JP5656242B2 - Shape measuring method, shape measuring device, and machine tool - Google Patents

Description

  The present invention relates to a shape measuring method shape measuring apparatus and a machine tool.

  In a machine tool, one of the systems for realizing improvement in machining accuracy is a machining system using on-machine measurement and correction machining. On-machine measurement refers to measuring the dimensions and shape of a workpiece on a processing machine. In a machining system based on on-machine measurement and correction machining, while measuring the shape of a workpiece while machining, the machining amount is corrected based on the measurement result. For this reason, high-precision machining is realized because feedback to error machining is easy, and no error occurs when a workpiece is attached or detached.

  As an on-machine measurement method, a shape measurement method is known, and one of the methods is to measure the shape of the target by obtaining the average displacement in the light spot surface applied to the surface of the measurement part. Are known. Conventionally, as a technique related to shape measurement using such an optical stylus, for example, those described in Patent Documents 1 and 2 have been proposed.

JP 2009-92387 A JP 2009-139234 A

  By the way, various disturbances such as temperature, vibration, electrical noise, and machining fluid have an effect on such on-machine measurement. In particular, relative vibration between the measuring device and workpiece causes measurement errors. . That is, the influence of vibration is superimposed on the measurement result of the shape of the surface of the measurement unit by on-machine measurement. Therefore, in order to perform highly accurate measurement of the surface shape of the measurement unit, it is necessary to remove the vibration component from the shape measurement result. However, in the conventional shape measurement method using the on-board device, the vibration component cannot be accurately obtained, and thus the measurement accuracy is naturally limited.

  On the other hand, it is theoretically possible to collect and analyze a huge amount of data with a complicated device, but it is easy to perform on-machine measurement, especially measurement with an on-machine device attached to each machine tool. A small, low-cost apparatus and a simple measurement method are required.

  The present invention has been made in view of such circumstances, and is a shape measurement method and shape capable of performing high-precision shape measurement by suitably removing the influence of vibration on a machine while being a relatively simple device. To provide a measuring device and a machine tool.

  In order to solve the above problems, in the invention according to claim 1 as the shape measuring method, the scattered light of the light spot applied to the surface of the measurement unit is condensed by the imaging lens, and the measurement unit is relatively moved. A method of measuring the shape of the surface of the measurement unit from the change in the condensing position by moving it and directly measuring the light spot obtained by imaging the scattered light and measuring the change in the condensing position In addition, the light receiving area in the feeding direction of the light spot obtained by imaging of the scattered light is limited to receive light and measure the change in the condensing position. The gist is that the shape of the surface of the measurement part is obtained.

The invention according to claim 2 is characterized in that, in the shape measuring method according to claim 1, a slit is used as the light receiving area limiting means for limiting the light receiving area.
The invention according to claim 3 is summarized in that, in the shape measuring method according to claim 1 or claim 2, the change in the condensing position is detected by an optical position sensor.

  In shape measurement by the triangulation method, light is applied to the surface of the measurement unit, and light scattered on the surface of the measurement unit is condensed on the light receiving unit by a lens. For example, the shape of the surface of the measurement unit is measured by measuring a change in the light collection position with a sensor such as an optical position sensor (PSD / Position Sensitive Detector). This optical position sensor is a spot light position sensor using the surface resistance of a photodiode. CCD, CMOS, etc. can also function as a position sensor, but unlike a CCD, the optical position sensor is a non-split type, so it can obtain continuous electrical signals (X or Y coordinates), and has excellent position resolution and responsiveness. ing. In the shape measurement by such an optical position sensor, the displacement of the center of gravity of the light spot applied to the surface of the measurement unit is obtained without processing or calculation regardless of the area.

  Therefore, if a sufficiently large light spot is applied to the surface of the measurement part, the fine irregularities of the measurement part are canceled and the average position is obtained, while the change in displacement acting on the entire spot surface such as vibration is It can be obtained with high sensitivity.

  On the other hand, in the shape measurement by the triangulation method as described above, the resolution in the spot light feed direction (Y-axis direction) of the displacement of the Z-axis (height direction) of the shape measuring device (herein referred to as “lateral resolution”). ) Depends on the size of the light spot applied to the surface of the measurement part. In order to perform measurement with high lateral resolution for precise shape measurement, it is necessary to apply a small light spot to the surface of the measurement unit. That is, in the shape measurement by the triangulation method as described above, since the average displacement in the spot surface of the light applied to the surface of the measurement part is obtained, if the light spot is made small, the average displacement in a narrow range and thus fine It becomes possible to measure various shape changes.

  However, in the on-machine measurement, as described above, many vibration components are superimposed on the measurement result, and in order to obtain the shape accurately, it is necessary to obtain the vibration component and remove that amount from the measurement result. is there. Therefore, in order to perform precise shape measurement, measurement with high lateral resolution using a small light spot (hereinafter referred to as St) is performed simultaneously with measurement with low lateral resolution using a large light spot ( Hereinafter, it is necessary to measure the vibration component on the surface of the measurement unit by performing Sk) and remove the influence of the vibration component by calculation.

  In order to perform St and Sk at the same time, the light in the central region of the light spot may be taken out with the large light spot for Sk being applied, and St may be performed by the extracted light. In that respect, in the invention described in claim 1, by directly receiving the light spot obtained by imaging the scattered light of the light spot applied to the surface of the measurement unit, and measuring the change in the condensing position. At the same time as performing Sk, St is performed by receiving the light spot obtained by imaging the scattered light through a light receiving area limiting means such as a slit and measuring the change of the light collection position. I have to. That is, in St, the peripheral portion of the light spot obtained by imaging the scattered light is masked by a light receiving area limiting means such as a slit, and only the light in the central area of the light spot is extracted. The average displacement, and thus the minute shape change, is measured. Then, by obtaining the difference between the measured changes in the condensing position, the influence of the vibration component is removed, and precise shape measurement is performed. Therefore, according to the measurement method, the influence of vibration can be suitably removed, and highly accurate shape measurement can be performed.

  The invention according to claim 4 is the shape measuring method according to any one of claims 1 to 3, wherein the light spot applied to the surface of the measuring unit is an elliptical shape in which the feeding direction of the light spot is a major axis. It is the gist of that.

  When the size of the light spot that hits the surface of the measurement unit is large, unevenness in brightness occurs in the spot of the light receiving unit that is obtained by collecting the scattered light due to the difference in reflectance of the surface of the measurement unit in the spot, resulting in measurement errors. May occur. On the other hand, the effect of the light skid mainly depends on the size of the light spot in the feeding direction. Therefore, the measurement error can be suppressed by making the light spot applied to the surface of the measurement portion as described above into an elliptical shape having the major axis of the light spot feed direction. The elliptical shape mentioned here does not mean an exact elliptical shape, but means that the length in the feed direction is sufficiently larger than the width orthogonal to the feed direction.

The gist of the invention according to claim 5 is that, in the shape measuring method according to claims 2 to 4, the width of the slit is set to 100 μm or less.
According to the results of experiments by the inventors, it has been confirmed that favorable shape measurement is possible by setting the width of the slit to 100 μm or less.

In order to solve the above-mentioned problem, the invention according to claim 6 as a shape measuring device includes a light irradiation unit that applies a light spot to the surface of the measurement unit, a moving unit that relatively moves the measurement unit, and the measurement unit. A first imaging lens that forms an image of light scattered on the surface; a first sensor that detects a change in a light collection position of the light imaged by the first imaging lens; and the measurement unit surface A second imaging lens that forms an image of the light scattered upon impingement, a second sensor that detects a change in the light collection position of the light imaged by the second imaging lens ,
Shape calculating means for obtaining the shape of the surface of the measurement unit from the difference between the amount of change in the condensing position detected by the first sensor and the amount of change in the condensing position detected by the second sensor ; The gist thereof is that the light receiving area of the second sensor is limited in the light spot feeding direction as compared with the light receiving area of the first sensor.

  The invention according to claim 7 is the shape measuring apparatus according to claim 6, wherein the second sensor has a light receiving area by a slit which is a light receiving area limiting means disposed immediately before the second sensor. The gist is limited.

  And in invention of Claim 8, in the shape measuring apparatus of Claim 6 or 7, the 1st sensor and 2nd sensor which detect the change of the said condensing position were comprised by the optical position sensor. This is the gist.

  In the above configuration, the scattered light of the light spot applied to the measurement unit surface is imaged by the first imaging lens, and the imaged light is directly received by the first sensor, so that the lateral resolution is low. Measurement (Sk) is performed. At the same time, the scattered light is imaged by the second imaging lens, and the imaged light is received by the second sensor via the light receiving area limiting means, so that measurement with high lateral resolution (St ) Is performed. In particular, it is preferable that the light receiving area limiting means is constituted by a slit. In addition, an optical position sensor is preferably used for this sensor. That is, in St, the peripheral portion of the light spot irradiated to the light receiving portion of the second sensor is masked by the light receiving area limiting means, and the center of the light spot is thus obtained. By taking out only the light in the region, the average displacement in a narrow range and, in turn, the minute shape change is measured. If the difference between the changes in the condensing position measured by the two sensors is obtained in this way, precise shape measurement can be performed without the influence of the vibration component. Therefore, according to the measurement apparatus, it is possible to appropriately remove the influence of vibration and perform highly accurate shape measurement.

  The invention according to claim 9 is the shape measuring apparatus according to any one of claims 6 to 8, wherein the first imaging lens, the first sensor, the second imaging lens, The gist of the second sensor is that the second sensor is arranged symmetrically with respect to the optical axis of the light irradiated on the surface of the measurement unit by the light irradiation unit.

  In order to perform simultaneous measurement of Sk and St satisfactorily, it is necessary to make the output change of the optical position sensor equal to the displacement of the surface of the measurement unit. In that respect, if the first imaging lens and the first sensor, and the second imaging lens and the second sensor are arranged symmetrically as described above, the output of the optical position sensor with respect to the displacement of the surface of the measurement unit. The changes can be made equal.

  According to a tenth aspect of the present invention, in the shape measurement apparatus according to any one of the sixth to eighth aspects, the first imaging lens and the second imaging lens are formed by the light irradiation unit. The lens arranged inclined with respect to the optical axis of the light irradiated on the surface of the measurement unit is shared, and the first sensor and the second sensor are separated after passing through the shared lens. The gist is to perform measurement in different light receiving areas with different optical axes.

By sharing the first imaging lens and the second imaging lens, although the illuminance to each sensor is lowered, it can be measured under the same conditions and the configuration can be made compact.
The invention according to claim 11 is summarized in that, in the shape measuring device according to any one of claims 6 to 10, the imaging lens is configured by a bifocal lens.

  By using a bifocal lens as the imaging lens, it is possible to focus only the area to be measured in the light spot and to reduce the influence on the measurement by using the other area as an out-focus. However, the light receiving area limiting means can be used. In particular, it is also preferable to limit the light receiving area only in the light spot feeding direction with a cylindrical lens. Moreover, according to the Fresnel lens, the lens thickness can be reduced and the mass can be reduced.

The “imaging lens” referred to in the present application includes a hologram lens, a diffraction lens, and the like for the purpose of the present invention.
The invention according to claim 12 is the shape measuring apparatus according to any one of claims 6 to 11, further comprising spot diameter changing means for changing the diameter of the light spot applied to the surface of the measurement unit. And

  In this invention, the diameter of the light spot can be adjusted according to the measurement object and the measurement accuracy. The illuminance can also be adjusted by the light reflectance of the measurement object. The adjustment of the diameter of the light spot is not limited to the focus adjustment of the convex lens including the zoom lens as in the embodiment, and a beam expander, a diaphragm, a slit, or the like may be used.

  In invention of Claim 13, in the shape measuring apparatus of any one of Claims 6-12, the light spot which hits the said measurement part surface is an elliptical shape whose feed direction of the same light spot becomes a major axis, and It is the gist of that.

  When the size of the light spot that hits the surface of the measurement unit is large, unevenness in brightness occurs in the spot of the light receiving unit that is obtained by collecting the scattered light due to the difference in reflectance of the surface of the measurement unit in the spot, resulting in measurement errors. May occur. On the other hand, the effect of the light skid mainly depends on the size of the light spot in the feeding direction. Therefore, the measurement error can be suppressed by making the light spot applied to the surface of the measurement portion as described above into an elliptical shape having the major axis of the light spot feed direction.

The gist of the invention described in claim 14 is that, in the shape measuring device according to any one of claims 6 to 13, the width of the slit is set to 100 μm or less.
According to the results of experiments by the inventors, it has been confirmed that favorable shape measurement is possible by setting the width of the slit to 100 μm or less.

  The invention described in claim 15 is the shape measuring device according to any one of claims 6 to 14, wherein the shape measuring device is configured as an on-machine measuring device installed on a machine tool. Is the gist.

  As described above, the shape measuring device of the present invention is a relatively simple device, which can suitably remove the influence of vibration on the surface of the measurement unit and perform highly accurate shape measurement, and is therefore installed on a machine tool. It can be suitably realized as an on-machine measuring device. In this case, since it is not affected by the vibration of the machine tool, it is possible to measure the shape with higher accuracy.

The gist of a sixteenth aspect of the present invention is a machine tool including the shape measuring device according to any one of the sixth to fifteenth aspects.
The machine tool here can be applied to a wide range of machine tools such as a machining center, a lathe, a milling machine, a grinding machine, a press machine, and a laser processing machine that require dimensional accuracy. Moreover, these machine tools are provided with the processing system which has the on-machine measuring device of this invention, and the control means for performing a known correction process. In this machine tool, since it is possible to perform measurement while suppressing the influence of vibration by providing the shape measuring device according to any one of claims 6 to 15, high-precision processing is performed by a control means for performing correction processing. realizable.

  According to the shape measuring method, the shape measuring device, and the machine tool of the present invention, it is possible to appropriately remove the influence of the vibration on the surface of the measurement portion and perform highly accurate shape measurement while being a relatively simple device. Become.

The perspective view which shows a part of layout of the optical system of the shape measuring apparatus which concerns on one Embodiment of this invention. The front view which shows typically the layout of the optical system of the shape measuring device which concerns on one Embodiment of this invention. (A) shows the shape of the light spot that hits the first optical position sensor, (b) shows the shape of the light spot that hits the second optical position sensor, and (c) shows the difference in detection position depending on the presence or absence of a slit. FIG. The graph which shows the effect of the slit with respect to the shape measurement result of the V-shaped groove in the shape measuring apparatus of the embodiment. The graph which shows the shape of a V-shaped groove, and its moving average shape. The front view which shows typically the optical system layout of the shape measuring apparatus which concerns on another embodiment of this invention. The perspective view which shows another structure of a 2nd position sensor. The front view which shows typically the optical system layout of the light-receiving part of the shape measuring device which concerns on another embodiment of this invention. The side view which shows the side structure of the experimental apparatus for the effect confirmation of the shape measuring apparatus of embodiment. The graph which shows the shape measurement result of the V-shaped groove at the time of no vibration in the shape measuring apparatus of the embodiment. The graph which shows the shape measurement result of the V-shaped groove at the time of the vibration in the shape measuring apparatus of the embodiment. The graph which shows the measurement error by the vibration in the shape measuring apparatus of the embodiment.

(First embodiment)
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying a shape measuring method and a shape measuring apparatus according to the present invention will be described in detail below with reference to FIGS. In addition, the shape measuring device of this embodiment is comprised as an on-machine measuring device installed on the machine tool.

FIG. 1 is a perspective view showing the layout of the optical system of the shape measuring apparatus of this embodiment, and FIG. 2 is a front view seen from the Y-axis direction that is the light spot feeding direction.
As shown in FIG. 2, this shape measuring apparatus includes two laser pointers, that is, an elliptical beam laser pointer 1 that outputs an elliptical beam having a major axis of 4 mm and a minor axis of 1 mm, and a circular beam that outputs a circular beam having a diameter of 1.1 mm. A laser pointer 3 is provided. The laser beam output from the elliptical beam laser pointer 1 is refracted at a right angle by the 90 ° prism 2, passes through a polarization beam splitter prism (hereinafter referred to as PBS prism 4), and is collected by zoom lenses 5 and 6. After being illuminated, the measurement unit surface 7 is irradiated such that the optical axis A _X 0 is perpendicular to the XY plane along the Z axis. The laser beam output from the circular beam laser pointer 3 is refracted by the PBS prism 4 at a right angle and then condensed by the zoom lenses 5 and 6, and then coaxial with the optical axis A _X 0 on the measurement unit surface 7. Irradiates vertically. In this embodiment, the elliptical beam laser pointer 1, the circular beam laser pointer 3, the 90 ° prism 2, the PBS prism 4, and the zoom lenses 5 and 6 constitute a light irradiation unit that applies a light spot to the measurement unit surface 7. ing.

This light irradiation part can change the diameter of the light spot on the measurement part surface 7 by the zoom lenses 5 and 6, and can also function as a spot diameter changing means.
Further, as shown in FIG. 9, the measuring unit surface 7 is provided with an automatic stage 14 as a moving means which is a well-known feeding device that sequentially scans the measurement target with respect to the light spot at a constant feeding direction and a constant speed. The light spot is relatively movable. Of course, the light irradiation unit may be moved and scanned while the measurement target is fixed.

As shown in FIGS. 1 and 2, the left and right sides of the zoom lenses 5 and 6 are respectively provided with light receiving portions that receive light scattered by the measurement point P ₀ on the measurement portion surface 7 and scattered.
In the first light receiving unit located on the left side in the figure, a first imaging lens 8 that forms an image of light scattered upon the measurement point P ₀ on the measurement unit surface 7 and the first imaging lens. And a first optical position sensor 9 for receiving the light imaged at 8. In addition, a second imaging lens 10 that forms an image of light scattered upon the measurement point P ₀ on the measurement unit surface 7 is formed on the second light receiving unit located on the right side of the zoom lenses 5 and 6 in the figure, A second optical position sensor 12 that receives light imaged by the second imaging lens 10 and a slit 11 disposed immediately before the second optical position sensor 12 are provided. These light receiving element elements are arranged on the same XY plane orthogonal to the Y axis as shown by two concentric circles in FIG.

As shown in FIGS. 1 and 2, in the present embodiment, the first imaging lens 8 and the first optical position sensor 9, and the second imaging lens 10 and the second optical position sensor 12 are Each extended surface is installed in a positional relationship where it intersects at one point on the Z-axis so as to satisfy the Shine-Pluke condition. Therefore, the measurement point P ₀ of the measuring area surface 7, and when it becomes the measurement point P _H shifted upward, even when a measurement point P _L shifted down, first the first imaging lens 8 The first optical position sensor 9 and the second imaging lens 10 can form an image on the second optical position sensor 12 without blurring.

The first imaging lens 8 and the first optical position sensor 9, and the second imaging lens 10 and the second optical position sensor 12 are measured by the elliptical beam laser pointer 1 and the circular beam laser pointer 3. The optical axis A _X 0 of the light irradiated on the surface 7 is arranged in line symmetry along optical axes A _X 1 and A _X 2 inclined at the same angle θ = 35 ° on the XZ plane with respect to the optical axis A _X 0. Thus, the output changes of the first and second optical position sensors 9 and 12 with respect to the displacement of the measurement unit surface 7 are made equal.

Incidentally, in the triangulation method, in principle, it is desirable that the XZ plane formed by the optical axis A _X 0 and the feed direction Y of the shape measuring device be orthogonal to each other when measuring an inclined surface or a step. In this embodiment, the feed direction of the shape measurement apparatus is designed to be a Y direction orthogonal to make the XZ plane of the optical axis A _{X 0.}

  In addition, when the size of the light spot applied to the measurement unit surface 7 is large, luminance unevenness may occur in the light receiving surface spot due to the difference in reflectance in the measurement unit spot, which may cause a measurement error. On the other hand, the effect of the light skid mainly depends on the size of the spot in the feeding direction. Therefore, in this embodiment, the measurement error is suppressed by using an elliptical spot whose feeding direction is the long axis.

The specifications of such a shape measuring apparatus are as follows. The lens position L shown in FIG. 2 indicates the distance from the light spot on the measurement unit surface 7 to the first and second imaging lenses 8 and 10. Further, the optical axis angle θ indicates an angle formed by the optical axis of the light irradiated on the measurement unit surface 7 and the optical axes of the two light receiving units.
-Magnification of zoom lenses 5 and 6: 0.1
・ Lens position L: 36mm
-Optical axis angle θ: 35 °
-Focal length of imaging lenses 8 and 10: 18 mm
In the shape measuring apparatus of this embodiment, the measurement range is 10 mm, and S3932 (light receiving surface size 1 × 12 mm) manufactured by Hamamatsu Photonics Co., Ltd. is used as the first optical position sensor 9 and the second optical position sensor 12. Adopted. Furthermore, the size of the spot imaged on the light receiving surfaces of the first optical position sensor 9 and the second optical position sensor 12 is set to be approximately one time the size of the light spot on the measurement unit surface 7.

Here, the principle of the triangulation method of the present invention will be described. As shown in FIGS. 1 and 2, when the measuring area surface 7 is in the measurement point P ₀ is imaged at _P'0 in the light-receiving surface of the first optical position sensor 9 and the second optical position sensor 12 . Then, relative movement in the measurement area surface 7 is the feeding direction (Y direction), when its height has come in the measurement point P _H is displaced upward, the light receiving surface of the first and second optical position sensor 9, 12 imaged in _P'H in. Similarly, relative movement in the measurement area surface 7 is the feeding direction (Y direction), when its height has come in the measurement point P _L is displaced downward, the first optical position sensor 9 and a second light position An image is formed at P ′ _{L on} the light receiving surface of the sensor 12. In this case, the distance L between the measurement unit surface 7 and the second imaging lens 10 changes, but the Shine-Pluke condition is satisfied, so that the light receiving surface of the second optical position sensor 12 is not adjusted without adjusting the focus. Focus. The relationship between the first imaging lens 8 and the first optical position sensor 9 is the same. The first optical position sensor 9 and the second optical position sensor 12 output a change in the light receiving surface to a control unit (not shown), and the control unit outputs the first and second optical position sensors 9 and 12. Then, the shape of the measurement part surface 7 is calculated from the feeding speed of the measurement part surface 7.

In the present embodiment, a first light spot that directly receives a light spot obtained by forming an image of the scattered light of the light spot applied to the measurement point P ₀ on the measurement unit surface 7 and measures a change in the light collection position is first. A light receiving unit and a second light receiving unit that receives a light spot obtained by first imaging the scattered light through the slit 11 and measures a change in the light collection position are provided. In the shape measuring apparatus of this embodiment, the first light position sensor 9 without the slit 11 receives the entire light spot as shown in FIG. On the other hand, in the second optical position sensor 12 provided with the slit 11 immediately before, the upper and lower parts of the light spot in the figure are masked by the slit 11, so that the central region along the XZ plane of the light spot is masked. Only light is received. Incidentally, in FIG. 1 and FIG. 3B, the light receiving surface of the second optical position sensor 12 and the slit 11 are schematically shown separated from each other, but in order to extract only the central region of the light spot, FIG. As shown, it is necessary to install the slit 11 at a position sufficiently close to the light receiving surface of the second optical position sensor 12.

Then, as shown in FIG. 3C, for example, when the surface of the measurement unit is locally convex, the shape imaged on the light receiving unit by the first optical position sensor is as shown in the figure. It becomes a “Kugi” shape. At this time, the first optical position sensor 9 and the second optical position sensor 12 detect different positions. That is, the position P ′ _X detected by the second optical position sensor having a high lateral resolution is higher than the position detected by the first optical position sensor averaged with the height before and after the feeding direction. Recognized as

As described above, in the present embodiment, in the first light receiving unit, the light spot (image spot obtained by imaging the scattered light of the light spot (measurement unit spot) applied to the measurement point P ₀ on the measurement unit surface 7). by receiving the movement in the X direction of the light receiving point _P'0 of the light-receiving portion spot) directly measures the change in the condensing position. With this, measurement (Sk) with low lateral resolution (resolution in the Y-axis direction which is the light spot feed direction) is performed. At the same time, the spot of the light receiving portion obtained by imaging the scattered light is received through the slit 11 with scattered light having a limited light receiving area in the Y direction, and the light receiving point P ′ _{0 in} the X direction is received. Measure changes in position. With this, measurement (St) with high lateral resolution is performed. That is, in St, the peripheral portion of the light receiving portion spot obtained by imaging the scattered light is masked by the slit 11, and only the light in the central region of the light receiving portion spot is extracted, so that the light spot feeding direction (Y axis Direction), and a small change in shape is measured. Then, by obtaining the difference between the measured changes in the condensing position, the influence of the vibration component is removed, and precise shape measurement is performed.

  That is, in such a shape measuring apparatus, the lateral resolution in the Y-axis direction, which is the sending direction of the Sk light spot related to vibration component detection, depends on the size of the measurement spot, whereas the lateral resolution of St 11 width.

(Experimental example 1)
In order to confirm the effect of improving the lateral resolution due to the installation of the slit 11, the shape measurement was performed by changing the slit width on the measurement surface 7 of the V-shaped groove shape. There are three experimental conditions: no slit, slit width 50 μm and slit width 100 μm. The results of such an experiment are shown in FIG. FIG. 5 shows an actual groove shape and a moving average shape obtained by calculation for comparison.

  For a V-shaped groove having a depth of 0.2 mm, the output amplitude without the slit used for Sk was about 0.08 mm, and a smoothing effect was confirmed. This value almost coincides with the calculation result obtained by moving average in the range of 400 μm. In addition, the output amplitude when the slit 11 having a width of 50 μm and 100 μm is installed is about 0.14 mm and about 0.13 mm, respectively, and the lateral resolution is improved as compared with the case where the slit 11 is not provided, and the slit width is increased. It was confirmed that the narrower the effect, the higher the effect.

  Further, when the measurement result and the calculation result are compared, the measurement result is smoothed. The reason for this is that the amount of light at the time of measurement is stronger in the groove recess, and the scattered light on the measurement unit surface 7 is further scattered on the other surface and directed to the light receiving unit. As a result, the measurement result is smoothed. Conceivable.

(Experimental example 2)
Next, an experiment for evaluating whether or not the shape measurement method and the shape measurement device of the present embodiment can actually measure the shape from which the influence of vibration is removed was performed. This experiment is performed using an experimental apparatus as shown in FIG. As shown in the figure, in this experimental apparatus, the shape measuring apparatus 13 of this embodiment is installed on the left side in the figure. In this experimental apparatus, an object to be measured 16 is installed on the right side of the shape measuring apparatus 13 in the figure. The object to be measured 16 has the same V-shaped groove as that used in the above-described experiment. The object to be measured 16 is vibrated by the PZT actuator 15 and is fed by the automatic stage 14 in the front-rear direction in the figure. A displacement sensor 17 for detecting the actual vibration of the device under test 16 is installed for verification on the right side of the experimental apparatus.

The experimental conditions are as follows.
・ Feed rate: 1mm / sec
・ Vibration amplitude: 16μm
・ Vibration frequency: 10, 20, 30, 40Hz
・ Slit width: 50μm
FIG. 10 shows the measurement results of St and Sk and no difference (St−Sk) when there is no vibration. FIG. 11 shows the measurement results of St and Sk and the difference (St−Sk) when the vibration frequency is 40 μm. In the measurement result at the time of vibration, a change in output due to vibration can be confirmed as compared with the case of no vibration. The St output is difficult to distinguish between noise and vibration, but the Sk output makes it possible to determine the influence of vibration relatively easily. In the calculation result of the difference between St and Sk (St-Sk), although the influence of noise appears, the outputs at the time of no vibration and at the time of vibration are almost the same. That is, the influence of vibration is suitably removed.

  In order to evaluate this error amount, the rms (error mean square deviation) value of the error amount obtained by subtracting the difference (St-Sk) of each vibration experiment from the difference (St-Sk) when there is no vibration, and PV ( FIG. 12 shows the result of obtaining the (shape error) value. Here, in order to confirm the influence of noise, the measurement at the time of no vibration is performed twice, and the amount of repetition error due to noise is calculated in the same manner. In any experiment, since the error amount is less than the repeated error amount, it can be said that St and Sk are simultaneously measured.

According to the shape measuring method and the shape measuring apparatus of the above embodiment, the following effects can be achieved.
(1) In the shape measurement method of the present embodiment, the light spot obtained by imaging the scattered light of the light spot applied to the measurement unit surface 7 is directly received and the change in the condensing position is measured. I have to. At the same time, the light spot obtained by imaging the scattered light is received through the slit 11 and the change in the light collection position is measured. And the shape of the measurement part surface 7 is calculated | required from the difference of the variation | change_quantity of these condensing positions measured. In this embodiment, Sk is performed simultaneously by directly receiving a light spot obtained by forming an image of the scattered light of the light spot applied to the measurement unit surface 7 and measuring the change in the condensing position. The light spot obtained by imaging the scattered light is received through the slit 11 and St is measured by measuring the change in the condensing position. That is, in St, the peripheral portion of the light spot obtained by imaging the scattered light is masked by the slit 11 and only the light in the central region of the light spot is taken out, so that the average displacement in a narrow range can be reduced. Various shape changes are measured. Then, by obtaining the difference between the measured changes in the condensing position, the influence of the vibration component is removed, and precise shape measurement is performed. Therefore, according to the shape measurement method of the present embodiment, it is possible to appropriately remove the influence of vibration and perform highly accurate shape measurement.

  (2) In the shape measuring apparatus of the present embodiment, a light irradiating unit that applies a light spot to the measuring unit surface 7, a first imaging lens 8 that forms an image of light scattered by hitting the measuring unit surface 7, and the first And a first optical position sensor 9 for detecting a change in the condensing position of the light imaged by the imaging lens 8. In addition, in the shape measuring apparatus according to the present embodiment, in addition to this, the second imaging lens 10 that forms an image of the light scattered upon hitting the measurement unit surface 7 and the light imaged by the second imaging lens 10 A second optical position sensor 12 that detects a change in the light condensing position, and a slit 11 disposed immediately before the second optical position sensor 12. In the shape measuring apparatus of this embodiment, the scattered light of the light spot applied to the measurement unit surface 7 is imaged by the first imaging lens 8, and the imaged light is the first optical position sensor 9. By directly receiving the light, measurement (Sk) with low lateral resolution is performed. At the same time, the scattered light is imaged by the second imaging lens 10, and the imaged light is received by the second optical position sensor 12 through the slit 11 so that the lateral resolution is high. Measurement (St) is performed. That is, in St, the peripheral portion of the light spot irradiated on the light receiving portion of the second optical position sensor 12 is masked by the slit 11, and only the light in the central region of the light spot is taken out, so that the average displacement in a narrow range is obtained. As a result, minute shape changes are measured. Thus, if the difference of the change amount of the condensing position measured by the two optical position sensors is obtained, it is possible to perform precise shape measurement without the influence of the vibration component. Therefore, according to the shape measuring apparatus of the present embodiment, it is possible to suitably remove the influence of vibration and perform highly accurate shape measurement.

  (3) In the shape measuring apparatus according to the first embodiment, the first imaging lens 8 and the first optical position sensor 9, and the second imaging lens 10 and the second optical position sensor 12 are light. They are arranged symmetrically with respect to the optical axis of the light irradiated to the measurement unit surface 7 by the irradiation unit. In order to perform simultaneous measurement of Sk and St satisfactorily, it is necessary to make the output change of the optical position sensor equal to the displacement of the measurement unit surface 7. In that respect, if the first imaging lens 8 and the first optical position sensor 9, and the second imaging lens 10 and the second optical position sensor 12 are arranged symmetrically as described above, the surface of the measurement unit The output change of the optical position sensor with respect to the displacement of 7 can be made equal.

  (4) In the present embodiment, the light spot applied to the measurement unit surface 7 has an elliptical shape with the major axis of the light spot feeding direction. When the size of the light spot applied to the measurement unit surface 7 is large, uneven brightness occurs in the light receiving unit spot obtained by condensing the scattered light due to the difference in reflectance of the measurement unit surface 7 in the spot. Measurement error may occur. On the other hand, the effect of the light skid mainly depends on the size of the light spot in the feeding direction. Therefore, the measurement error can be suppressed by making the light spot applied to the measurement part surface 7 as described above into an elliptical shape in which the feeding direction of the light spot is a major axis.

  (5) In the present embodiment, the width of the slit 11 is 100 μm or less. As a result of experiments by the inventors, favorable shape measurement is possible by setting the width of the slit 11 to 100 μm or less.

(Second Embodiment)
Next, another embodiment in which the shape measuring method and the shape measuring apparatus of the present invention are embodied will be described in detail with reference to FIGS. Note that only the configuration different from that of the first embodiment will be described, and the same configuration is denoted by the same reference numeral and description thereof is omitted.

  Since the first embodiment is based on an experimental apparatus, the configuration can be easily changed. However, in the present embodiment, the configuration is simple and compact.

First, as shown in FIG. 6, the shape measuring apparatus includes a single elliptical beam laser pointer 1 that outputs an elliptical beam having a major axis of 4 mm and a minor axis of 1 mm.
The elliptical beam laser pointer 1 is arranged so that the optical axis of the laser beam output to the measurement unit surface 7 is vertical. This laser light is directly condensed by the single-focus lens 5 instead of the zoom lens 5 without using the prisms 2 and 4, and then the optical axis A _X 0 is on the measurement unit surface 7 along the Z axis with respect to the XY plane. It is irradiated so as to be vertical.

In the present embodiment, the elliptical beam laser pointer 1 and the lens 5 constitute a light irradiation unit that applies a light spot to the measurement unit surface 7.
As shown in FIG. 6, a light receiving unit that receives light scattered upon the measurement point P ₀ on the measurement unit surface 7 is provided on the right side of the lens 5.

The light scattered around P ₀ passes through the same imaging lens 18 shared as the first imaging lens 8 and the second imaging lens 10. Then, this light beam is equally divided by the beam splitter 19 into an optical path that travels straight as it is and an optical path that reflects 90 degrees in half light amounts.

  A first optical position sensor 9 is provided in the optical path reflected and bent by the beam splitter 19. Then, the light imaged by the imaging lens 18 is received and imaged as it is by the first optical position sensor 9.

  On the other hand, a second optical position sensor 12 and a slit 11 disposed immediately before the second optical position sensor 12 are provided in the optical path of the light beam that has traveled straight through the beam splitter 19. Therefore, the light beam whose light receiving area is limited in the light spot feeding direction (Y-axis direction) is incident on the second optical position sensor 12.

  As described above, since the first optical position sensor 9 and the second optical position sensor 12 use a common optical path, the light received by the both is detected by the optical position sensor 12 through the slit 11 in the Y-axis direction. Except that the light receiving area is limited.

The second embodiment has the following effects in addition to the effects (1), (2), (4), and (5) of the first embodiment.
(6) By making the first imaging lens and the second imaging lens a common lens, the conditions of the first optical position sensor 9 and the second optical position sensor 12 may be equal. Can be measured with higher accuracy.

In addition, by sharing the lens, it is possible to reduce the number of components, reduce the cost with a compact configuration.
In addition, you may change this embodiment as follows.

  In the above embodiment, the light spot applied to the measurement unit surface 7 has an elliptical shape in which the feeding direction of the light spot is the long axis. However, if the measurement error can be sufficiently suppressed, the shape of the light spot is circular. The shape may be changed to an arbitrary shape such as a rectangular shape.

  In the light irradiation unit of the shape measuring apparatus of the above embodiment, the two laser pointers are provided in order to check the influence of the spot shape on the measurement result. Accurate shape measurement can be performed even with only one laser pointer as in the second embodiment.

・ Needless to say, a simple laser pointer can be used instead of a laser oscillator with higher output.
-The number and shape of each prism and condenser lens in the shape measuring apparatus of the above embodiment may be changed as appropriate.

  -It is good also as multifocal lenses, such as a single focus lens and a bifocal lens, instead of a zoom lens. As the bifocal lens, a bifocal hologram lens used for DVD reproduction or the like can be suitably used.

-The prism may be a reflector.
In addition, the light receiving unit can be changed as follows.
First, although the slit is illustrated as the light receiving area limiting means for limiting the light receiving area of the second sensor, the light receiving area limiting means is not limited to the slit for the purpose of the invention. Although the slit is a simple method, for example, the light receiving area may be limited by limiting the light receiving area of the optical position sensor itself.

For example, a configuration similar to that of the slit may be adopted by shielding a part of the transparent optical element.
For example, instead of the optical position sensor as in the embodiment, the present invention can be implemented even if the condensing position is detected by a matrix array sensor using CCD or CMOS.

  In this case, as shown in FIG. 7, the slit 11 provided immediately before the second optical position sensor 12 is omitted, and instead of this, the input range from the individual elements of the CCD and CMOS is limited, thereby receiving light. The light receiving range in the feed direction of the part can be limited. Then, the received data is subjected to image processing by a computer using a known method to detect the position.

  In addition, although illustration is abbreviate | omitted if such an array-shaped sensor is used, the structure which abbreviate | omits the beam splitter 19 and can share a light-receiving part with one CCD is also possible in 2nd Embodiment. .

  As shown in FIG. 8, in order to limit the light receiving area, a non-cylindrical double-focus cylindrical lens 20 can be used instead of the slit. That is, this cylindrical lens is arranged so that its longitudinal direction is orthogonal to the feeding direction, and only a part of the feeding direction of the measurement unit surface 7 is focused on the optical position sensor 12, and the light in other areas is By performing out-focusing, the same function as the slit 11 is achieved. Further, an aspherical double focus lens may be used.

  Further, conversely, only a specific part of the feeding direction of the measurement unit surface 7 is out-focused, and from the difference between the output of the first optical position sensor and the output of the second optical position sensor, the measurement unit surface 7 Calculate a specific part of the data in the feed direction. Further, a method of removing the vibration component from the difference between the data of the first optical position sensor and the specific partial data of the feeding direction of the measurement unit surface 7 may be used.

  -The dimension shape of each part of a shape measuring apparatus is not restricted to what was shown in the said embodiment, You may change suitably. First, the light irradiation part which irradiates a light spot to the measurement part surface is provided. A first imaging lens that forms an image of the scattered light, a first optical position sensor that detects a change in the condensing position, a second imaging lens that forms an image of the scattered light, and a change in the condensing position. A second optical position sensor, and a slit disposed immediately before the second optical position sensor; With such a measuring device, it is possible to suitably remove the influence of vibration of the measuring unit and perform highly accurate shape measurement.

  In the above embodiment, the first imaging lens 8 and the first optical position sensor 9, and the second imaging lens 10 and the second optical position sensor 12 are applied to the measurement unit surface 7 by the light irradiation unit. They are arranged symmetrically with respect to the optical axis of the irradiated light. As a result, the output changes of the optical position sensor with respect to the displacement of the measurement unit surface 7 are made equal in both light receiving units. In order to ensure measurement accuracy, it is desirable to arrange the two light receiving portions symmetrically. However, when it is difficult to arrange the light receiving portions symmetrically on the layout, the two light receiving portions may be arranged asymmetrically. .

Y (axis): lateral direction, feed direction, Z (axis): height direction, A _X 0, A _X 1, A _X 2 ... optical axis, 1 ... elliptical beam laser pointer (light irradiation unit), 2 ... 90 ° Prism (light irradiation part), 3 ... Circular beam laser pointer (light irradiation part), 4 ... PBS prism (light irradiation part), 5, 6 ... Zoom lens (light irradiation part), 7 ... Surface of measurement part, 8 ... DESCRIPTION OF SYMBOLS 1st imaging lens, 9 ... 1st optical position sensor, 10 ... 2nd imaging lens, 11 ... Slit, 12 ... 2nd optical position sensor, 13 ... Shape measuring device, 14 ... Automatic stage, 15 DESCRIPTION OF SYMBOLS ... PZT actuator, 16 ... Measuring object, 17 ... Displacement sensor, 18 ... Imaging lens, 19 ... Beam splitter, 20 ... Cylindrical lens.

Claims (16)

In this method, the scattered light of the light spot applied to the surface of the measurement unit is condensed by the imaging lens, and the shape of the measurement unit surface is measured from the change of the condensing position by relatively moving the measurement unit. There,
The light spot obtained by imaging the scattered light is directly received to measure the change in the condensing position, and the light receiving area in the light spot feeding direction obtained by imaging the scattered light is limited. Receive light and measure the change of the light collection position,
A shape measuring method characterized in that the shape of the surface of the measuring part is obtained from the difference between the measured changes in the condensing position. The shape measuring method according to claim 1, wherein a slit is used as the light receiving area limiting means for limiting the light receiving area. The shape measurement method according to claim 1, wherein a change in the light collecting position is detected by an optical position sensor. The shape measuring method according to any one of claims 1 to 3, wherein the light spot applied to the surface of the measurement part is formed into an elliptical shape in which a feeding direction of the light spot is a major axis. The shape measurement method according to claim 2, wherein a width of the slit is 100 μm or less. A light irradiating unit that applies a light spot to the surface of the measuring unit;
Moving means for relatively moving the measurement unit;
A first imaging lens for imaging light scattered upon hitting the measurement unit surface;
A first sensor for detecting a change in a condensing position of light imaged by the first imaging lens;
A second imaging lens that forms an image of light scattered upon striking the measurement unit surface;
A second sensor for detecting a change in a light collecting position of light imaged by the second imaging lens ;
A shape calculating means for obtaining a shape of the measurement unit surface from a difference between a change amount of the light collection position detected by the first sensor and a change amount of the light collection position detected by the second sensor ;
The light receiving area of the second sensor is limited in the light spot feeding direction as compared with the light receiving area of the first sensor.   The shape measuring apparatus according to claim 6, wherein the second sensor has a light receiving area limited by a slit which is a light receiving area limiting unit disposed immediately before the second sensor.   The shape measuring apparatus according to claim 6 or 7, wherein the first sensor and the second sensor that detect a change in the condensing position are configured by an optical position sensor.   The first imaging lens and the first sensor, and the second imaging lens and the second sensor are configured with respect to an optical axis of light irradiated on the surface of the measurement unit by the light irradiation unit. The shape measuring apparatus according to claim 6, wherein the shape measuring apparatus is arranged symmetrically. The first imaging lens and the second imaging lens share a lens disposed to be inclined with respect to the optical axis of the light irradiated to the measurement unit surface by the light irradiation unit,
9. The method according to claim 6, wherein the first sensor and the second sensor measure in different light receiving areas by optical axes separated after passing through the shared lens. The shape measuring apparatus according to claim 1.   The shape measuring apparatus according to claim 6, wherein the imaging lens is configured by a bifocal lens.   The shape measuring apparatus according to any one of claims 6 to 11, further comprising spot diameter changing means for changing a diameter of a light spot applied to the surface of the measurement unit.   The shape measuring apparatus according to any one of claims 6 to 12, wherein the light spot applied to the surface of the measurement unit is an elliptical shape having a major axis in a direction in which the light spot is fed. The shape measuring apparatus according to claim 7, wherein a width of the slit is 100 μm or less. The shape measuring device according to any one of claims 6 to 14, wherein the shape measuring device is configured as an on-machine measuring device installed on a machine tool.   A machine tool comprising the shape measuring device according to any one of claims 6 to 15.

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