JP6478603B2 - Surface shape measuring method and surface shape measuring apparatus - Google Patents

Description

  The present invention relates to a measuring method of a shape measuring apparatus for measuring a three-dimensional shape of an optical element typified by a lens or a similar structure.

  An optical element such as a lens is an object that requires processing accuracy and shape accuracy below the wavelength of light. For such an object requiring high accuracy, it is widely performed to measure the shape with a contact-type or non-contact-type shape measuring device and evaluate whether the processing accuracy and the shape accuracy are satisfied. .

  Many optical elements are axisymmetric and aspherical. When manufacturing such an axially symmetric aspherical optical element, first, a desired axisymmetric aspherical design shape is determined and processed according to the design shape to obtain an optical element. The shape of the optical element is measured by a shape measuring device, and the measurement of the optical element is evaluated by comparing the measurement data with the design shape data.

  The design shape of the axisymmetric aspheric surface is expressed as a polynomial that represents a coordinate in the height direction with respect to a radial coordinate from the origin to the end with one point of the rotation center axis of the object as the origin.

  In order to compare the measured data with the data of the design shape expressed by a polynomial, first measure a two-dimensional cross section along the diameter through the rotation center axis of the object to be measured (hereinafter referred to as workpiece). Hereinafter, it may be referred to as cross-sectional measurement) to obtain measurement data.

  When the workpiece has an ideal axisymmetric shape, the cross-sectional shape along the diameter passing through the rotation center axis of the workpiece is the same shape in any direction. Therefore, it is sufficient to obtain only one shape measurement data for such an ideal workpiece.

  However, in reality, it is rare that a workpiece having a completely axisymmetric finish is obtained due to a machining error in the machining process. Such an actual workpiece shape often includes non-axisymmetric shape errors such as partial unevenness with respect to an axisymmetric design shape.

  Therefore, in reality, it is impossible to correctly evaluate the shape of the workpiece only with measurement data in one direction.

  Therefore, conventionally, using a mechanism for scanning the probe in one direction with respect to the workpiece and a rotary stage on which the workpiece is mounted, workpiece measurement data for a plurality of directions is obtained, and the shape of the workpiece is evaluated from the combined data. There was a shape measuring device. Such a shape measuring apparatus can also acquire and evaluate the shape of a workpiece by obtaining a plurality of concentric data while rotating the workpiece, or measuring in a spiral manner. (Patent Document 1)

  In such a shape measuring apparatus, based on the coordinates of the probe provided in the orthogonal stage mechanism and the rotation angle of the rotary stage, the measurement data is coordinate-converted into an orthogonal coordinate system with the rotation axis of the work rotation stage as the origin. . This coordinate transformation assumes that the rotary axis of the rotary stage and the rotary axis of the workpiece are sufficiently aligned, and that the probe and rotary axis of the rotary stage are also positioned with sufficient accuracy. It is said.

  Therefore, an adjustment process is required in which the probe is strictly arranged with respect to the rotation axis of the rotary stage by the orthogonal stage mechanism. When the mechanical accuracy is pursued with the accuracy below the wavelength of light as described above, the apparatus becomes large, for example, it is necessary to separately provide a highly accurate position measuring device. Further, even when the mechanical accuracy is achieved, the deviation may occur due to the temperature environment and the change with time.

  Patent Document 2 discloses a method for measuring the shape of a workpiece without performing an adjustment process in which the probe is strictly arranged on the rotation axis of the rotary stage.

  That is, circumferential or spiral measurement has been solved by making the coordinates of the probe of the orthogonal stage within the plus range and minus range with respect to the rotation axis. In this method, the workpiece is repeatedly corrected while correcting the probe offset so that the difference between the shape data obtained in the plus range and the shape data obtained in the minus range is less than the allowable value. The shape data of the entire surface is acquired (Patent Document 2). However, this method requires two times of measurement time in the process of measuring the workpiece, and the probe needs to perform measurement twice in the plus and minus ranges, resulting in low productivity. was there.

No. 07-003331 Patent No. 4242700

  In view of the above, the shape measurement device with a probe that can scan in one direction and a rotary stage can accurately obtain shape data without positioning the probe strictly on the rotation axis and without significantly increasing the measurement time. The purpose is to get to.

In order to solve the above-described problems, the shape measuring method of the present invention uses a shape measuring device including a probe capable of scanning in one direction and a rotary table to scan the surface of a workpiece with the probe and to scan the probe. A shape measuring method for measuring the shape of the workpiece by measuring a position, the step of setting the workpiece on the rotary table, the step of obtaining measurement data at different rotation angles of the rotary table, and the measurement Obtaining a reverse measurement data of the workpiece while being rotated 180 ° with respect to a rotation angle corresponding to at least one forward measurement data of the data, and the rotation from the forward measurement data and the reverse measurement data A step of calculating the rotation center Xc of the table, and correcting the measurement data based on the data of the rotation center Xc, To the calculated shape of the surface of the workpiece, the rotation center Xc moving amount x ₁ and x generated upon fitting each said inverted measurement data and the forward measurement data to the design shape data of the workpiece ₂ is obtained by the following general formula 1.

  With the shape measuring machine, correct shape data can be acquired without strictly positioning the probe on the rotation axis and without significantly increasing the measurement time.

The figure which shows the shape measuring apparatus which comprises the 1st Example of this invention The figure which shows the measurement sequence of this invention The figure which shows the relationship between the apparatus coordinate system of this invention, and a workpiece | work coordinate system. Diagram showing cross-sectional measurement of the present invention The figure showing the fitting of the measurement section of the present invention

Example 1
An embodiment according to the present invention will be described below with reference to the drawings as appropriate. FIG. 1 shows a shape measuring apparatus. In FIG. 1, a rotary stage 2 or a tilt stage further provided on the rotary stage is drawn, and a state in which a workpiece is not attached to these stages is shown. A group of these stages for placing the workpiece on the shape measuring apparatus may be referred to as a “work stage”.

  The work may be placed on the work stage through hiring (Yatoi), or may be placed directly on the work stage.

  (A) of FIG. 1 is the perspective view seen from the front, (b) is the perspective view seen from back.

  Hereinafter, the main body configuration and operation of the shape measuring apparatus of the present invention will be described with reference to FIG.

  A rotation stage 2 is fixed to the reference base 1, and an X work stage 3 and a Y work stage 4 are fixed on the rotation stage 2. On the Y work stage 4, there are installed a hiring mounting surface 5 and hiring mounting standards 6 and 7. A work is placed on a work stage composed of these groups.

  When placing the work on the work stage, the work can be held and attached to the hire mounting surface 5 and hiring mounting standards 6 and 7 in FIG. Of course, you can attach the work directly to the work stage without using hire. In addition, the workpiece can be placed on the shape measuring device in various configurations according to the user's wishes.

  Columns 12 and 13 are fixed to the reference base 1, and these two columns support the end portion of the X guide fixing portion 14. The X guide movable portion 16 is supported on the X guide fixing portion 14 by a static pressure pad (not shown). As shown in FIG. 1B, the X guide movable portion 16 is generated between an X linear motor stator 17 fixed to the X guide fixed portion and an X linear motor mover 19 fixed to the X guide movable portion 16. Drive in the X direction in the figure by force. An X laser scale head 20 is mounted on the X guide movable unit 16, and the X coordinate with respect to the X laser scale 22 on the X scale base 21 mounted on the reference base 1 is measured.

  Referring to FIG. 1A again, the X guide movable portion 16 is fixed with a Z guide fixing portion 23, Z linear motor stators 25 and 26, and Z laser scale heads 27 and 28. The Z guide fixing portion 23 supports the Z guide movable portion 30 via a static pressure pad (not shown). Z linear motor movable elements 31 and 32 are attached to the Z guide movable part 30, and a force is generated between the Z linear motor stators 25 and 26 and driven.

  Z laser scales 33 and 34 are fixed to the Z guide movable unit 30, and the Z coordinates with respect to the Z laser scale heads 27 and 28 are measured. A probe 38 for measuring the workpiece is fixed.

  The rotary stage 2 is a rotary stage using an air bearing, a coupling, and a servo motor (not shown). However, there is no particular limitation on the rotary stage using any mechanism. The rotary stage 2 is attached with an encoder that detects a rotation angle.

  The X work stage 3 and the Y work stage 4 are general uniaxial stages using a cross roller guide, a ball screw, a coupling, and a stepping motor (not shown). The drive mechanism and the guide are not particularly limited, and any mechanism may be used. By having the X work stage 3 and the Y work stage 4, it is possible to correct and align the work error in the translational direction and the employment, but if there is no correction, neither may be necessary. It is desirable that the X work stage 3 and the Y work stage 4 are adjusted substantially orthogonally.

  Although a static pressure guide using compressed air is used as the X guide and the Z guide, other guides such as an LM guide and a cross roller guide may be used.

  Although a shaft type linear motor is used as the X drive motor and two linear motors are used as the Z drive motor, the drive mechanism is not particularly limited, such as a combination of a rotary motor and a ball screw.

  Although the laser scale was used for XZ coordinate measurement and drive control, any position measurement means such as a laser interferometer, mirror, displacement meter, and magnetic scale may be used as long as the position can be measured. It is not something to do.

  The probe may be a known probe composed of a contact supported by a leaf spring (not shown) and a laser displacement meter (not shown) for measuring the distance from the reference position to the contact. The contact is supported by a leaf spring and is controlled so that the contact pressure is constant when measuring the shape. The laser displacement meter can control the contact pressure by measuring the displacement of the contact supported by the leaf spring. Therefore, any mechanism such as a non-contact length measuring mechanism that measures the distance by focusing may be adopted.

  Although not shown for the motor, each scale, sensor wiring, and static pressure pad piping, a cable bear (registered trademark) or the like is appropriately prepared and supported. Also, although not shown, a driver for supplying current to the motor and an interface for issuing instructions from a measurer and a host controller are prepared as appropriate.

  On the other hand, the drive processing unit 70 in the control unit 74 controls the following operations. That is, an operation for rotating the rotary stage 2 to an arbitrary angle, and an operation for scanning by driving the X linear motor movable element 19 and the Z linear motor movable elements 31 and 32 in a state where the probe is in contact with the workpiece surface.

  Also, the operation of moving the probe 38 by a desired diameter from the center of the rotation axis of the rotary stage 2 and rotating the workpiece by the rotary stage 2 while the probe 38 is in contact with the workpiece is scanned similarly. It is.

  At that time, the rotation angle of the rotary stage 2 is detected by an encoder.

  Similarly, the positions of the X linear motor movable element 19 and the Z linear motor movable elements 31 and 32 are detected by the X laser scale head 20, the X laser scale 35, the Z laser scale heads 27 and 28, and the Z laser scales 33 and 34. The

  Each detected value is processed by the measurement data processing unit 71 and stored in the storage unit 72. Further, the analysis processing unit 73 converts the detection values of each sensor stored in the storage unit 72 by the measurement data processing unit 71 into coordinates on the workpiece surface, performs a fitting process on the design shape, and calculates a shape error. To do. The shape error refers to the difference between the measurement data and the design shape data. Based on this difference, the shape accuracy of the workpiece may be judged or reworked to reduce the difference.

  FIG. 3A shows the relationship between the apparatus coordinate system and the work coordinate system. In FIG. 3, 51 is the origin of the apparatus coordinate system, and 52 is the origin of the work coordinate system. Note that the X work stage 3 and the Y work stage 4 mounted on the rotary stage 2 are omitted for the sake of simplicity. The apparatus coordinate system is a coordinate system in which a known position in the shape measuring apparatus is taken as the origin, and the X, Y, and Z axes are determined from the origin.

  In this embodiment, the coordinate system is an orthogonal coordinate system in which the X axis and the Z axis are taken in the drive directions of the X guide movable unit 16 and the Z guide movable unit 30, respectively.

  In general, the origin of the measuring instrument for each axis is usually the origin of the apparatus coordinate system, and this origin is also taken in this embodiment.

  Further, in the shape measuring apparatus of the present embodiment, when the probe or the X laser scale 22 is attached, the X axis deviation of the X laser scale 22 with respect to the rotation axis of the work stage is finely adjusted to be 1 μm or less. is there.

  However, as described above, if the X laser scale 22 is further pursued for mechanical accuracy with accuracy less than the wavelength of light, the apparatus becomes large and unrealistic. In addition, as described above, even if the mechanical accuracy that can be applied to the measurement of the optical element is pursued, the deviation may occur due to the temperature environment and the change with time. Hereinafter, the technical features of the present embodiment will be specifically described.

  The present invention measures the shape of the workpiece by scanning the surface of the workpiece with the probe and measuring the position of the probe using a shape measuring device having a probe capable of scanning in one direction and a rotary table. Perform shape measurement.

  As specific shape measuring steps, there are a step of setting a workpiece on the rotary table and a step of obtaining measurement data at different rotation angles of the rotary table.

  Furthermore, as one technical feature of the present invention, it is important to obtain the workpiece reversal measurement data in a state of being rotated by 180 ° with respect to the rotation angle corresponding to at least one of the measurement data in the forward direction.

  As a result, the rotation center Xc of the rotary table can be calculated from the forward direction measurement data and the reverse measurement data, so that the measurement data is corrected based on the data of the rotation center Xc, the coordinates are converted, and the shape of the surface of the workpiece is obtained. Can be calculated.

  The workpiece coordinate system shown in FIG. 3A is an orthogonal coordinate system in which the Z axis is taken in the direction along the rotation axis of the workpiece, and the X axis and the Y axis are taken on a plane orthogonal to the Z axis.

  Referring to FIG. 3A, ideally, when the Y axis of the apparatus coordinate system and the Y axis of the workpiece coordinate system are on the same straight line, or the relative positions of the two Y axes are known. In that case, the problem to be solved by the present invention and this embodiment does not arise in the first place.

  In such an ideal state, the apparatus coordinate system and the rotary axis of the rotary stage are aligned with high accuracy, and the rotary axis of the rotary stage and the rotary axis of the workpiece are aligned with good accuracy. Correspond.

  However, in reality, there is a limit to pursuing mechanical accuracy, and the two Y axes shown in the figure do not lie on the same straight line in consideration of the accuracy required when measuring the shape with accuracy below the wavelength of light. The relative position is also considered unknown. This means that there is a non-negligible deviation at the origin position in the X-axis direction.

  In this apparatus, the measurement origin of the probe 38 in the apparatus coordinate system is adjusted so as to substantially coincide with the rotation axis of the rotary stage 2. If the measurement origin of the probe 38 is adjusted so as to exactly match the rotation axis of the rotary stage 2, the following general formula 1 is established.

In equation (1), Xw and Yw are XY coordinates of the workpiece coordinate system, Xp is the X coordinate of the probe 38 with respect to the measurement origin of the probe in the apparatus coordinate system, and θc is the rotation angle of the rotary stage 2 with respect to the shape measuring apparatus. The counterclockwise direction is positive. For example, as shown in FIG. 3B, the measurement data obtained by measuring the cross-section with the rotary stage 2 rotated by + θ _C in the apparatus coordinate system is centered on the rotation axis of the rotary stage 2 in the workpiece coordinate system. -Θ _C undergoes coordinate transformation.

(1) Based on equation, it is possible to convert the Xp is measurement data obtained by the probe 38, the rotation angle theta _c of the rotary stage 2 coordinates Xw on the workpiece surface, the Yw.

That is, by obtaining measurement data at several rotation angles θ _C and combining a plurality of measurement data obtained with reference to the workpiece coordinate system, data indicating the three-dimensional surface shape of the workpiece is calculated. be able to.

  However, it is difficult to adjust the measurement origin of the probe 38 so as to be exactly coincident with the rotation axis of the rotary stage 2, and the measurement origin of the probe 38 and the rotation axis of the rotary stage 2 due to changes in temperature environment and the like. The positional relationship of can vary.

  When there is a deviation (error) between the position of the measurement origin of the probe 38 and the position of the rotation axis of the rotary stage 2, an axis for coordinate conversion for rotating the measurement point sequence in three dimensions and an axis for actually rotating the workpiece As a result, the measurement data cannot be acquired correctly.

  At this time, if the positional relationship between the measurement origin of the probe 38 and the rotary axis of the rotary stage 2 is known, the following general formula 2 is used to measure on the rotary axis of the rotary stage 2 where the workpiece has actually rotated. It is possible to convert the coordinates of the point sequence.

  In the equation (2), Xc is the rotation center of the rotation axis of the rotary stage 2.

  Therefore, Xp-Xc corresponds to measurement data having the rotation axis of the rotary stage 2 as the origin. That is, calculating the workpiece coordinates using Xp-Xc instead of Xp corresponds to correcting the rotation center to the correct position.

  In this embodiment, every time the surface shape is measured, the X coordinate of the rotation axis of the rotary stage 2 with respect to the measurement origin of the probe 38 at the time of measurement is calculated from the measurement result, and the coordinate conversion by the equation (2) is performed, It becomes possible to correctly acquire the surface shape of the remaining dimension.

  In the so-called cross-section measuring machine represented by this embodiment, there are many cases in which the equator diameter of an axisymmetric measuring object is measured and evaluated. Therefore, an axially symmetric lens or mold that is a measurement target of the shape measuring apparatus of the present embodiment is not subject to error even if the shape is measured along a measurement line that deviates slightly from the equator diameter (a few percent of the workpiece diameter). Is negligible. Therefore, first, the workpiece is set in the shape measuring device so that the center axis is substantially coincident with the rotation axis of the rotary stage 2 when the rotary stage 2 is rotated 180 °. It is important to set the cross-sectional shape so that the change in the cross-sectional shape is sufficiently smaller than the shape accuracy of the workpiece.

  Based on such a premise, the shape measuring apparatus of the present embodiment will be described below with reference to the flowchart shown in FIG.

  In step S101, the drive processing unit 70 and the measurement data processing unit 71 perform cross-sectional measurement in a plurality of predetermined directions. The orientation at this time may be an equally divided orientation according to the number of cross sections to be measured or a freely determined orientation. FIG. 5B is a schematic diagram of multi-section measurement in step S101. FIGS. 4A and 4A show the state of multi-section measurement, and FIGS. 4A and 4B show the trajectory of multi-section measurement. The rotary stage 2 is indexed in each designated direction, the probe 38 is brought into contact with the workpiece 41 in each direction, and scanning is performed in a plurality of directions.

  In step S102, one measurement cross section 201 is selected, and the reverse measurement cross section 202 is measured (reverse measurement) in a state where the rotary stage 2 is rotated 180 ° (reverse) from the measured orientation. FIG. 4B is a schematic diagram of inversion cross-section measurement in step S102. FIGS. 4B and 4A show the state of inversion cross-section measurement, and FIGS. 4B and 4B show the trajectory of inversion cross-section measurement. Since the center axis of the workpiece and the rotation axis of the rotary stage 2 are substantially matched, the measurement cross section 201 and the inverted measurement cross section 202 are substantially the same cross section in which the left and right sides of the work are reversed.

  In step S103, the analysis processing unit 73 performs a calculation for fitting the measurement cross section 201 measured in step S101 to a design shape having the origin of the work coordinate system as the origin. Fitting is performed by the least square method or the like, and the amount of movement of coordinates at the time of fitting is also calculated.

  In step S104, the analysis processing unit 73 performs a calculation for fitting the inverted measurement cross section 202 measured in step S102 to a design shape having the origin of the workpiece coordinate system as the origin as in step S103. Fitting is performed by the least square method or the like, and the amount of movement of coordinates at the time of fitting is also calculated.

  In step S105, the analysis processing unit 73 calculates the relative position of the rotation axis of the rotary stage with respect to the origin of the probe from the movement amount of each coordinate at the time of fitting calculated in steps S103 and S104.

  In actual measurement, the workpiece center axis is not set to be strictly coincident with the rotation axis of the rotary stage 2 in most cases. FIG. 5A is a diagram showing the state of the workpiece and the state of fitting at that time. A case is assumed in which the center axis 301 of the workpiece is displaced by an amount a in the X direction with respect to the rotation axis 304 of the rotation stage 2. FIGS. 5A and 5A show a state where one measurement cross section 201 among the plurality of cross sections measured in step S101 is fitted to the design shape 203 in step S103. On the other hand, FIGS. 5A and 5B show a state where the inverted measurement cross section 202 measured in step S102 is fitted to the design shape 203 in step S104. In either case, the central axis 303 of the design shape 203 is the X origin of the probe. When the center axis 301 of the workpiece is displaced by an amount a in the X direction with respect to the rotation axis 304 of the rotary stage 2, the movement amount in the X direction when fitting the measurement cross section 201 and the inverted measurement cross section 202 is the following ( 3)

  Solving the equation (3) with respect to Xc, the following equation (4) is obtained, and the movement amount in the X direction at the time of fitting of the measurement cross section 201 and the inverted measurement cross section 202 is averaged, whereby the center axis of the workpiece and the rotation of the rotary stage 2 are obtained. Errors caused by axis misalignment are canceled out.

  In addition, when the workpiece has an asymmetric shape error, an error occurs at the position where the workpiece converges by fitting. FIG. 5B is a schematic diagram showing cross-sectional measurement and fitting at that time.

  FIGS. 5B and 5B show one measurement cross section 201 (forward measurement data) among the plurality of cross sections measured in step S101, and design shape 203 (design shape data) in step S103. This shows the situation when fitting. When the measurement cross section 201 has an asymmetric shape error, when fitting by the least square method, the measurement cross section 201 converges to the convergence cross section 211 at a position shifted by an amount d with respect to the design shape 203 due to the shape error.

On the other hand, (c) and (d) of FIG. 5 (B) show how the inverted measurement cross section 202 measured in step S102 is fitted to the design shape 203 in step S104. When the measurement is performed in directions different by 180 °, the workpiece shape data (inversion measurement data) is inverted in the X direction with respect to the rotation axis 304 of the rotary stage 2, and the measured cross section becomes a reverse measurement cross section 202. When the fitting is performed, the convergence position is reversed to the convergence section 211 with respect to the design shape data because the shape is inverted in the X direction, and converges to the inverted convergence section 311 shifted by an amount of −d. Accordingly, the respective X-direction moving amount x ₁ and x ₂ when the fitting of the following equation (5).

  When equation (5) is solved, the following equation (6) is obtained, and the fitting error caused by the asymmetrical shape error of the workpiece is canceled by averaging the amount of movement in the X direction when fitting the measurement cross section 201 and the inverted measurement cross section 202. It is.

As described above, the error a caused by the setting deviation between the center axis of the workpiece and the rotation axis of the rotary stage 2 and the error d caused by the asymmetric shape error of the workpiece can be adversely affected by using the inversion measurement in this embodiment. Can be suppressed. That is, it is canceled by averaging the amount of movement in the X direction during fitting of the measurement cross section 201 and the inverted measurement cross section 202. Therefore, the rotation center Xc of the rotation axis of the rotary stage 2 with respect to the measurement origin of the probe 38 averages the movement amounts x ₁ and x ₂ in the X direction when fitting the measurement data obtained by the forward measurement and the reverse measurement. Can be obtained.

  In step S106, the analysis processing unit 73 performs coordinate conversion of the plurality of cross sections measured in step S101 using equation (2) according to the rotation angle of the rotary stage when each is measured.

  At this time, in the equation (2), the rotation center is corrected using the rotation center Xc of the rotary stage 2 with respect to the measurement origin of the probe 38 calculated in step S105. By this correction, the three-dimensional surface shape of the workpiece can be calculated more accurately.

  As described above, the coordinate conversion is performed by correcting the position of the origin of the probe 38 and the position of the rotation axis of the rotary stage 2 simply by adding a reversal measurement process to the conventional cross-sectional measurement process in a plurality of directions. The three-dimensional surface shape can be acquired correctly.

  Further, it is possible to omit a complicated adjustment process in which the measurement origin of the probe 38 exactly matches the rotation axis of the rotary stage 2.

  Note that the three-dimensional surface shape acquired in step S106 is differentially offset after setting the center axis of the workpiece and the rotation axis of the rotary stage 2.

  When the surface shape error is evaluated by the analysis processing unit 73, the user may use the measurement data for a desired application by using a known method of performing residual calculation after fitting to the surface shape.

  In the above description, Xc is calculated from a pair of forward measurement data and inverted measurement data. However, an average value is obtained from Xc1, Xc2,... Of course, more accurate Xc may be calculated.

  Of course, a configuration may be adopted in which a control program according to the above-described shape measuring method is stored in the control unit in advance, and the control unit of the shape measuring machine is executed and automatically controlled. You may record on the computer-readable recording medium in which such a program was stored.

  According to the above method, when measuring the shape, the positional relationship between the origin of the probe and the rotation axis can be calculated by simply measuring one inverted section in addition to the conventional process of measuring the section in a plurality of directions. Can do. Then, each cross section measured in a plurality of directions can be corrected based on the calculated positional relationship between the origin of the probe and the rotation axis, and coordinate-converted into a three-dimensional surface shape. Therefore, it is possible to acquire an axisymmetric aspherical shape without accurately positioning the probe on the rotation axis and without significantly increasing the measurement time.

DESCRIPTION OF SYMBOLS 1 Reference base 2 Rotation stage 9 Employment side installation reference 10 Employment side installation reference 15 X guide fixed part 16 X guide movable part 20 X Laser scale head 38 Probe 41 Work 51 Origin of apparatus coordinate system 52 Origin of work coordinate system

Claims (7)

Using a shape measuring device with a probe that can scan in one direction and a rotary table,
In the shape measuring method for measuring the shape of the workpiece by scanning the surface of the workpiece with the probe and measuring the position of the probe,
Setting the workpiece on the rotary table;
Obtaining measurement data respectively at different rotation angles of the rotary table;
Obtaining inverted measurement data of the workpiece in a state rotated by 180 ° with respect to a rotation angle corresponding to at least one forward measurement data among the measurement data;
Calculating a rotation center Xc of the rotary table from the forward direction measurement data and the reverse measurement data;
After correcting the measurement data based on the data of the rotation center Xc, coordinate conversion is performed to calculate the shape of the surface of the workpiece,
The rotation center Xc is based on the movement amount x ₁ and x ₂ produced upon fitting each said inverted measurement data and the forward measurement data to the design shape data of the workpiece, characterized in that calculated according to the following general formula 1 The shape measurement method.

  The shape measuring method according to claim 1, wherein the workpiece has an axisymmetric shape. When the measurement data is Xp and the rotation angle θc of the rotary stage is XY coordinates in the work coordinate system, Xw and Yw are used, the shape data of the work in the work coordinate system is calculated based on the following general formula 2. The shape measuring method according to claim 1 or 2.

  The program which makes each control process of any one of Claims 1 thru | or 3 perform a control part of a shape measuring apparatus.   A computer-readable recording medium in which the program according to claim 4 is stored. A shape measuring device comprising a probe capable of scanning in one direction and a rotary table, and scanning the surface of the workpiece with the probe and measuring the shape of the workpiece by measuring the position of the probe,
Measuring means for obtaining measurement data by measuring the workpiece set on the rotary table at different rotation angles of the rotary table;
The rotation center Xc of the rotary table from one forward measurement data measured by the measuring means and inverted measurement data which is measurement data rotated by 180 ° with respect to the rotation angle corresponding to the forward data. Calculating means for calculating
Correcting means for correcting the measurement data based on the data of the rotation center Xc and then converting the coordinates to calculate the shape of the surface of the workpiece;
The rotation center Xc is based on the movement amount x ₁ and x ₂ produced upon fitting each said inverted measurement data and the forward measurement data to the design shape data of the workpiece, characterized in that calculated according to the following general formula 1 A shape measuring device.

When the measurement data is Xp and the rotation angle θc of the rotary stage is XY coordinates in the work coordinate system, Xw and Yw are used, the shape data of the work in the work coordinate system is calculated based on the following general formula 2. The shape measuring apparatus according to claim 6.

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