JP2020020647A - Method and device for measuring shape - Google Patents

Abstract

To provide a method and a device for measuring a shape which can measure the shape of the surface of a measuring target object without using a reference member for correction.SOLUTION: The present invention includes the steps of: equipping a first probe to probe supporting means and obtaining first surface shape data of a measuring target object supported by measuring target object supporting means (S1); equipping a second probe to the probe supporting means and obtaining second surface shape data of a measuring target object supported by the measuring target object supporting means (S2); obtaining third surface shape data of the first probe supported by the measuring target object supporting means with the second probe being equipped to the probe supporting means (S3); equipping the second probe to the probe supporting means with at least one of the second probe and the measuring target object positioned in a changed direction and obtaining fourth surface shape data of the measuring target object supported by the measuring target object supporting means (S4); and calculating the surface shape of the measuring target object on the basis of the first to fourth surface shape data (S5).SELECTED DRAWING: Figure 8

Description

  The present invention relates to a shape measuring method and a shape measuring device.

  For example, a manufacturing error of an element surface of an optical element used for various optical devices such as a camera and a microscope needs to be suppressed within an allowable range in order to obtain necessary optical performance. For this reason, in the manufacturing process of the optical element, it is necessary to measure the surface to be measured such as the element surface of the optical element or the surface shape of the mold for manufacturing the optical element with high accuracy.

  2. Description of the Related Art As a shape measuring apparatus for measuring a surface shape, an apparatus for measuring a surface shape of an object to be measured by causing a stylus probe to follow the surface is known (for example, see Patent Documents 1 and 2). In the shape measuring device described in Patent Literature 1, by measuring a reference sphere formed with high accuracy as an object to be measured, the shape error of the surface of the stylus (probe) with the object to be measured is determined with reference to the reference sphere. Measure according to the angle. Then, when measuring the surface shape of the DUT whose manufacturing error is unknown, the magnitude of the shape error of the surface of the stylus based on the measurement of the reference sphere is corrected from each measurement data.

  Further, in the shape measuring device and the shape measuring method described in Patent Literature 2, an object to be measured having an axisymmetric aspherical shape having a known design shape, a first probe and a second probe having a known designable spherical shape are provided. , Three types of surface shape measurements are performed. Thereby, the true surface shape of at least one of the DUT, the first probe, and the second probe is measured.

Japanese Patent No. 479,753 Japanese Patent No. 4766851

  In the shape measuring device described in Patent Literature 1, the shape error of the stylus is obtained based on the shape measurement of the reference sphere. For this reason, it is assumed that the manufacturing error of the surface shape of the reference sphere is extremely small. However, in reality, it is not possible to eliminate the manufacturing error of the reference sphere, and there is a problem that the manufacturing error of the reference sphere is added to the correction of the stylus shape error.

  Furthermore, stylus calibration must be performed each time the stylus is changed. For this reason, there is a problem that the reference sphere needs to be strictly managed so that the surface shape does not change due to handling and aging. Further, when such management is difficult, it is necessary to update the data of the surface shape of the reference sphere every time the stylus is calibrated, so that there is a problem that the calibration work takes time.

  According to the technique described in Patent Literature 2, it is not necessary to use a calibration jig having a small shape error such as a reference sphere, and high-precision measurement can be performed using only a shape measuring device. However, the technique described in Patent Literature 2 is applied to an object to be measured having an axisymmetric aspherical shape only to a two-dimensional cross section passing through the top of the surface to be measured. Therefore, when measuring the three-dimensional shape of the object to be measured, it is necessary to perform measurement on a large number of two-dimensional cross sections passing through the top of the surface to be measured. For this reason, three types of surface shape measurement are required for each measurement in one cross section, and there is a problem that the measurement takes time.

  Furthermore, if the measurement path by the probe is measured off the top of the object to be measured, a measurement error occurs, and there is a problem that high-precision three-dimensional measurement may not be performed. In addition, the technique described in Patent Document 2 has a problem that an object to be measured having a shape other than an axisymmetric aspheric surface, such as a free-form surface, cannot be measured.

  The present invention has been made in view of the above-described problems, and the design shape is known without using a calibration reference member having a small shape error compared to the shape error of the measurement target. It is an object of the present invention to provide a shape measuring method and a shape measuring device capable of measuring the surface shape of an object to be measured having various three-dimensional surface shapes with high accuracy.

  In order to solve the above-described problems, a shape measurement method according to one embodiment of the present invention is to scan a surface of a measured object in at least two different directions by bringing a probe into contact with the measured object having a known design shape. In the shape measuring method for evaluating a three-dimensional surface shape by mounting, a first probe is attached to probe supporting means for supporting the probe, and the object to be measured supported by the object supporting means for supporting the object to be measured. A first three-dimensional shape measuring step of measuring a three-dimensional surface shape to obtain first surface shape data, and mounting the second probe on the probe support means and supporting the object supported by the object support means. A second three-dimensional measurement step of measuring a three-dimensional surface shape of the object to obtain second surface shape data; and attaching the second probe to the probe support means, The said supported A third three-dimensional measurement step of measuring a three-dimensional shape of the probe to obtain third surface shape data, and supporting the probe in a state in which at least one of the second probe and the object to be measured is changed in direction. Attaching the second probe to the means, measuring the three-dimensional surface shape of the object to be measured supported by the object support means, and obtaining fourth surface shape data; Calculating a surface shape of the object to be measured based on the first surface shape data, the second surface shape data, the third surface shape data, and the fourth surface shape data.

  In the calculating step, the weighted average of a result of performing a plurality of affine transformations on the first surface shape data, the second surface shape data, the third surface shape data, and the fourth surface shape data is used. The surface shape of the measurement object may be calculated.

  In the fourth three-dimensional shape measurement step, at least one of the second probe and the object to be measured may be rotated by 90 ° or −90 ° around a central axis.

  The shape measuring apparatus according to one aspect of the present invention includes a probe having a design surface with a known design surface brought into contact with a measurement target having a design surface with a known design shape, and a three-dimensional shape of the measurement surface. A shape measuring device for measuring a surface shape, wherein the first holding portion holds a first work having a first surface; a second holding portion holds a second work having a second surface having a convex shape; A moving mechanism that moves the first holding unit and the second holding unit in a direction parallel to the measurement reference axis that is a normal line of the measurement reference plane and in at least two directions that are orthogonal to the measurement reference axis and intersect with each other. The first work and the second work are relatively translated in a state where the second surface is in contact with the first surface, and the three-dimensional movement trajectory of the representative point of the second work is defined by the second work. 2 Conversion based on surface design shape A surface shape data acquisition unit that acquires surface shape data of the first surface, and the object to be measured having the surface to be measured as the first surface as the first work is held by the first holding unit. Holding a first probe having, as the second surface, a first probe surface having a convex shape having a known design shape as the second workpiece in the first measurement posture with respect to the object to be measured by the second holding portion; In this case, first surface shape data that is the surface shape data is obtained, and the object to be measured having the surface to be measured as the first surface as the first work is held by the first holding unit, A second probe having, as the second surface, a second probe surface, which is a convex surface having a known design shape as the second workpiece, is held by the second holding portion in a second measurement posture with respect to the workpiece. The surface shape data The second surface shape data is acquired, the respective positive directions of relative translation with respect to the first surface at the time of acquiring the first surface shape data, and the second surface at the time of acquiring the second surface shape data. When the first probe is held as the first work and the second probe is held as the second work so that the respective positive directions of the relative translation relative to In a state in which certain third surface shape data is obtained and at least one of the direction of the second probe and the object to be measured is changed, the object to be measured is held by the first holding unit as the first work, When the second probe is held by the second holding unit in the third measurement posture with respect to the object to be measured as the second workpiece, fourth surface shape data that is the surface shape data is acquired. A control unit; A storage unit that stores the one-surface shape data, the second-surface shape data, and the third-surface shape data, and stores the first-surface shape data, the second-surface shape data, and the third-surface shape data, A variable conversion processing unit that converts into a function of a contact angle that is an angle between a design normal and the measurement reference axis at each measurement position, and the first surface shape data that is variable-converted by the variable conversion processing unit; A surface shape for estimating at least one true surface shape of the measured surface, the first probe surface, and the second probe surface by arithmetically processing the second surface shape data and the third surface shape data And an estimation processing unit.

According to the shape measuring method and the shape measuring apparatus of the present invention, without using a calibration reference member in which the shape error is minutely formed compared to the shape error of the measurement target, various three-dimensional shapes whose design shapes are known can be used. The surface shape of an object to be measured having a surface shape can be measured with high accuracy.
Further, the present invention can be similarly applied to non-contact three-dimensional shape measurement using an interferometer, and the surface shape of an object to be measured can be measured with high accuracy.

It is a typical front view showing the example of composition of the shape measuring device of a 1st embodiment of the present invention. FIG. 2 is a plan view as viewed from A in FIG. 1. FIG. 2 is a schematic plan view showing a state at the time of measurement in the X-axis direction in the shape measuring device according to the first embodiment of the present invention. It is a typical front view showing the example of composition of the probe used for the shape measuring device of a 1st embodiment of the present invention. FIG. 2 is a schematic front view illustrating a configuration example at the time of probe measurement of the shape measuring apparatus according to the first embodiment of the present invention. It is a typical front view showing the 1st holding part at the time of the probe measurement of the shape measuring device of a 1st embodiment of the present invention. FIG. 2 is a functional block diagram illustrating a functional configuration of a control unit of the shape measuring device according to the first embodiment of the present invention. It is a flowchart which shows the measurement procedure of the shape measuring apparatus in the same Example. FIG. 9 is a diagram illustrating a state of each measurement step in FIG. 8. (A), (b) is an explanatory view of a contact angle between the workpiece and the probe, and (c) is a contact angle between the probe and the probe.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In all the drawings, the same or corresponding members are denoted by the same reference numerals, and the common description is omitted, even when the embodiments are different.

A shape measuring device according to a first embodiment of the present invention will be described.
FIG. 1 is a schematic front view showing a configuration example of a shape measuring apparatus 1 according to the first embodiment of the present invention. FIG. 2 is a plan view as viewed from A in FIG. FIG. 3 is a schematic plan view showing a state at the time of measurement in the X-axis direction in the shape measuring device according to the first embodiment of the present invention. FIG. 4 is a schematic front view illustrating a configuration example of a probe used in the shape measuring device according to the first embodiment of the present invention. FIG. 5 is a schematic front view showing a configuration example at the time of probe measurement of the shape measuring apparatus according to the first embodiment of the present invention. FIG. 6 is a schematic front view showing the first holding unit during probe measurement of the shape measuring apparatus according to the first embodiment of the present invention. FIG. 7 is a functional block diagram showing a functional configuration of a control unit of the shape measuring device according to the first embodiment of the present invention.

The shape measuring device 1 includes a support unit 3 that supports a first work having a first surface, and a measurement unit 2 that holds a second work having a second surface and measures the surface shape of the first work. ing. The support unit 3 and the measurement unit 2 are arranged on the base 4 so as to face each other. Further, the shape measuring device 1 includes a control unit (described later) that controls each device part of the shape measuring device 1.
As shown in FIG. 1, at the time of measurement, the workpiece W is used as the first work, and the probe P1 (first probe) or the probe P2 (second probe) is used as the second work.

Hereinafter, when referring to the direction in the shape measuring device 1, an XYZ orthogonal coordinate system (hereinafter, referred to as an XYZ coordinate system) shown in FIG. 1 may be used.
In the illustrated XYZ coordinate system, the Y axis is parallel to the vertical axis. The ZX plane is parallel to the horizontal plane. The support unit 3 and the measurement unit 2 face each other in the Z-axis direction (direction along the Z-axis).
The sign of each axis direction in the XYZ coordinate system follows the rule of the right-handed system. In FIG. 1, the positive X-axis direction is a direction perpendicular to the paper surface from the near side to the far side in the drawing. The positive direction of the Y axis is a vertically upward direction (a direction from the lower side to the upper side in the drawing). The positive direction of the Z axis is a direction from the left side to the right side in the figure.
The XYZ rectangular coordinate system is a fixed coordinate system fixed to the shape measuring device 1.

The object to be measured W has a surface to be measured Ws having an appropriate three-dimensional shape as the first surface. The design shape of the measured surface Ws is known before the measurement by the shape measuring device 1 starts. The design shape of the surface to be measured Ws may be a convex surface or a concave surface as long as the probe for measurement can be contacted along one direction. The measured surface Ws may have a surface shape in which a convex surface and a concave surface are mixed. For example, the measured surface Ws may be a quadratic surface such as a spherical surface, an axisymmetric aspheric surface, or a free-form surface other than these.
The measured surface Ws may be known by a mathematical expression described by an appropriate function, or may be known by a set of a large number of point coordinates on the measured surface Ws. For example, when the design value of the surface to be measured Ws is known by a set of a large number of point coordinates, a continuous function representing the design site is obtained by interpolation processing passing through each point.
Hereinafter, the description will be made assuming that the design shape of the surface to be measured Ws is represented by z ₁ = Hd (x ₁ , y ₁ ). Here, the variable _x 1, _{y 1} is, _{x 1} coordinate in the _{x 1 y} 1 _z 1 right-handed orthogonal coordinate system fixed to the object to be measured W (hereinafter, simply referred to _{x 1 y} 1 _z 1 coordinate system), _{y 1} Coordinates. z ₁ represents the z ₁ coordinate of the measured surface Ws at the point (x ₁ , y ₁ ).
The direction and the origin of the x ₁ y ₁ z ₁ coordinate system are appropriately set according to the shape of the measured surface Ws so that the function Hd (x ₁ , y ₁ ) is simplified. For example, if the workpiece W is rotationally symmetric shape, it is more preferable that the rotation symmetry axis is chosen z ₁ axis. In this case, z ₁ axis of the workpiece W is arranged parallel to the Z axis.

The measuring section 2 includes a measuring machine base 7, a measuring machine plate 6, and a measuring unit 5.
The measuring machine base 7 supports the measuring machine plate 6 and the measuring unit 5 from below. The measuring machine stand 7 is arranged on the base 4 via the first moving stage 25.
The first moving stage 25 reciprocates the measuring machine base 7 in the X-axis direction (the direction along the X-axis). As shown in FIG. 3, the first moving stage 25 can move the measuring machine base 7 in the X-axis direction in a range wider than the width in the X-axis direction in which the first work is arranged on the support unit 3. it can.
As shown in FIG. 1, a first axis length measuring device 43 for detecting the position of the measuring machine stand 7 in the X-axis direction is arranged on the base 4 on the Z-axis negative direction side of the measuring machine stand 7. .
The specific configuration of the first axis measuring device 43 is not particularly limited as long as the position of the measuring machine stand 7 in the X-axis direction can be measured. For example, as the first axis length measuring device 43, a configuration including a reference scale and a reading head that reads the movement amount of the reference scale may be used. In this case, the reference scale 20b is fixed to the measuring machine stand 7.
The detection output of the first axis length measuring device 43 is sent to a control unit described later.

The measuring device plate 6 is a plate-like member that moves in parallel with the measuring device stand 7 in the X-axis direction and supports a measuring unit 5 described below from below.
The measuring machine plate 6 is fixed on the measuring machine base 7 via the driving units 24a and 24b.
The driving units 24a and 24b are shaft-shaped members that independently drive the measuring instrument plate 6 in the Y-axis direction (the direction along the Y-axis). The drive units 24a and 24b are arranged in this order in a direction away from the support unit 3 in the Z-axis direction. In FIG. 1, each of the driving units 24 a and 24 b is illustrated one by one, but the number of the driving units 24 a and 24 b is not particularly limited as long as the posture of the measuring instrument plate 6 can be stably held. For example, two or more drive units 24a and 24b may be provided respectively.
The driving amounts of the driving units 24a and 24b are controlled by a control unit described later.
The driving units 24a and 24b are used for adjusting the position of the measuring instrument plate 6 in the Y-axis direction, adjusting the inclination posture of the measuring instrument board 6, and the like. For example, when each of the driving amounts of the driving units 24a and 24b is changed by a control unit described later, the measuring instrument plate 6 rotates around the X axis. For this reason, the measuring instrument plate 6 can be inclined in the YZ plane with respect to the ZX plane.

The measurement unit 5 is a device part that measures the surface shape of the first surface of the first work. The measuring unit 5 is provided on the upper surface of the measuring instrument plate 6. Hereinafter, unless otherwise specified, the configuration and the positional relationship of the measuring unit 5 will be described with an example in which the upper surface of the measuring instrument plate 6 is parallel to the ZX plane.
The measurement unit 5 includes an air slide shaft 8 formed in a column shape extending in the Z-axis direction, and an air slide bearing 9 having a substantially rectangular parallelepiped shape.

The air slide bearing 9 is formed with a through hole (not shown) penetrating in the Z-axis direction, and is fixed on the measuring instrument plate 6 with the through hole facing the support portion 3. The air slide shaft 8 is inserted into this through hole. A plurality of outlet holes (not shown) are formed on the inner wall surface inside the through hole of the air slide bearing 9. A small gap of several μm is formed between the air slide shaft 8 and the inner wall surface by blowing compressed clean and dry compressed air from a blowing hole. The air slide shaft 8 is floatingly supported by the air slide bearing 9 without being in contact with the inner wall surface of the air slide bearing 9 due to the ejection of the compressed air from the blowout hole.
Air slide bearing 9, in the direction along the central axis C ₈ air slide shaft 8, and the air slide shaft 8 is reciprocably supported.
Further, a not-shown ridge is formed in the through hole and extends in the longitudinal direction of the through hole. The protruding ridge portion is configured to slidably fit into a not-shown concave ridge portion formed in the outer peripheral portion of the air slide shaft 8 so as to extend in the longitudinal direction of the air slide shaft 8. The fitting of such a ridge and concave portion, if the air slide shaft 8 is moved along the central axis C _8, the rotation of the central axis C ₈ around the air slide shaft 8 is suppressed .

For example, if the upper surface of the measuring plate 6 is parallel to the ZX plane, the central axis C ₈ is arranged parallel to the Z axis. However, when the driving units 24a and 24b are driven such that the height of the driving unit 24a is lower than the height of the driving unit 24b, the measuring instrument plate 6 moves from the positive direction in the Z-axis direction to the negative direction. Since the air slide shaft 8 is inclined so as to descend, the air slide shaft 8 moves in a direction in which the air slide shaft 8 approaches the support portion 3 and is inclined downward by its own weight.

A second work can be detachably attached to the end (tip) of the air slide shaft 8 on the Z-axis negative direction side.
In this embodiment, the distal end of the air slide shaft 8, as an example, to hold the second workpiece, the female screw portion 8a (the second holding portion) having a center axis parallel to the center axis C ₈ is formed I have.
A reference mark 8b is provided above the outer peripheral surface of the distal end portion of the air slide shaft 8.
Reference marks 8b, the second workpiece is in reference marks for aligning upon being mounted on the female screw portion 8a, the rotational position of the second workpiece central axis C ₈ around.
In the following, as an example, the reference mark 8b will be described an example in the case of being formed at a position facing the central axis C ₈ and Y-axis direction.
The configuration of the reference mark 8b is not particularly limited as long as the measurer can position and attach the second work. For example, the reference mark 8b is a mark formed by a figure of an appropriate shape having a different color from the outer surface of the air slide shaft 8, a mark formed by a stamp, a groove, a protrusion, or the like formed on the outer surface of the air slide shaft 8. And so on.

Here, the configuration of the probes P1 and P2, which are examples of the second work held by the female screw portion 8a, will be described.
Probe P1 has a first end portion in the longitudinal direction of the central axis C _P1 probe shaft 10c formed in a columnar shape extending along the (left end shown) male thread portion 10b is provided on the second end (shown right end Part) is provided with a spherical part 10a.
The male screw part 10b has a screw shape to be screwed with the female screw part 8a. Male thread portion 10b is formed in the central axis line _{C P1} coaxially. Therefore, the probe P1 is detachably fixed to the end of the air slide shaft 8 on the negative side in the Z-axis direction by screwing the male screw portion 10b and the female screw portion 8a. When mounting the probes P1, the probe P1 is in a coaxial and central axis C ₈ air slide shaft 8.

The spherical portion 10a has a surface _SP1 (first surface) formed of a spherical surface in a range in which the spherical portion 10a can come into contact with a measurement target at the time of shape measurement at a front end portion along the central axis _CP1 . Hereinafter, for simplicity, an example in which the entire surface of the spherical portion 10a except the connection portion with the probe shaft 10c is formed of the surface _SP1 will be described.
Design shape of the surface _{S P1} is the radius from the center _{O P1} on the center axis _{C P1} is spherical in _{R P1.} The size of the position and _{R P1} of the center _{O P1} in the probe P1 is known in advance. However, the production error of the surface of the surface _SP1 may not be known.
The radius of the surface S _P1 at each point on the measurement surface Ws of the measurement object W, if it is large enough to be able configure the measurement surface Ws and the point-contactable sphere is not particularly limited.
The material of the spherical portion 10a is not particularly limited. For example, the spherical portion 10a may be formed of a precisely processed ruby ball or the like.

On the surface of the probe shaft 10c, for example, such as during fixation to the air slide shaft 8, and the first mark 40a for aligning the central axis C _P1 around, a second mark 40b, are formed .
The first mark 40a is formed at a fixed position in the circumferential direction on the surface of the probe shaft 10c.
The second mark 40b is formed on the surface of the probe shaft 10c at a position facing the first mark 40a with the center axis _CP1 interposed therebetween.
The configuration of the first mark 40a and the second mark 40b is not particularly limited as long as the measurer can position and attach the probe P1. For example, the first mark 40a and the second mark 40b may be marks similar to those exemplified as the configuration example of the reference mark 8b.

  In the probe P1, the male thread 10b is screwed into the female thread 8a of the air slide shaft 8 by a predetermined length, and the first mark 40a is aligned with the reference mark 8b in the Y-axis negative direction. In the arranged state, it is fixed to the air slide shaft 8.

The probe P2 includes a spherical portion 10d instead of the spherical portion 10a of the probe P1. Hereinafter, the points different from the probe P1 will be mainly described.
Spherical portion 10d has at the distal end of the direction along the central axis C _P2 probe P2, the surface S _P2 consisting of spherical surface extent possible contact with the measurement target at the time of shape measurement _(the second surface). For simplicity in the following description an example of a case where the entire surface of the spherical portion 10d excluding the connection portion of the probe shaft 10c is made of a surface S _P2.
Design shape of the surface _{S P2} is the radius from the center _{O P2} on the central axis _{C P2} is spherical in _{R P2.} Position and size of the radius _{R P2} of the center _{O P2} in the probe P2 is known in advance. However, the manufacturing error of the surface _SP2 may not be known.
Similarly to the surface S _P1, the radius of the surface S _P2 are at each point on the measurement surface Ws of the measurement object W, if it is large enough to be able configure the measurement surface Ws and the point-contactable sphere is not particularly limited .
The size of R _P2 may be equal to the above-described _{R P1,} may be different from the _{R P1.}
When R _P1 = R _P2 , the design shapes of the surfaces S _P1 and S _P2 are the same as each other, but generally, the magnitudes of the production errors and the distributions of the production errors of the surfaces S _P1 and S _P2 are different.
Like the spherical portion 10a, the material of the spherical portion 10d is not particularly limited. For example, the spherical portion 10d may be formed of a precisely processed ruby ball or the like.

  In the probe P2, the male thread 10b is screwed into the female thread 8a of the air slide shaft 8 by a predetermined length, and the first mark 40a is aligned with the reference mark 8b when viewed in the negative Y-axis direction. In the arranged state, it is fixed to the air slide shaft 8.

Here, the description returns to the configuration of the air slide shaft 8.
As shown in FIGS. 1 and 2, a step portion 21 for positioning and fixing the probe axis length measuring device 20 is formed at a rear end portion (an end portion in the positive direction of the Z axis) of the air slide shaft 8. ing.
The probe axis length measuring device 20 detects the position of the second work mounted on the tip of the air slide shaft 8 by measuring the amount of movement of the air slide shaft 8 from the reference position in the direction along the central axis C ₈ . This is the part of the device that performs.
As a specific configuration of the probe shaft length measuring devices 20, if Okonaere the position measurement in the direction along the central axis C _8, are not particularly limited. For example, a configuration including a glass scale (reference scale) 20 b made of a plate-like member and a glass scale head 20 a fixed to the measuring instrument plate 6 may be used as the probe axis length measuring device 20. In this case, one end of the glass scale 20b is fixed to the step portion 21 by, for example, screwing.
A glass scale 20b is inserted into the glass scale head 20a so as to be able to reciprocate. The glass scale head 20a sequentially detects the movement position of the glass scale 20b and outputs the detected position to a control unit described later.
For this reason, the probe axis length measuring device 20 can detect the moving position of the air slide shaft 8 with respect to the measuring instrument plate 6 in the Z-axis direction.

In the vicinity of the step portion 21 of the air slide shaft 8, rod-shaped Sutoppahane 22 extending in a direction perpendicular to the center axis C ₈ is fixed. 2, the length of the stopper spring 22 in the X-axis direction is longer than the width of the air slide shaft 8 in the X-axis direction. When the stopper spring 22 is fixed to the air slide shaft 8, both ends in the longitudinal direction of the stopper spring 22 project outward from the air slide shaft 8 in the X-axis positive direction and the X-axis negative direction, respectively.
A stopper 23 is provided on the measuring plate 6 near the stopper slide 22 on the X-axis positive direction side of the air slide shaft 8.
As shown in FIG. 1, the stopper 23 is formed in a substantially U-shape (U-shape) opened in the Y-axis positive direction when viewed from the X-axis direction. Inside the opening of the stopper 23, the end of the stopper spring 22 on the X-axis positive direction side extends.
Therefore, the stopper 23, air slide shaft 8 is to restrict the range of movement capable of reciprocating in a direction along the center line C _8. Thus, the movable range of the air slide shaft 8 in the direction along the central axis C ₈ is coincident with the movable range of Sutoppahane 22 inside the both inner walls 23a of the stopper 23.
Therefore, even when the air slide shaft 8 moves in the tilt direction when the measuring instrument plate 6 is tilted, the air slide shaft 8 is prevented from falling out of the air slide bearing 9.

As shown in FIG. 1, the support unit 3 includes a second moving stage 27 and a holding wall 28.
The second moving stage 27 is fixed on the base 4 and supports the holding wall 28 from below. Further, the second moving stage 27 reciprocates the holding wall portion 28 in the Y-axis direction. Second moving stage 27, in a range wider than the width of the y ₁ axially of the workpiece W, it can be moved parallel to the retaining wall portion 28 in the Y-axis direction.
On the base 4 on the Z-axis negative direction side of the second moving stage 27, a second axis length measuring device 41 for detecting the position of the second moving stage 27 in the Y-axis direction is arranged.
The specific configuration of the second axis measuring device 41 is not particularly limited as long as the position of the second moving stage 27 in the Y-axis direction can be measured. For example, the second axis length measuring device 41 may have the same configuration as the first axis length measuring device 43.
The detection output of the second axis length measuring device 41 is sent to a control unit described later.

The holding wall 28 is formed in a rectangular parallelepiped shape, and is fixed to an upper portion of the second moving stage 27. A mounting portion 28b for mounting a first holding portion for holding the first work is provided on a front surface 28a, which is a side surface on the X-axis positive direction side, of the outer wall surface of the holding wall portion 28.
The specific configuration of the mounting portion 28b is not particularly limited as long as the first holding portion can be accurately attached and detached. For example, the mounting portion 28b may be a combination of a positioning engaging portion and a female screw, or may be formed of an appropriate mount including a positioning uneven fitting portion.
In the shape measuring device 1, a plurality of first holding units are prepared according to the type of the first work. Each of the first holding portions has a mounting portion that is detachably fixed to the mounting portion 28b.

  For example, the DUT holder 29 shown in FIG. 1 is a first holder for holding the DUT W as a first work. Hereinafter, the positional relationship related to the DUT holder 29 will be described based on the posture in which the DUT holder 29 is mounted on the holding wall portion 28 as shown in FIG.

  When the DUT W is attached to the holding wall portion 28 via the DUT holder 29, the DUT W is detachably held while protruding toward the measuring section 2. The DUT W does not need to be axially symmetric, and may have a known design shape such as a free-form surface shape. Thus, when the DUT W is held by the DUT holder 29, the DUT W and the probe P1 provided on the measurement section 2 side are arranged to face each other. The device under test W can be moved in the Y-axis direction by a y-axis moving mechanism (second moving stage) 27 via the support 3. The movement of the object W is detected by a y-length measuring device (second axis length measuring device) 41 provided in the vicinity of the support portion 3 and the detection result is sent to a calculating portion (calculating means) 26 to be described later. They are output one by one. The probe holder 30 holding the probe P1 is attached to the attachment portion 28b by removing the device holder 29, as shown in FIG.

DUT holder 29, x ₁ axis of the object W, y ₁ axis, z ₁ axis, respectively, X-axis of the shape measuring apparatus 1, Y-axis, to be parallel to the Z-axis, the object to be measured Hold W.
The means for holding the DUT W in the DUT holder 29 is not particularly limited. For example, the DUT holder 29 may include a chucking mechanism that grips the outer shape of the DUT W.
Although not shown, the DUT holder 29 has a mounting portion for detachably fixing to the mounting portion 28b.

For example, the probe holder 30 shown in FIG. 5 is a first holding unit for holding the probe P1 as a first work. Hereinafter, the positional relationship of the probe holder 30 will be described based on the posture in which the probe holder 30 is mounted on the holding wall 28 as shown in FIG.
The probe holder 30 holds the probe P1 such that the central axis _CP1 is parallel to the Z-axis of the shape measuring device 1 with the spherical portion 10a of the probe P1 facing the positive direction of the Z-axis.
As shown in FIG. 6, the probe holder 30 holds the probe P1 by having the female screw portion 30b into which the male screw portion 10b of the probe P1 is screwed. The center axis of the female screw portion 30b is parallel to the Z axis when the probe holder 30 is mounted on the holding wall portion 28.
Although not shown, the probe holder 30 has a mounting portion on the side surface opposite to the side surface on which the female screw portion 30b is formed for detachably fixing the mounting portion 28b.

On the side surface of the probe holder 30 on the positive side in the Z-axis direction, a reference mark 30a is provided on the positive side in the Y-axis direction with respect to the female screw portion 30b.
Reference mark 30a, the probe P1 is in reference marks for aligning upon being mounted on the female screw portion 30b, a rotational position of the center axis C _P1 around the probe P1.
In the following, as an example, the reference mark 30a will be described using an example in the case of being formed at a position facing the central axis C ₈ and Y-axis direction of the female screw portion 30b.

For example, as shown in FIG. 3, a state where the first mark 40a of the probe P1 is circumferentially aligned with the reference mark 8b so as to face the positive direction of the Y axis, and the probe P1 is fixed to the air slide shaft 8 is shown. This is referred to as a first attachment state. As shown in FIG. 6, a state in which the second mark 40b of the probe P1 is circumferentially aligned with the reference mark 30a and fixed to the probe holder 30 so as to face the positive direction of the Y axis is referred to as a second mounting state.
In this case, the posture of the surface _SP1 in the second mounted state is equal to the posture obtained by rotating the surface _SP1 in the first mounted state by 180 ° around the Y axis and then by 180 ° around the Z axis. Therefore, if properly translate the surface S _P1 of the second mounted state, the surface S _P1 of the second mounted state, the surface S _P1 of the first mounted state has a positional relationship of point symmetry to each other.

As shown in FIG. 7, the control unit 100 includes a measurement control unit 101, a surface shape data acquisition unit 102, a storage unit 103, a variable conversion processing unit 104, and a surface shape estimation processing unit 105.
The measurement control unit 101 controls the entire measurement operation in the shape measurement device 1.
For example, the measurement control unit 101 is communicably connected to the first movement stage 25, the second movement stage 27, and the driving units 24a and 24b, and the measurement control unit 101 is connected to the first movement stage 25 and the second movement stage. By transmitting control signals to the stage 27 and the driving units 24a and 24b, respective driving controls are performed.

Next, the operation of the shape measuring apparatus 1 according to the present embodiment configured as described above will be described. In this embodiment, the shape of the test object (stylus spherical error) is extracted by four types of measurements using two styluses and one test sample.
The outline of the measurement procedure of the shape measuring apparatus 1 in the present embodiment is as follows. FIG. 8 is a flowchart of the measurement procedure, and FIG. 9 is a diagram showing a state of each measurement step.
First, the test sample (work W) is measured by the stylus A (probe P1) (first three-dimensional measurement step S1).
Subsequently, the same test sample (work W) is measured by the stylus B (probe P2) (second three-dimensional measurement step S2).
Then, stylus A (probe P1) is measured by stylus B (probe P2) (third three-dimensional measurement step S3).
Further, the direction of the stylus B (probe P2) is changed, the test sample (work W) is rotated at a predetermined angle, and the rotated test sample (work W) is measured (fourth three-dimensional measurement step S4). .
In this way, four measurement results are obtained in four different measurements.
Next, 28 data (the above four measurement results × 7 affine transformations) are created by affine transformation. Conditions for the seven affine transformations include, for example, -90 ° rotation, 90 ° rotation, 180 ° rotation, horizontal mirror inversion, vertical mirror inversion, -90 ° rotation after horizontal mirror inversion, horizontal mirror inversion. A later 90 ° rotation.
Then, the control unit 100 performs a predetermined operation from the combination of all 32 (4 + 28) measurement results and the 32 weighting coefficients, so that a value close to the true value representing the shape of the work W is obtained. It is calculated (calculation step S5). The weighting coefficient is determined by solving a simultaneous equation so as to minimize the residue.
As described above, a more realistic pattern generated in the lens processing step can be effectively extracted by obtaining a coefficient giving a typical surface shape error such as ascoma or spherical aberration.

  Note that the affine transformation conditions are not limited to those described above. For example, the process may be performed in steps of 180 °, 120 °, 60 °, or 45 °. Further, the number of affine transformations is not limited to seven.

  Here, the operation for measuring the work W using the probes P1 and P2 as described above and obtaining the measurement result will be described in detail.

(First three-dimensional measurement step)
First, the probe P1 is attached to the air slide shaft 8 by screwing the male thread 10b into the female thread 8a. At this time, the probe P1 is arranged at a position where the reference mark 8b and the marking 40 match, that is, at a position where the marking 40 faces upward. Further, the first work W to be measured is attached to the holding wall portion 28 via the workpiece holder 29. Then, as shown in FIG. 2, the workpiece W and the probe P1 face each other. In this state, when the driving unit is driven, the driving unit 24b is driven, and the measuring instrument plate 6 is tilted toward the support unit 3, and at the same time, the measuring unit 5 also has the probe P1 side obliquely downward at one end. The other end on the axis length measuring device 20 side is inclined so as to face obliquely upward. Therefore, the air slide shaft 8 is moved toward the probe P1 along the axial direction, and at the same time, the stopper spring 22 is also moved between the inner side walls 23a of the stopper 23.

  When the stopper splash 22 comes into contact with the inner wall 23a on the probe P1 side, the movement of the air slide shaft 8 is stopped. This position is a point at which the probe P1 is horizontally separated from the initial contact point where the probe P1 first contacts the surface of the work W. In other words, in the initial state, when the air slide shaft 8 protrudes the maximum stroke, the probe P1 passes through the center of the work W and extends horizontally from a vertical plane including the axis L (hereinafter, referred to as a reference plane) (see FIG. 4). It is arranged on the side of the work W which is separated from the reference plane by a predetermined distance (in the direction of arrow A). Then, from this state, that is, from the side of the workpiece W, the measuring machine base 7 starts horizontal movement in the direction of arrow A toward the reference plane side. The measuring stand 7 moves at a high speed over a certain distance, is switched from a predetermined point to a low speed movement, and further keeps moving horizontally so that the probe P1 moves toward the initial contact point on the reference plane side.

  As a result, the spherical portion 10a of the probe P1 contacts the initial contact point of the workpiece W at a certain timing with a predetermined contact angle. Here, the contact angle means an angle θ1 between the normal line N and the axis L at the contact point, as shown in FIG. Then, after the contact, the probe P1 is moved following the smooth protruding surface of the work W. The contact point between the two is moved in accordance with the movement of the probe P1, and the contact angle θ1 of P1 with respect to the work W is also gradually changed. Then, when the probe P1 reaches a predetermined point, measurement is started by the probe axis length measuring device 20. Further, the probe P1 passes through the most protruding portion of the work W and is horizontally moved toward the end of the measurement by the movement of the measuring machine stand 7. By these movements, the contact point draws a fixed trajectory on the surface of the spherical portion 10a of the probe P1. Further, since the probe P1 is moved along the projecting surface of the work W, the air slide shaft 8 is also moved linearly in the direction of the axis L accordingly.

In the present embodiment, for example, the probe P1 is horizontally moved from the side of the workpiece W at a rapid traverse speed until the relative distance from the reference plane to the workpiece W of 20 mm in diameter is 10 mm. Upon reaching that point, the approach speed is switched to a lower approach speed of 2.5 mm per minute. Then, the probe P1 comes into contact with the workpiece W at a point 9 mm away from the reference plane. The contact force at this time is generated only by the axial component of the own weight of the member including the probe P1. That is, since the total weight of the probe P1, the air slide shaft 8, the stopper spring 22, and the glass length measuring device 20 is 52 gf and the inclination angle is 2 minutes,
52 (gf) × sin (2/60) = 0.03 (gf)
That is, the contact force is about 30 mgf.

  Further, the probe P1 continues to relatively move while being in contact with the workpiece W, and measurement by the probe axis length measuring device 20 is started at a point where the air slide shaft 8 is pushed back by 2 mm due to the convex shape of the workpiece W. At this time, since the air slide shaft 8 is pushed back, the stopper spring 22 is in a state of being separated from both inner side walls 23a. Thereafter, the probe P1 keeps moving relative to the work W only in the axial direction of its own weight in the opposite direction across the reference plane while contacting the work W, and is separated from the work W at a predetermined point on the opposite side. During that time, the probe shaft length measuring device 20 continues to detect the position of the air slide shaft 8, and the information is output to the control unit 100 one by one. Further, the position of the movement of the measuring machine stand 7 in the direction of arrow A is detected by the second axis length measuring device 41, and the information is output to the control unit 100 one by one in the same manner as described above.

Then, the output information from the second axis length measuring device 41 and the output information from the second axis length measuring device 41 are made to correspond to the change in the contact angle θ1 by the control unit 100. The relationship with the output information is converted into the relationship between the output information from the probe axis length measuring device 20 and the contact angle θ1, and the measurement result of the work W is obtained as a function M ₁ (θ1) related to the contact angle θ1.

The measurement coordinate x and the contact angle θ can be converted by the following equation. Here, R indicates the radius of curvature of the measured object.
θ = sin ⁻¹ (R / x)
Note that a derivative coefficient can be used as a variable that can be substituted for the contact angle θ. This is an effective means when applied to an object to be measured having no radius of curvature such as a free-form surface. If the three-dimensional shape f (x, y) of the measured object is known, the differential coefficient f ′ (x, y) becomes a variable corresponding to the contact angle θ.

(Second three-dimensional measurement step)
Next, the probe P1 is removed from the female screw portion 8a, and the probe P2 is attached. Then, using the probe P2, the work W is measured again by the same operation as described above. The control unit 100 processes the measurement result obtained by this, and the measurement result of the work W becomes a function M related to the contact angle θ2 of the probe P2 at the contact point between the probe P2 and the work W (see FIG. 10B). ₂ (θ2).

(Third three-dimensional measurement step)
Thereafter, the workpiece W is removed from the holding wall portion 28, and the probe P1 used for the above measurement is attached again via the probe holder 30 instead. Also at this time, the probe P1 is arranged at a position where the holder marking (reference mark) 30a and the marking 40 match, that is, at a position where the marking 40 faces upward. Thus, the probe P1 is attached such that the marking 40 always faces upward when the probe P1 is attached to the air slide shaft 8 and the probe holder 30. Therefore, the respective contact points of the probes P1 and P2 with the workpiece W when measuring the workpiece W using both probes P1 and P2, and the mutual contact points when measuring the probe P1 using the probe P2. Are equal, and the contact points move on the same trajectory on the surface of the spherical portion 10a. That is, the probes P1 and P2 are always brought into contact on the same trajectory during measurement. When the probe P1 is mounted on the holding wall holder 28, the probe P1 and the probe P2 mounted on the air slide shaft 8 are arranged so as to face each other as shown in FIG. From this state, the probe P1 is measured by the same operation as described above.

Although there is no restriction on the radius of curvature of the probe in terms of the measurement principle, it is preferable that any one of the probes has a radius of curvature of 0.5 mm or more in view of the state of measurement between probes. In this case, it is desirable that the other probe is a diamond stylus having a radius of curvature of 2 μm. Also, the probe need not be specific to a sphere. The present measurement principle can be applied to a known design shape similarly to the measured object. The control unit 100 processes the measurement result obtained by this, and the measurement result of the probe P1 becomes a function M related to the contact angle θ3 of the probe P2 at the contact point between the probe P2 and the probe P1 (see FIG. 10C). ₃ (θ3).

(Fourth three-dimensional measurement step)
Next, the direction of the stylus B (probe P2) is changed (reversed), the test sample (work W) is rotated at a predetermined angle, and then the test sample (work W) rotated by the stylus B (probe P2). ) Is measured, and measured by the same operation as described above. The control unit 100 processes the obtained measurement result, and the measurement result of the work W is obtained as a function M ₄ (θ4) relating to the contact angle θ4 of the probe P2 at the contact point between the probe P2 and the work W.

The angle at which the test sample (work W) is rotated is, for example, 180 ° or 90 ° around the Z-axis. The measuring method for obtaining the fourth surface shape data is not limited to this. For example, at least one of the stylus B and the test sample W may be rotated 90 ° or −90 °.
That is, in the fourth three-dimensional measurement step, the sample (work W) is detected by the stylus B (probe P2) in a state where at least one of the stylus B (probe P2) and the sample to be tested (work W) is turned. Is measured.

Next, the four function M ₁ ~M ₄ corresponding to each of the above four measurement results obtained by the action (first to fourth surface shape data), calculates the true value of the work W Will be described.
The spherical portions 10a of the probes P1 and P2 may have a small sphericity error due to manufacturing, that is, a shape error with respect to the design shape of the spherical portion 10a. Therefore, the four functions as measurement results include these shape errors. The workpiece W also has a shape error with respect to the design shape.

In the following examples, in the measurement from M ₁ M ₄ in all, the stylus side (the side to get the top) is moved as rotated by 180 ° about the Y axis, based on the use of a stylus. Further, the test sample side (object side) does not rotate until _M 1 ~M _3, was measured in a state where the test sample is rotated in the Z-axis center at _{M 4.} The measurement results M _{1 to} M ₄ according to this posture can be expressed as follows.

  Here, θx and θy are contact angles at the probe contact point, and f (x, y) is a design shape. In addition, since the measurement is performed for the one having a different radius of curvature, the calculation is performed not by the xy coordinate but by the coordinate converted (converted) into the inclination angle θ using the following equation.

M _{1 to} M ₄ are functions corresponding to each of the four measurement results (first to fourth surface shape data). A is a function corresponding to the stylus A, B is a function corresponding to the stylus B, and C is a function corresponding to the test sample W. In this embodiment, the correspondence between the function _M 1 ~M ₄ and functions A~C is given by the following table.

M ₁ (first surface shape data) is obtained by rotating the stylus A by 180 ° around the Y axis and measuring the test sample W with the stylus A.
M ₂ (second surface shape data) is obtained by rotating the stylus B by 180 ° around the Y axis and measuring the test sample W with the stylus B.
M ₃ (third surface shape data) is obtained by rotating stylus A by 180 ° around the Y axis and measuring stylus B with stylus A.
M ₄ (fourth surface shape data) is obtained by rotating the test sample W by −90 ° around the Z axis and measuring the test sample W with a stylus. The measurement method of M ₄ is not limited thereto.

(Calculation process)
Seven kinds of affine transformations are performed on the four measurement results obtained by the above operation, and a total of 32 data of 4 original data (measurement data) +28 numerical data obtained by the affine transformation Get. If it is considered that the original data (measurement data) is obtained by performing an affine transformation that does not move (no conversion), it can be considered that eight kinds of affine transformations have been performed.

Four measurement data (M 1 _{~M 4)} each determine the shape C of the workpiece W from the weighted average of the results obtained by performing the affine transformation of the eight (affine transformation of the measured data +7 patterns) with respect to the formula Is defined as follows.

w _{i, j} is a weighting coefficient. In order to determine the shape C of the device under test W, it is necessary to determine the weighting coefficients w _{i, j} . Here, (X ₁ , Y ₁ ) represents one of eight radially located coordinates obtained by combining 90 degrees and inversion.
X and Y in the following equation (4) are no conversion (original data), 180 ° rotation, X inversion (horizontal mirror inversion), Y inversion (vertical mirror inversion), + 90 ° rotation, and −90 ° rotation. , X inversion + 90 ° (+ 90 ° rotation after horizontal mirror inversion), and X inversion −90 ° (−90 ° rotation after horizontal mirror inversion). j is an index corresponding to eight affine transformations.

  In Table 2 below, f, mx, my, rp, rm, rot, mxp, and mxm represent no conversion (original data), X inversion (horizontal mirror inversion), Y inversion (vertical mirror inversion), Index conversion corresponding to eight types of affine transformations of + 90 ° rotation, −90 ° rotation, 180 ° rotation, a combination of X inversion and 90 ° rotation, and a combination of X inversion and −90 ° rotation.

  Expanding C in equation (2) using equation (1) gives equation (5) below.

  Formula (5) can be summarized as the following formula (6) for each of A, B, and C.

  Since the equation (6) is an identity, the following equation (7) is satisfied.

Similarly, by deriving three equations for C (X _k , Y _k ) (k = 2, 3,..., 8), a total of 192 simultaneous equations can be obtained. By solving the simultaneous equations with excessive conditions by the least-squares method, the weighting coefficients w _{i, j} are determined, and the formula for obtaining the shape C of the DUT W is completed. Then, the control unit 100 performs a predetermined calculation from the combination of all 32 measurement results and 32 weighting coefficients, so that a value close to the true value representing the shape C of the workpiece (work) W is obtained. Is calculated.

  In the above description, a case has been described in which seven types of affine transformations are performed, but the number of affine transformations is not limited to seven. The type of affine transformation is not limited to the above example. Further, the above-described calculation method and mathematical formula are examples, and the present invention is not limited to the above-described calculation method and mathematical formula.

  In the present embodiment, there is an advantage that the shape of the workpiece W can be directly obtained without performing calibration of the probe shape using the reference sphere. Further, there is an advantage that the shape of the workpiece W can be obtained by a simple calculation from a measurement result performed using a probe having a shape error.

As described above, according to the shape measuring apparatus 1 of the present embodiment, an approximate value of a true value representing the shape of the workpiece W can be easily calculated without using the reference sphere. Further, it is not always necessary to use the same measurement coordinates.
In the description of each of the above embodiments, the probe P1 and the probe P2 are interchangeable.
The tips of the probes P1 and P2 may be pointed or may be ball-shaped (provided with a spherical portion). However, if the tips of both the probe P1 and the probe P2 are sharp, it is inappropriate because the third three-dimensional measurement step is difficult to perform.

The preferred embodiments and examples of the present invention have been described above, but the present invention is not limited to these embodiments and examples. Additions, omissions, substitutions, and other modifications of the configuration can be made without departing from the spirit of the present invention.
The present invention is not limited by the above description but is limited only by the appended claims.

  DESCRIPTION OF SYMBOLS 1 ... Shape measuring device, 2 ... Measuring part, 3 ... Support part, 4 ... Base, 5 ... Measuring unit, 6 ... Measuring machine board, 7 ... Measuring machine stand, 8 ... Air slide shaft, 8a ... Female screw part (No. 2b) Reference mark, 9b Air slide bearing, 10a spherical part, 10b male screw part, 10c probe axis, 10d spherical part 10, 20 probe length measuring instrument (glass measuring instrument) , 20a: glass scale head, 20b: reference scale (glass scale), 21: stepped portion, 22: stopper spring, 23: stopper, 23a: both inner side walls, 24a, 24b: drive unit, 25: first moving stage, 26 ... Arithmetic operation unit (arithmetic means), 27 second moving stage (y-axis moving mechanism), 28 holding wall (holding wall holder), 28a front surface, 28b mounting unit, 29 subject holder (second 1 holding part), 30 ... pro Holder (first holding part), 30a: reference mark (marker for holder), 30b: female screw part, 40: marking, 40a: first mark, 40b: second mark, 41: second axis measuring device (y measurement) 43 ... first axis length measuring device, 100 ... control unit, 101 ... measurement control unit, 102 ... surface shape data acquisition unit, 103 ... storage unit, 104 ... variable conversion processing unit, 105 ... surface shape estimation process Department

Claims (4)

In a shape measurement method for evaluating a three-dimensional surface shape by bringing a probe into contact with a measured object whose design shape is known, and scanning the surface of the measured object in at least two different directions.
A first probe is mounted on probe support means for supporting the probe, and a three-dimensional surface shape of the object to be measured supported by the object support means for supporting the object is measured to obtain first surface shape data. A first three-dimensional shape measurement step of obtaining
A second three-dimensional measuring step of attaching a second probe to the probe support means and measuring a three-dimensional surface shape of the object supported by the object support means to obtain second surface shape data When,
A third tertiary method for measuring a three-dimensional shape of the first probe supported by the object-to-be-measured in a state where the second probe is mounted on the probe supporting means to obtain third surface shape data; Original measurement process,
With the direction of at least one of the second probe and the device under test changed, the second probe is mounted on the probe support means, and the device under test supported by the device under test support is A fourth three-dimensional shape measurement step of measuring a three-dimensional surface shape to obtain fourth surface shape data;
A calculating step of calculating a surface shape of the DUT based on the first surface shape data, the second surface shape data, the third surface shape data, and the fourth surface shape data;
A shape measuring method comprising:   In the calculating step, the weighted average of a result of performing a plurality of affine transformations on the first surface shape data, the second surface shape data, the third surface shape data, and the fourth surface shape data is used. The shape measuring method according to claim 1, wherein a surface shape of the measurement object is calculated.   The at least one of the second probe and the object to be measured in the fourth three-dimensional shape measuring step is in a state of being rotated 90 ° or −90 ° around a central axis. Shape measurement method. A shape measuring apparatus for measuring a three-dimensional surface shape of the measured surface, by contacting a probe having a known probe surface with the designed shape having a known measured surface having a known measured shape,
A first holding unit that holds a first work having a first surface;
A second holding unit that holds a second work having a convex second surface;
Movement for moving the first holding part and the second holding part so as to be relatively parallel movable in a direction along a measurement reference axis which is a normal line of a measurement reference plane and in at least two directions orthogonal to the measurement reference axis and intersecting each other. Mechanism and
The first work and the second work are relatively translated in a state where the second surface is in contact with the first surface, and a three-dimensional movement locus of a representative point of the second work is defined on the second surface. A surface shape data acquisition unit that acquires surface shape data of the first surface by converting based on the design shape of
The object to be measured having the surface to be measured as the first surface as the first work is held by the first holding portion, and the first probe surface formed by a convex surface having a known design shape is used as the second work. When the first probe having the second surface is held in the second holding unit in the first measurement posture with respect to the object to be measured, first surface shape data that is the surface shape data is obtained;
The object to be measured having the surface to be measured as the first surface as the first work is held by the first holding portion, and the second probe surface formed by a convex surface having a known design shape is used as the second work. When the second probe having the second surface is held by the second holding portion in the second measurement posture with respect to the object to be measured, second surface shape data that is the surface shape data is obtained;
Each positive direction of relative translation with respect to the first surface when acquiring the first surface shape data and each positive direction of relative translation with respect to the second surface when acquiring the second surface shape data are mutually different. In order to match, when the first probe is held as the first work and the second probe is held as the second work, third surface shape data that is the surface shape data is acquired,
In a state in which at least one of the second probe and the object to be measured is turned, the object to be measured is held as the first work by the first holding unit, and the second probe is used as the second work. Acquiring the fourth surface shape data, which is the surface shape data, when the object to be measured is held by the second holding unit in the third measurement posture.
A measurement control unit;
A storage unit that stores the first surface shape data, the second surface shape data, and the third surface shape data,
The first surface shape data, the second surface shape data, and the third surface shape data are converted into a function of a contact angle, which is an angle between a design normal at each measurement position and the measurement reference axis. A variable conversion processing unit;
By subjecting the first surface shape data, the second surface shape data, and the third surface shape data subjected to variable conversion by the variable conversion processing unit to arithmetic processing, the measured surface, the first probe surface, and the A surface shape estimation processing unit that estimates at least one true surface shape of the second probe surface;
A shape measuring device comprising:

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