Measurement device and method

Abstract

To provide a measurement device and method capable of accurately and easily measuring a shape of an inner surface of a workpiece over a wide range in a height direction.SOLUTION: A cylindrically shaped workpiece is placed on a measurement device. The measurement device includes: a rotation stage to be rotatable around a rotation axis in the height direction of the workpiece; a straight movement stage to be movable straight in a straight movement direction vertical to the rotation axis of the rotation stage; a mirror member having a reflection surface inclined at 45° with respect to the rotation axis and the straight movement direction, fixed onto the straight movement stage, and arranged to penetrate a hole formed in the rotation stage; a white interference microscope for allowing measurement light to be reflected against the reflection surface so as to irradiate an inner surface of the workpiece with the measurement light, and measuring the shape of the inner surface of the cylindrically shaped workpiece; and a control section for allowing the straight movement stage to be moved straight so as to move a measurement visual field which is irradiated with the measurement light in the height direction, and rotating the rotation stage so as to move the measurement visual field in a circumferential direction of the workpiece.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a measuring device and method, and more particularly to a measuring device and method capable of measuring the shape of the inner surface of a cylindrical workpiece. [Background technology]

[0002] Conventionally, a shape measuring device that measures the shape of the inner surface of a cylindrical workpiece without contact has been proposed. For example, Patent Document 1 discloses a shape measuring device that arranges conical prisms in a cylindrical workpiece so that their central axes coincide with each other, and deflects the measurement light at a right angle by the conical prism to irradiate the measurement light onto the inner surface of the workpiece to measure the three-dimensional shape of the inner surface of the workpiece. According to the shape measuring device described in Patent Document 1, the three-dimensional shape of the inner surface of the cylindrical workpiece can be measured without cutting the workpiece. Also, according to the shape measuring device described in Patent Document 1, the shape of the entire circumferential direction of the cylindrical inner surface can be measured at once by emitting light in the entire circumferential direction centered on the central axis of the conical prism. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-075577 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the shape measuring device described in Patent Document 1, when measuring the three-dimensional shape of the inner surface of a workpiece over a wide range in the height direction (Z direction), the relative position between the measurement area set on the inner surface of the workpiece and the shape measuring device needs to be changed in the Z direction. When scanning the inner surface of the workpiece from top to bottom, the magnification of the optical system deteriorates as the measurement area of ​​the workpiece moves from top to bottom, and the spatial resolution deteriorates.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a measuring device and method that can accurately and easily measure the shape of the inner surface of a workpiece over a wide range in the vertical direction. [Means for solving the problem]

[0006] In order to solve the above problems, a measuring device according to a first aspect of the present invention comprises a rotating stage on which a cylindrical workpiece is placed, the rotating stage being rotatable around a rotation axis along the height direction of the workpiece; a linear stage being capable of linear movement in a linear movement direction perpendicular to the rotation axis of the rotating stage; a mirror member having a reflective surface inclined at 45° with respect to the rotation axis and the linear movement direction, the mirror member being fixed on the linear stage and positioned so as to pass through a hole formed in the rotating stage, and being capable of linear movement relative to a base on which the linear stage is mounted as the linear stage moves linearly; a white light interference microscope that irradiates the measurement light onto the inner surface of the workpiece by reflecting the measurement light on the reflective surface, thereby measuring the shape of the inner surface of the cylindrical workpiece; and a control unit that moves the measurement field of view irradiated with the measurement light along the height direction by linearly moving the linear stage, and moves the measurement field of view in the circumferential direction of the workpiece by rotating the rotating stage.

[0007] The measurement device according to a second aspect of the present invention further comprises an image processing section that connects together measurement data for each measurement visual field.

[0008] A third aspect of the present invention is a measurement method in a measuring device including a rotating stage on which a cylindrical workpiece is placed, the rotating stage being rotatable around a rotation axis along the height direction of the workpiece, a linear stage being capable of linear movement in a linear movement direction perpendicular to the rotation axis of the rotating stage, a mirror member having a reflective surface inclined at 45° with respect to the rotation axis and the linear movement direction, the mirror member being fixed on the linear stage and positioned so as to pass through a hole formed in the rotating stage, and being capable of linear movement relative to a base on which the linear stage is mounted as the linear stage moves linearly, and a white light interference microscope that irradiates the measurement light onto the inner surface of the workpiece by reflecting the measurement light off the reflective surface, thereby measuring the shape of the inner surface of the cylindrical workpiece, the measurement method including a step of moving a measurement field onto which the measurement light is irradiated along the height direction by linearly moving the linear stage, and a step of moving the measurement field in a circumferential direction of the workpiece by rotating the rotating stage. Effect of the Invention

[0009] According to the present invention, the shape of the inner surface of a workpiece can be measured easily and with high accuracy over a wide range in the height direction. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing a measurement device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a procedure for scanning the inner surface of a workpiece in the height direction (Z direction). [Diagram 3] FIG. 3 is a diagram showing a procedure for scanning the inner surface of a workpiece in the height direction (Z direction) and the circumferential direction. [Figure 4] FIG. 4 is a flowchart showing a measurement method according to one embodiment of the present invention. [Diagram 5] FIG. 5 is a flowchart showing the Z direction measurement process of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a measuring device and method according to the present invention will be described with reference to the accompanying drawings.

[0012] [Measurement device configuration] FIG. 1 is a block diagram showing a measurement device according to an embodiment of the present invention.

[0013] The measuring device 1 according to this embodiment is a device for measuring the shape (including surface roughness, three-dimensional shape, contour, etc.) of a workpiece (object to be measured) W placed on a stage ST, and includes the stage ST, a control device 10, and a white light interference microscope 50. In the following explanation, a three-dimensional orthogonal coordinate system is used in which a plane along the mounting surface of the stage ST on which the workpiece W is placed is defined as an XY plane, and the height direction is defined as the Z direction.

[0014] (Stage ST) First, the stage ST on which the workpiece W is placed will be described.

[0015] As shown in FIG. 1, the stage ST includes a rotation stage ST1, a linear motion stage ST2, and a base ST3.

[0016] The linear stage ST2 is provided on a base ST3 and is capable of linear movement relative to the base ST3. That is, the rotation stage ST1 and the linear stage ST2 are structured to move linearly in the linear movement direction (X direction) relative to the base ST3. A beveled cylindrical mirror member M is fixed to the linear stage ST2.

[0017] The rotating stage ST1 is provided on the linear motion stage ST2 so as to be rotatable around the Z axis. A hole H having a larger diameter than the mirror member M is formed in the rotating stage ST1, and the mirror member M is disposed so as to pass through this hole H. The mirror member M is capable of linear movement relative to the base ST3 in accordance with the linear movement of the linear motion stage ST2.

[0018] As shown in Figure 1, the inner surface W of the workpiece W inWhen performing the measurement, a cylindrical workpiece W, which is the object to be measured, is placed so as to overlap a hole H formed in the rotating stage ST1. Here, in the example shown in FIG. 1, the optical axis AX (see FIG. 2(b)) of the objective part 64 and the central axis of the hole H formed in the rotating stage ST1 coincide with each other. Also, the central axis of the workpiece W is held by a holding means (e.g., a clamp, etc.) (not shown) so as to coincide with the central axis of the rotating stage ST1.

[0019] The measurement light L0 emitted from the white light interference microscope 50 is reflected by the reflecting surface M of the mirror member M. S is reflected by the inner surface W of the work W. in This causes the inner surface of the workpiece W to in This makes it possible to measure the surface roughness of the surface.

[0020] In this embodiment, the mirror member M has an obliquely cut cylindrical shape, but the present invention is not limited to this. For example, the mirror member M may have an obliquely cut polygonal prism shape, a cone shape, or a polygonal pyramid shape, or may have a structure in which a reflector of any shape is supported by a pillar.

[0021] (Control device 10) Next, the control device 10 of the measuring device 1 will be described.

[0022] The control device 10 is a device that controls each part of the white light interferometer 50 and processes the results of measurements made by the white light interferometer 50, and includes a control unit 12, an input / output unit 14, a storage unit 16, and a signal processing unit 18. The control device 10 can be realized by a general-purpose computer such as a personal computer or a workstation.

[0023] The control unit 12 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The control unit 12 receives operation input from an operator via the input / output unit 14 and controls each unit of the control device 10. The control unit 12 also controls the output of the light source unit 52 of the white light interference microscope 50 to adjust the amount of illumination light irradiated onto the workpiece W. The control unit 12 also controls the drive of the rotation stage drive unit 80 and the linear stage drive unit 82 to operate the stages ST1 and ST2, and adjusts the observation target position (measurement position) of the workpiece W (see Figs. 2 and 5). The control unit 12 also controls the relative position (distance) between the lens barrel 56 and the stage ST1 in the height direction (Z direction). The control unit 12 is an example of a control unit and an image processing unit of the present invention.

[0024] The input / output unit 14 includes an operating member (e.g., a keyboard, a pointing device, etc.) for accepting operational input from the operator, and a display unit (e.g., an LCD display, etc.) for displaying the results of measurement of the workpiece W by the white light interference microscope 50, etc.

[0025] The signal processing unit 18 acquires a detection signal from the detector 76 of the white light interference microscope 50, and performs signal processing on this detection signal to calculate the shape and amplitude of the interference fringes, etc.

[0026] The memory unit 16 is a storage device for storing the measurement data, as well as programs for controlling the white light interference microscope 50 and for processing measurement data such as the measurement results of the workpiece W. As the memory unit 16, for example, a hard disk drive (HDD), a solid state drive (SSD), etc. can be used.

[0027] (White light interference microscope 50) Next, the white light interference microscope 50 of the measuring device 1 will be described. In the following description, the inner surface W of the cylindrical workpiece W is in An example of measuring the above will be described.

[0028] The white light interference microscope 50 includes a light source unit 52, a light guide 54, and a lens barrel 56. A turret 62 is attached to the lower end of the lens barrel 56, and a detector 76 is attached to the upper end of the lens barrel 56. A plurality of objective units 64 (three in the example shown in FIG. 1) are attached to the turret 62. The interference objective lenses 66 included in the plurality of objective units 64 have mutually different magnifications, and by rotating the turret 62, it is possible to switch between the interference objective lenses 66 used to measure the workpiece W.

[0029] The light source unit 52 is a light source that outputs white light, and is, for example, a halogen lamp, a laser light source, an LED (Light Emitting Diode) light source, etc. Here, the white light is a light obtained by mixing visible light rays having wavelengths in the visible light region (wavelengths of about 400 nm to about 720 nm), and may be, for example, a light obtained by mixing light of three colors (three primary colors) of red, green, and blue in an appropriate ratio.

[0030] The light guide 54 is a member that forms an optical path along which the white light output from the light source unit 52 propagates to the lens barrel 56, and is, for example, an optical fiber.

[0031] The lens barrel 56 has a coaxial epi-illumination type illumination optical system. An illumination lens 58, a beam splitter 60, an imaging lens 72, and an aperture 74 are arranged in the lens barrel 56. The relative position (distance) in the height direction (Z direction) between the lens barrel 56 and the stage ST1 can be changed by the control unit 12. Note that, although the lens barrel 56 is moved in the Z direction in the example shown in Fig. 1, a Z direction drive mechanism may be provided on the base ST3 to move the stage ST1, or both may be movable.

[0032] The illumination lens 58 has an optical system that guides (images) the white light (illumination light) that enters the lens barrel 56 via the light guide 54 to the pupil position of the interference objective lens 66. The illumination light output from the illumination lens 58 is reflected by the beam splitter 60 and guided to the objective section 64.

[0033] The illumination light guided through the beam splitter 60 is guided to the exit side of the objective unit 64 by the interference objective lens 66. The component (measurement light L0) of the illumination light guided to the exit side of the objective unit 64 that is transmitted through the half mirror 68 is guided to the inside of a cylindrical workpiece W placed on the stage ST1, and then reflected by the reflecting surface M of the mirror member M. S is reflected by the inner surface W of the work W in Then, it is reflected by the inner surface W of the workpiece W. in The first reflected light L1 from the objective lens 66 passes through the half mirror 68 and reaches the imaging lens 72. On the other hand, the component of the illumination light guided to the exit side of the objective unit 64 that is reflected by the half mirror 68 (second reflected light L2) is guided to the reference mirror 70 and reflected there. The reference mirror 70 is disposed at a position conjugate with the focal position of the exit side (workpiece W side) of the interference objective lens 66. The second reflected light L2 from the reference mirror 70 is reflected by the half mirror 68 and reaches the imaging lens 72.

[0034] The imaging lens 72 is configured to focus on the inner surface W of the work W. in The optical system forms an image of a reflected light L1 from the reference mirror 70 and a second reflected light L2 from the reference mirror 70 on the light detection surface of the detector 76.

[0035] The diaphragm 74 is provided between the imaging lens 72 and the detector 76, and blocks a part of the first reflected light L1 and the second reflected light L2 guided from the imaging lens 72 to the detector 76.

[0036] The detector 76 includes a light detection array element (hereinafter referred to as an image sensor) such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). The detector 76 generates an analog or digital detection signal indicating the light intensity detected by each light receiving element of the image sensor, and outputs the signal to the signal processing unit 18. As a result, the inner surface W of the workpiece W is in In addition, the detector 76 acquires an interference waveform (interferogram) of each pixel of this image.

[0037] The detector 76 detects the inner surface W of the workpiece W. in The reflector 18 receives the first reflected light L1 from the reflector 70 and the second reflected light L2 from the reference mirror 70 to generate a detection signal and outputs it to the signal processing unit 18.

[0038] The signal processing unit 18 acquires a detection signal from the detector 76 of the white light interference microscope 50, performs predetermined signal processing on this detection signal, and calculates the shape, amplitude, etc. of the interference fringes. Here, the brightness change curve (interference waveform) obtained when the interference objective lens 66 is scanned in the height direction (Z direction) is called an interferogram.

[0039] The control unit 12 detects the inner surface W of the workpiece W based on the shape and amplitude of the interference fringes calculated by the signal processing unit 18 when the interference objective lens 66 is scanned in the height direction (Z direction). in Specifically, the control unit 12 measures the shape, surface roughness, etc. of the inner surface W of the workpiece W. in The difference between the distance between the reference mirror 70 and the half mirror 68 and the distance between the reference mirror 70 and the half mirror 68 (hereinafter referred to as the optical path difference) is used to obtain the inner surface W in This method measures the shape, surface roughness, etc. of the object. This type of measurement method is called the Vertical Scanning Interferometry (VSI). The Vertical Scanning Method is described in, for example, U.S. Patent No. 4,340,306. The Vertical Scanning Method has been standardized as Coherence Scanning Interferometry (CSI) by the International Organization for Standardization (ISO) (ISO25178-604:2013).

[0040] When the optical path difference changes, the phase difference between the first reflected light L1 and the second reflected light L2 changes, and the interference fringes change according to the change in phase difference. inWhen the first reflected light L1 and the second reflected light L2 are focused on the same point, no phase difference occurs between them. Therefore, the interference intensity is maximized, and the amplitude of the interference fringes is maximized. On the other hand, when the optical path difference is large, the interference intensity is small.

[0041] The control unit 12 acquires, for example, the position in the height direction (Z direction) of the interference objective lens 66 (Z-axis height) when the amplitude of the interference fringes calculated by the signal processing unit 18 is maximum. Here, the position in the height direction of the interference objective lens 66 when the amplitude of the interference fringes is maximum can be obtained from the envelope in the interferogram. Then, the control unit 12 calculates the height of the inner surface W of the workpiece W based on the position of the interference objective lens 66. in Calculate the height position (focus position) of the inner surface W of the work W. in The control unit 12 is capable of storing the results of this measurement in the memory unit 16 and displaying them on the display unit of the input / output unit 14.

[0042] In addition, the inner surface W of the work W in The method of measuring the height position of the workpiece W is not limited to VSI or CSI. in As a method for measuring the height position of the workpiece W, for example, a frequency domain analysis (FDA) or a phase shifting interferometry (PSI) may be applied. The frequency domain analysis performs a Fourier transform on the interferogram and obtains a phase gradient with respect to the wave number near the peak position of the amplitude spectrum, thereby obtaining the height position of the workpiece W. in The frequency domain method is described in, for example, U.S. Patent No. 5,398,113. The phase shift method calculates the height position of the inner surface W of the workpiece W based on the change in the density value of the pixel when the focal position of the interference objective lens 66 is shifted in the optical axis direction. inThe phase shift method is described, for example, in JH Bruning et al.: "Digital Wavefront Measuring Interferometer for Testing Optical Surfaces and Lenses, Applied Optics, Vol. 13, Issue 11, pp. 2693-2703 (1974)."

[0043] Inner surface W of work W in When measuring the shape of, scanning along the Z direction is performed by the linear stage driving unit 82. The linear stage driving unit 82 includes a driving mechanism (e.g., an actuator) for linearly moving the rotation stage ST1 and the linear stage ST2 in the X direction relative to the base ST3.

[0044] Moreover, scanning along the circumferential direction of the workpiece W is performed by a rotation stage driving unit 80. The rotation stage driving unit 80 includes a driving mechanism (for example, an actuator or the like) for rotating the rotation stage ST1 around the Z axis.

[0045] The control unit 12 controls the rotation stage drive unit 80 and the linear stage drive unit 82 to move the inner surface W of the workpiece W. in The control unit 12 then stitches together the images captured sequentially to create a composite image of the entire measurement range of the workpiece W (see, for example, JP 2020-159759 A). This makes it possible to measure the shape of the entire measurement range of the workpiece W.

[0046] [Inner surface W of work W in Scanning Procedure Next, the inner surface W of the cylindrical workpiece W in The scanning procedure for measuring the above will be described.

[0047] Figure 2 shows the inner surface W of the workpiece W. in2A and 2B are diagrams (front view and partial cross-sectional view) showing the procedure for scanning the mirror member M in the height direction (Z direction). In Fig. 2, (b) shows a state in which the central axis of the mirror member M coincides with the optical axis AX of the objective section 64, and (a) and (c) show states in which the cylindrical workpiece W and mirror member M have each been linearly moved in the ±X direction with (b) as the reference. The central axis of the workpiece W is arranged to coincide with the central axis of the rotating stage ST1.

[0048] As shown in FIG. 2, the reflecting surface M of the mirror member M S is inclined at 45° with respect to the Z axis (the rotation axis of the rotating stage ST1) and the X axis (the linear movement direction), and the measurement light L0 irradiated to the workpiece W is reflected by the reflecting surface M S The workpiece W is bent at a right angle to the inner surface W in The irradiation position (observation target position) of the measurement light L0 irradiated on the workpiece W can be changed in the Z direction by moving the linear stage ST2 in the X direction by the linear stage driving unit 82.

[0049] As shown in FIG. 2(b), the reflecting surface M of the mirror member M S is position M S When it is at (0), the irradiation position V(0) of the measurement light L0 becomes a measurable area (hereinafter referred to as the measurement visual field).

[0050] In FIG. 2(b), the objective lens 64 is S The distance to the arrival position (reflection position) P(0) of the measurement light L0 in the above is defined as Z, and the distance from position P(0) to position V(0) is defined as X. In this case, the optical path length D(0) from the objective lens 64 to position V(0) is given by D(0) = Z + X.

[0051] Next, as shown in FIG. 2(a), when the rotary stage ST1 also moves ΔX in the +X direction in conjunction with the linear movement of the linear stage ST2, the inner surface W of the workpiece W in Position W in Position W moved by ΔX in the +X direction from (0) in (+), and the reflective surface M of the mirror member M S is position M SPosition M moved by ΔX in the +X direction from (0) S In this case, the irradiation position of the measurement light L0 moves upward (to the +Z side) by ΔZ, and the measurement field of view becomes V(+).

[0052] In FIG. 2(a), the objective lens 64 is S The distance to the arrival position P(+) of the measurement light L0 in the above is (Z-ΔZ), and the distance from position P(+) to position V(+) is (X+ΔX). In this case, the optical path length D(+) from the objective lens 64 to position V(+) is D(+)=(Z-ΔZ)+(X+ΔX). Here, since the inclination angle of the reflecting surface MS is 45°, ΔX=ΔZ. Therefore, D(+)=Z+X.

[0053] In addition, as shown in FIG. 2(c), when the rotary stage ST1 also moves ΔX in the −X direction in conjunction with the linear movement of the linear stage ST2, the inner surface W in Position W in Position W moved by ΔX in the -X direction from (0) in (-), and the reflective surface M of the mirror member M S is position M S Position M moved by ΔX in the -X direction from (0) S In this case, the irradiation position of the measurement light L0 moves downward (to the -Z side) by ΔZ, and the measurement field of view becomes V(-).

[0054] In FIG. 2(c), the objective lens 64 is S The distance to the arrival position P(-) of the measurement light L0 in the above is (Z+ΔZ), and the distance from position P(-) to position V(-) is (X-ΔX). In this case, the optical path length D(+) from the objective lens 64 to position V(-) is D(+) = (Z-ΔZ) + (X+ΔX) = Z+X.

[0055] In this way, the linear motion is repeated to form the inner surface W of the workpiece W. inBy sequentially scanning the mirror member M, it is possible to obtain measurement data for the entire measurement range in the Z direction. As shown in FIG. 2, in this embodiment, scanning in the Z direction is performed by linearly moving the mirror member M, so that the inner surface W of the workpiece W is visible from the objective unit 64 before and after the linear movement. in The distance to the workpiece W does not change (D(0) = D(-) = D(+)). in Since there is no need to refocus when scanning from top to bottom, the inner surface W of the workpiece W can be in The shape of the object can be measured easily and accurately over a wide range in the height direction.

[0056] Figure 3 shows the inner surface W of the workpiece W. in 13 is a diagram showing a procedure for scanning in the height direction (Z direction) and the circumferential direction.

[0057] When the linear stage ST2 is moved sequentially in the -X direction, the measurement field of view moves to positions V(1,1), V(1,2), ..., V(1,N) in this order, as shown in Figure 3. Here, the linear movement amount ΔX and the number of repetitions of the linear movement (number of movements) N are determined by the shape and size of the measurement field of view V(i,j) and the size Z of the overlapping area (a group of pixels used for alignment. See, for example, JP 2020-159759 A) for stitching together the measurement data (images). m In the example shown in FIG. 3, since the measurement visual field V(i,j) is substantially rectangular, the linear movement amount ΔX and the number of linear movement repetitions N are determined by the Z-direction measurement range (Z-direction measurement range) Z A , the Z-direction dimension Z of the measurement field of view V(i,j) V and the size of the overlapping area for stitching the measurement data (images) Z m In this case, the linear motion amount ΔX is determined by Z V -Z m The number of repetitions of linear motion, N, is N×Z V -(N-1)×Z m ≧Z A Depending on the shape of the measurement field of view V(i,j), Z m can be different above and below.

[0058] Z-direction measuring range Z A When the entire scan is completed, the rotation stage ST1 is rotated around the Z axis by a rotation angle θ to scan the next rows V(2,1), V(2,2), ..., V(2,N). Here, the rotation angle θ is determined based on the shape and size of the measurement field of view V(i,j) and the size C of the overlapping area for stitching together the measurement data (images). m In the example shown in FIG. 3, since the measurement visual field V(i,j) is substantially rectangular, the number of repetitions of the rotation movement M is determined by the inner surface W in The circumference of C A , the circumferential dimension C of the measurement field of view V(i,j) V and the size of the overlapping area for stitching the measurement data (images) C m In this case, the number of rotations M is determined by M × C V -(M-2)×C m ≧C A Depending on the shape of the measurement field of view V(i,j), m can be different on the left and right.

[0059] As described above, by repeating scanning in the Z direction and the circumferential direction, the inner surface W of the workpiece W is in Measurements can be performed over the entire measurement range.

[0060] In the above example, the scanning in the Z direction and the scanning in the circumferential direction are performed in the order of V(1,1) to V(1,N), V(2,1) to V(2,N), ..., V(M,1) to V(M,N), but the scanning order is not limited to the above example. A more efficient scanning order can be selected depending on the shape and size of the workpiece W. For example, the scanning order in the Z direction may be reversed in alternate rows (V(1,1) to V(1,N), V(2,N) to V(2,1), V(3,1) to V(3,N), ...). Also, the scanning in the circumferential direction may be performed first (for example, V(1,1) to V(M,1), V(M,2), V(1,2) to V(M-1,2), V(M-1,3), ...).

[0061] [Measurement method] FIG. 4 is a flowchart showing a measurement method according to an embodiment of the present invention, and FIG. 5 is a flowchart showing the Z direction measurement process of FIG.

[0062] First, the workpiece W is placed on the rotating stage ST1 (step S10), and the optical system (barrel 56) of the white light interference microscope 50 and the workpiece W are moved relatively in the Z direction to adjust the focus (step S12). In step S10, the central axis of the workpiece W is positioned so as to coincide with the optical axis AX of the objective unit 64. Then, the focusing in step S12 is performed in a state in which the central axis of the mirror member M and the optical axis AX of the objective unit 64 coincide (see FIG. 2(b)).

[0063] Next, the inner surface W of the workpiece W is measured by the input / output unit 12. in Z-direction measuring range Z A is set (step S14).

[0064] Next, the amount of movement ΔX, the number of movements N, and the rotation angle θ of the linear stage are calculated based on the size of the measurement visual field V(i, j) (step S16).

[0065] Next, the repetition parameter i of the circumferential scan is initialized to i=1 (step S18), and the Z-direction measurement range Z A Measurements of the measurement fields of view V(i,j) are carried out sequentially (step S20).

[0066] 5, in step S20 (Z-direction measurement step), first, the Z-direction scanning repetition parameter j is initialized to j=1 (step S200), and the measurement field of view V(1,1) is measured (step S202). Next, the linear stage ST2 is moved by ΔX (No in step S204, step S206), j=j+1 is set (step S208), and the measurement field of view V(1,2) is measured (step S202).

[0067] As described above, by repeating steps S202 to S208, the Z-direction measurement range Z A(Measurement field of view V(1,1) to V(1,N)) is measured. Then, j = N, and the Z-direction measurement range Z of the workpiece W is A When the measurement of the measurement fields of view V(1,1) to V(1,N) is completed (Yes in step S204), the inner surface W of the workpiece W is in Z-direction measuring range Z A The measurement data (of the measurement visual fields V(1,1) to V(1,N)) are stitched together (step S210).

[0068] In this way, after the Z-direction measurement step (step S20) is performed, as shown in FIG. 4, if i=M is ​​not met, that is, if the measurement of the entire circumference of the workpiece W is not completed (No in step S22), the rotating stage ST1 is rotated by θ (step S24), i=i+1 is set (step S26), and the Z-direction measurement range Z of the workpiece W is A Perform measurements in the measurement field of view V(2,1) to V(2,N).

[0069] As described above, steps S20 to S26 are repeated to repeatedly scan the workpiece W in the circumferential direction. Then, when i=M is ​​reached and measurement of the entire circumference of the workpiece W is completed (Yes in step S22), the measurement data for the entire circumference of the workpiece is stitched together (step S28). in It is possible to obtain measurement data (synthetic image) of the entire measurement range.

[0070] According to this embodiment, the inner surface W of the workpiece W in Since there is no need to refocus when scanning from top to bottom, the inner surface W of the workpiece W can be in The shape of the object can be measured easily and accurately over a wide range in the height direction.

[0071] 5, the images are stitched together for each loop of the Z-direction measurement process, but all the measurement data may be stitched together after the measurement of the entire circumference is completed (step S28). Also, when the circumferential scanning is performed first, the circumferential stitching may be performed first. [Explanation of symbols]

[0072] Reference Signs List 1: measuring device, 10: control device, 12: control unit, 14: input / output unit, 16: memory unit, 18: signal processing unit, 50: white light interference microscope, 52: light source unit, 54: light guide, 56: lens barrel, 58: illumination lens, 60: beam splitter, 62: turret, 64: objective unit, 66: interference objective lens, 68: half mirror, 70: reference mirror, 72: imaging lens, 74: aperture, 76: detector, 80: rotation stage drive unit, 82: linear stage drive unit, ST: stage, ST1: rotation stage, ST2: linear stage, ST3: base, M: mirror member

Claims

1. A rotation stage on which a cylindrical workpiece is placed, the rotation stage being rotatable around a rotation axis along a height direction of the workpiece; a linear motion stage that is linearly movable in a linear motion direction perpendicular to a rotation axis of the rotation stage; a mirror member having a reflection surface inclined at 45° with respect to the rotation axis and the linear movement direction, the mirror member being fixed on the linear movement stage and disposed so as to pass through a hole formed in the rotation stage, and being linearly movable with respect to a base on which the linear movement stage is provided in association with the linear movement of the linear movement stage; a white light interference microscope that reflects a measurement light on the reflecting surface to irradiate the measurement light onto the inner surface of the workpiece, thereby measuring the shape of the inner surface of the cylindrical workpiece; a control unit that moves a measurement field of view irradiated with the measurement light along the height direction by linearly moving the linear stage, and moves the measurement field of view in a circumferential direction of the workpiece by rotating the rotation stage; an image processing unit that stitches together the measurement data for each measurement field of view; Equipped with When the number of repetitions of the linear movement of the linear stage is N, the measurement target range in the height direction of the workpiece is Z A , the measurement field of view is V, the height direction dimension of the measurement field of view is Z V , and the size of the overlapping area for joining the measurement data in the height direction is Z m , The number of repetitions N of the linear movement is determined within a range of N×Z V −(N−1)×Z m ≧Z A , When the number of times the rotational movement of the rotating stage is repeated is M, the circumferential length of the inner surface of the work is C A , the circumferential dimension of the measurement field of view is C V , and the size of the overlapping area for joining the measurement data in the rotational direction is C m , The number of times M to repeat the rotational movement is determined within the range of M×C V −(M−2)×C m ≧C A .

2. A rotation stage on which a cylindrical workpiece is placed, the rotation stage being rotatable around a rotation axis along a height direction of the workpiece; a linear motion stage that is linearly movable in a linear motion direction perpendicular to a rotation axis of the rotation stage; a mirror member having a reflection surface inclined at 45° with respect to the rotation axis and the linear movement direction, the mirror member being fixed on the linear movement stage and disposed so as to pass through a hole formed in the rotation stage, and being linearly movable with respect to a base on which the linear movement stage is provided in association with the linear movement of the linear movement stage; A measurement method for a measurement apparatus including a white light interference microscope that irradiates an inner surface of the workpiece with a measurement light by reflecting the measurement light on the reflecting surface, thereby measuring a shape of the inner surface of the cylindrical workpiece, comprising: moving a measurement field of view irradiated with the measurement light along the height direction by linearly moving the linear stage; moving the measurement field of view in a circumferential direction of the workpiece by rotating the rotary stage; A step of stitching together the measurement data for each measurement field of view; Including, When the number of repetitions of the linear movement of the linear stage is N, the measurement target range in the height direction of the workpiece is Z A , the measurement field of view is V, the height direction dimension of the measurement field of view is Z V , and the size of the overlapping area for joining the measurement data in the height direction is Z m , The number of repetitions N of the linear movement is determined within a range of N×Z V −(N−1)×Z m ≧Z A , When the number of times the rotational movement of the rotating stage is repeated is M, the circumferential length of the inner surface of the work is C A , the circumferential dimension of the measurement field of view is C V , and the size of the overlapping area for joining the measurement data in the rotational direction is C m , A measuring method in which the number of times M to repeat the rotational movement is determined within a range satisfying M×C V −(M−2)×C m ≧C A .

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