JP6599137B2 - Plane shape measuring apparatus and plane shape calculating system - Google Patents

Description

  The present invention relates to a planar shape measuring apparatus and a planar shape calculating system.

  In recent years, a flatness measuring apparatus for measuring a relatively large planar shape such as a surface plate has been proposed. Patent Document 1 discloses a flatness measuring apparatus that forms a reference plane by scanning a laser beam by rotation of a pentaprism and measures the flatness of an object to be measured using the reference plane. Details of the flatness measuring apparatus disclosed in Patent Document 1 will be described with reference to FIGS.

  FIG. 7 is a schematic diagram showing a flatness measuring apparatus according to Patent Document 1. As shown in FIG. Laser light R emitted from the laser light source 11 passes through the half mirror 12. The laser beam R that has passed is reflected downward by the plane mirror 13, and the reflected light is incident on the pentaprism 14 (having the incident / exit surfaces 14A and 14B and the reflecting surfaces 14C and 14D). The pentaprism 14 is rotated by a turntable 15 around a light source in the vertical direction as a rotation axis. The turntable 15 includes an XY table 15A, a turntable 15B provided on the XY table 15A, and an adjustment screw 15C provided on the lower side of the XY table 15A. Thereby, a horizontal reference plane for measuring the surface 1A to be measured of the surface plate 1 is formed. The flatness measuring apparatus measures the flatness of the measurement target surface 1A by measuring the distance between each measurement point on the measurement target surface 1A and the reference plane.

  The above-described measurement of the distance between the measured surface 1A and the reference plane is realized by the following method. The corner cube 16 placed on the measured surface 1A inputs reflected light parallel to the incident light to the pentaprism 14. The corner cube 16 is mounted on a moving table 17 having a turntable 17A. At this time, when the corner cube 16 is displaced by ΔH in the vertical direction, the reflection position of the reflected light from the corner cube 16 is parallel to the vertical direction by 2ΔH from the reflection position of the reflected light when there is no displacement. It is displaced to. The details of the displacement of the reflected light are shown in FIG. The light receiving position detector 18 (for example, PSD (Position Sensitive Detector)) detects this displacement, and measures the distance between the reference plane and the measured surface 1A based on the detected displacement. Then, the measurer acquires the flatness of the measurement target surface 1A by sequentially moving the mounting position (that is, the measurement point) of the corner cube 16 along the optical axis and measuring.

JP-A-6-102030

  The flatness measuring apparatus according to Patent Document 1 described above scans the laser beam by rotating the pentaprism 14. In the flatness measuring device, the light receiving position detector 18 detects the displacement of the height of the emitted light and the incident light, thereby acquiring the flatness of the measured surface 1A. However, when the pentaprism 14 is rotated, a motion error of the turntable 15 may occur, which may cause the pentaprism 14 to fluctuate up and down. When the pentaprism 14 fluctuates up and down, the optical axis position of the light bent vertically (the height of the optical axis from the pentaprism 14 toward the corner cube 16) changes. For this reason, the light receiving position detector 18 acquires information including an error as information for calculating the planar shape of the measurement target surface 1A. Since the flatness of the surface to be measured 1A is calculated based on information including an error, there is a problem that it is difficult to measure the flatness with high accuracy.

  One aspect of the planar shape measuring apparatus according to the first aspect of the present invention is an angle measuring device that emits a first light beam and measures an angle between the first light beam and the second light beam, and the first light beam. A first pentaprism that emits a third light beam reflected at a right angle, and a fourth light beam that is movable in the optical axis direction of the third light beam in the previous period and reflects the third light beam at a right angle, is covered by the object to be measured. A second pentaprism that emits a fifth light beam that is emitted to a measurement surface and reflected light from the measurement surface is reflected at right angles to the direction of the first pentaprism. The second light beam is emitted by reflecting the fifth light beam at a right angle to the direction of the angle measuring device.

  One aspect of the planar shape measuring apparatus according to the second aspect of the present invention is the planar shape measuring apparatus, wherein the angle measuring device is an autocollimator, and the autocollimator is capable of performing multi-axis measurement. It is characterized by this.

  One aspect of the planar shape measuring apparatus according to the third aspect of the present invention is characterized in that in the planar shape measuring apparatus, the first pentaprism is rotatable about the first light beam as a rotation axis. It is.

  One aspect of the planar shape measuring apparatus according to the fourth aspect of the present invention is the planar shape measuring apparatus, wherein the angle measuring device is physically separated from the first pentaprism and fixed to a fixed surface. It is characterized by being.

  A planar shape calculation system according to a fifth aspect of the present invention is a planar shape calculation system including the above-described planar shape measurement device and a planar shape calculation device, and the planar shape measurement device includes a plurality of measurements. A first data group obtained by measuring an angle between the first light beam and the second light beam at each point where the second pentaprism is moved is obtained on each measurement line of the first measurement line group composed of lines. The first measurement is performed, and the angle of the first light beam and the second light beam at each point where the second pentaprism is moved on one or more measurement lines set to intersect with the first measurement line. The planar shape calculation apparatus performs a second measurement to acquire the measured second data group, the coordinate system setting unit that sets a coordinate system used for defining the planar shape of the surface to be measured, and the first data group Based on the first measurement Based on the first measurement shape formula calculation unit for obtaining the shape formula indicating the shape of each measurement line in the coordinate system and the second data group, the shape of each measurement line in the coordinate system in the second measurement A shape equation calculated by the first measurement shape equation calculating unit with respect to a definition equation of the planar shape of the surface to be measured using a basis function, a shape equation calculated by the first measurement shape equation calculating unit, A measurement surface shape calculation unit that calculates the shape of the surface to be measured by substituting and solving the shape equation calculated by the two measurement shape equation calculation unit.

  The planar shape calculation system according to the sixth aspect of the present invention is characterized in that the second measurement is performed on a plurality of measurement lines intersecting with the first measurement line.

  The present invention can provide a planar shape measuring apparatus that can realize highly accurate flatness measurement.

1 is a conceptual diagram illustrating a configuration of a planar shape measuring apparatus 100 according to a first embodiment. It is a conceptual diagram which shows angle (theta) between the light ray F1 and the light ray F2. It is a conceptual diagram which shows the calculation method of the measurement line shape of the planar shape measuring apparatus 100 concerning Embodiment 1. FIG. It is a figure which shows the measurement (1st measurement, 2nd measurement) of the planar shape measuring apparatus 100 concerning Embodiment 1. FIG. 1 is a block diagram showing a configuration of a planar shape calculation apparatus 300 according to a first embodiment. It is a figure which shows the measurement (1st measurement) of the planar shape measuring apparatus 100 concerning Embodiment 1. FIG. It is a figure which shows the measurement (2nd measurement) of the planar shape measuring apparatus 100 concerning Embodiment 1. FIG. It is the schematic which shows the flatness measuring apparatus concerning patent document 1. FIG. It is a conceptual diagram which shows the displacement of the reflected light at the time of using the flatness measuring apparatus concerning patent document 1. FIG.

<Embodiment 1>
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram showing a configuration of a planar shape measuring apparatus 100 according to the present embodiment. The planar shape measuring apparatus 100 includes an autocollimator 101, a first pentaprism 102, a second pentaprism 103, and a pentaprism rotating table 104. The object to be measured by the planar shape measuring apparatus 100 is the device under test 200. The DUT 200 has a DUT 200A on the surface. First, an outline of the operation of each component of the planar shape measuring apparatus 100 will be described along the incident order of light rays.

  The autocollimator 101 operates as a flatness measurement system. The autocollimator 101 also operates as a light source and emits a light beam F1 (first light beam). The light ray F1 is substantially parallel to the normal line of the measurement target surface 200A. The autocollimator 101 measures an angle θ between the light beam F1 and a light beam B1 (second light beam) described later.

  The first pentaprism 102 emits a light beam F2 (third light beam) obtained by reflecting the light beam F1 at a right angle. By being reflected at a right angle, the light beam F2 becomes a light beam substantially parallel to the surface on which the DUT 200 is placed. The pentaprism turntable 104 is configured to rotate about the light beam F1 as a rotation axis. As the pentaprism turntable 104 rotates, the first pentaprism 102 can emit the light beam F2 radially. That is, the planar shape measuring apparatus 100 can scan the light beam F2 radially with the light beam F1 as the center. Here, the radially scanned light beam F2 is always perpendicular to the optical axis of the light beam F1 due to the optical characteristics of the pentaprism.

  The second pentagonal prism 103 emits a light beam F3 (fourth light beam) reflected from the light beam F2 at a right angle to the surface to be measured 200A. The light beam F3 is reflected by the measurement target surface 200A. The light beam B 3 reflected by the light beam F 3 is incident on the second pentaprism 103.

  The second pentaprism 103 emits a light beam B2 (fifth light beam) obtained by reflecting the light beam B3 at a right angle toward the first pentaprism 102. The first pentaprism 102 emits a light beam B1 obtained by reflecting the light beam B2 at a right angle toward the autocollimator 101. The light beam B1 enters the autocollimator 101. The autocollimator 101 measures the angle θ between the light beam F1 and the light beam F2. Details of the measurement of the angle θ will be described with reference to FIG.

  FIG. 2 is a conceptual diagram showing the relationship between the inclination of the measured surface 200A and the angle θ. When the measurement point of the measurement target surface 200A is deviated from the parallel plane by an angle α, the light ray B3 is reflected by being shifted by an angle θ corresponding to the light rays F3 and 2α. The light beam B3 reflected from the surface to be measured 200A is reflected twice at a right angle and enters the autocollimator 101. That is, a light beam shifted by an angle θ is incident on the autocollimator 101. The autocollimator 101 measures this angle θ.

  Refer to FIG. 1 again. The measurer scans the second pentaprism along the optical axis of the light beam F2 while the first pentaprism 102 is stopped (the pentaprism 1 turntable 104 is fixed without being rotated). That is, the measurer moves the second pentaprism 103 along the optical axis of the light beam F2 while the first pentaprism 102 is stopped (fixed). The autocollimator 101 measures the angle θ for each measurement point. The shape of this measurement line (that is, the direction of the optical axis of the light beam F2) can be calculated by integrating the angle θ with respect to the scanning distance r. The concept of calculating the shape of the measurement line will be described with reference to FIG.

  As shown in FIG. 3, the second pentagonal prism 103 is moved along the optical axis of the light beam F2. The autocollimator 101 measures the angle θ at each measurement point. Then, by performing integration using the scanning distance r and the angle θ of each measurement point, the calculated shape 200B in the measurement line (the direction of the optical axis of the light beam F2) is calculated.

After completing the measurement of a certain measurement line, the measurer performs the measurement of a new measurement line (measurement of the angle θ at each point) by the same method. That is, the measurer operates the pentaprism turntable 104 to rotate the first pentaprism 102 by an appropriate angle and performs the same measurement. By repeating this measurement, the planar shape measuring apparatus 100 performs measurement over the entire surface to be measured 200A. FIG. 4 is a diagram showing a measurement concept using the planar shape measuring apparatus 100. In FIG. 4, reference signs A, B, C, and D are attached to the four corners of the measured surface 200 </ b> A in the counterclockwise direction from the upper left.

As shown in the first measurement in FIG. 4, the measurement over the entire surface to be measured 200 </ b> A is performed by repeatedly performing the measurement a plurality of times at the same point. By performing measurement over the entire surface, a planar shape (calculated shape 200B in FIG. 3) on each measurement line that spreads radially around the rotation axis of the first pentaprism 102 can be calculated.

  However, the height of the shape of each measurement line calculated based on the first measurement is indefinite. Therefore, the shape of each measurement line calculated based on the first measurement cannot be directly used as the planar shape of the measurement target surface 200A. In order to solve the problem that the height is indefinite, the measurer performs measurement at a plurality of points. That is, as shown in the second measurement in FIG. 4, the measurer moves the position of the planar shape measuring apparatus 100 and performs measurement again. This second measurement is performed with the light beam direction determined so as to intersect with each measurement line measured radially in the first measurement. And the height of the measured value of each measurement line is adjusted, and each measured value is matched so that the shape measured radially in the 1st measurement and the 2nd measurement may intersect. By this matching process, the planar shape of the measurement target surface 200A is calculated. Details of the matching method will be described later.

  Note that the autocollimator 101 is preferably capable of biaxial measurement. That is, it is desirable that the autocollimator 101 can calculate the angle between the light beam F1 and the light beam B1 with respect to the first axis direction, and can calculate the angle between the light beam F1 and the light beam B1 with respect to the second axis direction. This is because the measurement sensitivity direction changes due to the rotation of the first pentaprism 102, and it is necessary to detect only the component (angle) in the axial direction that coincides with the scanning direction of the second pentaprism 103.

  If the autocollimator 101 can perform only one-axis measurement, the measurement direction of the autocollimator 101 changes due to the rotation of the first pentaprism 102. For this reason, it is necessary to calculate the shape of the measurement target surface 200A in consideration of the change in measurement sensitivity accompanying the change in the measurement direction. Further, it is not preferable to rotate the autocollimator 101 in synchronization with the first pentaprism 102 because the reference light beam F1 fluctuates. Therefore, as described above, it is desirable that the autocollimator 101 can perform biaxial measurement. That is, the autocollimator 101 outputs only the component (angle) in the axial direction that coincides with the scanning direction of the second pentaprism 103 among the measured components (angles) related to the two axes as the measurement result.

  Of course, the autocollimator 101 may be capable of not only 2-axis measurement but also 3-axis measurement. That is, it is desirable that the autocollimator 101 has a configuration capable of performing multi-axis measurement.

  It is desirable that the autocollimator 101 and the first pentaprism 102 are physically separated as shown in the figure, and the autocollimator 101 is configured to be fixed to a fixed surface such as a wall surface, the ground, or the ceiling. In other words, it is desirable that the autocollimator 101 is not physically connected to the first pentaprism 102 and is fixed so that the installation position does not change. Thus, even when the first pentaprism 102 rotates, the emission direction of the light beam F1 emitted from the autocollimator 101 is fixed, and accurate measurement can be performed.

  Next, a method for matching each measurement value measured in the first measurement and the second measurement (FIG. 4) will be described in detail. To outline this matching method, the height at which the intersections of the measurement lines are indefinite is calculated using the property that the heights are equal.

  First, a coordinate system for displaying the shape of the measurement target surface 200A is set. Specifically, the xy plane is determined so as to coincide with the least mean square plane of the measured surface 200A, the z-axis is defined in the upward direction of the measured surface 200A, and the center of gravity of the measured surface 200A is defined as the origin. Is done. The x-axis and y-axis directions are set to arbitrary directions.

The shape of the surface to be measured 200A is treated as a difference from the xy plane, and the shape of the surface to be measured 200A is expressed as the following equation (1) using the following function f (x, y).

If the i (i = 1 to n) th measurement line of the first measurement is defined as l _i, the shape measurement line l _i is represented as the following equation (2). However, [x, y] is defined as a point on l _i .

The relationship between the shape z = f (x, y) of the measurement target surface 200A and the measurement value z = g ₁ (x _li , y _li ) of the first measurement is defined as the following equation (3).

U _l × x _li + v _l × y _li + w _{li which} is the second term to the fourth term on the right side represents the slope and height of the measurement value on the measurement line l _l . The slope components u _l and v _l do not change even if the measurement line changes. However, the height w _li varies from measurement line to measurement line.

If the j (j = 1 to m) th measurement lines of the second measurement is defined as s _j, the shape measurement line s _j can be expressed as the following equation (4). However, [x, y] is defined as a point on s _j .

The relationship between the shape z = f (x, y) of the measured surface 200A and the measured value z = g ₂ (x _sj , y _sj ) of the second measurement is defined as the following equation (5).

U _s × x _sj + v _s × y _sj + w _{sj which} is the second term to the fourth term on the right side represents the inclination and height on the measurement line S _j . The slope components u _s and v _s do not change even if the measurement line changes. However, the height w _sj varies from measurement line to measurement line.

The shape of the measurement target surface 200A is represented by a function f (x, y) shown in the following formula (6).

In equation (6), B _k (x, y) represents a basis function, and a _k represents a coefficient. By redefining the above equations (4) and (5) using this equation (6), it can be expressed as the following equation (7).

The unknowns a, u _l , v _l , w _l , u _s, by solving the simultaneous equations by adding the following condition (equation (8)) where the least mean square plane is 0 to this equation (7) v _s and w _s are calculated, and the following f (x, y), which is the shape of the measured surface 200A, is calculated.
f (x, y) = B (x, y) × a

  An apparatus configuration for performing the above-described calculation processing is shown in FIG. The planar shape calculation device 300 is a computer device incorporating a CPU (Central Processing Unit), a hard disk, and the like, for example. The planar shape calculation device 300 is used together with the planar shape measurement device 100. That is, the planar shape calculation device 300 and the planar shape measurement device 100 constitute one system (planar shape calculation system).

  The planar shape calculation apparatus 300 includes a CPU (Central Processing Unit) 310, a coordinate system setting unit 320, a first measurement shape formula calculation unit 330, a second measurement shape formula calculation unit 340, and a measured surface shape calculation unit 350. In addition, the planar shape calculation apparatus 300 appropriately includes various storage devices (memory, hard disk, etc.) not shown.

  The planar shape calculation device 300 is connected to the output device 400. The output device 400 is, for example, a general display device or a printer. The output device 400 may be in a form integrated with the planar shape calculation apparatus 300 (for example, a form in which a display device and an arithmetic device are integrated like a notebook computer).

  The CPU 310 is a calculation unit that performs various calculations of the planar shape calculation apparatus 300. The coordinate system setting unit 320, the first measurement shape formula calculation unit 330, the second measurement shape formula calculation unit 340, and the measured surface shape calculation unit 350 are controlled by the CPU 310. That is, the coordinate system setting unit 320, the first measurement shape formula calculation unit 330, the second measurement shape formula calculation unit 340, and the measured surface shape calculation unit 350 are realized as programs that operate in the computer. The CPU 310 executes various programs.

  The program can be stored and supplied to a computer using various types of non-transitory computer readable media. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (for example, flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (for example, magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / W and semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (random access memory)) are included. The program may also be supplied to the computer by various types of transitory computer readable media. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

  The coordinate system setting unit 320 determines the xy plane so as to coincide with the least mean square plane of the measurement target surface 200A, and defines the direction perpendicular to the placement direction of the measurement target surface 200A (that is, the upward direction) as the z direction. To do. The coordinate system setting unit 320 sets the center of gravity of the DUT 200 as the origin. Thus, the coordinate system setting unit 320 sets a coordinate system for representing the planar shape of the measurement target surface 200A. Note that the coordinate system setting unit 320 does not necessarily need to have the center of gravity of the DUT 200 as the origin, and may take any point as the origin.

  The first measurement shape formula calculation unit 330 reads a data group (first data group) of each measurement line on the measurement target surface 200A measured by the planar shape measurement apparatus 100 at the first position (first measurement in FIG. 4). . The first measurement shape formula calculation unit 330 defines the above-described formulas (2) and (3) concerning each measurement line of the first measurement using these data.

  The second measurement shape formula calculation unit 340 reads a data group (second data group) of each measurement line on the measurement target surface 200A measured by the planar shape measurement apparatus 100 at the second position (second measurement in FIG. 4). . The second measurement shape formula calculation unit 340 defines the above formulas (4) and (5) for each measurement line of the second measurement using these data.

  The measured surface shape calculation unit 350 defines the shape of the measured surface 200A using the above formulas (1) and (6). The to-be-measured surface shape calculation unit 350 defines an equation (7) obtained by substituting the above equation (6) for the equation (4) of each measurement line defined by the first measurement shape equation calculation unit 330. Similarly, the to-be-measured surface shape calculation unit 350 defines the equation (7) obtained by substituting the above equation (6) for the equation (5) of each measurement line defined by the second measurement shape equation calculation unit 340.

  The measured surface shape calculation unit 350 calculates an unknown by solving a simultaneous equation obtained by adding a condition that the least mean square is 0 to the calculated equation (7) (that is, the equation (8)) to calculate the unknown surface. The shape of 200A is calculated. The measured surface shape calculation unit 350 outputs the calculated shape of the measured surface 200A to the output device 400 in an arbitrary format (for example, a drawing that graphically represents the calculated shape).

  The planar shape calculation system including the above-described planar shape measuring apparatus 100 and the planar shape calculating apparatus 300 includes data (first data group) measured by the planar shape measuring apparatus 100 in the first measurement and data measured in the second measurement ( The second data group) is input to the planar shape calculation device 300 to calculate the shape of the measurement target surface 200A.

  Note that the measurer may perform the first measurement and the second measurement described above by fixing the mounting position of the planar shape measuring apparatus 100 and rotating the DUT 200. 6A and 6B are conceptual diagrams of the measurement method. In FIG. 6A, as in FIG. 4B, reference signs A, B, C, and D are attached to the four corners of the measured surface 200 </ b> A in the counterclockwise direction from the upper left. 6A and 6B, the second measurement is performed by fixing the position of the first pentaprism 102 and moving the object 200 to be measured. FIG. 6B shows a case where the measured surface 200A is rotated 90 ° counterclockwise as compared to FIG. 6A. Even in this case, the mounting position of the DUT 200 is adjusted so that the measurement line for the first measurement and the measurement line for the second measurement intersect.

  The measurer does not need to measure a plurality of measurement lines in the second measurement, and may perform the measurement in at least one measurement line. This is because the second measurement is for adjusting the height, and a plurality of measurement lines are not necessarily required in the second measurement. However, by performing measurement in a plurality of measurement lines in the second measurement, the planar shape of the measurement target surface 200A calculated from more data can be obtained. That is, by performing measurement in a plurality of measurement lines in the second measurement, the planar shape of the measurement target surface 200A can be calculated with higher accuracy.

  Next, effects of the planar shape calculation system (planar shape measuring apparatus 100 and planar shape calculating apparatus 300) according to the present embodiment will be described. The planar shape measuring apparatus 100 measures the angle θ between the light beam F1 (first light beam) and the light beam B1 (second light beam) as described above. Specifically, the planar shape measuring apparatus 100 detects the angle θ that is not affected by the vertical movement caused by the rotation of the pentaprism rotating table 104. That is, the planar shape measuring apparatus 100 can measure accurate data (angle θ) that is not affected by vertical movement.

  The planar shape calculation apparatus 300 calculates the shape of the measurement target surface 200A from information (first data group, second data group) based on the angle θ. Accordingly, the planar shape calculation system can accurately calculate the shape of the measurement target surface 200 </ b> A without being affected by the rotation operation of the pentaprism rotating table 104.

  The planar shape calculation apparatus 300 performs the first measurement and the second measurement (FIG. 4), and the shape of the measurement target surface 200A is determined based on the two measurement data (first measurement data group and second measurement data group). calculate. The planar shape calculation apparatus 300 can calculate the shape of the measurement target surface 200 </ b> A in consideration of the height by solving the indeterminate height by the above-described calculation process.

  The planar shape measuring apparatus 100 according to the present embodiment uses an autocollimator 101 as a measurement system. In the description of Patent Document 1, PSD is used as a measurement system. When PSD is used, the resolution is about 0.1 μm, and there is a problem that it is difficult to measure with higher accuracy than this resolution. Further, when the transmission distance of the light beam becomes long, the light beam spreads due to the influence of diffraction. In this case, it becomes difficult to perform highly accurate measurement with a position detection element such as PSD. On the other hand, the autocollimator 101 is used like the planar shape measuring apparatus 100 according to the present embodiment. Since the autocollimator 101 has a high detection accuracy and is configured to perform angle measurement instead of position measurement, high-accuracy measurement that solves the above-described problems can be performed.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments. However, the present invention is not limited to the embodiments already described, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

DESCRIPTION OF SYMBOLS 100 Planar shape measuring apparatus 101 Autocollimator 102 1st pentaprism 103 2nd pentaprism 104 Penta prism turntable 200 Measured object 200A Measured surface 300 Planar shape calculation apparatus 310 CPU
320 Coordinate system setting unit 330 First measurement shape formula calculation unit 340 Second measurement shape formula calculation unit 350 Surface to be measured shape calculation unit 400 Output device

Claims (4)

An angle measuring device that emits a first light beam and measures an angle between the first light beam and the second light beam;
A first pentagonal prism that emits a third light beam reflecting the first light beam at a right angle;
The fourth light beam, which is movable in the optical axis direction of the third light beam, is reflected by the third light beam at a right angle, is emitted to the surface to be measured of the object to be measured, and the reflected light from the surface to be measured is the first light beam. A second pentaprism that emits a fifth light beam reflected at right angles to the direction of the one pentaprism,
The first penta prism, said second light beam emitted by reflecting at a right angle to the fifth light beam in the direction of the goniometer,
The first pentaprism is rotatable about the first light beam as a rotation axis,
The second pentaprism is rotatable around the first light beam in conjunction with the first pentaprism,
The planar shape measuring apparatus , wherein the angle measuring device is physically separated from the first pentaprism and fixed to a fixed surface . The angle measuring device is an autocollimator,
The planar shape measuring apparatus according to claim 1, wherein the autocollimator is configured to perform multi-axis measurement. A planar shape calculation system comprising: the planar shape measuring device according to claim 1 or 2 ; and a planar shape calculating device.
The planar shape measuring apparatus is configured to measure the first ray and the second ray at each point where the second pentaprism is moved on each measurement line of a first measurement line group including a plurality of measurement lines. Performing a first measurement to obtain a first data group measuring the angle;
Measure the angles of the first ray and the second ray at each point where the second pentaprism is moved on one or more measurement lines set to intersect with each measurement line of the first measurement line group. The second measurement to obtain the second data group,
The planar shape calculation device
A coordinate system setting unit for setting a coordinate system used for defining the planar shape of the surface to be measured;
Based on the first data group, a first measurement shape formula calculation unit for obtaining a shape formula indicating the shape in the coordinate system of each measurement line in the first measurement;
Based on the second data group, a second measurement shape formula calculation unit for obtaining a shape formula indicating the shape in the coordinate system of each measurement line in the second measurement;
Substituting the shape equation calculated by the first measurement shape equation calculation unit and the shape equation calculated by the second measurement shape equation calculation unit into the definition equation of the planar shape of the surface to be measured using the basis function A measurement surface shape calculation unit for calculating the shape of the measurement surface by solving
A plane shape calculation system comprising: The planar shape calculation system according to claim 3 , wherein the second measurement is performed on a plurality of measurement lines that intersect with each measurement line of the first measurement line group .

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