by the beam splitter 103.

  When the workpiece 105 irradiated with white light is imaged by the imaging unit, the optical path of white light incident on the imaging unit is transmitted through the beam splitter 103 and reflected from the workpiece 105, and is a measurement optical path that is an optical path of white light. And a reference optical path which is an optical path of white light reflected by the beam splitter 103 and the reference mirror 104. For this reason, interference occurs due to these optical path differences. When imaging is performed while moving the position of the objective lens 100 in the direction of white light irradiation, an interference waveform IW as shown in FIG. 3 is obtained in each of the plurality of pixels included in the captured image. The three-dimensional measurement system specifies the position in the optical axis direction of the objective lens 100 at which the interference light intensity is maximum in the pixel included in the captured image, thereby increasing the height in the optical axis direction of the position on the workpiece corresponding to the pixel. Can be measured.

JP 2013-104998 A

  When the normal direction of the workpiece is not parallel to the optical axis of the objective lens, when the light reflected from the workpiece is not regular reflection, the optical path changes and the phase of the light wave changes. Then, a phase shift occurs in the first optical path, and a shift occurs as shown by the interference waveform IW ′ in FIG. Therefore, when the workpiece inclination is not uniform and the normal direction of the workpiece is not uniform, there arises a problem that the height of the workpiece cannot be accurately measured due to the deviation of the interference waveform. .

  Therefore, the present invention has been made in view of these points, and an object thereof is to provide a relationship identification method, a relationship identification device, and a relationship identification program that enable correction of an interference waveform. It is another object of the present invention to provide a correction method, a correction device, and a correction program that can correct an interference waveform.

  The relationship specifying method according to the first aspect of the present invention is a computer-implemented three-dimensional measuring machine including a white interferometer, which is mounted on the three-dimensional measuring machine with respect to an optical path of white light emitted by the white interferometer. A first acquisition step of acquiring an interference waveform corresponding to each of the plurality of tilt angles when the tilt angle that is the angle of the workpiece is changed, and a plurality of interference waveforms acquired at the plurality of tilt angles A relationship between the tilt angle and the phase offset based on a first specifying step for specifying a plurality of phase offsets between each of the reference interference waveform and the reference interference waveform, and the plurality of tilt angles and the plurality of phase offsets. A second specifying step of specifying.

  In the relationship specifying method, the interference waveform corresponding to each of the plurality of tilt directions when the tilt direction of the workpiece is changed with the white light irradiation direction as a central axis in a state where the tilt angle is fixed. A second acquisition step of acquiring a plurality of phase offsets between each of the plurality of interference waveforms acquired in the plurality of tilt directions and the reference interference waveform; and A fourth specifying step of specifying a relationship between the tilt direction and the phase offset based on the tilt direction and the plurality of phase offsets may be further included.

  In the first acquisition step, the relationship specifying method acquires the interference waveform while changing the tilt angle in a state where the tilt direction is fixed to the tilt direction when the phase offset is maximum. Also good.

  The relationship specifying method includes a third acquisition step of acquiring the interference waveform while changing the tilt angle in a state in which the tilt direction is fixed so that a component of the phase offset depending on the tilt direction is zero. , A fifth specifying step for specifying a plurality of phase offsets between each of the plurality of interference waveforms acquired in the third acquiring step and the reference interference waveform, the plurality of inclination angles, and the fifth specifying step A sixth specifying step of specifying a relationship between the tilt angle and the phase offset component that does not depend on the tilt direction but depends on the tilt angle based on the plurality of phase offsets specified in step You may have.

  The relationship specifying device according to the second aspect of the present invention is a three-dimensional measuring machine including a white interferometer, wherein an angle of a workpiece placed on the three-dimensional measuring machine with respect to an optical path of white light irradiated by the white interferometer An acquisition unit that acquires an interference waveform corresponding to each of the plurality of inclination angles, and each of the plurality of interference waveforms acquired at the plurality of inclination angles and a reference interference waveform A phase offset specifying unit that specifies a plurality of phase offsets between, a relationship specifying unit that specifies a relationship between the tilt angle and the phase offset based on the plurality of tilt angles and the plurality of phase offsets; Have

  The relationship specifying program according to the third aspect of the present invention is a computer mounted on the three-dimensional measuring machine with respect to the optical path of the white light irradiated by the white interferometer in the three-dimensional measuring machine including the white interferometer. An acquisition unit that acquires an interference waveform corresponding to each of the plurality of inclination angles when the inclination angle that is a workpiece angle is changed, and each of the plurality of interference waveforms acquired at the plurality of inclination angles and a reference interference A phase offset specifying unit that specifies a plurality of phase offsets between waveforms, and a relationship specification that specifies a relationship between the tilt angles and the phase offsets based on the plurality of tilt angles and the plurality of phase offsets Function as part.

  In the correction method according to the fourth aspect of the present invention, in a three-dimensional measuring machine using a white interferometer, a computer is mounted on the three-dimensional measuring machine with respect to an optical path of white light emitted by the white interferometer. A correction method for correcting a phase offset of an interference waveform associated with an inclination angle that is an angle of a workpiece, which is based on a plurality of captured images of the workpiece captured while moving the white light interferometer in the irradiation direction of the white light Acquiring an interference waveform corresponding to each of the plurality of pixels included in the captured image, specifying the tilt angle at the position of the workpiece corresponding to each of the plurality of pixels, The phase offset corresponding to the tilt angle specified for each of a plurality of pixels based on the relationship between the tilt angle and the phase offset. Comprising identifying, based on the identified the phase offset, and correcting the interference waveforms corresponding to each of the plurality of pixels, a.

  A correction apparatus according to a fifth aspect of the present invention is a three-dimensional measuring machine using a white interferometer, wherein the workpiece placed on the three-dimensional measuring machine with respect to the optical path of white light emitted by the white interferometer is used. A correction device that corrects a phase offset of an interference waveform associated with an inclination angle that is an angle, based on a plurality of captured images of the workpiece that are captured while moving the white light interferometer in the irradiation direction of the white light, An acquisition unit that acquires an interference waveform corresponding to each of the plurality of pixels included in the captured image, an inclination angle specifying unit that specifies the inclination angle at the position of the workpiece corresponding to each of the plurality of pixels, and specification in advance The phase offset corresponding to the tilt angle specified for each of a plurality of pixels is identified based on the relationship between the tilt angle and the phase offset. Comprising a set specifying unit, based on the identified said phase offset, and a correction section that corrects the interference waveforms corresponding to each of the plurality of pixels, a.

  A correction program according to a sixth aspect of the present invention is a three-dimensional measuring machine using a white interferometer, wherein the workpiece placed on the three-dimensional measuring machine with respect to the optical path of white light irradiated by the white interferometer The computer that corrects the phase offset of the interference waveform with the tilt angle that is the angle of the image is based on a plurality of captured images of the workpiece that are captured while moving the white light interferometer in the irradiation direction of the white light. An acquisition unit that acquires an interference waveform corresponding to each of the plurality of pixels included in the image, an inclination angle specifying unit that specifies the inclination angle at the position of the workpiece corresponding to each of the plurality of pixels, and the inclination specified in advance Based on the relationship between the angle and the phase offset, the phase offset corresponding to the tilt angle specified for each of a plurality of pixels is specified. Offset identifying unit, and, based on the identified said phase offset correction unit, to function as correcting the interference waveforms corresponding to each of the plurality of pixels.

  According to the present invention, it is possible to correct an interference waveform.

It is a figure which shows the structure of the three-dimensional measurement system which concerns on 1st Embodiment. It is a figure which shows the structure of the computer which concerns on 1st Embodiment. It is a figure which shows an example of an interference waveform. It is a figure which shows an example of the interference waveform from which the waveform position shifted | deviated. It is a flowchart which shows the flow of the process which specifies the relationship between an inclination angle and a phase offset by the computer which concerns on 1st Embodiment. It is a flowchart which shows the flow of the process which concerns on correction | amendment of the phase offset by the computer which concerns on 1st Embodiment. It is a flowchart which shows the flow of the process which specifies the relationship between an inclination angle, an inclination direction, and a phase offset by the computer which concerns on 2nd Embodiment. It is a flowchart which shows the flow of the process which specifies the relationship between an inclination angle, an inclination direction, and a phase offset by the computer which concerns on 3rd Embodiment. It is a figure which shows the structural example of an interference objective lens of a Millo interferometer type.

<First Embodiment>
FIG. 1 is a diagram illustrating a configuration of a three-dimensional measurement system S according to the first embodiment.
The three-dimensional measuring system S includes a three-dimensional measuring machine 1 and a computer 2 as a relationship specifying device and a correction device.

The coordinate measuring machine 1 includes a stage 11, a white interferometer 12, and a drive control unit 13.
The stage 11 is a measurement board on which the workpiece W is placed.
The white interferometer 12 includes an irradiation unit 121, a collimator lens 122, a beam splitter 123, an objective lens unit 124, and an imaging unit 129.

The irradiation unit 121 irradiates the collimator lens 122 with white light.
The collimator lens 122 emits the incident white light as parallel light.
The beam splitter 123 reflects the white light emitted from the collimator lens 122 and enters the objective lens unit 124. Further, the beam splitter 123 transmits the white light incident from the objective lens unit 124 and causes the white light to enter the imaging unit 129.

The objective lens unit 124 includes an objective lens 125, a glass substrate 126, a reference mirror 127, and a beam splitter 128.
The objective lens 125 converges the white light incident from the beam splitter 123 and causes it to enter the glass substrate 126.
The glass substrate 126 transmits the incident white light. A reference mirror 127 is placed on the upper surface of the glass substrate 126. The reference mirror 127 reflects the white light reflected from the beam splitter 128 to the beam splitter 128.

The beam splitter 128 reflects a part of the white light incident from the objective lens 125 so as to be incident on the reference mirror and transmits the other part to be incident on the workpiece W. The white light incident on the reference mirror is reflected by the reference mirror 127 and enters the beam splitter 128 again. The beam splitter 128 reflects the white light reflected by the reference mirror 127 and makes it incident on the objective lens 125.
Further, the beam splitter 128 transmits the reflected light reflected from the workpiece W and makes it incident on the objective lens 125.

  As described above, the white light incident on the objective lens 125 passes through the beam splitter 128, is reflected by the workpiece W and is transmitted through the beam splitter 128, and the measurement light path, which is the white light optical path, passes through the beam splitter 128. And a reference optical path that is an optical path of white light reflected by the reference mirror 127 and then reflected by the beam splitter 128 again. Due to the optical path difference between the reference optical path and the measurement optical path, interference occurs in the white light incident on the objective lens 125. Hereinafter, white light that enters the objective lens 125 and enters the imaging unit 129 is also referred to as interference light.

  The imaging unit 129 is a CCD camera or the like including a two-dimensional imaging element. The imaging unit 129 detects the interference light transmitted through the objective lens unit 124 and transmitted through the beam splitter 123, and generates a captured image. The imaging unit 129 outputs the generated captured image to the computer 2.

  The drive control unit 13 changes the distance between the objective lens unit 124 and the workpiece W by moving the white interferometer 12 in the white light irradiation direction. The drive control unit 13 outputs height position information indicating the height position of the objective lens unit 124 based on the position of the white interferometer 12 to the computer 2.

  The imaging unit 129 generates a captured image and outputs it to the computer 2 every time the objective lens unit 124 moves. Since the optical path difference between the measurement optical path and the reference optical path changes according to the change in the height position of the objective lens unit 124, the intensity of the interference light detected in each pixel included in the captured image is the intensity of the objective lens unit 124. It changes according to the change of the height position.

FIG. 2 is a diagram illustrating a configuration of the computer 2 according to the first embodiment.
The computer 2 includes a storage unit 21 and a control unit 22.
The storage unit 21 is, for example, a ROM and a RAM. The storage unit 21 stores various programs for causing the computer 2 to function. The storage unit 21 stores a relationship specifying program that causes the control unit 22 to function as the interference waveform acquisition unit 221, the phase offset specifying unit 222, the relationship specifying unit 223, and the correction unit 224, and a three-dimensional measurement program as a correction program. To do.

  The storage unit 21 stores the height position information output from the drive control unit 13 and the captured image output from the imaging unit 129 in association with each other. Further, the storage unit 21 stores interference waveform information indicating the interference waveform generated by the control unit 22.

  The control unit 22 is, for example, a CPU. The control unit 22 controls functions related to the computer 2 by executing various programs stored in the storage unit 21. The control unit 22 functions as an interference waveform acquisition unit 221, a phase offset specification unit 222, a relationship specification unit 223, and a correction unit 224 by executing a three-dimensional measurement program.

  The interference waveform acquisition unit 221 generates an interference waveform based on the position information indicating the height position of the objective lens unit 124 output from the drive control unit 13 and the captured image output from the imaging unit 129. First, the interference waveform acquisition unit 221 acquires height position information from the drive control unit 13 and acquires a captured image from the imaging unit 129 each time the white interferometer 12 moves. The interference waveform acquisition unit 221 generates an interference waveform indicating the relationship between the intensity of white light and the height position of the objective lens unit 124 for each of a plurality of pixels included in the captured image. The interference waveform acquisition unit 221 causes the storage unit 21 to store interference waveform information indicating the interference waveform generated for each of the plurality of pixels.

  FIG. 3 is a diagram illustrating an example of an interference waveform. FIG. 3 shows an interference waveform IW as an example of the interference waveform. As shown in FIG. 3, the interference waveform IW has a peak position where the interference high intensity is maximum, and the control unit 22 of the computer 2 determines the height position of the objective lens unit 124 corresponding to the peak position. The height of the position of the work W to which the pixel related to the interference waveform corresponds can be measured.

  Here, when the workpiece W is inclined with respect to the irradiation direction of the white light at the pixel corresponding position that is the position of the workpiece W to which the pixel corresponds, the waveform position of the interference waveform shifts, and the pixel corresponding position at the pixel corresponding position. There is a problem that the height of the workpiece W cannot be measured accurately. FIG. 4 is a diagram illustrating an example of an interference waveform whose waveform position is shifted. 4 is the same interference waveform as the interference waveform IW shown in FIG. 3, and the solid interference waveform is an interference waveform IW ′ whose waveform position is shifted. As shown in FIG. 4, it can be confirmed that the waveform position of the interference waveform IW ′ is deviated from the interference waveform IW.

  The computer 2 according to the present invention uses the interference waveform acquisition unit 221, the phase offset specification unit 222, the relationship specification unit 223, and the correction unit 224 to determine the angle of the workpiece W with respect to the optical path of white light that the white interferometer 12 irradiates the workpiece W. It is possible to specify the relationship between the tilt angle and the amount of deviation of the interference waveform, and correct the interference waveform based on the relationship. Hereinafter, functions of the interference waveform acquisition unit 221, the phase offset specification unit 222, the relationship specification unit 223, and the correction unit 224 will be described in detail. In the following description, the interference waveform when the workpiece W is not inclined is referred to as a reference interference waveform. The amount of deviation between the reference interference waveform and the interference waveform when the workpiece W is tilted is called a phase offset.

[Identification of relationship between tilt angle and phase offset]
First, while explaining the flow of processing for specifying the relationship between the tilt angle and the phase offset, the functions of the interference waveform acquisition unit 221, the phase offset specification unit 222, and the relationship specification unit 223 related to the processing will be described. FIG. 5 is a flowchart showing a flow of processing for specifying the relationship between the tilt angle and the phase offset by the computer 2 according to the first embodiment.
First, the operator places the calibration work on the stage 10 (S10). The calibration work is, for example, a flat work having a variable inclination angle.

Subsequently, the interference waveform acquisition unit 221 acquires an interference waveform corresponding to each of a plurality of inclination angles when the inclination angle of the calibration work is changed (S20).
Specifically, first, the operator generates a captured image in the imaging unit 129 of the white interferometer 12 while moving the white interferometer 12 in the irradiation direction of white light with the tilt angle of the calibration work fixed. Let

  Subsequently, the interference waveform acquisition unit 221 includes a plurality of captured images when the distance between the objective lens unit 124 and the calibration work corresponding to one inclination angle is changed, and height position information of the objective lens unit 124. Are obtained from the coordinate measuring machine 1. The interference waveform acquisition unit 221 generates interference waveform information indicating an interference waveform based on a plurality of captured images corresponding to one inclination angle and height position information. For example, the interference waveform acquisition unit 221 generates interference waveform information corresponding to one predetermined pixel. The interference waveform acquisition unit 221 stores the generated interference waveform information and the tilt angle in association with each other.

  When the interference waveform acquisition unit 221 generates interference waveform information corresponding to one inclination angle, the operator changes the inclination angle of the work for calibration and moves the white interferometer 12 in the irradiation direction of white light while moving white. The imaging unit 129 of the interferometer 12 is caused to generate a captured image. The interference waveform acquisition unit 221 obtains a plurality of captured images when the distance between the objective lens unit 124 and the calibration work corresponding to the changed tilt angle and height position information of the objective lens unit 124 are obtained. Obtained from the coordinate measuring machine 1. The interference waveform acquisition unit 221 generates interference waveform information corresponding to the changed tilt angle. The interference waveform acquisition unit 221 stores the interference waveform information and the changed tilt angle in association with each other.

  Each time the interference waveform acquisition unit 221 generates the interference waveform information, the operator changes the tilt angle of the calibration work, causes the computer 2 to generate the interference waveform information, and obtains the interference waveform information and the tilt angle. Relate to remember. In the present embodiment, the operator changes the inclination angle of the calibration work, but the present invention is not limited to this. For example, the tilt angle of the calibration work may be changed by the control of the computer 2, and the computer 2 may change the tilt angle of the calibration work in response to the generation of the interference waveform information.

  Subsequently, the phase offset specifying unit 222 specifies a plurality of phase offsets between each of the interference waveforms acquired at a plurality of inclination angles and the reference interference waveform (S30).

Subsequently, the relationship identifying unit 223 identifies the relationship between the tilt angle and the phase offset based on the plurality of tilt angles and the plurality of phase offsets (S40).
Specifically, the relationship specifying unit 223 specifies a function ψ (φ) indicating a phase offset when the tilt angle is φ. For example, a parameter corresponding to a phase offset component that depends on the tilt angle φ is α, a constant as a phase offset component that does not depend on the tilt angle φ is γ, and the phase offset is expressed by a function expressed by the following equation (1). .
Ψ (φ) = αφ + γ (1)

  The relationship specifying unit 223 specifies the parameter α and the constant γ based on the phase offset Ψ (φ) corresponding to at least two inclination angles φ specified by the phase offset specifying unit 222, thereby determining the phase offset. The function Ψ (φ) to be shown is specified.

[Correction of phase offset]
Next, processing related to phase offset correction will be described.
The interference waveform acquisition unit 221 generates an interference waveform corresponding to each of a plurality of pixels included in the captured image based on a plurality of captured images of the workpiece captured while moving the white light interferometer 12 in the white light irradiation direction. get.

  The correction unit 224 specifies the tilt angle φ at the position of the workpiece corresponding to each of the plurality of pixels, and is specified based on the function Ψ (φ) indicating the relationship between the previously specified tilt angle φ and the phase offset. The phase offset corresponding to the tilt angle φ is specified, and the interference waveform corresponding to each of the plurality of pixels is corrected based on the specified phase offset.

The functions of the interference waveform acquisition unit 221, the phase offset specification unit 222, and the correction unit 224 related to the processing will be described below while describing the flow of processing related to the correction of the phase offset. FIG. 6 is a flowchart showing a flow of processing relating to the correction of the phase offset by the computer 2 according to the first embodiment.
First, the worker places the workpiece W to be measured on the stage 10 (S110).

Subsequently, the interference waveform acquisition unit 221 corresponds to each of a plurality of pixels included in the captured image based on a plurality of captured images of the workpiece W captured while moving the white interferometer 12 in the white light irradiation direction. An interference waveform to be acquired is acquired (S120).
Subsequently, the correction unit 224 selects one pixel from which the phase offset is not corrected among the plurality of pixels included in the captured image (S130).

  Subsequently, the correcting unit 224 specifies the inclination angle at the position of the workpiece W corresponding to the selected one pixel (S140). For example, the correction unit 224 specifies the height of the workpiece W at the position of the workpiece W corresponding to the pixel based on the interference waveform of the pixel. In addition, the correction unit 224 specifies the height of the workpiece W at the position of the workpiece W corresponding to each of the adjacent pixels based on the interference waveform of the adjacent pixels. The height of the workpiece W specified here is calculated based on the interference waveform before correction. The correction unit 224 determines the work W corresponding to one pixel based on the amount of change between the height of the work W specified in the selected pixel and the height of the work W specified in the adjacent pixels. Specify the tilt angle at the position.

  Subsequently, the correcting unit 224 specifies a phase offset corresponding to the selected one pixel (S150). Specifically, the correcting unit 224 specifies the phase offset corresponding to the specified inclination angle φ based on the function ψ (φ) specified in advance.

Subsequently, the correcting unit 224 corrects the interference waveform corresponding to the selected pixel based on the identified phase offset (S160).
Subsequently, the correction unit 224 determines whether or not the interference waveform has been corrected for all the pixels (S170). If the correction unit 224 determines that the interference waveform has been corrected for all the pixels, the correction unit 224 ends the process according to this flowchart. If the correction unit 224 determines that the interference waveform has not been corrected for all the pixels, the process proceeds to S130.

[Effect in the first embodiment]
As described above, the computer 2 according to the present embodiment acquires interference waveforms corresponding to each of a plurality of inclination angles when the inclination angle of the workpiece W placed on the coordinate measuring machine 1 is changed, Identify multiple phase offsets between each of the multiple interference waveforms acquired at multiple tilt angles and the reference interference waveform, and based on the multiple tilt angles and multiple phase offsets, Identify the relationship. In this way, the computer 2 can correct the interference waveform based on the relationship between the tilt angle and the phase offset.

  Further, the computer 2 acquires an interference waveform corresponding to each of the plurality of pixels included in the captured image generated by the imaging unit 129, specifies an inclination angle at the position of the workpiece W corresponding to each of the plurality of pixels, Based on the relationship between the tilt angle and the phase offset specified in advance, the phase offset corresponding to the specified tilt angle is specified, and the interference waveform corresponding to each of the plurality of pixels is determined based on the specified phase offset. to correct. Thereby, the computer 2 can correct | amend the phase offset of the interference waveform which generate | occur | produces with an inclination angle.

Second Embodiment
[Enables correction of phase offset depending on distortion of beam splitter 128]
Subsequently, the three-dimensional measurement system S according to the second embodiment will be described. In the first embodiment, the computer 2 specifies the relationship between the workpiece tilt angle and the phase offset. However, the phase offset may include a component that depends on the distortion of the beam splitter 128, and the measurement accuracy may deteriorate due to the component. On the other hand, in the three-dimensional measurement system S according to the second embodiment, the computer 2 can correct the phase offset depending on the distortion of the beam splitter 128. Hereinafter, a different part from 1st Embodiment is demonstrated. The description of the same parts as in the first embodiment will be omitted as appropriate.

  The phase offset depending on the beam splitter 128 is caused by a deviation between the normal direction of the surface of the beam splitter 128 facing the workpiece and the irradiation direction of white light. Therefore, the computer 2 according to the second embodiment has each of a plurality of tilt directions when the tilt direction is changed with the irradiation direction of white light as the central axis in a state where the tilt angle of the work W for calibration is fixed. The interference waveform corresponding to each of the plurality of interference waveforms acquired in the plurality of tilt directions and the plurality of phase offsets between the reference interference waveform and the plurality of tilt directions and the plurality of phase offsets are identified. Based on the above, the relationship between the inclination direction and the phase offset is specified.

  Hereinafter, the flow of processing for specifying the relationship between the tilt angle, the tilt direction, and the phase offset by the computer 2 according to the second embodiment will be described. FIG. 7 is a flowchart showing a flow of processing for specifying the relationship between the tilt angle, the tilt direction, and the phase offset by the computer 2 according to the second embodiment.

  First, the operator places the calibration work on the stage 10 (S210). The calibration work is, for example, a flat work whose inclination angle is variable in two axes. The calibration work can change the tilt direction with the white light irradiation direction as the central axis in a state where the tilt angle is constant.

  Subsequently, the interference waveform acquisition unit 221 acquires an interference waveform corresponding to each of the plurality of inclination directions when the inclination direction is changed in a state where the inclination angle of the calibration work is fixed (S220). For example, the operator causes the imaging unit 129 of the white interferometer 12 to generate a captured image while moving the white interferometer 12 in the irradiation direction of the white light with the tilt direction of the calibration work fixed.

  Subsequently, the interference waveform acquisition unit 221 includes a plurality of captured images when the distance between the objective lens unit 124 and the calibration work corresponding to one tilt direction is changed, and height position information of the objective lens unit 124. Are obtained from the coordinate measuring machine 1. The interference waveform acquisition unit 221 generates interference waveform information indicating the interference waveform based on the plurality of captured images corresponding to one tilt direction and the height position information. For example, the interference waveform acquisition unit 221 generates interference waveform information corresponding to one predetermined pixel. The interference waveform acquisition unit 221 specifies a rotation angle indicating an angle formed by the reference inclination direction of the calibration work and the one inclination direction, and stores the rotation angle and the generated interference waveform information in association with each other.

  Each time the interference waveform acquisition unit 221 generates the interference waveform information, the operator changes the tilt direction (rotation angle) of the calibration work, causes the computer 2 to generate the interference waveform information, The rotation angle corresponding to the tilt direction is stored in association with each other. In the present embodiment, the operator changes the inclination direction of the calibration work, but the present invention is not limited to this. For example, the tilt direction of the calibration work may be changed by the control of the computer 2, and the computer 2 may change the tilt direction of the calibration work in response to the generation of the interference waveform information.

  Subsequently, the phase offset specifying unit 222 specifies a plurality of phase offsets between each of the interference waveforms acquired in the plurality of tilt directions and the reference interference waveform (S230).

Subsequently, the relationship specifying unit 223 specifies the relationship between the tilt direction and the phase offset based on the plurality of tilt directions and the plurality of phase offsets (S240). Specifically, the relationship specifying unit 223 specifies a function Ψ (θ, φ) indicating a phase offset when the tilt angle is φ and the rotation angle corresponding to the tilt direction of the calibration work is θ. For example, the parameter corresponding to the phase offset component depending on the tilt angle φ is α, and the axial distortion angle, which is the angle formed by the normal direction of the surface facing the calibration work of the beam splitter 128 and the irradiation direction of white light, is A constant as a component of the phase offset independent of β and the inclination angle φ is γ, and the phase offset is expressed by a function expressed by the following equation (2).
Ψ (θ, φ) = αcos (θ−β) φ + γ (2)

  The relationship specifying unit 223 maximizes Ψ (θ, φ) based on the relationship between the rotation angles θ corresponding to each of the plurality of inclination directions specified by the phase offset specifying unit 222 and the plurality of phase offsets. The rotation angle θ at this time is specified as the axial distortion angle β.

  Subsequently, the operator fixes the inclination direction of the calibration work in a direction corresponding to the axial strain angle β (S250). Specifically, the operator changes the rotation angle of the calibration workpiece with respect to the reference tilt direction to the axial strain angle β. In this case, ψ (θ, φ) shown in the equation (2) is the same as ψ (φ) shown in the equation (1). By doing so, the relationship specifying unit 223 can eliminate the influence of the distortion of the beam splitter 128 and specify the parameter α and the constant γ in a state where the phase offset component depending on the tilt angle φ is the largest. . Thereby, the relationship specifying unit 223 can specify the parameter α and the constant γ with high accuracy.

  Subsequently, the interference waveform acquisition unit 221 acquires an interference waveform corresponding to each of a plurality of inclination angles when the inclination angle of the calibration work is changed (S260). The process according to S260 is the same as the process according to S20 shown in FIG.

Subsequently, the phase offset specifying unit 222 specifies a plurality of phase offsets between each of the interference waveforms acquired at a plurality of inclination angles and the reference interference waveform (S270).
Subsequently, the relationship identifying unit 223 identifies the relationship between the tilt angle and the phase offset based on the plurality of tilt angles and the plurality of phase offsets (S280). The process according to S280 is the same as the process according to S40 shown in FIG.

[Effects of Second Embodiment]
As described above, the computer 2 according to the present embodiment generates interference waveforms corresponding to each of a plurality of tilt directions when the tilt direction of the calibration work is changed in a state where the tilt angle of the calibration work is fixed. Acquire and identify multiple phase offsets between each of the multiple interference waveforms acquired in multiple tilt directions and the reference interference waveform, and based on the multiple tilt directions and multiple phase offsets, the tilt direction And the relationship between the phase offset. By doing in this way, the computer 2 can specify the phase offset depending on the beam splitter 128 included in the interference waveform, and can correct the interference waveform.

<Third Embodiment>
[Enables correction of the phase offset that does not depend on the distortion of the beam splitter 128 but depends on the tilt angle of the workpiece]
Subsequently, the three-dimensional measurement system S according to the third embodiment will be described. In the second embodiment, the computer 2 can correct the phase offset depending on the distortion of the beam splitter 128 by specifying the relationship between the tilt direction of the workpiece and the phase offset. However, the phase offset may include a component that does not depend on the distortion of the beam splitter 128 but depends on the tilt angle of the workpiece, and the measurement accuracy may deteriorate due to the component. In contrast, in the three-dimensional measurement system S according to the third embodiment, the computer 2 can correct the phase offset that does not depend on the distortion of the beam splitter 128 but depends on the tilt angle of the workpiece.

FIG. 8 is a flowchart showing a flow of processing for specifying the relationship between the tilt angle, the tilt direction, and the phase offset by the computer 2 according to the third embodiment.
Since the process flow from S310 to S330 is the same as the process flow from S210 to S230 shown in FIG.

  Subsequently, the relationship identifying unit 223 identifies the relationship between the tilt direction and the phase offset based on the plurality of tilt directions and the plurality of phase offsets (S340). Specifically, the relationship specifying unit 223 specifies a function Ψ (θ, φ) indicating a phase offset when the tilt angle is φ and the rotation angle is θ.

For example, the parameter corresponding to the phase offset component depending on the tilt angle φ is α, and the axial distortion angle, which is the angle formed by the normal direction of the surface facing the calibration work of the beam splitter 128 and the irradiation direction of white light, is β, a constant as a phase offset component independent of the tilt angle φ, γ, and a second parameter corresponding to the phase offset component dependent on the workpiece tilt angle independent of the distortion of the beam splitter 128 as δ, and the phase offset Is expressed by a function represented by the following equation (3).
Ψ (θ, φ) = (αcos (θ−β) + δ) φ + γ (3)

  The relationship specifying unit 223 maximizes Ψ (θ, φ) based on the relationship between the rotation angles θ corresponding to each of the plurality of inclination directions specified by the phase offset specifying unit 222 and the plurality of phase offsets. The rotation angle θ at this time is specified as the axial distortion angle β.

Subsequently, the operator fixes the tilt direction of the calibration work in a direction in which the component of the phase offset depending on the distortion of the beam splitter 128 becomes zero (S350). For example, the operator changes the rotation angle θ with respect to the reference tilt direction of the tilt direction of the calibration work to an axial strain angle β + 180 °. As a result, α cos (θ−β) becomes 0, and equation (3) is transformed into equation (4) shown below.
Ψ (θ, φ) = δφ + γ (4)

Subsequently, the interference waveform acquisition unit 221 acquires an interference waveform corresponding to each of a plurality of inclination angles when the inclination angle of the calibration work is changed (S360). Since the process according to S360 is the same as the process according to S20 illustrated in FIG. 5, detailed description thereof is omitted.
Subsequently, the phase offset specifying unit 222 specifies a plurality of phase offsets between each of the interference waveforms acquired at a plurality of inclination angles and the reference interference waveform (S370).

  Subsequently, the relationship identifying unit 223 identifies the relationship between the tilt angle and the phase offset component that does not depend on the tilt direction but depends on the tilt angle based on the plurality of tilt angles and the plurality of phase offsets (S380). ). Specifically, the relationship specifying unit 223 specifies the second parameter δ based on the phase offset Ψ (φ) corresponding to at least two inclination angles φ specified by the phase offset specifying unit 222.

Subsequently, the operator fixes the inclination direction of the calibration work in a direction corresponding to the axial strain angle β (S390).
Subsequently, the interference waveform acquisition unit 221 acquires an interference waveform corresponding to each of a plurality of inclination angles when the inclination angle of the calibration work is changed (S400).
Subsequently, the phase offset specifying unit 222 specifies a plurality of phase offsets between each of the interference waveforms acquired at a plurality of inclination angles and the reference interference waveform (S410).
The relationship identifying unit 223 identifies the relationship between the tilt angle and the phase offset based on the multiple tilt angles and the multiple phase offsets (S420). Since the processes related to S390 to S420 are the same as the processes related to S250 to S280 shown in FIG. 7, detailed description thereof will be omitted.

[Effect in the third embodiment]
As described above, the computer 2 according to the present embodiment generates interference waveforms corresponding to each of a plurality of tilt directions when the tilt direction of the calibration work is changed in a state where the tilt angle of the calibration work is fixed. Acquire and identify a plurality of phase offsets between each of the plurality of interference waveforms acquired in the plurality of tilt directions and the reference interference waveform, and based on the relationship between the plurality of tilt directions and the plurality of phase offsets, The relationship between the tilt direction and the phase offset is specified. By doing so, the computer 2 can correct the phase offset that depends on the tilt angle of the workpiece without depending on the distortion of the beam splitter 128.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. Further, it is apparent from the scope of the claims that embodiments with such changes or improvements can also be included in the technical scope of the present invention.

  For example, in the above-described embodiment, the computer 2 functions as the interference waveform acquisition unit 221, the phase offset specification unit 222, the relationship specification unit 223, and the correction unit 224, but is not limited thereto. In at least one of the coordinate measuring machine 1 and the computer 2, functions related to the interference waveform acquisition unit 221, the phase offset specification unit 222, the relationship specification unit 223, and the correction unit 224 may be realized.

  In the above-described embodiment, the relationship specifying unit 223 of the computer 2 specifies the relationship between the tilt angle corresponding to one pixel and the phase offset. However, for each of a plurality of pixels constituting the captured image, the tilt angle is determined. And the phase offset may be specified. Then, when correcting the interference waveform corresponding to each of the plurality of pixels, the correction unit 224 corrects the interference waveform based on the relationship between the tilt angle specified in each of the plurality of pixels and the phase offset. May be.

  In the above-described embodiment, the relationship specifying unit 223 of the computer 2 expresses the expression indicating the phase offset as a linear expression of the inclination angle. However, the present invention is not limited thereto, and the degree of the inclination angle may be 2 or more.

DESCRIPTION OF SYMBOLS 1 ... Three-dimensional measuring machine, 11 ... Stage, 12 ... White interferometer, 121 ... Irradiation part, 122 ... Collimator lens, 123 ... Beam splitter, 124 ... Objective lens , 125 ... objective lens, 126 ... glass substrate, 127 ... reference mirror, 128 ... beam splitter, 129 ... imaging unit, 13 ... drive control unit, 2 ... computer , 21 ... storage unit, 22 ... control unit, 221 ... interference waveform acquisition unit, 222 ... phase offset identification unit, 223 ... relationship identification unit, 224 ... correction unit, S · ..3D measurement system

Claims (9)

The computer runs,
In a three-dimensional measuring machine provided with a white interferometer, a plurality of the above-mentioned when the tilt angle, which is the angle of the workpiece placed on the three-dimensional measuring machine, with respect to the optical path of white light irradiated by the white interferometer is changed A first acquisition step of acquiring an interference waveform corresponding to each of the inclination angles;
A first specifying step of specifying a plurality of phase offsets between each of a plurality of interference waveforms acquired at a plurality of the tilt angles and a reference interference waveform;
A second specifying step of specifying a relationship between the tilt angle and the phase offset based on the plurality of tilt angles and the plurality of phase offsets;
A relationship identification method. A second acquisition for acquiring an interference waveform corresponding to each of the plurality of tilt directions when the tilt direction of the workpiece is changed with the irradiation direction of the white light as a central axis in a state where the tilt angle is fixed. Steps,
A third identifying step of identifying a plurality of phase offsets between each of the plurality of interference waveforms acquired in the plurality of tilt directions and the reference interference waveform;
A fourth specifying step of specifying a relationship between the tilt direction and the phase offset based on the plurality of tilt directions and the plurality of phase offsets;
The relationship identification method according to claim 1. In the one acquisition step, the interference waveform is acquired while changing the tilt angle in a state where the tilt direction is fixed to the tilt direction when the phase offset is maximum.
The relationship specifying method according to claim 2. A third acquisition step of acquiring the interference waveform while changing the tilt angle in a state in which the tilt direction is fixed so that a component of the phase offset depending on the tilt direction becomes zero;
A fifth specifying step of specifying a plurality of phase offsets between each of the plurality of interference waveforms acquired in the third acquiring step and the reference interference waveform;
Based on the plurality of tilt angles and the plurality of phase offsets specified in the fifth specifying step, the tilt angle and the phase offset component that does not depend on the tilt direction but depends on the tilt angle; And a sixth specifying step for specifying the relationship of
The relationship identification method according to claim 2 or 3. In a three-dimensional measuring machine provided with a white interferometer, a plurality of the above-mentioned when the tilt angle, which is the angle of the workpiece placed on the three-dimensional measuring machine, with respect to the optical path of white light irradiated by the white interferometer is changed An acquisition unit for acquiring an interference waveform corresponding to each of the inclination angles;
A phase offset specifying unit that specifies a plurality of phase offsets between each of a plurality of interference waveforms acquired at a plurality of the tilt angles and a reference interference waveform;
Based on the plurality of inclination angles and the plurality of phase offsets, a relationship specifying unit that specifies the relationship between the inclination angles and the phase offsets;
A relationship identification device. Computer
In a three-dimensional measuring machine provided with a white interferometer, a plurality of the above-mentioned when the tilt angle, which is the angle of the workpiece placed on the three-dimensional measuring machine, with respect to the optical path of white light irradiated by the white interferometer is changed An acquisition unit for acquiring an interference waveform corresponding to each of the inclination angles;
A phase offset identifying unit that identifies a plurality of phase offsets between each of a plurality of interference waveforms acquired at a plurality of the tilt angles and a reference interference waveform; and
A relationship identifying unit that identifies a relationship between the tilt angle and the phase offset based on the plurality of tilt angles and the plurality of phase offsets;
A relationship identification program to function as. In a three-dimensional measuring machine using a white interferometer, the computer has an interference waveform associated with an inclination angle that is an angle of a work placed on the three-dimensional measuring machine with respect to an optical path of white light irradiated by the white interferometer. A correction method for correcting a phase offset,
Obtaining an interference waveform corresponding to each of a plurality of pixels included in the captured image, based on a plurality of captured images of the workpiece imaged while moving the white light interferometer in the irradiation direction of the white light;
Identifying the tilt angle at the position of the workpiece corresponding to each of the plurality of pixels;
Identifying the phase offset corresponding to the tilt angle specified for each of a plurality of pixels based on a relationship between the tilt angle specified in advance and the phase offset;
Correcting the interference waveform corresponding to each of a plurality of pixels based on the identified phase offset;
A correction method comprising: In a three-dimensional measuring machine using a white interferometer, a phase offset of an interference waveform associated with an inclination angle that is an angle of a workpiece placed on the three-dimensional measuring machine with respect to an optical path of white light irradiated by the white interferometer. A correction device for correcting,
An acquisition unit that acquires an interference waveform corresponding to each of a plurality of pixels included in the captured image, based on a plurality of captured images of the workpiece captured while moving the white light interferometer in the irradiation direction of the white light; ,
An inclination angle specifying unit for specifying the inclination angle at the position of the workpiece corresponding to each of the plurality of pixels;
An offset specifying unit that specifies the phase offset corresponding to the tilt angle specified for each of a plurality of pixels based on the relationship between the tilt angle specified in advance and the phase offset;
A correction unit that corrects the interference waveform corresponding to each of a plurality of pixels based on the identified phase offset;
A correction device comprising: In a three-dimensional measuring machine using a white interferometer, a phase offset of an interference waveform associated with an inclination angle that is an angle of a workpiece placed on the three-dimensional measuring machine with respect to an optical path of white light irradiated by the white interferometer. The computer to be corrected
An acquisition unit that acquires an interference waveform corresponding to each of a plurality of pixels included in the captured image, based on a plurality of captured images of the workpiece captured while moving the white light interferometer in the irradiation direction of the white light,
An inclination angle specifying unit for specifying the inclination angle at the position of the workpiece corresponding to each of the plurality of pixels;
An offset specifying unit that specifies the phase offset corresponding to the tilt angle specified for each of a plurality of pixels based on the relationship between the tilt angle specified in advance and the phase offset; and
A correction unit that corrects the interference waveform corresponding to each of a plurality of pixels based on the identified phase offset;
Correction program to function as

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