JP2000266524A - Three-dimensional shape measuring machine and its measuring method - Google Patents

Abstract

[PROBLEMS] To provide a three-dimensional shape measuring machine and a three-dimensional shape measuring method capable of measuring a three-dimensional shape of an object to be measured with high accuracy and in a short time. SOLUTION: The coordinate axes of the three-dimensional shape measuring machine are R-θ-Z.
The DUT 1 is mounted on the θ stage 7, the optical probe 2 is disposed on the R stage 3 and the Z stage 4, and a laser length measuring device 9 (9 a to 9 c) as an optical probe position detecting means is provided.
In 9h), all are arranged in the same RZ plane, and the shape of the DUT 1 is measured two-dimensionally in the RZ plane. R used for laser length measuring device 9
And the Z reference mirrors 5 and 6 can be reduced in width to facilitate manufacture and improve the flatness, and the measurement error by the laser length measuring device 9 only needs to be considered in two dimensions. Measurement errors can be reduced.

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 machine for measuring the surface shape of an object such as an optical component or a mold with high accuracy, and a measuring method therefor.

[0002]

2. Description of the Related Art The use of a three-dimensional shape measuring machine is widely known as a method for measuring the surface shape of an object such as an optical component or a mold with high accuracy. In general, a three-dimensional shape measuring machine scans a workpiece by bringing a contact or non-contact probe close to the workpiece and controlling the probe position so that both have a substantially constant distance or a constant force relationship. Then, the shape is measured.

A measuring instrument of this type is disclosed in Japanese Unexamined Patent Publication No.
A shape measuring machine described in Japanese Patent Application Laid-Open No. 11024 and Japanese Patent Application Laid-Open No. 04-299206 is known. As an example of a conventional shape measuring device, a configuration as shown in FIG. 9 is provided, for example. In the figure, reference numeral 101 denotes an object to be measured fixed to a support (not shown), 103 denotes an X stage,
A Z stage 104 is mounted thereon, and the Z stage 10
4, a displacement meter 102 is arranged. That is, the displacement meter 102 can move in the XZ axis direction.
A Z-axis laser length measuring device 10
9c and an X-axis laser length measuring device 109g are arranged. The distance between the fixed Z reference mirror 105 and the X reference mirror 106 and the respective laser length measuring devices 109c and 109g is detected. The Z-axis coordinate position and the X-axis coordinate position are measured. Here X stage 10
In order to eliminate Abbe errors caused by the pitching component and the yawing component generated when the 3 and Z stages 104 move, the central axes of the measuring optical paths of the respective laser length measuring devices pass through the measuring points of the displacement meter 102, It is mounted so as to be parallel to the movement axis of each stage. The displacement meter 104 is brought closer to the object to be measured 101, and the X and Z-axis coordinate positions are measured with a servo applied so that the distance between the two is within 0.5 μm. Thus, the Z-axis coordinate position Z1 at the X-axis coordinate position X1 has been obtained. Next, the X stage 103 is moved to move the displacement meter 102 in the X-axis direction, and X2 and Z2 are measured in the same manner. By moving the displacement meter 102 along the measured object 101 in this manner, the X cross-sectional shape is obtained.

As another conventional shape measuring machine, there is one which is configured as shown in FIG. In the figure, reference numeral 203 denotes an X stage, on which a Y stage 208 and a Z stage 204 are further mounted, and a plane perpendicular to the XYZ axes, that is, a YZ plane, An X reference mirror 206, a Y reference mirror 207, and a Z reference mirror 205 are disposed on the XZ plane and the XY plane, respectively. The object to be measured 20 is placed on the Z stage 204.
A probe 202 for detecting a distance Z1 between the first stage 1 and a specific point on the Z stage 204; a measuring means 209c for detecting a distance Z2 between a specific point on the Z stage 204 and a fixed Z reference mirror 205; a specific point on the Z stage 204 And fixed position X
Measurement means 209 for detecting distance X of reference mirror 206
g, a measuring means 209i for detecting the distance Y between the specific point on the Z stage 204 and the fixed Y reference mirror 207 (note that the measuring means 209i is not shown in FIG. 10 because it is a shadow). Have been. Therefore, the probe 202 arranged on the Z stage 204 is XYZ
It can be moved in the axial direction, and the three-dimensional coordinates at that time can be (X, Y, Z calculated from Z1 and Z2). As described above, by scanning the entire surface of the object 201 with the probe 202 and detecting the three-dimensional coordinates at that time, the three-dimensional shape of the object can be measured.

[0005]

By the way, the shape measuring machine as shown in FIG. 9 has a configuration in which the Abbe error is considered in the XZ cross-sectional shape of the object to be measured, and high precision measurement can be expected. However, since there is no means for moving the object or the optical probe in the Y-axis direction, there is a problem that the three-dimensional shape of the object cannot be measured.

A three-dimensional shape measuring machine as shown in FIG. 10 has the following problems. That is, X-
YZ plane, XZ plane, XY each perpendicular to the YZ axis
The reference mirrors are arranged on the surfaces, respectively. These reference mirrors usually require a reference surface having a flatness of about λ / 10 to λ / 20 in two dimensions. It was difficult to manufacture a large product due to the cost and other factors. Therefore, the measurement range of the device under test is restricted. Further, by moving the probe on the X or Y section, for example, the axially symmetric lens or the like is measured on the XZ plane or the YZ plane with a large change in the Z direction relative to a change in the X direction or the Y direction. In this case, the moving speed of the probe cannot be increased, and the measuring time becomes longer. Further, in the shape measuring machine shown in FIG. 9, even if a Y stage is attached and the displacement meter can be moved in the XYZ axis directions, there is a similar problem.

Therefore, the present invention has been made in view of the above-mentioned unsolved problems of the prior art,
It is an object of the present invention to provide a three-dimensional shape measuring instrument and a three-dimensional shape measuring method capable of measuring a three-dimensional shape of an object to be measured with high accuracy in a short time.

[0008]

In order to achieve the above object, a three-dimensional shape measuring apparatus of the present invention measures a three-dimensional shape of a measured object using a probe that scans along the shape of the measured object. A three-dimensional shape measuring machine, a θ stage provided to support an object to be measured and movable in a θ-axis direction as a rotation component with respect to a Z-axis direction perpendicular to the object to be measured; An R stage provided movably in an R-axis direction that is horizontal with respect to the DUT on the stage;
A Z stage provided so as to be movable in a Z-axis direction perpendicular to the object to be measured; the probe is disposed on the R stage and the Z stage; and the R stage, the θ stage, and the The position detecting means provided on each of the Z stages is all arranged on the same RZ plane.

In the three-dimensional shape measuring instrument of the present invention, four laser length measuring devices are arranged on the R stage and the Z stage, and the laser length measuring devices are mounted on the R stage and the Z stage. The two arranged probes are respectively arranged in the R-axis direction and the Z-axis direction in the freely movable R-Z plane, and each of the two probes is arranged such that a distance from the object to be measured is always constant. Is configured to scan along the shape of the DUT while moving in the Z-axis direction. When the entire surface of the DUT is scanned by the probe, the R of the three-dimensional coordinate position of the probe is set. , Θ,
Z are simultaneously detected, and R at the three-dimensional coordinate position is Z
R arranged at a position parallel to the axis and passing on the R axis
It is calculated from a reference mirror and two laser length measuring devices arranged side by side in the Z-axis direction, and the Z at the three-dimensional coordinate position is calculated.
Is calculated from a Z reference mirror arranged at a position parallel to the R axis and passing on the Z axis and two laser length measuring instruments arranged side by side in the R axis direction, and the three-dimensional coordinates are calculated. Θ at the position is calculated from a scale arranged in a radial direction of a rotor part of a rotation mechanism constituting the θ stage and a scale detector fixed outside the θ stage, and R, of three-dimensional coordinates of the probe, It is preferable that the shape of the object is measured based on θ and Z.

In the three-dimensional shape measuring apparatus according to the present invention, the θ stage is constituted by an air bearing, and a θ reference mirror is integrally mounted on a rotor portion of the air bearing in a radial direction and a thrust direction. Is preferred.

The three-dimensional shape measuring method of the present invention
In a measuring method for measuring a three-dimensional shape of an object to be measured using a probe that scans along the shape of the object to be measured, the probe is moved in an R-axis direction that is a horizontal direction of the object to be measured. In the θ-axis direction which is a rotation component with respect to the Z-axis direction which is the vertical direction of the device under test, the probe is moved simultaneously or independently, and the distance between the probe and the device under test is always constant. The entire surface is scanned along the shape of the object to be measured while moving so that R, θ, and Z of the three-dimensional coordinate position of the probe are simultaneously detected, and the detected R, θ, and R of the three-dimensional coordinates are detected. The three-dimensional shape of the object to be measured is measured based on Z.

In the three-dimensional shape measuring method of the present invention,
When calculating the R coordinate in the three-dimensional coordinates of the probe, two different positions P in the same RZ plane
R coordinates R1, R2 detected at P1, P2 respectively
And the distance D in the Z direction between the two positions P1 and P2 and at the intersection of the probe tip and the object to be measured.
1 and the distance D of the Z-direction component between the two positions P1 and P2.
2 to calculate the R coordinate value R considering the Abbe error, and calculating the Z coordinate at the three-dimensional coordinate position of the probe at two different positions P3 and P4 in the same RZ plane. Z coordinate Z detected respectively
1, Z2, the distance D3 of the R-direction component between the two positions P3 and P4, and the intersection of the probe tip and the object to be measured, and the distance D4 of the R-direction component between the two positions P3 and P4. It is preferable to calculate the Z coordinate value Z in consideration of the Abbe error.

In the three-dimensional shape measuring method of the present invention,
The amount of surface shake in the thrust direction and the amount of axial shake in the radial direction that occur when rotating the object to be measured in the θ-axis direction are detected. It is preferable to consider this as a correction value, and to consider the axis shake amount as a correction value in the R coordinate value at the three-dimensional coordinate position of the probe.

In the three-dimensional shape measuring method of the present invention,
When the object to be measured has an axially symmetric shape, it is possible to perform shape measurement after performing alignment so that the axis of the object to be measured and the Z axis serving as the rotation axis in the θ-axis direction substantially coincide with each other. preferable.

[0015]

According to the present invention, an R stage moving in parallel with the object to be measured, a Z stage moving in the vertical direction of the object to be measured, and a rotation axis in the Z direction, with the coordinate axis being an R-θ-Z system. That is, a θ stage having a rotation axis in a vertical direction of the object to be measured, and the object to be measured is mounted on the θ stage,
The optical probe is provided on the R stage and the Z stage, and all the optical probe position detecting means are arranged in the same RZ plane, and the shape of the object to be measured is measured two-dimensionally in the RZ plane. By doing so, the R reference mirror and the Z reference mirror used in the laser length measuring device serving as the optical probe position detecting means can be obtained.
Since the reference mirror is used only in a substantially one-dimensional (on a straight line) range, the width of the reference mirror can be reduced, thereby facilitating the manufacture and improving the flatness of the reference mirror.

The measurement error in the position detecting means only needs to be considered on two dimensions in the RZ plane, and the pitching component error of the stage is length-measured, but the yaw and rolling components are considerably less affected. Therefore, the number of correction items can be reduced, and the measurement error can be reduced. Also, when the shape of the measured object is axially symmetric,
When the object to be measured is rotated with the axis of the object to be measured substantially coincident with the rotation axis of the θ stage, the shape of the object to be measured on the same radius becomes substantially constant. And the measurement time can be shortened.

As described above, according to the present invention, it is possible to measure a three-dimensional shape of an object to be measured with high accuracy and in a short time.

[0018]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view schematically showing a main part of a three-dimensional shape measuring machine of the present invention, and FIG. 2 is a schematic side view of a main part of the three-dimensional shape measuring machine of the present invention. FIG. 3 is an arrangement diagram showing the arrangement relationship of the optical probe and the laser length measuring device on the RZ plane in the three-dimensional measuring machine of the present invention.

In FIGS. 1 and 2, reference numeral 1 denotes an object to be measured such as an aspherical lens which is mounted on the θ stage 7 and which is symmetrical with the axis, and 2 denotes a probe which scans along the shape of the object 1 to be measured. In this embodiment, a non-contact optical probe that does not damage a lens or the like is used. However, a contact probe can be used. Reference numeral 3 denotes an R stage that moves in parallel with the DUT 1, and 4 denotes a Z stage that moves in the vertical direction of the DUT 1. Therefore, the optical probe 2 provided on the R stage 3 and the Z stage 4 is configured to be movable in the RZ direction. 5 is a Z reference mirror arranged at a position parallel to the R axis and passing on the Z axis, and 6 is an R reference mirror arranged at a position parallel to the Z axis and passing on the R axis. Reference numeral 7 denotes an air bearing unit serving as a θ stage, which is means for rotating the DUT 1 in the θ axis direction.
It comprises a housing part 7A on the fixed side and a rotor part 7B on the rotating side. The θ reference mirror 12 is provided on the rotor portion 7B.
a and 12b (see also FIGS. 3 and 4). 9
Reference numerals 9a and 9b denote laser length measuring devices serving as position detecting means.
Is a laser length measuring instrument for R measurement arranged on the Z stage 4 at a distance in the Z direction, and 9c and 9d are laser length measuring instruments for Z measurement arranged at a distance on the Z stage 4 in the R direction. , 9
Reference numerals e, 9f, 9g, and 9h denote laser length measuring instruments for θ measurement arranged outside the RZ stages 3 and 4. Reference numeral 10 denotes a scale detection unit (rotary encoder) of a scale 11 (see FIGS. 3 and 4) described later, which is an angle detection unit of the θ stage 7. Reference numeral 29 denotes a mount on which the R stage 3 and the Z stage 4 are mounted.

FIG. 3 is a diagram showing the arrangement of the optical probe and the laser length measuring device serving as the position detecting means on the same plane of the RZ. FIG.
RD2 indicates the distance between the laser length measuring device 9b and the R reference mirror 6, and indicates the distance between the R stage 3 and the R stage 3.
This is used for correcting the amount of movement and the measurement error that occurs during movement. ZD1 indicates the distance between the laser length measuring device 9c and the Z reference mirror 5, and ZD2 indicates the distance between the laser length measuring device 9d and the Z reference mirror 5.
The distance between the Z stages 4 is used to correct the amount of movement of the Z stage 4 and the measurement error that occurs during the movement. θD1 and θD2 are θ
Θ reference mirror 12 provided on the thrust surface of stage 7
indicates the distance between a and the Z reference mirror 5 and is used to detect the amount of shake (surface shake) in the thrust direction of the θ stage 7;
θD3 and θD4 indicate the distance between the θ reference mirror 12b and the R reference mirror 6a provided on the radial surface of the θ stage 7, and are used for detecting the amount of shake (axial shake) of the θ stage 7 in the radial direction. As described above, in the present invention, the optical probe 2 and the laser length measuring device 9 serving as the optical probe position detecting means are all arranged on the same plane of the RZ plane.

In FIG. 3, D1 is the distance in the Z direction between the center of the laser measuring devices 9a and 9b and the cat's eye point of the optical probe 2, and D2 is the laser measuring devices 9a and 9b.
The distance in the Z direction between b, D3 is the laser length measuring device 9c, 9
The distance of the R direction component from the middle of d to the center line of the optical probe 2, D4 is the distance of the R direction component between the laser length measuring devices 9c and 9d, and D5 is the R direction component between the laser length measuring devices 9e and 9f. Indicates the distance.

FIG. 4 is an enlarged view of an air bearing portion serving as a θ stage. The θ stage 7 is composed of a fixed housing portion 7A and a rotating rotor portion 7B, and a surface of the rotor portion 7B is formed. In some cases, a θ reference mirror is manufactured by aluminum evaporation and polishing after precision processing, and the θ reference mirror in the thrust direction is 12a and the θ reference mirror in the radial direction is 12b. In the radial direction, the scale 11
Is affixed, and using the scale detection unit 10
The angle of the stage 7 can be detected.

FIG. 5 shows a detailed structure of the optical probe. In FIG.
A laser light source that produces two light waves,
The light beam emitted from is expanded by the beam expander 14 and then divided by the polarization beam splitter 15a into a reflected light wave and a transmitted light wave. The reflected light wave is changed from linearly polarized light to circularly polarized light by passing through the λ / 4 plate 16a.
The light is incident on the DUT 1 through the line 0a. Here, the light beam is incident on the DUT 1 in a state where the light beam is focused (cat's eye point) by the condenser lens, and is reflected as a measurement light wave. This measurement light wave has surface information of the DUT 1 in the Z direction in the area of the irradiated light beam.
The reflected measurement light wave returns to the original optical path, becomes linearly polarized light rotated by 90 ° as compared with the outgoing light at the λ / 4 plate 16a that passes again, and is transmitted this time by the polarization beam splitter 15a. The other transmitted light wave changes from linearly polarized light to circularly polarized light through the λ / 4 plate 16b, enters the reference plane mirror 17, and is reflected as a reference light wave. The reflected reference light wave becomes linearly polarized light rotated by 90 ° as compared with the outgoing light at the λ / 4 plate 16b which passes again, and is reflected by the polarization beam splitter 15a this time. Polarizing beam splitter 15a
Then, the measurement lightwave and the reference lightwave overlap each other, and pass through the polarizing plate 18 in the 45 ° azimuth to become an interference lightwave. This interference light wave is split into two by the beam splitter 15b, and the transmitted interference light wave is detected by the line sensor 19.
The line sensor 19 usually has several tens to several thousands of channels, but here, one having several tens of channels corresponding to a high frequency is used. Also, one channel from a plurality of line sensor channels
The selection conditions for selecting a channel and using it as a measurement signal are as follows: the inclination angle is calculated from the design shape of the DUT at the measurement point, and the ray is traced in the normal direction to the DUT, i.e. Which channel on the line sensor receives the light beam is calculated and stored in advance, and the channel to be used is selected by the multiplexer according to the measurement position. The interference light wave reflected by the beam splitter 15b is captured by the photodetector 21 via the condenser lens 20b and becomes a reference signal.

FIG. 6 is a configuration diagram showing the configuration of the Z-axis servo. The Z stage 4 is moved so that the light beam from the optical probe 2 enters the DUT 1 at the cat's eye point. The measurement signal and the reference signal detected from the interference light wave in that state are input to the phase meter 30 to calculate the phase difference, and when stored in the computer 31, the servo lock is started. Next, the R stage 3 and the θ stage 7 are moved simultaneously or independently, and the phase difference obtained at that time is compared with the stored phase difference. The Z servo controller 32 sets the Z difference so that the deviation always becomes zero. The stage 4 is moved (servo lock state). This makes it possible to always keep the distance between the DUT 1 and the optical probe 2 constant.

FIGS. 7A and 7B show the structure of a laser length measuring device. FIG. 7A shows laser length measuring devices 9a and 9b.
It is a block diagram of b, 9c, 9d, and measures the distance between a laser length measuring device and one reference mirror. FIG. 7B is a configuration diagram of the laser length measuring devices 9e, 9f, 9g, and 9h, and measures the distance between two reference mirrors. In this case, the measurement resolution of the laser length measuring device is doubled because the double path method is used in which the optical path to be measured is reciprocated twice. In FIG. 7A, reference numeral 13 denotes a laser light source that generates two light waves whose polarization directions are orthogonal to each other. The light beam emitted from the laser light source 13 is divided into a reflected light wave and a transmitted light wave by the polarization beam splitter 15c. The transmitted light wave is reflected twice by the corner cube 22a to become a reference light wave, and passes through the polarization beam splitter 15c again. One reflected light wave changes from linearly polarized light to circularly polarized light by passing through the λ / 4 plate 16c, and is reflected by the reference mirrors 5 and 6 (for example, the Z reference mirror 5) to become a measurement light wave. The measuring light wave returns to the original optical path, and passes through the λ / 4 plate 16c again, which is 90 ° as compared with the going light wave.
The beam becomes the rotated linearly polarized light, and the polarization beam splitter 15
c, and is reflected twice by the corner cube 22b, and is again reflected by the polarizing beam splitter 15c and the λ / 4 plate 1.
The light returns to reference mirrors 5 and 6 through 6c. The measurement light wave reflected again is 90 ° in comparison with the outgoing light at the λ / 4 plate 16c.
The beam becomes the rotated linearly polarized light, and the polarization beam splitter 15
It will be reflected at c. Here, the measurement lightwave and the reference lightwave overlap, and when they pass through the polarizing plate 18, they become interference lightwaves, which are detected by the length measuring device receiver 28. The fluctuation of the phase difference between the measurement light wave and the reference light wave is observed by the length measuring device as the count of the fringe of the interference light wave. Since the optical path length of the reference light wave is always constant, a change in the optical path length of the measured light wave, that is, two round trips of each stage movement amount from each reference mirror can be detected here from the count of the interference light wave fringes. . Similarly, a laser length measuring device for measuring the distance between two reference mirrors will be described with reference to FIG. In the figure, two orthogonal light waves emitted from the laser light source 13 are divided into a reflected light wave and a transmitted light wave by the polarization beam splitter 15c. The transmitted light wave is reflected twice by the corner cube 22a to become a reference light wave, and passes through the polarization beam splitter 15c again. One reflected light wave changes from linearly polarized light to circularly polarized light by passing through the λ / 4 plate 16c, and is reflected by the reference mirrors 5 and 6 (for example, the Z reference mirror 5) to become a measurement light wave. The measurement light wave returns to the original optical path, becomes linearly polarized light rotated by 90 ° as compared with the outgoing light at the λ / 4 plate 16c passing again, transmits through the polarization beam splitter 15c this time, passes through the λ / 4 plate 16d, The light is reflected by the reference mirrors 12a and 12b (for example, the θ reference mirror 12a) and returns to the original optical path. Again λ / 4 plate 16
The measurement lightwave incident on c becomes linearly polarized light rotated by 90 ° as compared with the outgoing light, and is then reflected by the polarization beam splitter 15c and incident on the corner cube 22a. The measurement light wave is reflected twice by the corner cube 22a, reenters the polarization beam splitter 15c, and is reflected there. Thereafter, the measurement light wave passes through the λ / 4 plate 16d, is reflected again by the reference mirrors 12a and 12b (for example, the θ reference mirror 12a), and is reflected by the λ / 4 plate 16d and the polarization beam splitter 15c.
And λ / 4 plate 16c, and again
6 (for example, the Z reference mirror 5) and is reflected. The measurement light wave reflected by the reference mirror passes through the λ / 4 plate 16c again to become linearly polarized light rotated by 90 ° as compared with the outgoing light, and is then reflected by the polarization beam splitter 15c. Here, the measurement lightwave and the reference lightwave overlap, and when passing through the polarizing plate 18, become an interference lightwave, which is detected by the length measuring device receiver 28. The fluctuation of the phase difference between the measurement light wave and the reference light wave is observed by the length measuring device as the count of the fringe of the interference light wave. Since the optical path length of the reference light wave is always constant, the variation of the optical path length of the measurement light wave, that is, the two round trips of the amount of change in the distance between the two reference mirrors is detected here from the count of the interference light wave fringes. it can.

Next, a specific measuring method using the three-dimensional shape measuring machine configured as described above will be described.

The axisymmetric aspherical lens 1 to be measured is set on the θ stage 7 so that its axis substantially coincides with the rotation axis of the θ stage 7. Thus, the optical probe 2 can be scanned over the entire surface in accordance with the shape of the DUT 1 by combining the θ-axis rotation on the DUT side and the RZ-axis scanning on the optical probe side. The optical probe 2 is moved to the rotation center of the θ axis, and then the Z stage 4
The servo lock is started in a state where the cat's eye point created by the light flux of the optical probe 2 is incident on the object 1 by lowering the distance. At this time, the output values of the laser length measuring devices 9a to 9h and the rotary encoder 10 are fetched, and RD1o, RD2o, ZD1o are taken, respectively.
, ZD2o, θD1o, θD2o, θD3o, θD4o
, REo in the computer. next,
With the servo locked state, the R stage 3 and the θ stage 7 are moved independently or simultaneously, and the laser length measuring devices 9a to 9h are measured at points to be measured (i = 1 to n, i: order of capture).
RD1i, RD2i, ZD1i, ZD2i respectively.
, ΘD1i, θD2i, θD3i, θD4i, REi
Is stored. Similarly, the entire surface of the DUT 1 is scanned by the optical probe 2 to acquire n sets of data, and for example, the following arithmetic processing is performed.

[0029]

(Equation 1)

By such an arithmetic processing, three-dimensional coordinates at each measurement point can be calculated with high accuracy. Therefore, a highly accurate three-dimensional shape of the device under test can be represented using n sets of three-dimensional coordinate data.

FIG. 8 is a graph showing the relationship between R and R by the three-dimensional measuring machine of the present invention.
An example of data acquisition of three patterns viewed on a -θ cross section is shown. It should be noted that the axes in FIG. 8 are shown after being converted to a commonly used XY coordinate system. In the present invention, if data is captured at regular intervals while simultaneously moving the R stage and the θ stage, the data can be detected as spiral data as shown in FIG. 8A, and the R stage or the θ stage can be used alone. If data is captured at regular intervals while moving, it can be detected as concentric circle data as shown in FIG. Generally, 3
Grid data ((c) in FIG. 8), which is often used in a dimension measuring machine, is obtained by adjusting the movement amounts of the R stage and the θ stage in a grid pattern, or converting spiral data or concentric data using coordinate conversion or interpolation. The present invention can also cope with such a method.

In the present invention, when the shape of the object to be measured is axially symmetric, if data detection is performed based on the spiral data, the Z direction of the optical probe that moves in the servo lock state with respect to the θ stage or minute R stage movement Since the moving amount is extremely small, high-speed optical probe scanning becomes possible. When data detection is performed using concentric circle data, the state is maintained after the R stage is moved, and then data is captured at regular intervals while the θ stage is independently moved. As a result, the amount of movement of the optical probe in the Z direction, which moves in the servo locked state, becomes extremely small, so that high-speed optical probe scanning becomes possible.

As described above, in the three-dimensional measuring machine and the three-dimensional measuring method according to the present invention, the object to be measured is placed on the θ stage, the optical probe is provided on the R stage and the Z stage, Is used for a laser length measuring device as an optical probe position detecting means by arranging everything in the RZ plane and measuring the shape of the object to be measured in two dimensions in the RZ plane. Since the R reference mirror and the Z reference mirror are used only in a substantially one-dimensional range (on a straight line), the width of the reference mirror can be reduced. For this reason, the manufacture becomes easy, and an improvement in the flatness of the reference mirror can be expected. Then, the measurement error in the position detection means only needs to be considered on two dimensions in the RZ plane. That is, although the pitching component error of the stage is length-measured, the yaw and rolling components have a considerably small degree of influence, so that the number of correction items can be reduced and the measurement error can be reduced. When the shape of the DUT is axially symmetric and the DUT is rotated with the axis of the DUT substantially aligned with the rotation axis of the θ stage, the shape of the DUT on the same radius is substantially constant. Therefore, the scanning speed of the measuring position detecting means such as a probe can be increased,
Measurement time can be reduced.

[0034]

As described above, according to the present invention,
In a three-dimensional measuring machine, an object to be measured is placed on a θ stage, and probes are provided on an R stage and a Z stage.
All the probe position detecting means are arranged in the R-Z plane,
The following operational effects can be obtained by measuring the shape of the object to be measured two-dimensionally in the RZ plane.

1. Since the R reference mirror and the Z reference mirror used for the laser length measuring device serving as the optical probe position detecting means are used only in a substantially one-dimensional (on a straight line) range, the width of the reference mirror can be reduced. . For this reason, the manufacture becomes easy, and an improvement in the flatness of the reference mirror can be expected.

2. The measurement error in the position detecting means is R-
Only two dimensions in the Z plane need to be considered. That is, although the pitching component error of the stage is length-measured, the yaw and rolling components have a considerably small degree of influence, so that the number of correction items can be reduced and the measurement error can be reduced.

3. When the shape of the DUT is axially symmetric and the DUT is rotated with the axis of the DUT and the rotation axis of the θ stage substantially coincident, the shape of the DUT on the same radius is substantially constant. The scanning speed of the measuring position detecting means such as a probe can be increased, and the measuring time can be shortened.

Therefore, according to the three-dimensional measuring device and the three-dimensional measuring method of the present invention, it is possible to measure the three-dimensional shape of the object to be measured with high accuracy and in a short time.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a main part schematically showing a main part of a three-dimensional shape measuring instrument of the present invention.

FIG. 2 is a schematic side view of a main part of the three-dimensional shape measuring instrument of the present invention.

FIG. 3 is an arrangement configuration diagram showing an arrangement relationship of an optical probe and a laser length measuring device on the RZ plane in the three-dimensional measuring device of the present invention.

FIG. 4 is a configuration diagram showing an enlarged part of a θ stage in the three-dimensional measuring machine of the present invention.

FIG. 5 is a configuration diagram of an optical probe in the three-dimensional measuring device of the present invention.

FIG. 6 is a configuration diagram showing a configuration of a Z-axis servo in the three-dimensional measuring machine of the present invention.

7A and 7B show the configuration of a laser length measuring device in the three-dimensional measuring device of the present invention, wherein FIG. 7A is used for measuring the distance between the laser length measuring device and one reference mirror, and FIG. ) Is used to measure the distance between two reference mirrors.

8A and 8B show examples of data acquisition by the three-dimensional measuring device of the present invention, wherein FIG. 8A shows spiral data, FIG. 8B shows concentric data, and FIG. 8C shows grid data.

FIG. 9 is a schematic configuration diagram showing an example of a conventional shape measuring instrument.

FIG. 10 is a schematic configuration diagram showing another example of a conventional shape measuring instrument.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 object to be measured (axis target lens) 2 optical probe 3 R stage 4 Z stage 5 Z reference mirror 6 R reference mirror 7 θ stage (air bearing unit) 7A housing unit 7B rotor unit 9 (9a to 9h) Laser length measuring device Reference Signs List 10 Angle detecting means (rotary encoder) 11 Scale 12a, 12b θ reference mirror 13 Laser light source 14 Beam expander 15a, 15b, 15c Polarizing beam splitter 16a, 16b, 16c, 16d λ / 4 plate 17 Reference plane mirror 18 Polarizing plate 19 Line sensor 20a, 20b Condenser lens 21 Photodetector 22a, 22b Corner cube 30 Phase meter 31 Computer 32 Z servo controller

Claims (7)

[Claims] 1. A three-dimensional shape measuring apparatus for measuring a three-dimensional shape of an object to be measured using a probe that scans along the shape of the object to be measured. A θ stage provided so as to be movable in the θ-axis direction as a rotation component with respect to the Z-axis direction, and movable in the R-axis direction which is horizontal to the object to be measured on the θ stage. An R stage provided, and a Z stage movably provided in a Z-axis direction perpendicular to the object to be measured, wherein the probe is disposed on the R stage and the Z stage. The position detecting means provided on each of the stage, the θ stage and the Z stage have the same R
-A three-dimensional shape measuring machine, which is arranged on a Z plane. 2. Four laser length measuring devices are arranged on the R stage and the Z stage, and the laser length measuring devices are:
The two probes arranged on the R stage and the Z stage are respectively arranged in the freely movable RZ plane in the R-axis direction and the Z-axis direction. It is configured to scan along the shape of the object to be measured while moving in the Z-axis direction so that the distance to the object to be measured is always constant, and when scanning the entire surface of the object to be measured by the probe, R, θ, and Z at the three-dimensional coordinate position of the probe are detected at the same time, and R at the three-dimensional coordinate position is determined by the R reference mirror disposed at a position parallel to the Z axis and passing on the R axis. Z at the three-dimensional coordinate position is calculated from two laser length measuring devices arranged side by side in the axial direction, and Z is a Z reference mirror arranged at a position parallel to the R axis and passing on the Z axis. Two units arranged side by side in the R-axis direction And the θ at the three-dimensional coordinate position is a scale arranged in a radial direction of a rotor portion of a rotating mechanism constituting the θ stage and a scale fixed outside the θ stage. 2. The three-dimensional shape measuring apparatus according to claim 1, wherein the shape of the object is measured based on R, θ, and Z of the three-dimensional coordinates of the probe, which are calculated from a detector. 3. The θ stage is constituted by an air bearing, and a θ reference mirror is integrally attached to a rotor portion of the air bearing in a radial direction and a thrust direction. The three-dimensional shape measuring machine according to the above. 4. A measuring method for measuring a three-dimensional shape of an object to be measured using a probe that scans along the shape of the object to be measured, wherein the probe is moved in an R-axis direction that is a horizontal direction of the object to be measured. The object to be measured is simultaneously or individually moved in the θ-axis direction, which is a rotation component with respect to the Z-axis direction, which is the vertical direction of the object, and the probe is moved with the object at the time of the movement. The entire surface is scanned along the shape of the object to be measured while moving so that the distance is always constant, and R, θ, and Z of the three-dimensional coordinate position of the probe are simultaneously detected,
A three-dimensional shape measuring method, comprising: measuring a three-dimensional shape of the object to be measured based on the detected R, θ, and Z of the three-dimensional coordinates. 5. When calculating the R coordinate in the three-dimensional coordinates of the probe, two different R coordinates in the same RZ plane are used.
R coordinates R1 and R2 respectively detected at the positions P1 and P2, a distance D1 of a Z-direction component at an intermediate point between the positions P1 and P2 and an intersection of the probe tip and the object to be measured, and From the distance D2 of the Z-direction component between the positions P1 and P2, an R coordinate value R in consideration of the Abbe error
And calculating the Z coordinate at the three-dimensional coordinate position of the probe, the Z coordinate Z1, Z2 respectively detected at two different positions P3, P4 in the same RZ plane, Abbe error was considered from the distance D3 of the R direction component between the positions P3 and P4 and the intersection of the probe tip and the object to be measured, and the distance D4 of the R direction component between the positions P3 and P4. Z
5. The method according to claim 4, wherein the coordinate value Z is calculated.
Dimensional shape measurement method. 6. A thrust-direction surface shake amount and a radial-direction axis shake amount generated when rotating the object to be measured in the θ-axis direction, and a Z-coordinate value at a three-dimensional coordinate position of the probe is detected. The three-dimensional shape measurement according to claim 4, wherein the surface shake amount is considered as a correction value, and the axial shake amount is considered as a correction value in an R coordinate value at a three-dimensional coordinate position of the probe. Method. 7. When the object to be measured has an axially symmetric shape,
7. The shape measurement is performed after performing alignment so that the axis of the object to be measured and the Z-axis serving as the rotation axis in the θ-axis direction substantially coincide with each other. Item 3. The three-dimensional shape measuring method according to item 1.