WO2015093459A1 - Probe unit and shape-measuring device - Google Patents

Abstract

　Provided are a probe unit and a shape-measuring device which are compact, have a simple configuration, and are capable of accurate measurement, even of objects to be measured that readily deform. This probe unit, together with a sensor, is attached a frame of a shape-measuring device, and is used to measure the shape of an object to be measured, wherein the probe unit has: a stylus for contacting an object to be measured; a probe structure linked to the stylus, the probe structure having an orientation detection plate that extends in a direction different from the direction of extension of the stylus and faces the sensor; a holding part for holding the probe structure in a relatively rotatable manner with respect to the frame; and a moving mechanism for moving the probe structure in the direction of extension of the stylus, with respect to the frame, the position of the orientation detection plate being detected by the sensor to calculate the orientation of the probe structure in a state in which the stylus has abutted the object to be measured, whereby the shape of the object to be measured is measured.

Description

Probe unit and shape measuring device

The present invention relates to a probe unit and a shape measuring apparatus suitable for measuring, for example, the shape of an optical element.

As an apparatus for measuring the surface shape of an object to be measured such as an optical element, a measurement probe having a stylus that is movable in the Z direction (vertical direction) and has a substantially spherical tip is placed on an XY stage. Touching the surface of the object to be measured, scanning along the XY direction (horizontal direction) along the surface, obtaining the three-dimensional coordinate position of the stylus position at an arbitrary pitch, 2. Description of the Related Art A measuring device that obtains a contour shape of a surface to be measured from a point group is known.

In a measuring apparatus that performs such measurement, in general, the stylus has a spherical shape, and it is likely that high-precision measurement becomes difficult as the inclination angle of the surface to be measured approaches 90 °. . However, in the case of a high NA lens used in an optical pickup device, for example, the tilt angle around the optical surface may exceed 80 degrees, and there is a demand for measuring this optical surface with high accuracy. There is also a demand for measuring in one step the shape of the side surface of the flange parallel to the optical axis without replacing the measurement probe that has measured the optical surface. Therefore, a shape measuring apparatus that measures the shape of the object to be measured with a large inclination angle has been desired based on a concept different from the conventional one.

In contrast, the measurement probe and the object to be measured placed on the surface plate are moved relative to each other using a three-dimensional moving stage, and the moment when the measurement probe contacts the object to be measured is captured. A measurement technique has been developed in which a three-dimensional coordinate value in each feed axis direction of a stage is read as a trigger, and the shape of an object to be measured is obtained from this coordinate value group. According to such a measurement technique, the three-dimensional coordinate value can be read from the touch of the measurement probe even on a vertical plane, so that measurement can be performed regardless of the shape of the object to be measured. In such a measurement technique, a touch signal type measurement probe that can electrically detect the contact state between the measurement probe and the object to be measured and output it as a touch signal is used.

Patent Document 1 discloses a touch signal type measurement probe in which a sphere is supported by a rolling device. The measurement probe with contact can be rotated around the center of the sphere, so that even if the shape of the object to be measured is a free-form surface, the probe contact is continuously brought into contact with the object to be measured at a high speed. Can be made.

JP 58-205801 A

By the way, although there is no clear description in Patent Document 1, the measurement probe is presumed to measure the shape of a rigid body such as a metal product from its rigid structure, A three-dimensional shape measuring machine generally requires a contact pressure of about 1 to 10 g · f. Therefore, when this type of three-dimensional shape measuring machine is used as a measurement object such as a resin lens, the measurement object can be deformed or slipped when pressed against the surface, enabling high-precision measurement. There is no fear. In addition, it is structurally unsuitable for scan measurement, for example, high-precision measurement of the order of 0.1 μm or less. Furthermore, the configuration of Patent Document 1 is a structure that is relatively long in the axial direction. In particular, when it is necessary to increase the displacement sensitivity of the measurement probe, it is necessary to further extend the length in the axial direction. There is a problem that the installation space is limited due to the increase in height. In addition, the sphere of the measurement probe used in Patent Document 1 is supported by a rolling device composed of a large number of rolling small spheres. When the axial force is received from the object to be measured in the axial direction of the measuring probe, the rolling sphere is small. When the measurement probe is tilted, the tilt may not be stable.

An object of the present invention is to provide a probe unit and a shape measuring apparatus that have been made in view of the above-described problems, have a small and simple configuration, and can accurately measure even a subject to be easily deformed. That is.

In order to realize at least one of the above-described objects, a probe unit reflecting one aspect of the present invention is attached to a frame of a shape measuring device together with a sensor and used to measure the shape of an object to be measured. A probe unit that is in contact with an object to be measured; and a posture detection plate that is connected to the stylus part and extends in a direction different from an extending direction of the stylus part and faces the sensor. A probe structure including: a holding portion that holds the probe structure relative to the frame so as to be rotatable relative to the frame; and a movement that moves the probe structure in the extending direction of the stylus portion relative to the frame. And detecting the position of the posture detection plate by the sensor to determine the posture of the probe structure in a state where the stylus part is in contact with the object to be measured, thereby measuring To measure the shape of the object.

This shape measuring apparatus includes the above-described probe unit, a frame that holds the probe unit, and a sensor attached to the frame.

According to the present invention, it is possible to provide a probe unit and a shape measuring apparatus that have a small and simple configuration and can accurately measure even a subject to be easily deformed.

It is a perspective view which shows the shape measuring apparatus by 1st Embodiment. It is a perspective view of the probe unit 100 of FIG. FIG. 3 is a cross-sectional view of the probe unit 100 of FIG. 2 as viewed from a direction perpendicular to the surface by cutting along a plane PL indicated by a one-dot chain line. FIG. 6 is a schematic diagram showing the relationship between the center position P0 of the ball 110a of the stylus part 110 and the measurement positions P1 to P3 of the attitude detection plate 111. FIG. 5 is a cross-sectional view similar to FIG. 3 of a probe unit 100 ′ according to a modification of the first embodiment. It is a perspective view of the probe unit 200 by 2nd Embodiment. It is sectional drawing which cut | disconnected the probe unit 200 of FIG. 6 by the surface PL shown with a dashed-dotted line, and was seen from the direction perpendicular | vertical to a surface. It is sectional drawing similar to FIG. 7 of probe unit 200 'by the modification of 2nd Embodiment. It is a perspective view of the probe unit 300 by 3rd Embodiment. It is sectional drawing which cut | disconnected the probe unit 300 of FIG. 9 by the surface PL shown with a dashed-dotted line, and was seen from the direction perpendicular | vertical to a surface.

Embodiments according to the present invention will be described below with reference to the drawings. However, although various technically preferable limitations for carrying out the present invention are given to the embodiments described below, the scope of the invention is not limited to the following embodiments and illustrated examples. Here, the Z-axis direction is a vertical direction, and the X-axis direction and the Y-axis direction are horizontal directions.

[First Embodiment]
FIG. 1 is a perspective view showing a shape measuring apparatus according to the first embodiment. In FIG. 1, a pair of pillars 11 are erected on a surface plate 10. The beam member 12 extends horizontally so as to connect the upper ends of the pair of columns 11. A Z-axis stage 15 is provided in the center of the beam member 12 via a holder 13. The Z-axis stage 15 can move the probe unit 100 arranged in the frame with the stylus part protruding downward in the Z-axis direction.

On the surface plate 10, an X-axis stage 17 movable in the X-axis direction and a Y-axis stage 18 movable in the Y-axis direction are stacked, and the mounting surface on the uppermost surface thereof. The object to be measured OBJ placed on 19 can be displaced independently in the X-axis direction and the Y-axis direction. The output signals from the three sensors of the probe unit 100 are input to the CPU and used to determine the shape of the object to be measured. Further, the mounting surface 19 is provided with a mirror MX facing the X-axis direction and a mirror MY facing the Y-axis direction. A laser length measuring device LX provided on the surface plate 10 faces the mirror MX, and a laser length measuring device LY provided on the surface plate 10 faces the mirror MY. The X-axis direction displacement amount and the Y-axis direction displacement amount of the mounting surface 19 can be measured.

FIG. 2 is a perspective view of the probe unit 100. FIG. 3 is a cross-sectional view of the probe unit 100 shown in FIG. 2 taken along a plane PL indicated by a one-dot chain line and viewed from a direction perpendicular to the plane. In the figure, the probe unit 100 has a box-shaped frame 101 attached to the Z-axis stage 15 (FIG. 1). Three capacitive sensors 102 are attached so as to penetrate the upper wall 101a of the frame 101. Since the configuration of the sensor 102 is well known, details are omitted.

The levitation guide portion 103 constituting the levitation mechanism is fixedly disposed on the upper surface of the lower wall 101b of the frame 101. As shown in FIG. 3, the levitation guide portion 103 includes a bottom wall 103a and a side wall 103b extending upward so as to surround the bottom wall 103a. An opening 103c is formed at the center of the bottom wall 103a, and the opening 103c communicates with the opening 101c formed at the center of the lower wall 101b. A cylindrical recess 103d is formed inside the side wall 103b. A communication hole 103e for introducing air from the outside is formed at the bottom of the recess 103d.

The disc 104 is formed so as to fit in the recess 103d with almost no gap. The disk 104 has an opening 104a at the center. The lower part of the opening 104a has an enlarged diameter, and a circular magnet 104b is disposed here. On the upper surface of the disk 104, concave portions 104c are formed at three locations (only one location is shown in FIG. 3) at equal intervals so as to surround the periphery of the opening 104a. In each recess 104c, for example, ceramic spheres 105 are disposed so as not to be displaced.

Also, one end of a plate-like support member 107 is attached to the upper end of a pole 106 planted on the upper surface of the disk 104. A recess 107a is formed in the lower surface near the other end of the support member 107, and a small ball 108 made of ceramic, for example, is disposed in the recess 107a so as not to be displaced. The small sphere 108 may have the same diameter as the small sphere 105.

A large sphere 109 that is a spherical body is placed on the three small spheres 105, and the small sphere 108 is in contact with the apex of the large sphere 109. That is, the small spheres 105 and 108 are in point contact with the spherical surface of the large sphere 109 without looseness. The disk 104 constitutes a holding unit.

From the lower part of the large sphere 109, a rod-like stylus part 110 extends so that the axis passes through the center of the large sphere 109, and the magnet 104 b in the opening 104 a of the disk 104, the opening 103 c of the levitation guide part 103, The wall 101b penetrates through the opening 101c with a gap and projects downward. A ball 110 a is formed at the tip of the stylus 110. The side surface of the stylus 110 is magnetized with the same polarity (N or S) as the inner peripheral surface of the magnet 104b. Therefore, the stylus 110 is biased with a magnetic force in the direction of centering with respect to the inner peripheral surface of the magnet 104b that functions as a control mechanism. If the position of the stylus 110 can be grasped at the start of measurement, it is not always necessary to perform centering. However, the centering causes the stylus 110 to be displaced outside the measurable range during measurement. This can be suppressed.

On the other hand, the inner ends of three elongated posture detection plates 111 are attached to the side of the large sphere 109 so as to extend along a plane orthogonal to the axis of the stylus 110. The longitudinal axis of each posture detection plate 111 passes through the center of the large sphere 109. The detection unit of the sensor 102 faces the upper surface in the vicinity of the outer end of each posture detection plate 111. The sensor 102 can measure the distance to the surface on the longitudinal axis of the facing posture detection plate 111. The large sphere 109 is located at the base where the stylus 110 and the posture detection plate 111 are connected. A probe structure 112 is configured by the large sphere 109, the stylus part 110, and the posture detection plate 111.

The probe structure 112 can move downward in the extending direction of the stylus part 110 by its own weight with respect to the frame 101, and can move up and down according to the shape of the measurement object OB with which the stylus part 110 comes into contact. Since the disk 104 floats while being held by the (disk 104) and is supported by the floating, the entire weight of the probe structure 112 is not added to the object to be measured OB. For this reason, the contact pressure with respect to the to-be-measured object OB of the stylus part 110 decreases.

Next, the measurement operation of this embodiment will be described. First, when a connector (not shown) is connected to the communication hole 103e and air whose pressure is controlled is supplied into the recessed space 103d of the levitation guide 103 and the sealed space in the disk 104, the disk 104 becomes a probe structure. In a state where 112 is held, the aircraft rises with respect to the floating guide portion 103. However, the air pressure is controlled so that the contact pressure of the stylus 110 during measurement is 5 to 50 mg · f.

The Z-axis stage 15 is driven, for example, the ball 110a of the stylus 110 is brought into contact with the highest position of the object OBJ, and the CPU reads the output signal of the sensor 102 with this point as the origin. When the X-axis stage 17 or the Y-axis stage 18 is driven from this state, the ball 110a moves along the surface of the object to be measured OBJ. Therefore, the stylus part 110 moves in the Z-axis direction according to the surface shape. Or tilt. When the stylus 110 is tilted, the large sphere 109 rolls in contact with the small spheres 105 and 108. Therefore, the stylus 110 can roll with almost no resistance except the magnetic force of the magnet 104b. Further, even after rolling, the center position of the large sphere 109 with respect to the disk 104 remains unchanged. When the ball 110a of the stylus 110 is moved, the measurement error can be reduced by moving the stylus 110 while keeping the contact pressure of the stylus 110 constant.

On the other hand, when the stylus part 110 moves in the Z-axis direction, the three attitude detection plates 111 also move in the same direction, and when the stylus part 110 tilts, three attitude detections are performed according to the direction and angle. The plate 111 is also inclined. The displacement amount of the posture detection plate 111 is detected by the sensor 102.

FIG. 4 is a schematic diagram showing the relationship between the center position P0 of the ball 110a of the stylus 110 and the measurement positions P1 to P3 of the posture detection plate 111. The center of the large sphere 109 is shown as a point O. Here, the three-dimensional coordinates of the measurement position P1 of the three posture detection plates 111 are (x1, y1, z1), the three-dimensional coordinates of the measurement position P2 are (x2, y2, z2), and the three-dimensional of the measurement position P3. When the coordinates are (x3, y3, z3), the three-dimensional coordinates (x0, y0, z0) of the center position P0 of the ball 110a can be represented as these functions. However, it is assumed that the length L of the stylus 110, the radius of the ball 110a, and the span S of the posture detection plate 111 are known. Note that the X-axis coordinate value and the Y-axis coordinate value of the measurement points P1 to P3 can be obtained from the movement amounts of the X-axis stage and the Y-axis stage, and the Z-axis coordinate value can be obtained from the output signal of the sensor 102. it can. Therefore, there is no problem even if the sensor 102 cannot detect the X-axis coordinate value and the Y-axis coordinate value.

Therefore, as shown by a dotted line in FIG. 4, when the stylus part 110 is inclined, the amount of displacement of the center position P0 of the ball 110a is obtained by obtaining the change in the measurement positions P1 to P3 of the posture detection plate 111, and further, By considering the radius of the ball 110a, the three-dimensional coordinates at the measurement point of the object OBJ can be obtained. By connecting the obtained three-dimensional coordinates, the surface shape of the object OBJ can be obtained.

According to the present embodiment, the posture of the posture detection plate 111 can be detected based on the output signal from the sensor 102 by bringing the stylus part 110 into contact with the surface of the object OBJ to be measured. The shape can be measured with high accuracy even at an angle close to vertical, and therefore the optical surface and flange of the high NA optical element can be measured in one step without replacing the stylus 110. In addition, since the flying guide portion 103 floats and supports the disk 104 holding the probe structure 112 with respect to the frame 101, it is avoided that the entire weight of the probe structure 112 is received by the object to be measured OBJ. Even if the measurement object OBJ is a relatively soft object such as a resin lens, the deformation of the surface with which the stylus 110 abuts can be suppressed. Further, since the number of parts of the probe unit 100 is small and the mass of the moving body can be reduced by detecting the position of the posture detection plate 111 in a non-contact manner, the follow-up performance of the floating control that makes the contact pressure constant can be improved. it can. In addition, the detection sensitivity of the inclination of the probe structure 112 can be improved by increasing the span of the posture detection plate 111, but even in that case, the height of the probe structure 111 can be suppressed, and thus the height of the shape measuring device can be suppressed. Can be suppressed.

FIG. 5 is a cross-sectional view similar to FIG. 3 of a probe unit 100 ′ according to a modification of the present embodiment. In the probe unit 100 ′ according to this modification, the stylus part 110 has a two-divided shape. More specifically, it includes a shaft-like root portion 110b fixed to the lower portion of the large sphere 109 and a tip portion 110c having a ball 110a attached to the tip. A screw hole 110d is formed at the lower end of the root part 110b, and a male screw part 110e is formed at the upper end of the tip part 110c. By screwing the male screw part 110e into the screw hole 110d, the root part 110b is formed. And the tip 110c are joined.

In this embodiment, instead of providing the magnet 104b as a control mechanism, a plurality of spring members 104d are provided in the opening 104a, fitted around the root portion 110b, and movable in the axial direction. The bush 110e is urged in the radial direction to provide a centering function for the stylus 110. Other than that, it is the same as the embodiment described above.

Since the stylus part 110 of the above-described embodiment is formed integrally with the large sphere 109, if the stylus part 110 is bent or broken due to inadequate handling, the probe structure 112 does not have to be replaced as a whole. It will cause an increase in repair costs. On the other hand, in the case of this embodiment, when the tip portion 110c is bent or broken, it can be removed from the root portion 110b and replaced with another tip portion 110c, and the repair cost can be reduced.

According to the present embodiment, the probe structure 110 based on the output signal from the sensor 102 in a state where the stylus 110 of the probe structure 112 having a relatively simple structure is in contact with the surface of the object OBJ. Since the posture of the body can be detected, it is possible to accurately measure the shape even when the surface to be measured is near vertical, while improving the followability of the stylus part during measurement and suppressing deformation of the object to be measured. Therefore, it is possible to measure the optical surface and flange portion of the high NA optical element in one step without replacing the stylus portion. Furthermore, the detection sensitivity of the probe structure tilt can be improved by lengthening the posture detection plate, but even in that case, the height of the probe structure can be suppressed, thereby suppressing the height of the shape measuring apparatus. . The spherical body at the base is preferably a spherical body, but it is sufficient if it has a spherical surface locally.

In addition, since the probe unit 100 has a floating mechanism that floats and supports the holding portion 104 with respect to the frame 101, the floating mechanism floats and supports the holding portion that holds the probe structure 112 with respect to the frame. It is avoided that the entire body weight is received by the object to be measured, so that even if the object to be measured is relatively soft, deformation of the surface with which the stylus part abuts can be suppressed.

This levitation mechanism can levitate and hold the holding portion with respect to the frame using a simple source of aerodynamic force or magnetic force. Since the probe structure is relatively light, the levitation force of the levitation mechanism is relatively small, and the holding portion can be easily supported without contact by aerodynamic force or magnetic force.

Also, the holding unit 104 preferably has four spheres (small spheres 105) that come into contact with the spherical surface of the base. Since the sphere of the measurement probe used in Patent Document 1 is supported by a rolling device composed of a large number of rolling globules, it is difficult to contact all the rolling globules evenly in consideration of variation in shape. There is a possibility that when the measurement probe is tilted, the rolling sphere supporting the sphere changes and the tilt is not stable. On the other hand, as in this embodiment, by using four spheres that contact the spherical surface of the base, the spherical surface of the base can be stably held regardless of the inclination of the probe structure. However, the number is not limited to four spheres contacting the spherical surface of the base, and may be five or more. For example, three spheres arranged so that each center is located at the apex of the equilateral triangle contact and support the lower part of the base, and three spheres arranged so that each center is located at the apex of the equilateral triangle are located above the base. The structure which touches may be sufficient.

Further, the probe unit has a control mechanism (magnet 104b) that regulates the inclination of the probe structure, so that the probe structure can be displaced to the reference position before the measurement is started, and the frame or the like is inadvertently moved. Can be prevented from touching. As such a control mechanism, for example, there is a mechanism that biases the probe structure with respect to the frame by a magnetic force or a spring force.

Further, it is preferable that three posture detection plates 111 of the probe structure are provided so as to extend at equal intervals along the same virtual plane, and the sensors each measure the distance from the three posture detection plates. . By calculating the output signals from the sensors that measure the distances from the three posture detection plates, the position of the stylus part can be obtained with high accuracy. However, a single disk may be used instead of the three attitude detection plates.

1 has a probe unit 100, a frame 101 that holds the probe unit 100, and a sensor 102 that is attached to the frame, and thus has a small and simple configuration and is easily deformed. It is possible to provide a shape measuring apparatus that can accurately measure even a measured object.

[Second Embodiment]
The second embodiment is different from the first embodiment only in the configuration of the probe unit. Therefore, the same parts are denoted by the same reference numerals, and the description thereof is omitted.

FIG. 6 is a perspective view of the probe unit 200 according to the second embodiment. FIG. 7 is a cross-sectional view of the probe unit 200 of FIG. 6 taken along a plane PL indicated by a one-dot chain line and viewed from a direction perpendicular to the plane. In the figure, the probe unit 200 has a box-shaped frame 101 attached to the Z-axis stage 15 (FIG. 1). Three capacitive sensors 102 are attached so as to penetrate the upper wall 101a of the frame 101.

A cylindrical holding portion 203 is fixedly disposed on the upper surface of the lower wall 101b of the frame 101. As shown in FIG. 7, the holding unit 203 has an opening 203 a at the center. The opening 203a communicates with the opening 101c formed at the center of the lower wall 101b.

The outer peripheries of the thin plate-like first spring plate material 204 and second spring plate material 205 are fixed in parallel to the upper end and the vicinity of the upper end of the holding portion 203, respectively. Circular openings 204a and 205a are formed at the centers of the first spring plate member 204 and the second spring plate member 205, respectively.

The probe structure 112 includes a rod-shaped stylus portion 110 extending in the vertical direction, a base portion 209 having a spherical surface 209 a formed at the upper end of the stylus portion 110, and an axis line from the base portion 209 to the stylus portion 110. It is integrally formed from three elongated posture detecting plates 111 connected so as to extend along orthogonal surfaces.

The rod-shaped stylus portion 110 protrudes downward through the opening 203a of the holding portion 203 and the opening 101c of the lower wall 101b with a gap therebetween. A ball 110 a is formed at the lower end of the stylus part 110.

The maximum diameter of the spherical surface 209 a of the base 209 is larger than the diameters of the openings 204 a and 205 a of the first spring plate material 204 and the second spring plate material 205. The first spring plate material 204 is slightly elastically deformed on the side closer to the posture detection plate 111 than the center of the spherical surface 209a, and the opening 204a is engaged with the spherical surface 209a, and the second spring plate material 205 is also formed on the spherical surface 209a. The opening 205a is engaged with the spherical surface 209a while being slightly elastically deformed on the side closer to the stylus part 110 than the center. Therefore, the probe structure 112 is supported in a floating manner with respect to the holding portion 203 by the base portion 209 being elastically supported by the first spring plate material 204 and the second spring plate material 205 which are elastic bodies. . For this reason, the contact pressure with respect to the to-be-measured object OB of the stylus part 110 decreases.

In the present embodiment, as shown in FIG. 7, the elastic body is composed of two spring plate members 204 and 205 each having openings 204a and 205a having a diameter smaller than that of the spherical surface 209a, and one of the spring plate members 204 is a spherical surface. The opening 204a is engaged with the spherical surface on the side closer to the posture detection plate 111 than the center of 209a, and the other spring plate member 205 is engaged with the spherical surface on the side closer to the stylus part 110 than the center of the spherical surface 205a. . By configuring the elastic bodies 204 and 205 from the two spring plate members 204 and 205 that sandwich the base portion 209, it is possible to achieve a simple and low cost.

The detection unit of the sensor 102 faces the upper surface near the outer end of each posture detection plate 111. The sensor 102 can measure the distance to the surface on the longitudinal axis of the facing posture detection plate 111. The probe structure 112 is constituted by the stylus part 110 and the posture detection plate 111.

Next, the measurement operation of this embodiment will be described. First, the probe structure 112 is controlled according to the elastic force of the first spring plate member 204 and the second spring plate member 205 so that the contact pressure of the stylus part 110 during measurement is 5 to 50 mg · f. Shall.

The Z-axis stage 15 is driven, for example, the ball 110a of the stylus 110 is brought into contact with the highest position of the object OBJ, and the CPU reads the output signal of the sensor 102 with this point as the origin. When the X-axis stage 17 or the Y-axis stage 18 is driven from this state, the ball 110a moves along the surface of the object to be measured OBJ. Therefore, the stylus part 110 moves in the Z-axis direction according to the surface shape. Or tilt.

Here, when the stylus part 110 moves or tilts in the Z-axis direction, the first spring plate material 204 and the second spring plate material 205 are slightly elastically deformed, but since the elastic force is slight, almost no resistance is obtained. In addition, the three posture detection plates 111 together with the base 209 also move in the same direction and tilt. The displacement amount of the posture detection plate 111 is detected by the sensor 102.

Similar to the description of FIG. 4, when the stylus 110 is tilted, the amount of displacement of the center position P0 of the ball 110a is obtained by obtaining the change in the measurement positions P1 to P3 of the posture detection plate 111, and further, By considering the radius, the three-dimensional coordinates at the measurement point of the object OBJ can be obtained. By connecting the obtained three-dimensional coordinates, the surface shape of the object OBJ can be obtained.

According to the present embodiment, the posture of the posture detection plate 111 can be detected based on the output signal from the sensor 102 by bringing the stylus part 110 into contact with the surface of the object OBJ to be measured, for example. The shape measurement can be performed with high accuracy even when the power surface is nearly perpendicular, and therefore the optical surface, flange portion, etc. of the high NA optical element can be measured in one step without replacing the stylus 110. In addition, the detection sensitivity of the inclination of the probe structure 112 can be improved by increasing the span of the posture detection plate 111, but even in that case, the height of the probe structure 111 can be suppressed, and thus the height of the shape measuring device can be suppressed. Can be suppressed. In addition, since the first spring plate member 204 and the second spring plate member 205 that elastically support the spherical surface 209a of the base 209 with respect to the frame 101 are provided, the probe structure 112 can be elastically supported and measured. The probe structure 112 can be easily moved and tilted in the Z-axis direction according to the position of the stylus part 110 in contact with the object OBJ, and the stylus part 110 is brought into contact with the object OBJ during measurement. The contact pressure at the time of contact can be controlled, so that even if the object OBJ is relatively soft, deformation of the surface with which the stylus 110 abuts can be suppressed. For example, it is possible to apply feedback control that relatively displaces the probe structure and the object to be measured so that the contact pressure is constant.

FIG. 8 is a cross-sectional view similar to FIG. 7 of a probe unit 200 ′ according to a modification of the present embodiment. The probe unit 200 ′ according to the present embodiment is provided with a single spring plate 204 having the same configuration as that of the above-described embodiment as an elastic body.

Furthermore, a disc-shaped slide portion 206 is provided in the holding portion 203 according to the modification of the present embodiment. The outer diameter of the slide part 206 is substantially equal to the inner diameter of the opening 203a of the holding part 203, and the slide part 206 can slide in the opening 203a. The slide part 206 has a through hole 206a through which the stylus part 110 penetrates with a gap in the center, and three places (see FIG. 5) on the upper surface of the slide part 206 at equal intervals so as to surround the periphery of the through hole 206a. In FIG. 8, a recess 206b is formed at only one location. In each recess 206b, a small metal ball 207 is disposed so that it cannot be displaced but can roll. A base 209 is placed on the three small spheres 207. At the time of assembly, the small sphere 207 is in point contact with the spherical surface 209a of the base 209 without backlash.

Below the slide portion 206, a communication hole 203b for introducing air from the outside is formed in the side wall of the holding portion 203. Other configurations are the same as those in the above-described embodiment.

In this modification, as shown in FIG. 8, the elastic body is composed of a spring plate material 204 having an opening 204a having a diameter smaller than the diameter of the spherical surface 209a, and the spring plate material 204 is closer to the posture detection plate 111 than the center of the spherical surface 209a. The opening 204a is engaged with the spherical surface 209a on the side, and the holding portion 203 includes three spheres 207 that are in contact with the spherical surface 209a of the base portion 209 on the side closer to the stylus portion 110 than the center of the spherical surface 209a. The slide unit 206 includes biasing means for biasing the slide unit 206 toward the base 209 with air or the like.

The measurement operation of this modification will be described. First, when a connector (not shown) is connected to the communication hole 203b and air whose pressure is controlled is supplied into the space surrounded by the slide part 206 in the opening 203a, the slide part 206 holds the probe structure 112. In this state, it floats with respect to the holding unit 203. Then, the opening 204a is engaged with the spherical surface 109a in a state where the first spring plate material 204 is slightly elastically deformed on the side closer to the posture detection plate 111 than the center of the spherical surface 209a.

When the ball 110a moves along the surface of the object to be measured OBJ at the time of measurement, the stylus part 110 moves or tilts in the Z-axis direction according to the surface shape, and the spring plate material 204 is slightly elastic at that time. Although deformed, the elastic force is slight, so there is almost no resistance, and the three posture detection plates 111 together with the base 209 move in the same direction and tilt. At this time, since the spherical surface 209a of the base portion 209 is evenly supported by the upper surface of the small sphere 207, the probe structure 112 can be stably tilted and can be stably held.

In addition, the shape measuring apparatus according to the present embodiment has a probe unit 200 or 200 ′, a frame 101 that holds the probe unit, and a sensor 102 attached to the frame, as in FIG. Even with an object to be measured that has a simple configuration and is easily deformed, measurement can be performed with high accuracy.

[Third Embodiment]
Since the third embodiment is different from the first embodiment only in the configuration of the probe unit, the same parts are denoted by the same reference numerals, and the description thereof is omitted.

FIG. 9 is a perspective view of the probe unit 300 according to the third embodiment. FIG. 10 is a cross-sectional view of the probe unit 300 of FIG. 9 as viewed from a direction perpendicular to the plane, cut along a plane PL indicated by a one-dot chain line. In the figure, the probe unit 300 has a box-shaped frame 101 attached to the Z-axis stage 15 (FIG. 1). Three capacitive sensors 102 are attached so as to penetrate the upper wall 101a of the frame 101.

A housing-like holding portion 103 is fixedly arranged on the upper surface of the lower wall 101b of the frame 101. As shown in FIG. 10, the holding unit 303 has an opening 303 a at the center. The opening 303a communicates with the opening 101c formed at the center of the lower wall 101b.

On the upper surface of the holding portion 303, concave portions 303b are formed at three locations (only one location is shown in FIG. 10) at equal intervals so as to surround the periphery of the opening 303a. In each recess 303b, a small metal ball 305 is disposed so as to be able to roll, although it cannot be displaced.

On the three small spheres 105, a levitation support portion 309 is placed. The levitation support portion 309 is formed around a flat upper surface 309a, a spherical surface 309b formed therebelow, a through hole 309c that vertically penetrates the center of the levitation support portion 309, and a lower end of the through hole 309c. And an annular protrusion (second restricting portion) 309d. At the time of assembly, the small balls 305 are in point contact with the spherical surface 309b of the levitating support portion 309 without play.

The rod-shaped stylus portion 110 extends so as to be inserted into the through hole 309c of the levitation support portion 309 with a small gap g, and further inside the opening 303a of the holding portion 303 and the opening 101c of the lower wall 101b, It penetrates with a gap and protrudes downward. For example, the stylus part 110 is formed with a floating support part 309 made of a porous material and introduces air supplied from the outside into the through hole 309c with respect to the through hole 309c. Thus, the gap g is held in a non-contact manner and can slide smoothly in the axial direction. Magnetic force may be used instead of air pressure.

A ball 110 a is formed at the lower end of the stylus part 110, and at the upper end of the stylus part 110, three elongated posture detection plates 111 are along a plane perpendicular to the axis of the stylus part 110. Are connected so as to extend. In the vicinity of the base portion 109 where the posture detection plate 111 and the stylus portion 110 are connected, the posture detection plate 111 faces the upper surface 309a of the levitation support portion 309 so as to be separated from and substantially parallel to the upper surface 309a.

A donut plate-like magnet 306 is embedded in the upper surface 309 a of the levitation support portion 309. On the other hand, the lower surface of the levitation support portion 309 facing this is magnetized with the same polarity (N or S) as the upper surface of the magnet 306. The posture detection plate 111 connected to the stylus part 110 is supported by levitation with respect to the levitation support part 309 by the magnetic force acting between them. For this reason, the contact pressure with respect to the to-be-measured object OB of the stylus part 110 decreases. In addition, the upper surface of the holding portion 303 as the first restricting portion is magnetized with a polarity (S or N) different from that of the lower surface of the magnet 306, so that the levitation support portion 309 is held by the holding portion 303 by the magnetic force acting between them. As a result, the separation of the floating support portion 309 from the holding portion 303 is restricted.

The detection unit of the sensor 102 faces the upper surface near the outer end of each posture detection plate 111. The sensor 102 can measure the distance to the surface on the longitudinal axis of the facing posture detection plate 111. The probe structure 112 is constituted by the stylus part 110 and the posture detection plate 111.

Next, the measurement operation of this embodiment will be described. First, in the probe structure 112, it is assumed that the contact pressure of the stylus part 110 during measurement is controlled to about 5 to 50 mg · f according to the magnetic force of the magnet 306.

The Z-axis stage 15 is driven, for example, the ball 110a of the stylus 110 is brought into contact with the highest position of the object OBJ, and the CPU reads the output signal of the sensor 102 with this point as the origin. When the X-axis stage 17 or the Y-axis stage 18 is driven from this state, the ball 110a moves along the surface of the object to be measured OBJ. Therefore, the stylus part 110 moves in the Z-axis direction according to the surface shape. Or tilt. When the stylus part 110 is tilted, the levitation support part 309 rolls in contact with the small balls 305 along the spherical surface 309b, so that the stylus part 110 can roll with little resistance. Further, even after rolling, the intersection of the axis of the stylus 110 and the axis of the attitude detection plate 111 remains unchanged.

On the other hand, when the stylus part 110 moves in the Z-axis direction, the three posture detection plates 111 also move in the same direction with respect to the levitation support part 309, and when the stylus part 110 tilts, the direction and angle depend on the direction. Thus, the three posture detection plates 111 are also tilted together with the floating support portion 309. The displacement amount of the posture detection plate 111 is detected by the sensor 102. When the posture detection plate 111 is tilted too much, the protrusion 309d of the levitation support portion 309 contacts the inner wall of the opening 303a of the holding portion 303, so that further tilting is suppressed.

Similar to the description of FIG. 4, when the stylus 110 is tilted, the amount of displacement of the center position P0 of the ball 110a is obtained by obtaining the change in the measurement positions P1 to P3 of the posture detection plate 111, and further, By considering the radius, the three-dimensional coordinates at the measurement point of the object OBJ can be obtained. By connecting the obtained three-dimensional coordinates, the surface shape of the object OBJ can be obtained.

According to the present embodiment, the posture of the posture detection plate 111 can be detected based on the output signal from the sensor 102 by bringing the stylus part 110 into contact with the surface of the object OBJ to be measured. The shape can be measured with high accuracy even at an angle close to vertical, and therefore the optical surface and flange of the high NA optical element can be measured in one step without replacing the stylus 110. In addition, the detection sensitivity of the inclination of the probe structure 112 can be improved by increasing the span of the posture detection plate 111, but even in that case, the height of the probe structure 111 can be suppressed, and thus the height of the shape measuring device can be suppressed. Can be suppressed. In addition, since the probe support 112 is levitated and supported while the levitation support unit 309 holds the stylus unit 110 (can move in the axial direction without backlash), the stylus unit 110 contacts the object OBJ. Even when receiving the axial force in contact, only the probe structure 112 is lifted, so that it is avoided that the entire weight of the probe structure 112 is received by the object OBJ, and the object OBJ is relatively soft. Even so, the deformation of the surface with which the stylus 110 abuts can be suppressed. Further, since the levitation support portion 309 can maintain the state of being held by the holding portion 303 via the small sphere 305, the floating probe structure 112 can be tilted in a stable state and can be stably held. .

Further, the probe structure 112 is levitated and supported with respect to the frame 101 by the aerodynamic force or magnetic force in the levitating support portion 309. Since the probe structure 112 is relatively light, the levitation force of the levitation support portion 309 is relatively small, and the probe structure 112 can be easily supported in a non-contact manner by aerodynamic force or magnetic force.

In addition, since the floating support portion 309 is kept in contact with the holding portion 303 by having the first restricting portion that restricts the floating support portion 309 from being separated from the holding portion 303, highly accurate measurement can be performed. As the first restricting portion, one in which the levitation support portion and the holding portion holding portion are close to each other by magnetic force, spring force, or the like can be used.

Further, by having the second restricting portion that restricts the inclination of the probe structure 112, it is possible to prevent the probe structure 112 from inadvertently contacting the frame 101 or the like. As the “second restricting portion”, in addition to the protrusion 309 d provided on the floating support portion 309, for example, there is one that urges the probe structure 112 against the frame 101 with a magnetic force or a spring force.

Moreover, the shape measuring apparatus of this embodiment is small and simple by having the probe unit 300, the frame 101 holding the probe unit 300, and the sensor 102 attached to the frame, as in FIG. Even if it is a to-be-measured object which is a structure and is easy to deform | transform, it can measure accurately.

The present invention is not limited to the embodiments described in the present specification, and includes other embodiments and modifications based on the embodiments and technical ideas described in the present specification. It is obvious to For example, the buoyancy imparted by the levitation mechanism of FIG. 3 is not limited to air, but is a biasing force of a spring, or magnets of the same polarity are arranged on the bottom surface of the disk 104 and the bottom wall of the levitation guide portion 103, Buoyancy can also be imparted using magnetic repulsion.

Further, in FIG. 10, the buoyancy for levitating the probe structure 112 is not limited to the magnetic force but may be air pressure. Specifically, the levitation support portion 309 is made hollow so that air can be supplied from the outside, and a plurality of small holes are provided on the upper surface 309a of the levitation support portion 309 instead of magnets to blow out the probe structure. 112 can be levitated.

10 Surface plate 11 Column 12 Beam member 13 Holder 15 Z-axis stage 17 X-axis stage 18 Y-axis stage 19 Placement surface 100 Probe unit 101 Frame 101a Upper wall 101b Lower wall 101c Opening 102 Sensor 103 Lifting guide part 103a Bottom wall 103b Side wall 103c Opening 103d Concave 103e Communication hole 104 Disc 104a Opening 104b Magnet 104c Concave 104d Spring member 104e Bush 105 Small ball 106 Pole 107 Support member 107a Recess 108 Small ball 109 Large ball, base 110 Contact portion 110a Ball 110b Root portion 110c Tip 110d Screw hole 110e Male thread 111 Attitude detection plate 112 Pro Probe structure 203, 303 Probe unit 203, 303 Holding part 204 First spring plate 205 Second spring plate 206 Slide part 309 Levitation support part LX Laser length measuring device LY Laser length measuring device MX Mirror MY Mirror OBJ object

Claims (17)

A probe unit that is attached to a frame of a shape measuring apparatus together with a sensor and used to measure the shape of an object to be measured,
A probe structure having a stylus part that comes into contact with an object to be measured, and a posture detection plate that is connected to the stylus part and extends in a direction different from the extending direction of the stylus part and faces the sensor; ,
A holding portion that holds the probe structure relative to the frame so as to be relatively rotatable;
A moving mechanism for moving the probe structure in the extending direction of the stylus part with respect to the frame,
By detecting the position of the posture detection plate by the sensor, the posture of the probe structure in a state where the stylus part is in contact with the measured object is obtained, and thereby the shape of the measured object is measured. A probe unit characterized by The probe unit according to claim 1, wherein the holding unit holds the probe structure so as to be rotatable relative to the frame at a base part where the stylus part and the posture detection plate are connected. The probe structure has a spherical surface at a base part where the stylus part and the posture detection plate are connected,
3. The probe unit according to claim 1, wherein the holding unit holds the probe structure so as to be relatively rotatable on the spherical surface with respect to the frame. The probe unit according to any one of claims 1 to 3, wherein the holding unit is supported to float on the frame by aerodynamic force or magnetic force. The probe unit according to any one of claims 1 to 4, wherein the holding portion includes four spheres that come into contact with the base portion or the spherical surface. The probe unit according to any one of claims 1 to 5, further comprising a control mechanism that regulates an inclination of the probe structure. 4. The probe unit according to claim 3, wherein the holding portion includes an elastic body that elastically supports the probe structure with the spherical surface with respect to the frame. The elastic body is composed of two spring plate members each having an opening having a diameter smaller than the diameter of the spherical surface, and one spring plate member has the opening on the side closer to the posture detection plate than the center of the spherical surface. The probe unit according to claim 7, wherein the other spring plate member is engaged with the spherical surface on the side closer to the stylus part than the center of the spherical surface. The elastic body is made of a spring plate material having an opening having a diameter smaller than the diameter of the spherical surface, and the spring plate material engages the opening with the spherical surface on the side closer to the posture detection plate than the center of the spherical surface. ,
The holding part is a side closer to the stylus part than the center of the spherical surface, and includes a slide part having three spheres contacting the spherical surface of the base part, and a biasing means for biasing the slide part to the base part side The probe unit according to claim 7. 3. The probe unit according to claim 1, wherein the holding unit includes a floating support unit that floats and supports the probe structure so as to be relatively rotatable with respect to the frame by aerodynamic force or magnetic force. The floating support portion has a spherical surface on the holding portion side,
The probe unit according to claim 10, wherein the holding portion holds the floating support portion with respect to the frame so as to be relatively rotatable on the spherical surface. 12. The probe unit according to claim 11, wherein the holding portion includes three spheres that come into contact with the spherical surface of the levitation support portion. The probe unit according to any one of claims 10 to 12, further comprising a first restricting portion that restricts the levitating support portion from being separated from the holding portion. The probe unit according to any one of claims 10 to 13, further comprising a second restricting portion that restricts an inclination of the probe structure. Three of the posture detection plates are provided so as to extend at equal intervals along the same virtual plane, and the sensor measures a distance from each of the three posture detection plates. 14. The probe unit according to any one of 14. The probe unit according to any one of claims 1 to 15, wherein a contact pressure when the stylus portion of the probe structure is in contact with an object to be measured is reduced by supporting the probe structure in a floating or elastic manner. . A shape measuring apparatus comprising the probe unit according to any one of claims 1 to 16, a frame for holding the probe unit, and a sensor attached to the frame.

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