JP3272952B2 - 3D shape measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional shape measuring apparatus for accurately measuring a curved surface shape such as a lens or a mirror, for example, with an error of 1 micrometer or less.

[0002]

2. Description of the Related Art A contact type three-dimensional shape measuring apparatus has conventionally been
For example, literature SPIE, Vol 733 (1986), pa
Ge149 to 155. FIG. 20 shows the structure. In FIG. 20, 3
The three-dimensional shape measuring apparatus includes a vibration isolation table 108, a bed 107 placed on the vibration isolation table 108, an XY slide 104 movably arranged on the bed 107 in the XY directions, and an XY
A column 103 fixed on a slide 104, and a Z slide 10 arranged on the column 103 so as to be movable in the Z direction.
2, an arm 114 fixed to the Z slide 102,
A probe head 112 supported by the tip of an arm 114 and having a probe (a stylus) oriented in the lateral direction (X-axis direction), a base platen 110 fixed on a bed 107, and arranged on the base platen 110 And three reference mirrors. The XY slide 104 is driven in XY directions by capstan drives 105 and 106 arranged on a bed 107. The Z slide 102 is driven by the tape drive 101 along the column 103 in the Z direction. Two of the three reference mirrors on the base platen 110 are arranged upright, and the other one is fixed on the base platen 110 with the mirror surface facing upward. The position of the probe head 112 is calculated by measuring the distance between the three reference mirrors and the five positions on the probe head by the provided five-axis optical interferometer.

In the three-dimensional shape measuring apparatus configured as described above, an object to be measured is fixed on a base platen 110,
By pressing the probe head 112 against the surface and measuring the coordinates with a 5-axis interferometer, the probe position is not affected by the position and attitude errors accompanying the movement of the probe head 112, in other words, the probe position is not affected by the Abbe error. A measurement can be made.

[0004]

However, in the above-mentioned conventional example, the base platen 11 is not fixed due to the following factors.
0 and the bed 107 are deformed, and the relative positions of the three reference mirrors 113 supported thereby change. In addition, there is a problem that the coordinate position of the probe that measures the reference mirror as a position reference also changes, and the change in the position eventually results in a measurement error. (1) The base 110 or the bed 10 depends on the weight of the object to be measured.
7 is deformed.

[0005] Due to this deformation, the relative positions of the three reference mirrors 113 change. Further, since the deviation of the relative position changes depending on the weight of the measured object, a different measurement error is given depending on the measured object. (2) The deformation state of the base platen 110 or the bed 107 changes with the movement of the XY slide 104 or the Z slide 102.

Due to this deformation, the relative positions of the three reference mirrors 113 change. Since the relative position changes depending on the positions of the XY slide 104 and the Z slide 102, different measurement errors are given depending on the shape of the measured object. (3) The reference mirror itself is deformed by its own weight.

Since the measurement error due to this deformation is constant regardless of the position of the slide and the weight of the object to be measured, it can be corrected by previously obtaining and storing the deformation. For example, since the correction amount in the Z direction changes at the positions in the X direction and the Y direction, a function of the correction amount δZ = f (x, y) is measured and obtained at an appropriate division point and interpolated. However, this method is prone to errors when measuring f (x, y).
For example, when calibrating using an interferometer, the conditions for mounting the object to be measured are not free, and the correction amount must be measured in a state where the object to be measured is mounted under conditions different from the actual measurement. Therefore, a measurement error occurs due to a difference in mounting conditions. In addition, an error at the time of interpolation is added. (4) The base platen 110 and the bed 107 are deformed due to a change in environmental temperature.

[0008] Due to this deformation, the relative positions of the three reference mirrors 113 change. Further, since the deviation of the relative position changes in accordance with the environmental temperature, a measurement error that changes with the measurement date and time and has no reproducibility is given.

[0009] In addition to the occurrence of measurement errors due to the deformation of each member as described above, there are the following problems. (5) Since the Z-axis is not oriented in the direction of displacement of the probe, the ability of the probe to follow the surface of the workpiece is poor.

When continuously tracing (scanning) the surface of the object to be measured while maintaining the contact state of the probe, the probe needs to move quickly according to the surface shape of the object to be measured. Particularly quick movement is required in the axial direction (the X-axis direction in FIG. 20) in which the pressing force against the object acts.
However, in the above-described conventional example, the XY slide 104 that moves in the X direction has the structure such as the column 103, the Z slide 102, and the measurement arm 114 placed thereon, so that the volume and the weight increase, and accordingly, The natural frequency (resonance point) is low and high-speed position control is difficult. Therefore, the speed at which the probe is scanned must be reduced, and the measurement takes time.

Further, since the Z slide 102 is driven through a member having low rigidity such as a tape, the response in the Z axis direction is poor. This also causes a reduction in the scanning speed of the probe, which in turn causes a longer measurement time. If the measurement takes a long time, the shape of the object to be measured and the components of the device change due to the temperature change during the measurement, and the measurement accuracy deteriorates. Conversely, if the scanning speed of the probe is increased, the ability of the probe to follow the surface of the workpiece is deteriorated, and in an apparatus in which the position of the probe is used as the shape of the surface of the workpiece, measurement accuracy is deteriorated. (6) The pressing force of the probe against the object to be measured changes.

As described in (5) above, the probe X
Since the response in the axial direction is poor, in the case of a contact probe using a spring, the pressing force changes. When the pressing force changes, the shape of the object to be measured and the shape of the probe itself also change with the change, so that the measurement accuracy deteriorates. (7) Since the mirror surface of the reference mirror in the Z direction faces upward, dust and the like are likely to adhere.

When the reference mirror faces upward, minute dust tends to accumulate on the reference mirror, and the quality of the reference mirror rapidly deteriorates. Therefore, in a device using the reference mirror as a reference for position measurement, the measurement accuracy deteriorates. In addition, there is a possibility that the mirror surface may be damaged due to dropping of the article or the like.

FIG. 21 shows another conventional stylus-type shape measuring device.

The apparatus shown in FIG. 21 differs from the above-described apparatus in that the height of the surface of the object to be measured in the Z direction is measured by measuring the position of the stylus in the Z axis direction. FIG.
1, a holder 205 supporting the stylus 203
Are supported by the linear motion guides 209 and 210 so as to be movable only in the Z-axis direction. The stylus 203 having the true sphere 202 attached to the distal end has parallel leaf springs 204a to 204a.
It is supported by the holder 205 via 4d so as to be movable only in the Z direction. The linear motors 208 and 210 are arranged to apply a thrust to the holder 205 in the Z-axis direction. The brake mechanism including the cylinder 501 and the brake pad 503 stops the movement of the holder 205 in the Z-axis direction by pressing the brake pad 503 against the holder 205 with the force generated by the cylinder 501.

The non-contact displacement meter 206 is a detection mechanism for detecting the displacement of the parallel leaf springs 204a to 204d by measuring the relative position between the holder 205 and the stylus 203. The pressure control calculation unit 217 includes the known parallel leaf spring 204.
a to-be-measured object 201 from the spring coefficients and
The pressing pressure (contact pressure) of the stylus 203 with respect to is calculated. Then, the linear motors 208 and 211 are driven so that this value becomes a set value, and the holder 205 is moved up and down on the Z axis to control the amount of deformation of the parallel leaf springs 204a to 204d. By controlling the amount of deformation of the parallel leaf springs 204a to 204d while the tip of the stylus 203 is in contact with the object 201, the contact pressure of the stylus 203 with the object 201 is controlled.

In a shape measuring apparatus having such a measuring section on the Z axis as shown in FIG. 21, in order to measure the surface shape of the object 201 at high speed, different points on the surface of the object 201 need to be measured. It is necessary to move the stylus 203 quickly. In this case, if the stylus 203 is once separated from the DUT 201 and is to be brought into contact again at the measurement point after the movement, it is necessary to bring the stylus 203 into contact with the DUT 201 without shock when re-contacting. However, the control takes time and is not suitable for performing high-speed measurement. Therefore, usually, the stylus 203 and the object 201 are relatively moved in the XY directions while the stylus 203 is in contact with the object 201 at a constant pressure, and the measurement is performed.

As described above, the stylus 203 is moved to the object 20 to be measured.
When performing shape measurement in a state where the probe is in contact with
3 may fall out of the range of the DUT 201 and fall. If the stylus 203 protrudes from the measured object 201 and falls, the stylus 203 or its moving mechanism may be damaged, which is a problem. To prevent this drop,
The measurement range in the X and Y directions of the DUT 201 may be input in advance to the control device. However, if this input is forgotten or the installation position of the DUT 201 on the measurement device is changed for some reason. There is a problem that it is not possible to cope with a deviation.

Further, in the above-described apparatus, when the height of the object 201 in the Z direction fluctuates greatly depending on the position in the XY directions, if the surface shape of the object 201 is to be measured at a high speed, The control of the displacement of the parallel leaf springs 204a to 204d requires high responsiveness.

However, when the contact pressure on the object to be measured 201 is controlled in a small state and scanning is performed at a high speed,
When the surface of the DUT 201 is rough, the stylus 203 may jump from the surface of the DUT 201. In particular, when dust adheres to the DUT 201 and enters between the stylus 203 and the DUT 201,
Jumps, and the relationship between the movement of the stylus 203 and the shape of the DUT 201 is lost, which may cause a failure in control such as a runaway of the holder 205 controlled by the pressure control. is there.

Normally, when the holder 205 runs away due to the stylus 203 moving away from the object 201, the pressure control is interrupted. However, if the control of the contact pressure is simply interrupted, the Z-axis holder 205 continues to move at the speed at which the control was interrupted. If the moving direction at this time is a direction in which the contact pressure is increased, the holder 20
5 presses the stylus 203 against the measured object 201 with an excessive force to scratch the measured object,
An accident such as plastic deformation of 04d occurs. Conventionally, in order to prevent such an accident, a method has been adopted in which the holder 205 is stopped at that position by a brake when control is interrupted.

However, the method for stopping the holder 205 with a mechanical brake together with the stop of the control has the following problems. (1) It is necessary to provide a brake mechanism for mechanically stopping the holder 205. However, since a brake mechanism capable of generating a force strong enough to stop the moving holder on the spot becomes large, this brake is used. Because it requires space for the mechanism and increases the weight,
It is difficult to reduce the size and weight of the Z axis. (2) In order to generate a strong force, a combination of a solenoid valve and a pneumatic cylinder is often used as a brake mechanism. However, such a mechanism has a slow response, and the mechanism before the holder completely stops. In such a case, the stylus may collide with the object to be measured, or may be damaged due to an increase in pressure. (3) When an error occurs in the Z-axis pressure control, the X-axis and the Y-axis also need to be stopped at the same time. However, when the X-axis and the Y-axis are moving at high speed, until these stops. It takes time. Therefore, if an error occurs while the stylus is located in a low part (valley) of the object to be measured, the stylus is moved by the XY axes even if only the Z axis is stopped immediately. Is pushed up by the peak of the object to be measured, and there is a possibility that damage may occur.

Therefore, the present invention has been made in view of the above-mentioned problems, and a first object of the present invention is to provide a measuring apparatus in which the deformation due to the weight, position change, temperature change, etc. of the constituent members affects the measurement accuracy. An object of the present invention is to provide a three-dimensional shape measuring device which is hard to give.

A second object of the present invention is to provide a three-dimensional shape measuring apparatus capable of improving the followability of a stage (a stylus) and performing more accurate measurement.

A third object of the present invention is to provide a three-dimensional shape measuring apparatus capable of eliminating a non-linear measurement error of the position of the stage and performing a more accurate measurement.

A fourth object of the present invention is to provide a three-dimensional shape measuring apparatus which can prevent the life of the reference mirror from being shortened.

A fifth object of the present invention is to provide a three-dimensional shape measuring apparatus capable of preventing a stylus from falling out of a range of an object to be measured.

A sixth object of the present invention is to provide a three-dimensional shape measuring apparatus which can prevent runaway of a stage for moving a stylus.

[0029]

In order to solve the above-mentioned problems and to achieve the object, a three-dimensional shape measuring apparatus according to the present invention provides a three-dimensional shape measuring device in which a stylus is brought into contact with a surface of an object fixed to a measuring table. A three-dimensional shape measuring apparatus for measuring the surface shape of the object to be measured by measuring the position of the stylus while moving the stylus along the surface of the object to be measured; A base for supporting a table, supporting means disposed between the base and the measurement table, for supporting the measurement table in a state where deformation of the base is difficult to be transmitted to the measurement table, and disposed on the base. And a stage for moving the stylus three-dimensionally, and a measuring means for measuring a three-dimensional position of the stage.

Further, in the three-dimensional shape measuring apparatus according to the present invention, the support means can not move the measuring table with respect to the base in the XYZ three directions orthogonal to each other at the first position on the base. A first support mechanism to be fixed; and a second position on the base separated by a predetermined distance in the Y direction from the first position to support the measurement table with respect to the base so as to be movable only in the Y direction. A second support mechanism and, at a third position on the base separated by a predetermined distance from the first position in the X and Y directions, respectively, the measurement table can be moved in the X and Y directions with respect to the base. And a third support mechanism for supporting.

In the three-dimensional shape measuring apparatus according to the present invention, the first support mechanism includes a substantially conical recess provided on each of the base and the measuring table, and A first spherical body to be inserted, wherein the second support mechanism is provided on each of the base and the measuring table, and has a substantially triangular prism-shaped recess extending in the Y direction; and the substantially triangular prism-shaped recess. And a third sphere inserted between the upper surface of the base and the lower surface of the measuring table. I have.

Further, in the three-dimensional shape measuring apparatus according to the present invention, the base and the measuring table are formed of a material having a small coefficient of thermal expansion.

In the three-dimensional shape measuring apparatus according to the present invention, a stylus is brought into contact with a surface of an object to be measured fixed to a measuring table, and the stylus is moved along the surface of the object to be measured. A three-dimensional shape measuring device for measuring the surface shape of the object to be measured by measuring the position of the stylus; and a stage for three-dimensionally moving the stylus; And a frame for supporting a mirror that constitutes a part of an optical system for measuring a three-dimensional position of the stage, and a frame disposed between the measurement table and the frame, the deformation of the measurement table. A first supporting means for supporting the frame in a state where it is difficult to transmit the frame to the frame.

Further, in the three-dimensional shape measuring apparatus according to the present invention, the first support means may move the frame in three directions of XYZ orthogonal to each other with respect to the measuring table at a first position on the measuring table. First to immovably fix
And a second mechanism for supporting the frame movably only in the Y direction with respect to the measurement table at a second position on the measurement table separated by a predetermined distance in the Y direction from the first position. A support mechanism and a third position on the measurement table separated by a predetermined distance from the first position in the X and Y directions, respectively, to support the frame movably in the X and Y directions with respect to the measurement table. And a third support mechanism.

Further, in the three-dimensional shape measuring apparatus according to the present invention, the first support mechanism is constituted by a first column for firmly fixing the measuring table and the frame in XYZ directions, and Is constituted by a second column which has an elongated cross section extending in the X direction and is easily deformable in the Y direction connecting the measuring table and the frame, and the third support mechanism has a narrow cross section. And a third column that connects the measuring table and the frame and that is easily deformed in the XY directions.

In the three-dimensional shape measuring apparatus according to the present invention, the first support mechanism includes a substantially conical recess provided on each of the measuring table and the frame, and A first spherical body to be inserted, wherein the second support mechanism comprises a substantially triangular prism-shaped recess provided in each of the measuring table and the frame and extending in the Y direction; and the substantially triangular prism-shaped recess. And a third sphere inserted between the upper surface of the measuring table and the lower surface of the frame. I have.

Further, in the three-dimensional shape measuring apparatus according to the present invention, the measuring table and the frame are formed of a material having a small coefficient of thermal expansion.

Further, in the three-dimensional shape measuring apparatus according to the present invention, the frame is provided with a second supporting means for holding the mirror in a state where the deformation due to its own weight is corrected.

Further, in the three-dimensional shape measuring apparatus according to the present invention, the second supporting means may be a three-dimensional shape measuring device.
The frame is provided with three abutting members arranged at three locations and abutting on the mirror, and tension springs arranged at at least three locations on the frame to draw the mirror so as to abut against the abutting member. .

Further, in the three-dimensional shape measuring apparatus according to the present invention, the three contact members are attached to the frame so as to adjust the amount of protrusion.

Further, in the three-dimensional shape measuring apparatus according to the present invention, the three contact members are disposed so as to be spaced apart from the first contact member in the longitudinal direction of the mirror from the first contact member. , Second and third contact members arranged in a direction substantially perpendicular to the longitudinal direction of the mirror,
The position along the longitudinal direction of the mirror between the contact member and the second and third contact members is a Vessel position where the amount of deformation of the mirror as a beam is minimized.

Further, in the three-dimensional shape measuring apparatus according to the present invention, the frame and the mirror are formed of a material having a small coefficient of thermal expansion.

In the three-dimensional shape measuring apparatus according to the present invention, a stylus is brought into contact with a surface of an object fixed to a measuring table, and the stylus is moved along the surface of the object. In a three-dimensional shape measuring apparatus for measuring a surface shape of the object to be measured by measuring a position of the stylus, a moving member supporting the stylus is three-dimensionally moved in XYZ directions orthogonal to each other. And a first measuring means for measuring a Z-axis direction distance Z1 from a Z-axis direction reference plane provided so as to be orthogonal to the Z-axis to a Z-axis direction reference point on the moving member. Second measuring means for measuring a distance X1 in the X-axis direction from an X-axis direction reference plane provided orthogonal to the X-axis to a first X-axis direction reference point on the moving member; A predetermined distance from the reference plane to the first X-axis direction reference point Only the X-axis direction distance X to the second X-axis direction reference point on the moving member spaced along the Z-axis direction
And a third measuring means for measuring the distance Y2, and measuring a Y-axis distance Y1 from a Y-axis reference plane provided orthogonal to the Y-axis to a first Y-axis reference point on the moving member. 4th
From the Y-axis direction reference plane and the first Y
The axial reference point is defined as a distance between the second Y-axis reference point on the moving member and the second reference point on the moving member separated by the predetermined distance along the Z-axis direction.
A fifth measuring means for measuring the axial distance Y2,
To the Z-axis distance Z output from the fifth to fifth measuring means.
1 and a calculating means for calculating the XYZ coordinates of the stylus from the X-axis distances X1, X2 and the Y-axis distances Y1, Y2.

In the three-dimensional shape measuring apparatus according to the present invention, a straight line parallel to the Z axis passing through the reference point in the Z axis direction and a straight line parallel to the X axis passing through the first reference point in the X axis direction. A straight line parallel to the Y-axis passing through the first reference point in the Y-axis direction intersects at one point, and a straight line parallel to the Z-axis passing through the reference point in the Z-axis direction and the second reference point in the X-axis direction. And a straight line parallel to the Y-axis passing through the second Y-axis direction reference point intersects at another point.

In the three-dimensional shape measuring apparatus according to the present invention, the stylus is elastically supported by the moving member via a spring, and a relative position of the stylus to the moving member is determined. It is characterized by further comprising a sixth measuring means for detecting.

Also, in the three-dimensional shape measuring apparatus according to the present invention, the first control means for controlling the moving means so that the position of the moving member becomes the target position, and the output of the sixth measuring means. And a second control means for controlling the moving means such that a pressure of the spring against the object to be measured by the spring becomes a target value.

Further, the three-dimensional shape measuring apparatus according to the present invention is further characterized by further comprising switching means for switching between the control state of the first control means and the control state of the second control means. I have. Further, in the three-dimensional shape measuring apparatus according to the present invention, the switching means selects a first control circuit when the stylus is separated from the object to be measured, and the stylus is connected to the object to be measured. Is characterized in that the second control circuit is selected when the contact is made.

In the three-dimensional shape measuring apparatus according to the present invention, the stylus is brought into contact with the surface of the object to be measured, and the position of the stylus is moved while moving the stylus along the surface of the object to be measured. In the three-dimensional shape measuring apparatus for measuring the surface shape of the object to be measured by measuring the distance, the holder for supporting the stylus and the object to be measured and the holder are relatively three-dimensionally arranged. Stage to move the
Position measuring means for measuring a relative position of the stylus with respect to the measured object, pressure detecting means for detecting a contact pressure of the stylus on the surface of the measured object, and Control means for controlling the movement of the stage based on the output so that the contact pressure of the stylus on the surface of the object to be measured becomes a predetermined value, and the touch based on the output from the position measuring means. A movement speed for calculating a first movement speed of a stylus in a direction substantially parallel to the surface of the object to be measured and a second movement speed of the stylus in a direction substantially perpendicular to the surface of the object to be measured. It is characterized in that it comprises a calculating means and a tilt angle calculating means for calculating a tilt angle of the surface of the object to be measured based on the first moving speed and the second moving speed.

Further, in the three-dimensional shape measuring apparatus according to the present invention, when the inclination angle of the surface of the object to be measured calculated by the inclination angle calculating means is equal to or larger than a predetermined value,
It is characterized by further comprising a judging means for judging that the stylus has reached an end of the object to be measured.

Further, in the three-dimensional shape measuring apparatus according to the present invention, when the determination means determines that the stylus has reached the end of the object to be measured, the control means stops the movement of the stage. It is characterized by having

Further, in the three-dimensional shape measuring apparatus according to the present invention, the stylus is supported by the spring so as to be relatively movable with respect to the holder, and the pressure detecting means is configured to detect the palpation relative to the holder. And detecting a contact pressure of the stylus on the object to be measured based on the moving amount and a spring constant of the spring.

In the three-dimensional shape measuring apparatus according to the present invention, a stylus is brought into contact with the surface of an object to be measured, and the position of the stylus is moved while moving the stylus along the surface of the object to be measured. In the three-dimensional shape measuring apparatus for measuring the surface shape of the object to be measured by measuring the distance, the holder for supporting the stylus and the object to be measured and the holder are relatively three-dimensionally arranged. Stage to move the
Position measuring means for measuring a relative position of the stylus with respect to the measured object, pressure detecting means for detecting a contact pressure of the stylus on the surface of the measured object, and First control means for controlling the movement of the stage so that the contact pressure of the stylus on the surface of the object to be measured becomes a predetermined value, based on the output, and based on the output from the position measurement means. A second control unit that controls a relative speed of the stylus to the object to be measured, and when a contact pressure detected by the pressure detection unit is out of a predetermined range,
And a third control means for switching from a control state by the first control means to a control state by the second control means.

Further, in the three-dimensional shape measuring apparatus according to the present invention, when the third control means switches to the control state by the second control means, the stylus moves the stylus at a predetermined speed. It is characterized by being evacuated from objects.

Further, in the three-dimensional shape measuring apparatus according to the present invention, the predetermined speed is a speed generated by a maximum thrust of the stage.

Further, in the three-dimensional shape measuring apparatus according to the present invention, the predetermined speed is a speed generated by a maximum acceleration that the stage can withstand.

[0056]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
FIG. 2 is a perspective view showing a configuration of the three-dimensional shape measuring apparatus according to the embodiment, and FIG. 2 is a side sectional view of FIG.

In FIGS. 1 and 2, a bed 16 serving as a base of the entire apparatus is arranged on a vibration isolating table 15a, 15b, 15c constituting a base of the three-dimensional shape measuring apparatus. Is supported in three places. With this structure, the minute vibration of the floor surface is attenuated and does not reach the bed 16.

The bed 16 has a support surface 44 for supporting the base surface plate 1, and supports the base surface plate 1 at three places on this support surface. The first support point is provided with a substantially conical depression 45 on both the bottom surface of the base platen 1 and the support surface 44, and sandwiches the ball 47a. The second support point is located on a straight line parallel to the Y axis passing through the first support point, and the direction of the ridge line is made coincident with the direction of the Y axis on both the bottom surface of the base platen 1 and the support surface 44. A substantially triangular prism-shaped depression 46 is provided to sandwich the sphere 47b. The third support point is located at a position separated from the first and second support points by a predetermined distance in the X-axis direction, and sandwiches the sphere 47c between both the bottom surface of the base platen 1 and the plane of the support surface 44. .

With this configuration, the XYZ direction is restricted at the first support point, the XZ direction is restricted at the second support point, and the Z direction is restricted at the third support point.
Here, consider the case where the bed 16 is deformed and the distance between the three support points changes. When the distance between the first support point and the second support point changes, the ball 4 located at the second support point
Since 7b moves along the triangular prism-shaped depression 46, unnecessary force caused by the deformation of the bed 16 is not transmitted to the base platen 1. The second of the bed 16
Even if the distance between the first and third support points and the distance between the first and third support points change, the third support point of the base 1 Since it is freely movable in the XY plane, unnecessary force caused by deformation of the bed 16 is not transmitted to the base platen 1. Therefore, even if the bed 16 is deformed, the base platen 1 can be prevented from being deformed.

A work (object to be measured) is placed on the base platen 1.
6 and three columns 5a, 5b and 5c are fixed, and the reference mirror holding frame 3 is fixed at three positions on the columns.
Support 2 At the first support point 29 on the first support 5a, the reference mirror holding frame 32 is firmly fixed. The second support point 31 on the second support 5b is on a straight line parallel to the Y axis passing through the first support point 29, and has a rectangular column shape (thin plate shape) whose cross section is long in the X axis direction and thin in the Y axis direction. ) Is formed.
Further, the third support point 30 is located at a position separated from the first support point 29 by a predetermined distance in the X-axis direction, and is formed in a columnar shape having a small diameter.

With this configuration, at the first support point 29, the reference mirror holding frame 32 is restrained in the XYZ directions with respect to the base platen 1, and at the second support point 31, the support point 31 is formed. Since the thin columnar column is easily bent and deformed in the Y direction, it is restricted in the XZ direction. Further, at the third support point 30, the thin columnar column forming the support point 30 is easily bent and deformed in the X direction and the Y direction, so that only the Z direction is restricted. Here, consider a case where the base platen 1 is deformed by the influence of the weight of the work 6 or the like, and the distance between three support points is changed. When the distance between the first support point and the second support point is changed, the second support point is movable in the Y direction. Unnecessary forces caused by the transmission are not transmitted. Further, even if the distance between the second support point and the third support point and the distance between the first support point and the third support point change,
Since the third support point can be easily moved in the XY plane with respect to the base platen 1, unnecessary force caused by deformation of the base platen 1 is not transmitted to the reference mirror holding frame 32. Therefore, even if the base surface plate 1 is deformed, the reference mirror holding frame 32 can be prevented from being deformed.

On the reference mirror holding frame 32, three X reference mirrors 7, Y reference mirrors 8, and Z reference mirrors 9 are mounted. This attachment is performed by providing pressing pins 33 at three positions of the reference mirror holding frame for each of the reference mirrors, and pressing the reference mirrors against the lower ends of the three pressing pins 33. The pressing pin 33 is fixed with a nut 34 after adjusting the protruding length from the reference mirror holding frame 32 as shown in FIG. As means for pressing the reference mirror against these pressing pins 33, locking pieces 35 are fixed at a plurality of points at three or more positions of the reference mirror, and one end of a tension spring 36 is locked to the locking pieces 35. And the other end of the reference mirror holding frame 32 via the mounting pin 38 and the spacer 37.
Is used. FIG. 3 shows an example of the pressing position of the pressing pin 33 and the pulling position by the tension spring 36 in this case. There are three pressing positions in any of the three types of reference mirrors. When viewed in the longitudinal direction of the reference mirror, it is supported at the Bessel point position, that is, the point where the deformation of the beam supported at the two points is minimized. The distance between the support points in this case is 0.5594 of the entire length. The tensile force at each tension position is adjusted by changing the thickness of the spacer 37 and the tension spring 36. This pulling point is calculated by using a FEM (finite element method) to calculate a position and a force at which the maximum deformation of the reference mirror is reduced. At this time, the total of the pulling forces is set to be at least larger than the weight of the suspended reference mirror.

FIG. 4 is a diagram for explaining this principle. By supporting the beam at the Bessel point as shown in FIG. 4A, the deformation of the beam in the case of two-point support is minimized. be able to. Further, as shown in FIG. 4B, by supporting the space between the support points with a compression spring, the deformation of the beam can be further reduced. This is the same even when the beam is hung down as shown in FIG.

By using a material having a small coefficient of thermal expansion as a material for forming the base surface plate 1 and the reference mirrors 7, 8, and 9, it is possible to further reduce a shape measurement error due to a change in environmental temperature. .

Next, the configuration of a tracing stylus for measuring the surface shape of the work 6 in contact with the work 6 will be described.

1 and 2, an X-axis slide guide 17 is fixed on a bed 16, and an X slide 3 is slidably supported on the X-axis slide guide 17 in the X-axis direction. . The X slide is slid by an X slide driving motor 18 and a ball screw 19.

A Y-axis slide guide 20 is fixed to the X-slide 3 along the Y-axis direction, and the Y-slide 2 supports the Y-slide 2 slidably in the Y-axis direction. The Y slide 2 is slid by a Y slide driving motor 21 and a ball screw 22.

Further, a Z-axis slide guide 23 is fixed to the Y slide 2 along the Z-axis direction, and the Z slide 4 is supported by the Z-axis slide guide so as to be slidable in the Z-axis direction. . The Z slide 4 is driven to slide by a Z slide driving motor 24 and a ball screw 25. The Z-slide drive motor 24 is provided with an encoder 45 for detecting the rotation angle of the motor. Further, a housing 26 on which a contact type probe 28 is supported is fixed to the Z slide 4.

With this configuration, the contact type probe 28 can be
The bed 16 can be moved three-dimensionally in the XYZ directions.

The contact type probe 28 is for measuring the height of the work surface in the Z-axis direction by coming into contact with the surface of the work 6.
Through 27d so as to be movable only in the Z-axis direction. At the lower end of the contact probe, a master ball 30, which is a sphere whose shape accuracy is compensated for, is attached, and a mirror 29 is provided at the upper portion. The optical interferometer 14 is provided at a position just above the contact type probe 28 of the Z slide 4, and measures a distance Z1 between the Z reference mirror 8 and the mirror 29 above the probe 28.

The housing 26 is provided with a displacement sensor 31 for detecting the position of the mirror 29.
The relative displacement of the contact type probe 28 with respect to 6 is detected.
The output signal of the displacement sensor 31 is input to the contact pressure control circuit 39, and the contact pressure control circuit 39 detects the deformation amount of the parallel leaf springs 27a to 27d based on the relative displacement amount of the probe 28 detected by the displacement sensor 31. Then, a signal for controlling the position of the Z slide 4 is output so that the pressing pressure of the probe 28 against the work 6 becomes constant. The control signal is input to the motor amplifier 46, and the Z slide drive motor 24 is driven via the amplifier.

The output signal of the encoder 45 is supplied to a position control circuit 47 for controlling the position of the Z slide 4 in the Z-axis direction.
And the position control circuit 47 outputs a signal for controlling the position of the Z slide 4 based on the rotation angle of the Z slide drive motor detected by the encoder 45. The control signal is input to the motor amplifier 46, and the Z slide drive motor 24 is driven via the amplifier.

The state where the contact pressure of the probe 28 is controlled and the state where the position of the Z slide 4 is controlled are switched by a switch 40. The operation of the switch 40 is controlled by a general control device 90 that further controls the entire device.
Is controlled by

At the tip of the Z slide 4, a Z slide 4
Optical interferometers 10 and 11 for measuring the distance in the X direction are provided.
The distances X1, X2 from the reference mirror 7 are measured. Similar optical interferometers 12 and 13 (see FIG. 7) are provided in the Y direction, and measure the distance between the upper and lower two points on the Z slide 4 and the Y reference mirror 8.

Next, the principle of measuring the distance Z1 between the Z reference mirror 8 and the mirror 29 by the optical interferometer 14 will be described with reference to FIG.

A laser beam 50 from a laser light source (not shown), which stabilizes the oscillation frequency and generates laser beams having different frequencies for vertical polarization and horizontal polarization, is guided to a polarization beam splitter (PBS) 51, where When the horizontally polarized light is separated, one of the light passes straight through the PBS, is reflected by the corner cube 52, reenters the PBS, passes therethrough, and is guided to the optical fiber incidence device 53.

The other is reflected by the PBS and
The light enters the wave plate 55a, and linearly polarized light is converted into circularly polarized light.
The light beam 54a is formed. This is referred to as a first reflecting mirror 56a
, And is again incident on the quarter-wave plate 55a to return the circularly polarized light to the linearly polarized light. Then, since the light passes through the quarter-wave plate twice, the polarization direction of the linearly polarized light is
It has rotated 0 degrees and now passes through the PBS.

The light beam is further transmitted to a quarter-wave plate 55.
b, and converts the linearly polarized light into circularly polarized light.
4b is formed. This is reflected by the second reflecting mirror 56b, and is again incident on the quarter-wave plate 55b to return the circularly polarized light to the linearly polarized light. Then, since the light has passed through the quarter-wave plate twice, the polarization direction of the linearly polarized light has been rotated by 90 degrees as before, so that it is reflected by the PBS, reflected by the corner cube 52, and returned to the PBS again. And is reflected here.

The light beam is further transmitted to a quarter-wave plate 55.
b, and converts the linearly polarized light into circularly polarized light.
4c is formed. This is reflected by the second reflecting mirror 56b, and is again incident on the quarter-wave plate 55b to return the circularly polarized light to the linearly polarized light. Then, since the light has passed through the quarter-wave plate twice, the polarization direction of the linearly polarized light has been rotated by 90 degrees as before, so that it now passes through the PBS.

This light beam is further transmitted to a quarter-wave plate 5.
5a, and converts the linearly polarized light into circularly polarized light to form a light beam 54d. This is reflected by the first reflecting mirror 56a, and is again incident on the quarter-wave plate 55a to return the circularly polarized light to the linearly polarized light. Then, since the light has passed through the quarter-wave plate twice, the polarization direction of the linearly polarized light has been rotated by 90 degrees as before, so it is reflected by the PBS and guided to the optical fiber incident device 53 this time. In this manner, one of the vertically and horizontally polarized light beams is passed between the two reflecting mirrors 56a and 56b.
By reciprocating and combining with the other again, an interference signal corresponding to the difference in optical path length between the two is obtained. The optical fiber 53 is guided to an optical electric circuit (not shown), and this signal is processed. Measure the difference in length.

Next, referring to FIG. 6, optical interferometers 10, 1
1 distances X1, X2 between X reference mirror 7 and Z slide 4
The principle of measuring is described.

A laser beam 60 from a laser light source (not shown), which stabilizes the oscillation frequency and generates laser beams having different frequencies between vertically polarized light and horizontally polarized light, is guided to a polarization beam splitter (PBS) 61, where the vertically polarized light and the horizontally polarized light are emitted. When the polarized light is separated, one of the two passes straight through the PBS, is reflected by the corner cube 62a, reenters the PBS, passes therethrough, and is guided to the optical fiber incidence device 63.

The other beam is reflected by the PBS and is incident on the quarter-wave plate 65, where the linearly polarized light is converted into circularly polarized light to form a light beam 64a. This is reflected by the reflector 66,
The light is again incident on the quarter-wave plate 65 to return the circularly polarized light to the linearly polarized light. Then, since the light has passed through the quarter-wave plate twice, the polarization direction of this linearly polarized light has been rotated by 90 degrees as before, so that it has now passed through the PBS, and
The light is reflected at 2b, reenters the PBS, and passes through the PBS.

Further, this light beam is applied to a quarter-wave plate 6.
5 and convert the linearly polarized light into circularly polarized light to form a light beam 6.
4b is formed. This is reflected by the reflecting mirror 66, and
The light is made incident on the half-wave plate 65 to return the circularly polarized light to linearly polarized light. Then, since it has passed through the quarter-wave plate twice,
Since the polarization direction of this linearly polarized light has been rotated by 90 degrees, the light is reflected by the PBS and guided to the optical fiber incident device 63.

Thus, one of the vertically and horizontally polarized light beams is reciprocated twice between the reflecting mirror 66 and the PBS 61.
By combining with the other again, an interference signal corresponding to the difference between the optical path lengths of the two is obtained. The optical fiber 63 is connected to a not-shown opto-electric circuit, and this signal is processed. Measure the difference.

According to the same principle, the aforementioned Z slide 4
The distances Y1 and Y2 between the upper and lower two points and the Y reference mirror 8 are measured.

Here, as shown in FIG. 7, the measurement axis of X1 and the measurement axis of Y1 intersect at a point C1 on the measurement axis of Z1, and X2
Each measurement axis is set so that the measurement axis of Y2 and the measurement axis of Y2 intersect at a point C2 on the measurement axis of Z1. The distance between C1 and C2 is L1, and the mirror 29 fixed to the upper end of C2 and the probe 28
Is L2, and the distance from that to the center C3 of the master ball 30 at the tip of the probe is L3.

Under these conditions, the coordinates (Xp, Yp, Z) of the center position of the master ball 30 at the tip of the probe 28
p) is determined by the following equation.

Xp = X1 + (X2-X1) × (L1 + L2 + L3) ÷ L1 + δx (1) Yp = −Y1- (Y2-Y1) × (L1 + L2 + L3) ÷ L1 + δy (2) Zp = −Z1 + δz (3) where δx, δy and δz are constants.

Here, the meaning of the above equation will be described. X slide, Y slide,
In the three-dimensional movement mechanism using the Z slide, when the probe 28 is moved, an error as shown in FIG. 8 occurs in the Z slide due to a movement error of each slide. Generally, the movement errors are the following six errors defined by the movement of the axis. (1) Position error There are three types of three-dimensional position errors in the X, Y, and Z directions.
Described as x, Δy, Δz. (2) Attitude error Attitude error is an error related to rotation, and is defined as three errors around the X, Y, and Z axes.
There are types, and they are described as Δθx, Δθy, and Δθz.

The six types of movement error components are X, Y, Z
Since it occurs for each of the slides, the position and attitude of the probe disposed at the tip thereof are affected by the accumulation of their movement errors, and change with the movement of the X, Y, and Z axes.

By calculating the position of the probe using the above equations (1) to (3), the center position of the master ball at the tip of the probe can be measured without being affected by this movement error. (1) Position Error The position errors Δx, Δy in the X, Y, Z directions are directly reflected in the lengths X1, X2 measured by the interferometer, and therefore do not become measurement errors of the probe position. Further, since the length Z1 measured by the interferometer is the distance between the probe and the Z reference mirror, ΔZ does not affect the measured value in the Z direction. (2) Posture Error For example, if a posture error Δθy around the Y axis occurs, the point C1
From the center position of the master ball 30 (point C
3) is shifted in the X direction by Δθy × (L1 + L2 + L3). Accordingly, the correct position Xp in the X direction of the center of the master ball (point C3) is expressed as Xp = X1 + Δθy × (L1 + L2 + L3) + δx (4) since the X direction position of the point C1 is X1. Here, δx is an error caused by an error in the mounting position of the work 6 and the like, and does not change but is a constant.

On the other hand, when viewed from the position of the point C1, the point C2 also shifts in the X direction by Δθy × L1 due to the posture error Δθy. Here, since the position of the point C2 in the X direction is measured as X2 by the interferometer, the deviation amount Δθy × L1 of the point C2 in the X direction is represented by Δθy × L1 = (X2−X1). When Δθy is calculated from this equation, Δθy = (X2−X1) ÷ L1. By substituting this into the above equation (4), Xp
Xp = X1 + (X2-X1) × (L1 + L2 + L3) ÷
L1 + δx, and the above equation (1) is obtained.

If the attitude error Δθx about the X axis is considered in the same manner, the correct position of the center of the master ball in the Y direction can be obtained as in the following equation (2).

Further, the attitude error Δθz around the Z axis does not become a measurement error since the tip of the probe is a sphere.

In the equations (1), (2) and (3),
δx, δy, δz are constant errors due to errors in the mounting position of the work 6 and are unknown, but there is no problem since the relative positions are sufficient for the purpose of measuring the shape of the work 6. . In other words, it is not necessary to know exactly where the workpiece is fixed with respect to the three reference mirrors, which are the measurement references.

As described above, by using the above equations (1) to (3), the three-dimensional position of the probe can be measured without being affected by the movement error of the movement axis.

Next, a procedure for measuring the shape of the work 6 in the above configuration will be described with reference to a flowchart shown in FIG.

First, the work 6 is mounted on the base platen 1. At this time, the base surface plate 1 is deformed by the weight of the work. However, as described above, the three support points 29, 30, 3
By the operation of 1, the reference mirror holding frame 32 is not deformed,
Therefore, the relative positions of the three reference mirrors 7, 8, and 9, which are references for the position of the three-dimensional shape measuring apparatus, do not change. In addition, the reference mirror holding frame 32 is not deformed by the same action as to the deformation of the base surface plate 1 due to a change in the environmental temperature.

Next, the position control circuit 47 is selected by the switch 40, and the position of the probe 28 in the Z-axis direction is controlled to a predetermined position away from the work 6 (step S1).
Next, the X slide 3 and the Y slide 2 are driven to move the probe 28 above the first measurement point of the work 6 (step S2). At this time, the position at which the weight of the slide acts on the bed 16 changes with the movement of the X and Y slides, so that the bed 16 is deformed. However, as described above, the base platen 1 is not deformed by the action of the three support points 45, 46, 47. The same applies to the case where the Z slide is moved. Even if the bed 16 is deformed due to the movement of the Z slide, the base platen 1 is not deformed. Further, even when the bed 16 is deformed due to a change in environmental temperature, the base platen 1 is not deformed by the same action.

Next, the Z slide 4 is driven and lowered until the tip of the probe 28 contacts the surface of the work 6 (step S3). At this time, the output of the displacement sensor 31 is monitored, and the Z slide 4 is lowered until the displacement amount of the parallel leaf springs 27a to 27d, in other words, the contact pressure of the probe 28 with the work 6 reaches a predetermined value (step S).
4). When the displacement amount of the parallel leaf springs 27a to 27d reaches a predetermined value, the switch 40 is switched to select the contact pressure control circuit 39, so that the output of the displacement sensor 31 becomes constant, in other words, the contact pressure of the probe 28. The position of the Z slide 4 is controlled so that is constant (step S5).

Next, from the outputs of the interferometers 10, 11, 12, 13, and 14, the position of the master ball 30 at the tip of the probe is calculated using equations (1) to (3) (step S).
6). The calculated coordinate position is stored in the integrated control device 9.
0 is stored in the memory (step S7).

Next, the X slide 3 and the Y slide 2 are driven to sequentially measure the position of the probe 28 while scanning the probe 28 in contact with the surface of the work 6. (Step S
8). Then, it is determined whether the scanning of all the measurement areas is completed (step S9). If the scanning is not completed, the process returns to step S6, and if the scanning is completed, the process proceeds to step S10. In step S10, the switch 40 is switched to bring the probe 28 into a state of position control, and further, the probe 28 is retracted from the work 6 to finish the measurement (step S11).

As described above, according to the above-described embodiment, the base platen 1 is supported on the bed 16 at three points, and at one point, the base platen 1 is firmly fixed. The other point is movably supported only in the Y-axis direction, and the other point is movably supported in the XY direction, so that deformation of the bed 16 is not transmitted to the base platen 1 and high-precision measurement is possible. Becomes

The reference mirror holding frame 32 is supported at three points with respect to the base platen 1. At one of the points, the reference mirror holding frame 32 is firmly fixed, and at the other point, Y is fixed.
By supporting the base plate 1 movably only in the axial direction and movably supporting the remaining one point in the X and Y directions, the deformation of the base surface plate 1 is not transmitted to the reference mirror holding frame 32, and high-precision measurement is possible.

Further, the reference mirrors 7, 8 and 9 are fixed to the reference mirror holding frame 3 by three pressing points and three or more pulling points.
2, the deformation of the reference mirror due to its own weight can be reduced, and highly accurate measurement can be performed.

Further, by forming the base, the reference mirror holding frame, and the reference mirror using a material having a small coefficient of thermal expansion, the deformation amount of these members can be suppressed even when the environmental temperature changes. And highly accurate measurement is possible.

Further, since the position of the Z slide is measured by five interferometers, by using these measured values, a highly accurate position measurement which is not affected by the movement errors of the X axis, Y axis and Z axis. Becomes possible.

Further, since the mirror surface of the Z-axis reference mirror 9 is disposed downward, it is possible to prevent the performance of the reference mirror from deteriorating due to accumulation of dust and the like in the air.

Since the lightest Z-slide 4 provided at the end of the XYZ moving mechanism causes the probe 28 to follow the height direction of the work 6, the follow-up performance of the probe in the height direction of the work 6 is achieved. And high-speed, high-precision measurement is possible.

In the above embodiment, the third support point 30 is described as being formed in a thin columnar shape. However, the same applies to a column having a regular polygonal cross section such as a square if the cross sectional area is small. It is. Further, the second support point 31 is described as being formed in a thin plate shape, but the present invention is not limited to this, and any cross-sectional shape that can be easily deformed in the Y direction may be used.

In the above embodiment, the five lengths measured using the five interferometers are used as the source of the position measurement. However, the accuracy of the length measured by the interferometer depends on the wavelength of the light source used. Depends. Therefore, if a system of six interferometers is added by adding a commercially available interferometer for wavelength correction, it is possible to perform shape measurement that is not affected by a change in wavelength due to a change in temperature or atmospheric pressure during shape measurement.

The circuit for guiding the output of the displacement sensor 31 to the Z-axis driving motor 24 via the feedback circuit 39 and the switch 40 is necessary for keeping the pressing force of the probe constant. High responsiveness is required. Therefore, in order to enhance the response performance of the Z-axis, for example, a configuration is adopted in which the guide 23 is an air bearing to reduce friction, or a driving method using a rotating motor and a ball screw is replaced with a linear motor to eliminate nonlinear elements such as backlash. It may be.

In this embodiment, the probe is moved in three axes of X, Y, and Z axes, and the surface of the work is two-dimensionally scanned. A configuration in which only one cross section of the surface of the measured object is scanned using only the Z axis may be used.

(Second Embodiment) FIG. 10 is a view showing a second embodiment of a method of supporting the reference mirror holding frame 32.

In FIG. 10, the work 6 is fixed to the base platen 1, and three columns 5a, 5b, 5c are provided, and the reference mirror holding frame 32 is supported at these three places. The first support point is provided with a substantially conical recess 41 in both the column 5a and the reference mirror frame 32, and sandwiches the sphere 43a.
The second support point is provided in both the column 5b and the reference mirror frame 32 with a substantially triangular column-shaped recess whose ridge line is aligned in the direction along the Y axis, and sandwiches the sphere 43b. The third support point sandwiches the ball 43c between the column 5c and the plane of the reference mirror holding frame 32.

With this configuration, the XYZ direction is restricted at the first support point, the XZ direction is restricted at the second support point, and the Z direction is restricted at the third support point.
Here, the case where the base platen 1 is deformed and the distance between the three support points changes is considered. When the distance between the first support point and the second support point changes, the sphere 43b at the second support point moves along the triangular prism-shaped depression, so that unnecessary force is applied to the reference mirror holding frame 32. Do not communicate. Even if the distance between the second and third support points and the distance between the first and third support points changes, the third support point can be freely moved in the XY plane. Does not transmit strong force. As a result, even if the base platen 1 is deformed, the reference mirror holding frame 32 is prevented from being deformed.

In the second embodiment, it is possible to cope with a larger deformation of the base surface plate as compared with the first embodiment in which the reference mirror holding frame is supported using columns having different cross-sectional shapes.

(Third Embodiment) The third embodiment is different from the first embodiment in that the Z axis is oriented in the horizontal direction. FIG. 11 shows the configuration of the device of the third embodiment.

In this embodiment, the measurement can be performed with the work 6 upright as shown in FIG.
For example, in the case of an optical element used in an upright state, the shape can be measured in the same state as the posture to be used. Therefore, the deformation due to its own weight becomes the same as that in the use state, and accurate measurement can be performed.

(Fourth Embodiment) FIG. 12 is a perspective view showing a schematic configuration of a three-dimensional shape measuring apparatus according to a fourth embodiment.

In FIG. 12, the shape measuring device is a base of the device, and is provided with a measuring table 303 on which a work 401 as an object to be measured is placed, and arranged on the measuring table 303 along the Y-axis direction. A Y-axis direction guide 305, a Y slide 302 that moves along the Y-axis direction guide 305,
A drive mechanism 429 (see FIG. 13) for moving the slide 302 in the Y-axis direction, and an X slide 301 slidably arranged on the Y slide 302 along the X-axis direction.
And a drive mechanism 428 (see FIG. 13) for moving the X slide 301 in the X axis direction.
Post 306 fixed in a state of extending along the axial direction
A Z-slide 405 arranged to be slidable in the Z-axis direction with respect to the column 306, a probe 403 supported by the Z-slide 405 to be elastically movable in the Z-axis direction,
A ball 402 is attached to the tip of the probe 403 and is compensated for having high shape accuracy. As the drive mechanism 429 of the Y slide 302 and the drive mechanism 428 of the X slide 301, for example, a feed mechanism using a ball screw and a motor or a feed mechanism using a linear motor is used.

In the three-dimensional shape measuring apparatus thus configured, the probe 4 is moved by X, Y and Z slides.
03 is scanned over the surface of the work 401 with its tip in contact with the work 401, and the position of the probe 403 is detected by a position sensor described later to measure the surface shape of the work 401.

FIG. 13 shows the Z slide 40 in FIG.
It is sectional drawing which expanded and showed the part of 5.

In FIG. 13, reference numeral 401 denotes a work to be measured, the surface of which is a ball 40 at the time of measurement.
2 is in contact. Ball 402 is a probe
The probe 403 is fixed to the distal end of the Z-slide 405 via parallel leaf springs 404a to 404d.
, And can move relative to the Z slide 405 only in the Z-axis direction. This parallel leaf spring 404
The probe 403 and the work 4
Give a contact pressure with 01. The non-contact displacement meter 406 is fixed to the Z-slide 405, and measures the relative position between the probe 403 and the Z-slide 405.
It is possible to measure the amount of deformation in the Z-axis direction from 04a to 404d. The Z slide 405 is connected to the guide movable section 4.
The support column 306 is movably supported in the Z-axis direction by 09a, 410a and guides 409b, 410b.

The linear motor movable parts 408a, 41
The Z slide 405 is given a thrust in the Z-axis direction by the thrust generated by 1a and the linear motor fixing portions 408b and 411b. A reflecting mirror 407 is fixed to the Z slide 405, and the laser length measuring device 417 applies a laser beam 412 to the reflecting mirror 407 so that the Z
Measure the axial position.

The control device 424 includes a command switching unit 420,
This is a calculation device having a position control calculation unit 416 and a pressure control calculation unit 417. If necessary, a thrust command for a linear motor output by these control calculation units is switched by a command switching unit 420, and a control method of the Z slide 405 is performed. Switch. The command switching unit 420 determines which command output of the position control calculation unit 416 or the pressure control calculation unit 417 is the linear motor command 421 and outputs the linear motor 408 or 41
Switch whether to output to 1.

The pressure control unit 417 is provided with the non-contact displacement meter 406
The linear motor thrust command 421 is output using the detection signal 415 as a feedback signal.

The speed conversion section 422 is provided with the laser length measuring device 41.
The position signal 414 of the Z slide 405 detected in
Is converted into a direction speed signal 423.
This Z-direction speed signal 423 is used as the X-axis moving speed signal 43.
1 and the moving speed signal 430 of the Y axis,
The inclination angle of the surface 01 is calculated.

The edge judging section 426 has a function of the inclination angle calculating section 42.
The tilt angle of the work surface calculated in step 5 is compared with a preset maximum tilt angle. If the current tilt angle is equal to or greater than the maximum tilt angle, the X-axis and Y-axis stop signals 427 are X-slided. A command is issued to the drive mechanism of the Y-slide 302 and the drive mechanism of the Y-slide 302. The driving mechanism of the X slide and the Y slide is
When this signal is received and stopped, the probe 4
03 is prevented from protruding from the end of the work 401.

FIG. 14 is a diagram specifically showing a method of detecting the end of the work 401. As shown in FIG.

FIG. 14A is a view showing a state where the probe 403 has not reached the end face 503 of the work 401, and FIG. 14B is a view showing a state where the probe 403 has reached the end face 503 of the work 401. FIG. FIG.
5A and 5B, 506a and 506b are contact points between the probe 403 and the work 401, and 504a and 504b.
04b represents the magnitude of the moving speed of the probe 403,
505a and 505b represent the magnitude of the velocity in the Z direction.
Also, 502a and 502b are inclination angles of the work surface at the contact points 506a and 506b, and the inclination angle θ is θ = t from the comparison between the X slide speed and the Z slide speed.
an ^-1 ｛(speed in the Z-axis direction 505 / speed in the X-axis direction 50
4) It can be obtained by a simple equation such as｝.

In FIG. 14B, the ball 402, which is the tip of the probe 403, is coming off the end face 503 of the work 401. When the inclination angle 502b in this state exceeds the specified value, the contact point 506b Is detected to be the end of the measurement surface, and the drive mechanism of the X slide is stopped.

As described above, in the present embodiment, since the mechanism for detecting the inclination angle of the work surface is provided, even when the work to be measured is mounted on the shape measuring device for the first time,
The shape measurement can be started without detecting the position of the work in the XY directions in advance, and the end of the work in the XY directions can be detected.

Further, even when the probe is about to move beyond the end of the work in the X and Y directions, the probe is not completely displaced from the end of the work. Can be.

(Fifth Embodiment) FIG. 15 is a diagram showing a configuration of a three-dimensional shape measuring apparatus according to a fifth embodiment. The device of the fifth embodiment is the same as that of the device of the fourth embodiment.
Since the slide part is only changed,
The same reference numerals are given to the same functional portions as in the embodiment, and the description thereof will be omitted.

The reflecting mirror 601 is attached to the upper end of the probe 403, and the laser length measuring device 603 applies the laser measuring light 602 to the reflecting mirror 601 so that the probe 40
Measure the position of 3. The pressure control calculator 420 compares the position of the Z slide 405 detected by the laser length measuring device 413 with the position of the probe 403 to detect the relative position of the Z slide 405 and the probe 403, and detects the relative positions of the parallel leaf springs 404a to 404d. The pressure control is performed by detecting the amount of deformation of.

(Sixth Embodiment) FIG. 16 is a view showing a configuration of a three-dimensional shape measuring apparatus according to a sixth embodiment. The same reference numerals are given to the same functional parts as in the fourth embodiment. The description is omitted. In this example, only the Z slide portion is shown, but the entire apparatus is configured in the same manner as the fourth embodiment shown in FIG.

In FIG. 16, a control unit 728 is an arithmetic unit having a command switching unit 726, a position control arithmetic unit 718, a speed control arithmetic unit 719, and a pressure control arithmetic unit 720. The command switching unit 726 switches the thrust command for the linear motor that is output by the controller, and switches the control method of the Z slide 405. The command switching unit 726 switches which command output of the position control calculation unit 718, the speed control calculation unit 719, and the pressure control calculation unit 720 is output to the linear motors 408 and 411 as the linear motor command 727.

The position / speed conversion unit 716 converts the Z slide position signal 414 detected by the laser length measuring device 413 into a Z slide speed signal 717, and the speed control calculation unit 719
Performs a PID control calculation using the Z slide speed signal 717 as a feedback signal, and outputs a thrust command 724 for the linear motor. At the time of speed control, the thrust command 72
4 is the linear motor 408,
411 is commanded to control the speed of the Z slide.
The speed command value 721 and the I component initial value 72 of the speed calculation unit
2 is transferred to the speed control calculation unit 719 at the start of control and used as calculation data.

The pressure control calculation section 720 is provided with the non-contact displacement meter 4
The thrust command 723 of the linear motors 408 and 411 is output using the detection signal 415 of 06 as a feedback signal.

The position control calculation section 718 performs PID control calculation using the Z slide position signal 414 detected by the laser length measuring device 413 as a feedback signal, outputs a thrust command 725 for the linear motors 408 and 411, The position of the Z slide 405 is controlled by adjusting the thrust of 408 and 411.

FIG. 17 and FIG. 18 are flow charts for explaining the operation of the apparatus configured as described above.

First, position control is started (step S20).
According to 2), the Z slide 405 is stopped by position control at an upper position where the probe 403 is not in contact with the workpiece 401.

In step S203, the target position for position control is rewritten to a lower position, and the Z slide 405 is brought closer to the work 401.

In step S204, the non-contact displacement meter 40
6, the probe 403 contacts the work 401 by moving the Z slide 405, and monitors whether the deformation amount of the parallel leaf springs 404a to 404d changes to a predetermined value.
Between the contact pressures. If the detected pressure has not reached the predetermined value, the process of step S203 is executed again, and when the pressure reaches the specified value, the process proceeds to the next step.

In step S205, since the pressure has reached the specified value, the position of the Z slide 405 is not changed and the position control is switched from the position control to the pressure control.

In the step S206, the Z slide 405 is set.
Is controlled by the pressure control, the X slide 301 or the Y slide
The slide 40 (see FIG. 12) allows the probe 40
The contact point of No. 3 is moved on the work 401 and the shape is measured.

In step S207, the feedback signal of the pressure control is monitored, and it is detected whether or not this value has deviated from the specified value for some reason. If the value is outside the specified value, the process is changed to the emergency evacuation operation in step S210. If within the specified value, step S208
Proceed to.

In step S208, X slide or Y slide
It is determined whether or not all the measurement points on the workpiece 401 have been scanned by the movement of the slide, and if the measurement has not been completed, the processes of step S206 and step S207 are continued.

Next, the emergency evacuation operation of step S210 will be described with reference to the processes from step S211 to step S219.

In step S212, for emergency evacuation,
A speed command value for switching the stage control from pressure control to speed control is set.

In step S213, an initial value of the I component is set for the PID control of the speed control calculation unit 719 for emergency evacuation. The initial value to be set is a value at which the thrust of the linear motor generates the maximum thrust in the direction in which the Z slide 405 moves away from the work 401.

In step S214, the control of the Z slide 405 is switched from pressure control to speed control for the emergency retreat operation. By this switching, the Z slide 405
Starts evacuation from the work 401.

In step S215, the Z slide 405 is retracted from the work 401 by speed control, and the retreat movement speed is controlled to a predetermined speed.

In the step S216, the Z slide 405 is set.
It is determined whether or not the position has moved to the upper end by speed control. If the position has not moved to the upper end, the process of step S215 is continued, and the Z slide 405 keeps moving away from the work 401.

In step S217, the Z slide 405
The command value of the speed control is changed so that the motor stops at the position where the motor reaches the upper end.

In the step S218, the Z slide 405
When the control is decelerated and stopped at the upper end, the control of the Z slide 405 is switched to the position control, stopped immediately, and the emergency evacuation operation is terminated.

As described above, according to the above-described embodiment, the mechanism for retracting the probe is provided. Therefore, when the shape of the workpiece is measured by the probe, the pressure control is performed for some reason. In the case of failure, the probe can be evacuated from the workpiece stably and at high speed, and damage to the workpiece due to excessive pushing of the probe and damage to the probe and the preload mechanism can be prevented.

Further, since a strong brake mechanism, which has been conventionally required for emergency stop of the Z slide, is not required, the size of the apparatus can be reduced.

(Seventh Embodiment) FIG. 19 is a view showing the configuration of a three-dimensional shape measuring apparatus according to a seventh embodiment. Since the device of the seventh embodiment is the same as the device of the sixth embodiment except that the Z-slide is changed, the same parts as those of the sixth embodiment are denoted by the same reference numerals and the description thereof will be omitted. Is omitted.

The reflecting mirror 801 is attached to the upper end of the probe 403, and the laser measuring device 803 applies the laser measuring light 802 to the reflecting mirror 801 so that the probe 40
Measure the position of 3. The pressure control calculation unit 720 detects the relative position between the Z slide 405 and the probe 403 by comparing and calculating the position of the Z slide 405 detected by the laser length measuring device 413 and the position of the probe 403, and detects the relative positions of the parallel plate springs 404a to 404d. The pressure control is performed by detecting the amount of deformation of.

The present invention can be applied to modifications or variations of the above embodiment without departing from the gist of the invention.

[0165]

As described above, according to the present invention,
The base is supported on the bed at three points, one of which
At the point, the base is firmly fixed, the other point is movably supported only in the Y-axis direction, and the other point is movably supported in the XY direction, so that the bed deformation is not transmitted to the base, Highly accurate measurement is possible.

Further, the reference mirror holding frame is supported at three points with respect to the base, and at one point, the reference mirror holding frame is firmly fixed, and at another point, it is movably supported only in the Y-axis direction. However, by supporting the remaining one point movably in the XY directions, the deformation of the base is not transmitted to the reference mirror holding frame, and high-precision measurement is possible.

The reference mirror is pressed at three points,
Since the reference mirror is held on the reference mirror holding frame at more than three pull points, deformation of the reference mirror due to its own weight can be reduced, and highly accurate measurement can be performed.

Further, by forming the base, the reference mirror holding frame, and the reference mirror using a material having a small coefficient of thermal expansion, the amount of deformation of these members can be suppressed even when the environmental temperature changes. And highly accurate measurement is possible.

Further, since the position of the Z slide is measured by five interferometers, by using these measured values, highly accurate position measurement which is not affected by movement errors of the X, Y, and Z axes can be performed. Becomes possible.

Further, since the mirror surface of the Z-axis reference mirror is arranged downward, it is possible to prevent the performance of the reference mirror from deteriorating due to accumulation of dust and the like in the air.

Further, since the lightest Z-slide provided at the end of the XYZ moving mechanism causes the probe to follow the height direction of the work, the follow-up performance of the probe in the height direction of the work is high. And highly accurate measurement is possible.

Further, since a mechanism for detecting the inclination angle of the work surface is provided, even when the work to be measured is first mounted on the shape measuring device, the shape measurement can be performed without previously measuring the position of the work in the XY directions. Is started, and the end of the workpiece in the X and Y directions can be detected.

Further, even when the probe is about to move beyond the end of the work in the X and Y directions, the probe does not completely come off the end of the work. Can be.

Further, since a mechanism for retracting the probe is provided, the probe can be stably and quickly operated even if the pressure control fails for some reason at the time of pressure control when measuring the shape of the workpiece with the probe. The probe can be retreated from the work, and damage to the work due to excessive pushing of the probe and damage to the probe and the preload mechanism can be prevented.

Further, since a strong brake mechanism, which has been conventionally required for emergency stop of the Z slide, is not required, the size of the apparatus can be reduced.

[0176]

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration of a three-dimensional shape measuring apparatus according to a first embodiment.

FIG. 2 is a side sectional view of FIG.

FIG. 3 is a diagram illustrating a pressing point and a pulling point when a reference mirror is supported.

FIG. 4 is a diagram showing a state of deformation due to a supporting state of a beam.

FIG. 5 is a diagram illustrating a principle of distance measurement by a reference mirror and an optical interferometer.

FIG. 6 is a diagram illustrating a principle of distance measurement by a reference mirror and an optical interferometer.

FIG. 7 is a diagram showing a positional relationship between an interferometer provided on a Z slide and an XYZ reference mirror.

FIG. 8 is a diagram showing a movement error of a Z slide.

FIG. 9 is a flowchart showing the operation of the device of the first embodiment.

FIG. 10 is a diagram showing a second embodiment.

FIG. 11 is a diagram showing a third embodiment.

FIG. 12 is a perspective view illustrating a configuration of a three-dimensional shape measuring apparatus according to a fourth embodiment.

FIG. 13 is a diagram showing a Z slide and a control device thereof.

FIG. 14 is a diagram illustrating a contact state of a probe with a workpiece.

FIG. 15 is a diagram showing a Z slide and a control device thereof.

FIG. 16 is a diagram showing a Z slide and a control device thereof.

FIG. 17 is a flowchart showing the operation of the device according to the sixth embodiment.

FIG. 18 is a flowchart showing the operation of the device according to the sixth embodiment.

FIG. 19 is a diagram showing a seventh embodiment.

FIG. 20 is a view showing a conventional three-dimensional shape measuring apparatus.

FIG. 21 is a view showing a conventional three-dimensional shape measuring apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base surface plate 2 Y slide 3 X slide 4 Z slide 5 Prop 6 Work (measured object) 7 X reference mirror 8 Y reference mirror 9 Z reference mirror 10 X1 measurement interferometer 11 X2 measurement interferometer 12 Y1 measurement Interferometer 13 Interferometer for Y2 measurement 14 Interferometer for Z1 measurement 15 Vibration isolation table 16 Bed 17 X-axis guide 18 X-axis drive motor 19 Ball screw 20 Y-axis guide 21 Y-axis drive motor 22 Ball screw 23 Z-axis guide 24 Z-axis drive motor 25 Ball screw 26 Housing 28 Contact probe 29 First support point 30 Third support point 31 Second support point 32 Reference mirror holding frame 33 Pressing pin 34 Nut 35 Locking piece 36 Tension spring 37 Spacer 38 mounting pin 41 cone-shaped depression 42 triangular prism-shaped depression 43 sphere 44 support surface 45 Cone-shaped depression 46 triangular prism-shaped depression 47 sphere 101 Z drive motor (capstan drive) 102 Z slide 103 granite column 104 XY slide 105 Y drive motor (capstan drive) 106 X drive motor (capstan drive) ) 107 Granite bed 108 Anti-vibration table 109 XY guide 110 Base platen 111 Cover 112 Probe head 113 Reference mirror 114 Measurement arm

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01B 5/20 101 G01B 11/24 G01B 21/20 101

Claims (28)

(57) [Claims] 1. A method in which a stylus is brought into contact with a surface of an object to be measured fixed to a measuring table, and the position of the stylus is measured while moving the stylus along the surface of the object to be measured. ,
In a three-dimensional shape measuring apparatus for measuring a surface shape of the object to be measured, a base for supporting the measuring table, and a base arranged between the base and the measuring table, wherein deformation of the base is measured by the measuring table. Support means for supporting the measuring table in a state where it is difficult to transmit the stylus; a stage arranged on the base for moving the stylus three-dimensionally; and measurement for measuring a three-dimensional position of the stage. Means for measuring three-dimensional shape. 2. The first support mechanism, wherein the first support mechanism fixes the measuring table to the base at a first position on the base so as to be immovable in three XYZ directions orthogonal to each other. A second position supporting the measurement table with respect to the base so as to be movable only in the Y direction at a second position on the base separated from the first position by a predetermined distance in the Y direction.
At a third position on the base spaced apart from the first position by a predetermined distance in the X and Y directions, respectively.
3. The three-dimensional shape measuring apparatus according to claim 1, further comprising a third support mechanism that supports the measurement table with respect to the base so as to be movable in an X direction and a Y direction. 3. The first support mechanism includes a substantially conical recess provided on each of the base and the measuring table, and a first sphere inserted into the substantially conical recess. The second support mechanism includes a substantially triangular prism-shaped recess provided in each of the base and the measurement table and extending in the Y direction, and a second sphere inserted into the substantially triangular prism-shaped recess. And
3. The three-dimensional shape measuring apparatus according to claim 2, wherein the third support mechanism includes a third sphere inserted between an upper surface of the base and a lower surface of the measuring table. 4. 4. The three-dimensional shape measuring apparatus according to claim 1, wherein the base and the measuring table are formed from a material having a small coefficient of thermal expansion. 5. A method in which a stylus is brought into contact with a surface of an object to be measured fixed to a measuring table, and the position of the stylus is measured while moving the stylus along the surface of the object to be measured. ,
In a three-dimensional shape measuring device for measuring a surface shape of the object to be measured, a stage for moving the stylus three-dimensionally, and a three-dimensional position of the stage which is arranged on the measuring table A frame for supporting a mirror that constitutes a part of an optical system for measuring the position of the measuring table, and the frame is disposed between the measuring table and the frame, and supports the frame in a state where deformation of the measuring table is not easily transmitted to the frame. A three-dimensional shape measuring apparatus, comprising: 6. A first support mechanism for fixing the frame immovably in three XYZ directions perpendicular to each other with respect to the measurement table at a first position on the measurement table. And a second support mechanism for supporting the frame movably only in the Y direction with respect to the measurement table at a second position on the measurement table separated by a predetermined distance in the Y direction from the first position. At a third position on the measuring table spaced apart from the first position by a predetermined distance in the XY directions, a third position supporting the frame movably in the X and Y directions with respect to the measuring table. The three-dimensional shape measuring apparatus according to claim 5, further comprising a support mechanism. 7. The first support mechanism includes a first support column for firmly fixing the measuring table and the frame in XYZ directions, and the second support mechanism extends in the X direction. The third support mechanism has an elongated cross section and is easily deformable in the Y direction connecting the measuring table and the frame, and the third support mechanism has a thin cross section and connects the measuring table and the frame. The 3rd column according to claim 6, comprising a third column that is easily deformed in the X and Y directions to be connected.
Dimensional shape measuring device. 8. The first support mechanism includes a substantially conical recess provided on each of the measuring table and the frame, and a first sphere inserted into the substantially conical recess. ,
The second support mechanism includes a substantially triangular prism-shaped recess provided in each of the measurement table and the frame and extending in the Y direction, and a second sphere inserted into the substantially triangular prism-shaped recess. 7. The three-dimensional shape measuring apparatus according to claim 6, wherein the third support mechanism comprises a third sphere inserted between an upper surface of the measuring table and a lower surface of the frame. . 9. The measuring table and the frame are made of a material having a small coefficient of thermal expansion.
3. The three-dimensional shape measuring device according to item 1. 10. The three-dimensional shape measuring apparatus according to claim 5, wherein said frame has a second support means for holding said mirror in a state where deformation due to its own weight is corrected. 11. The second support means includes three contact members disposed at three locations on the frame and abutting on the mirror, and the second support means is disposed on at least three locations on the frame and attaches the mirror to the abutment member. The three-dimensional shape measuring apparatus according to claim 10, further comprising a tension spring for pulling the three-dimensional shape so as to abut. 12. The three-dimensional shape measuring apparatus according to claim 11, wherein the three contact members are attached to the frame so as to adjust an amount of protrusion. 13. The three contact members are arranged in a longitudinal direction of the mirror away from the first contact member and in a direction substantially orthogonal to the longitudinal direction of the mirror. The first and second contact members are arranged along the longitudinal direction of the mirror, and the first and second contact members are arranged along the longitudinal direction of the mirror. 12. The three-dimensional shape measuring apparatus according to claim 11, wherein the position is a vessel position where the amount of deformation is smallest. 14. The three-dimensional shape measuring apparatus according to claim 10, wherein said frame and said mirror are formed of a material having a small coefficient of thermal expansion. 15. A method in which a stylus is brought into contact with a surface of an object to be measured fixed to a measuring table, and the position of the stylus is measured while moving the stylus along the surface of the object to be measured. A three-dimensional shape measuring apparatus for measuring a surface shape of the object to be measured;
Moving means for moving three-dimensionally in a direction, a Z-axis direction distance Z1 from a Z-axis direction reference plane provided orthogonal to the Z-axis to a Z-axis direction reference point on the moving member
And a first measuring means for measuring a distance X1 in an X-axis direction from an X-axis direction reference plane provided orthogonal to the X-axis to a first X-axis direction reference point on the moving member. (2) measuring means, from the X-axis direction reference plane to a second X-axis direction reference point on the moving member separated from the first X-axis direction reference point by a predetermined distance along the Z-axis direction A third measuring means for measuring a distance X2 in the X-axis direction, and a Y-axis direction from a Y-axis direction reference plane provided orthogonal to the Y axis to a first Y-axis direction reference point on the moving member. A fourth measuring means for measuring a distance Y1, a second measuring means for measuring a distance Y1, a second measuring means for measuring a distance from the Y-axis direction reference plane to the first Y-axis direction reference point by a predetermined distance along the Z-axis direction; Distance Y2 in the Y-axis direction to the reference point in the Y-axis direction
And a Z-axis distance Z1, X-axis distances X1, X2, and a Y-axis distance Y output from the first to fifth measuring means.
3. A three-dimensional shape measuring apparatus comprising: a calculating means for calculating the XYZ coordinates of the stylus from 1, Y2. 16. A straight line parallel to the Z-axis passing through the Z-axis direction reference point, a straight line parallel to the X-axis passing through the first X-axis direction reference point, and the first Y-axis direction reference point. A straight line parallel to the passing Y axis intersects at one point and passes through the Z axis reference point.
An X-axis passing through a straight line parallel to the axis and the second X-axis direction reference point.
A straight line parallel to the axis and Y passing through the second Y-axis reference point.
The three-dimensional shape measuring apparatus according to claim 15, wherein a straight line parallel to the axis also intersects at another point. 17. The stylus is elastically supported on the moving member via a spring, and further includes a sixth measuring means for detecting a relative position of the stylus to the moving member. The three-dimensional shape measuring apparatus according to claim 15, comprising: 18. A control device for controlling said moving means so that a position of said moving member becomes a target position, and said cover of said stylus by said spring based on an output of said sixth measuring means. 18. The three-dimensional shape measuring apparatus according to claim 17, further comprising a second control unit that controls the moving unit such that a pressure applied to the measurement object becomes a target value. 19. The three-dimensional shape measuring apparatus according to claim 18, further comprising a switching unit for switching between a control state of the first control unit and a control state of the second control unit. apparatus. 20. The switching means selects a first control circuit when the stylus is separated from the object to be measured, and selects the first control circuit when the stylus is in contact with the object to be measured. The three-dimensional shape measuring apparatus according to claim 19, wherein the second control circuit is selected. 21. A method in which a stylus is brought into contact with the surface of an object to be measured, and the position of the stylus is measured while moving the stylus along the surface of the object to be measured. In a three-dimensional shape measuring apparatus for measuring a surface shape, a holder for supporting the stylus, a stage for relatively moving the object to be measured and the holder three-dimensionally, Position measuring means for measuring a relative position of the stylus with respect to a measurement object; pressure detection means for detecting a contact pressure of the stylus on the surface of the measurement object; and an output of the pressure detection means. Control means for controlling the movement of the stage so that the contact pressure of the stylus on the surface of the object to be measured becomes a predetermined value, based on an output from the position measuring means, In a direction substantially parallel to the surface of the object to be measured Moving speed calculating means for calculating a first moving speed of the stylus and a second moving speed of the stylus in a direction substantially perpendicular to the surface of the object to be measured; and the first moving speed and the second moving speed. A tilt angle calculating means for calculating a tilt angle of the surface of the object to be measured based on the moving speed of the object. 22. It is determined that the stylus has reached the end of the object to be measured when the angle of inclination of the surface of the object to be measured calculated by the inclination angle calculating means is equal to or larger than a predetermined value. 3. The apparatus according to claim 2, further comprising a determination unit.
3. The three-dimensional shape measuring device according to 1. 23. The apparatus according to claim 21, wherein the control means stops the movement of the stage when the determination means determines that the stylus has reached an end of the object to be measured. 3D shape measuring device. 24. The stylus is supported by a spring so as to be relatively movable with respect to the holder, and the pressure detecting means detects a relative movement amount of the palpation with respect to the holder, and detects the movement amount. 22. The three-dimensional shape measuring apparatus according to claim 21, wherein a contact pressure of the stylus on the object to be measured is calculated based on a spring constant of the spring. 25. A method in which a stylus is brought into contact with the surface of an object to be measured, and the position of the stylus is measured while moving the stylus along the surface of the object to be measured. In a three-dimensional shape measuring apparatus for measuring a surface shape, a holder for supporting the stylus, a stage for relatively moving the object to be measured and the holder three-dimensionally, Position measuring means for measuring a relative position of the stylus with respect to a measurement object; pressure detection means for detecting a contact pressure of the stylus on the surface of the measurement object; and an output of the pressure detection means. A first control unit that controls the movement of the stage so that a contact pressure of the stylus on the surface of the object to be measured becomes a predetermined value, based on an output from the position measurement unit, Relative speed of the stylus to the object to be measured Control means for controlling the control of the first control means from the control state of the first control means when the contact pressure detected by the pressure detection means is out of a predetermined range. A three-dimensional shape measuring apparatus comprising: a third control unit configured to switch to a state. 26. The apparatus according to claim 26, wherein the third control means retreats the stylus from the object at a predetermined speed when switching to a control state by the second control means. 25. The three-dimensional shape measuring apparatus according to 25. 27. The three-dimensional shape measuring apparatus according to claim 26, wherein the predetermined speed is a speed generated by a maximum thrust of the stage. 28. The three-dimensional shape measuring apparatus according to claim 26, wherein the predetermined speed is a speed generated by a maximum acceleration that the stage can withstand.