JP6976107B2 - Inclined surface boundary position identification method, inclined surface boundary position identification device, inclined surface boundary position identification program - Google Patents

Description

The present invention relates to an inclined surface boundary position identification method, an inclined surface boundary position identification device, and an inclined surface boundary position program.

A laser range finder is known as a device for measuring an absolute distance from a certain point to a measurement point with high accuracy. For example, Patent Document 1 describes a rangefinder that measures a distance from a time difference between an interference signal of measurement light and an interference signal of reference light.

Japanese Unexamined Patent Publication No. 2010-14549

As an application example of the laser range finder, identification of the boundary position between two surfaces having different inclinations can be mentioned. This is useful, for example, for verifying the machining accuracy of machine parts. 11 (A) and 11 (B) show an example of identification of the boundary position. FIG. 11A is a cross-sectional view of a part of the object to be measured 100, and the object 100 to be measured has two inclined surfaces 101 and 102 having different inclinations. It is assumed that the boundary 103 between the inclined surface 101 and the inclined surface 102 is circular as shown in FIG. 11B and is included in one plane 105.

If the measurement object 100 can be scanned in the X and Y directions of FIG. 11B and the distance y of each measurement point 104 from the reference plane 111 can be obtained, the position of the boundary 103 can be identified, that is, the boundary 103. It is possible to obtain the distance h from the reference plane of the plane 105 including the above. For example, it can be identified by generating a two-dimensional image in which the color of the pixel corresponding to each measurement point is determined according to the distance y based on the measurement result and extracting the contour from the image.

In the laser distance meter, it is necessary for the detector 113 to detect the light reflected / scattered by the measurement object 100 by the measurement light 110, but the incident angle θ of the measurement light 110 is as shown in the inclined surface 102 of FIG. 11 (A). When is small, the intensity of the light 112 directed toward the measuring instrument 113 among the reflected / scattered light is small, so that there is a problem that the measurement accuracy of the distance y is lowered and the boundary 103 cannot be accurately identified. Further, there is a similar problem when the surface of the object to be measured has a metallic luster, such as a machined metal material.

Therefore, the present invention provides a method for identifying the boundary position of an inclined surface, which can accurately identify the boundary position of an inclined surface even when the intensity of light reflected / scattered by the object to be measured and detected by the detector is small. Aim for that.

The method for identifying an inclined surface position of the present invention is a plane including a boundary between the first surface and the second surface of a measurement object having a first surface and a second surface having different inclinations and having known design dimensions. The virtual surface of the boundary surface is set with an inclination given in advance based on the design dimensions with respect to the reference surface orthogonal to the measurement light, and the virtual surface height, which is the distance between the virtual surface and the reference surface, is changed. However, among the measurement points in the measurement area including the boundary, those whose measurement point height, which is the distance from the optically measured reference plane, is smaller than the virtual surface height are extracted by the extraction step and the extraction step. About the measurement point The integrated brightness calculation that calculates the integrated brightness by logarithmically converting the measurement point brightness, which is the brightness of the reflected light from the first surface or the second surface of the measurement light used for measuring the measurement point height, and totaling them. It includes a step and an identification step of identifying the position of the boundary surface by identifying the turning point of the curve showing the relationship between the integrated brightness and the virtual surface height.

The inclined surface position identifying device of the present invention includes a first surface and a second surface having different inclinations, and a plane including a boundary between the first surface and the second surface of a measurement object whose design dimensions are known. The virtual surface of the boundary surface is set with an inclination given in advance based on the design dimensions with respect to the reference surface orthogonal to the measurement light, and the virtual surface height, which is the distance between the virtual surface and the reference surface, is changed. However, among the measurement points in the measurement area including the boundary, those whose measurement point height, which is the distance from the optically measured reference plane, is smaller than the virtual surface height are extracted by the extraction means and the extraction step. About the measurement point The integrated brightness calculation that calculates the integrated brightness by logarithmically converting the measurement point brightness, which is the brightness of the reflected light from the first surface or the second surface of the measurement light used for measuring the measurement point height, and totaling them. The means include identification means for identifying the position of the boundary surface by identifying the turning point of the curve showing the relationship between the integrated brightness and the virtual surface height.

The inclined surface position identification program of the present invention comprises a first surface and a second surface having different inclinations from each other, and the boundary between the first surface and the second surface of a measurement object whose design dimensions are known. based on the design dimension set in inclination previously given with respect to a reference plane orthogonal to the measurement light a virtual plane of the boundary surface is a plane including the virtual surface height is the distance between the virtual plane and the reference plane Extraction process and extraction process to extract those whose measurement point height, which is the distance from the optically measured reference plane, is smaller than the virtual surface height among each measurement point in the measurement area including the boundary. For the measurement points extracted in step 1, the measurement point brightness, which is the brightness of the reflected light from the first surface or the second surface of the measurement light used for measuring the measurement point height, is logarimetrically converted and totaled to calculate the integrated brightness. It is characterized in that the integrated brightness calculation process and the identification process of identifying the position of the boundary surface by specifying the bending point of the curve showing the relationship between the integrated brightness and the virtual surface height are executed.

According to the present invention, it is possible to accurately identify the boundary position of the inclined surface even when the intensity of the light reflected / scattered by the object to be measured and detected by the detector is small.

It is a figure which shows the shape of the valve seat part of an engine which is an example of a measurement object, (A) is a sectional view, (B) is a plan view. It is a figure explaining the principle of the boundary position identification method. It is a flowchart explaining the procedure of the boundary position identification method. It is a graph which shows the relationship between the height of a virtual surface and the integrated luminance. It is a graph which shows the differential value of FIG. It is a figure which shows the example of the measurement object which the boundary is rectangular, (A) is a sectional view, (B) is a plan view. It is a figure which shows the example of the measurement object which has a convex part, (A) is a sectional view, (B) is a plan view. It is a figure which shows the example of the measurement object which has an open boundary, (A) is a sectional view, (B) is a plan view. It is a structural diagram of the boundary position identification apparatus. It is a figure which shows the output of a light source schematically. It is a figure explaining the conventional method of identifying the boundary position of an inclined surface.

Hereinafter, the method for identifying the boundary position of the inclined surface, which is an embodiment of the present invention, will be described in detail with reference to the drawings. Although the valve seat portion of the engine will be described as an example of the object to be measured, the present invention can be applied to other objects to be measured.

1A and 1B are views showing the shape of a valve seat portion of an engine, which is an example of an object to be measured, where FIG. 1A is a cross-sectional view and FIG. 1B is a plan view. The valve seat 10 is provided at a connecting portion between the cylinder 2 of the cylinder head 1 and the intake or exhaust port 3, and has a conical valve contact surface 11 (an example of the first surface) that abuts on the valve 4 and a valve contact surface. It is composed of a conical outer peripheral surface 12 (an example of a second surface) provided on the outside of the valve 11 and having a gentle inclination from the valve contact surface 11. In this method, the measurement region 23 including the valve seat 10 shown in FIG. 1 (B) is scanned in the X direction and the Y direction by a laser range finder to measure the distance from the reference plane of each measurement point and the intensity of the reflected light. Then, the boundary 13 between the valve contact surface 11 and the outer peripheral surface 12 is identified based on these data.

FIG. 2 is a diagram illustrating the principle of the inclined surface boundary position identification method, and FIG. 3 is a flowchart illustrating a procedure of the inclined surface boundary position identification method. The detailed procedure of this method will be described with reference to these figures.
As a premise for identification, the design dimensions of the valve seat 10 are known, and the position of the boundary 13 (the position in the vertical direction in FIG. 2) is identified in order to verify the machining accuracy. Further, it is assumed that the boundary 13 is included in the boundary surface 15 which is a plane perpendicular to the sliding shaft 16 of the valve 4.

The measurement area 23 (see FIG. 1) is scanned by, for example, a laser rangefinder 60 (an example of a rangefinder) to measure the height y of each measurement point 17 and the reflection intensity of the measurement light (ST1, an example of a measurement process). .. As shown in FIG. 2, the height y is the distance from the reference plane 21 perpendicular to the measurement light 20 at the measurement point 17. In the present embodiment, the measurement light 20 is telecentric (the direction of the measurement light 20 is constant when measuring any measurement point 17), but this is not essential, and the measurement light 20 is the valve contact surface 11 and the outer periphery. It does not have to be telecentric as long as the surface 12 can be irradiated. The measurement area 23 is a square area in which the length of one side is slightly larger than the design diameter of the valve seat 10. The distance between the measurement points 17 in the X direction and the Y direction is appropriately determined in consideration of the desired identification accuracy and the measurement time.

The virtual surface 22 of the boundary surface 15 is set to the initial position (ST2). The virtual surface 22 of the boundary surface 15 is a surface orthogonal to the sliding axis 16 of the bulb 4, and is set with an inclination given in advance with respect to the reference surface 21 orthogonal to the measurement light based on the design dimensions. .. For the initial position, the height h is set so that the virtual surface 22 is below the boundary surface 15. Here, h is the distance between the intersection of the sliding shaft 16 and the virtual surface 22 and the reference surface 21 in the direction parallel to the measurement light 20.

Using the information of the height y acquired in step ST1, the measurement point 17 located above the virtual surface 17 (y <h) is extracted (ST3, extraction step).

The integrated brightness is calculated by logarithmically converting the reflection intensity of each measurement point extracted in step ST3 and summing the logarithmically converted reflection intensity of each measurement point (ST4, integrated brightness calculation step).

While moving the position of the virtual surface 22 upward, the above ST3 and ST4 are repeated until the position of the virtual surface reaches a predetermined end position (ST5, ST6). The end position is set in advance so as to be above the design position of the boundary surface 15.

An integrated luminance-virtual area graph showing the relationship between the integrated luminance and the height h of the virtual surface is created (ST7). FIG. 4 is an example of an integrated luminance-virtual area graph. In FIG. 4, the height h is shown as a relative height from the initial position. The integrated brightness-virtual surface graph is ideally as shown in FIG. 4, in which a straight line 25 having a small gradient in the section where the virtual surface 22 is located in the valve contact surface 11 and a section in which the virtual surface 22 is located in the outer peripheral surface 22. It is a polygonal line composed of a straight line 26 having a large gradient, and the height y1 corresponding to the inflection point 27, which is a point where the gradient of the curve suddenly changes, is the position of the boundary surface 15. However, in reality, since a large amount of measurement noise is included, the ideal shape as shown in FIG. 4 is not obtained, and it is often difficult to obtain a clear inflection point directly from this graph. In other words, when an ideal graph as shown in FIG. 4 is obtained, it is highly possible that the boundary can be identified only from the height information without obtaining the integrated luminance.

The method of finding the inflection point of the integrated luminance-virtual area graph is arbitrary, but in the present embodiment, for example, the inflection point is obtained by differentiating the integrated luminance-virtual area graph (ST8, ST9, ST7 to ST9 are An example of the identification process). FIG. 5 is a graph obtained by differentiating the integrated luminance-virtual area graph of FIG. When the ideal integrated luminance-virtual area graph as shown in FIG. 4 is differentiated, the step 28 becomes a clear stepped graph as shown in FIG. 5, and the position of the step 28 can be set as the boundary position. However, as described above, the integrated luminance-virtual area graph often does not have an ideal shape, so that the differential value does not actually have a clear step as shown in FIG.

Therefore, the threshold value T of the differential value is set, and the height y1 corresponding to the threshold value T is identified as the height of the boundary surface 15. By doing so, for example, the height of the boundary can be identified even when the step does not clearly appear as shown by the broken line 29 in FIG.

The case where the boundary is circular has been described above using the valve seat as an example, but this method can also be applied to the case where the boundary shape is a closed figure other than the circular shape. The measurement object 30, whose cross-sectional view is shown in FIG. 6A and whose plan view is shown in FIG. 6B, has a concave portion formed by a bottom surface 31 and a side surface 32 on the upper surface 33. The planar shape of the boundary 34 between the bottom surface 31 and the side surface 32 and the boundary 35 between the side surface 32 and the top surface 33 is rectangular. In this way, even if the shape of the boundary is not circular, if the measurement light 20 can be applied to the two surfaces for which the boundary is to be identified as shown in FIG. 6 (A), this method is applied to the boundary 34. , 35 can be identified in the vertical direction.

The measurement object 40, whose cross-sectional view is shown in FIG. 7A and a plan view shown in FIG. 7B, has a convex portion formed by a top surface 41 and a side surface 42 on the upper surface 43. The planar shape of the boundary 44 between the top surface 41 and the side surface 42 and the boundary 45 between the side surface 42 and the upper surface 43 is circular. In this way, even if the boundary is a corner portion or a rising portion of the convex portion, if the measurement light 20 can be applied to the two surfaces for which the boundary is to be identified as shown in FIG. 7 (A), By this method, the positions of the boundaries 44 and 45 in the vertical direction can be identified.

The measurement object 50, whose cross section is shown in FIG. 8 (A) and is shown in plan view in FIG. 8 (B), is a strip-shaped member having a step between the left upper surface 51 and the right upper surface 53, and the left upper surface 51 and the right upper surface 53. The portion between and is an inclined surface 52. The boundary line 54 between the left upper surface 51 and the inclined surface 52 and the boundary line 55 between the inclined surface 52 and the right upper surface 53 are straight lines extending in the width direction of the object to be measured 50. In this way, even if the boundary is an open figure such as a straight line, a curved line, or a polygonal line, if the measurement light 20 can be applied to the two surfaces for which the boundary is to be identified as shown in FIG. 8 (A). By this method, the positions of the boundaries 54 and 55 in the vertical direction can be identified. When the boundary is a straight line, the virtual surface of the boundary surface including the boundary is set with a predetermined inclination with respect to the reference surface orthogonal to the measurement light 20 based on the design dimensions.

FIG. 9 is a schematic structural diagram of the laser rangefinder 60 of FIG. Laser rangefinder 60 includes a first light source 61 for emitting reference light _{S 1,} a second light source 62 for emitting measuring light _{S 2,} the reference light _{S 1} interference light _{S 3} of the measuring beam _{S 2} a reference photodetector 63 to be detected, a reference plane 64 the reference light S ₁ is being irradiated, the measurement surface 65 is the measuring light is irradiated (for example, the valve contact surface 11 in FIG. 2, the outer circumferential surface 12), the reference plane and the measurement light detector 66 for detecting the interference light S ₄ of the _'measurement luminous S ₂ reflected by the measurement surface 65 _and' criteria light S ₁ reflected by 64, the interference light S ₃ by the reference photodetector 63 comprising a signal processing unit 67 that the interference signal obtained by detecting interference light S ₄ detected interference signal obtained by the by the measurement photodetector 66 are supplied.

_{The first and second light sources 61 and 62 emit the reference light S 1} and the measurement light S ₂ , which are cyclically modulated in intensity or phase and have different modulation cycles from each other, respectively. modulated periodically intensity or phase, two light sources, an optical frequency comb mode spacing different comprising a light modulator for emitting reference light S ₁ and the measurement light S ₂ with the modulation period different interfering with each other It consists of two optical frequency comb generators or two pulse light sources with different optical pulse repetition frequencies.

The emitted reference light S ₁ from the first and second light sources 61 and 62 measuring beam S ₂ is superposed is mixed by the light mixing element 71 comprising a semi-transparent mirror or a polarizing beam splitter, light separating consisting half mirror The element 72 separates the light toward the reference photodetector 63 and the light toward the measurement target.

Here, the measuring beam S ₂ emitted reference light S ₁ from the first and second light sources 61 and 62, it is assumed that orthogonal polarization planes with each other are mixed by the light mixing device 71 made of semi-transparent mirror The mixed light is reflected by the light separating element 72 and incident on the reference light detector 63 via the polarizing element 73, and the mixed light passing through the light separating element 72 is referred to by the polarizing beam splitter 74 according to the polarization. The light S ₁ and the measurement light S ₂ are separated, and the reference light S ₁ is incident on the reference surface 64, and the measurement light S ₂ is incident on the measurement surface 65.

Furthermore, the reference light S ₁ that is reflected by the reference surface 64 _'and, measurement luminous S ₂ reflected by the measuring surface _65' is mixed by the polarization beam splitter 74, the mixed light is reflected by the light splitting element 72 It is adapted to be incident on the measuring light detector 66 via the polarizing element 75.

The reference photodetector 63, than to receive mixed light of the reference light S ₁ that is incident through the polarizer 73 and the measuring light S _2, emitted from the first and second light sources 61 and 62 and it detects the reference light S ₁ and the interference light S ₃ of the measuring beam S ₂ was.

The measurement photodetector 66, by receiving the mixed light of the _'measurement beam S _{2 and'} reference beam S ₁ is incident through the polarizer 75, the reference light S ₁ that is reflected by the reference surface 64 ' and it is adapted to detect the interference light S ₄ of the measuring light S _{2 'that} is reflected by the measurement surface 5.

The interference signal obtained by the reference photodetector 63, the difference in the emitted reference light S ₁ and a carrier light frequency of the measuring beam S ₂ from the carrier frequency first and second light sources 61 and 62, the reference beam S ₁ and the same interference wave at a frequency of the difference between the optical pulse repetition frequency of the measuring beam S ₂ is repeated.

In this laser rangefinder 60, the role of the reference photodetector 63 is to generate a reference for delay time measurement. Reference light S ₁ and the measurement light S ₂ emitted from the first and second light sources 61 and 62, since unequal repetition frequency, be shifted timing when the light source starts operating, the timing slightly There will always be a moment when the optical pulse of the reference light S _{1 and} the optical pulse of the measurement light S _{2 overlap each other.} Further, the overlapping moment appears periodically at a repetition frequency of the difference between the repetition frequency of the reference light S ₁ and the measurement light S _2. The moment when the optical pulse and the optical pulse overlap is the standard for measuring the delay time.

Furthermore, interference signal obtained by the measurement photodetector 66 is the difference of the carrier light frequency of the interference signal obtained by the reference photodetector 3 also carrier frequencies _'and measuring light S _2' reference light S _1, the reference light pulses of light S ₁ and the measuring beam S ₂ repeated with the same repetition frequency as the difference frequency. However, the light pulse input to the measurement photodetector 66, the absolute value of the distance difference between the distance L ₂ between the distance L ₁ to the reference reflector 64 to a measurement reflector 65 min only (L 2 _{-L 1)} Since the timing of the optical pulse is delayed, the moment when the optical pulse and the optical pulse overlap is delayed as compared with the interference signal obtained by the reference optical detector 63. This delay time is the delay time due to the propagation of the optical pulse at a distance twice the absolute value of the distance difference (L _2- L ₁ ), and is the distance obtained by multiplying the speed of light C in vacuum and dividing by the refractive index ng. Is obtained.

As described above, when the distance is measured by the interference of two pulse light sources having different periods, the reference light detector 63 for the interference signal that gives a time reference is indispensable, and the reference light detector 63 and the measurement light detector 66 are used. Distance measurement is possible only by comparing the time difference of each of the obtained interference signals.

Therefore, the laser rangefinder 60, the signal processing unit 67, the interference signal obtained by detecting interference light S ₃ by the interference signal obtained by detecting interference light S3 and the measurement light detector 66 by the reference photodetector 63 from the time difference, performs a process for obtaining the speed of light and the absolute value of the distance difference between the distance L ₂ of a distance L ₁ and the measurement surface to the reference plane from the refractive index at a measurement wavelength (L 2 _{-L 1).}

That is, in the laser rangefinder 60, respectively cyclically intensity or phase emitted from the first and second light sources 61 and 62 is modulated, the reference light S ₁ and the measuring light with the modulation period different interfering with each other with irradiated with S ₂ to the reference plane 64 and the measuring surface 65 is detected by the reference light S ₁ and the measurement light S ₂ reference photodetector 63 an interference light S ₃ and irradiating the reference surface 64 to the measurement surface 65, the interference light S ₄ of the _'measurement luminous S ₂ reflected by the measurement surface 65 _and' criteria light S ₁ reflected by the reference surface 64 is detected by measuring light detector 66, the signal processing unit 67, the reference light detected distance from the time difference of the interference signal detected interference light S4 by the interference signal detected interference light S ₃ and the measurement light detector 66 by the vessel 63, until the distance between the measurement surface from the refractive index at the speed of light and the measuring wavelength to the reference plane (Measurement of height in ST1 in FIG. 3).

The principle of distance measurement is based on a rangefinder that calculates the distance from the time delay of an optical pulse. That is, the time delay ΔT = 2 × ng × (L _2- L _{1 ) / c when reciprocating the distance (L 2-} L ₁ ) is measured, and the group refractive index ng of the optical path and the speed of light c in vacuum are used. Calculate (L _2- L ₁ ).

The signal processing unit 67 is composed of, for example, a microcomputer, and calculates the intensity of the reflected light in addition to the above-mentioned distance calculation process (measurement of the reflected light intensity in ST1 of FIG. 3). The signal processing unit 67 further executes a computer program that performs the processing of ST2 to ST9 in FIG. 3 to identify the position of the boundary line.

Here, when two optical frequency comb generators are used as the first and second light sources 61 and 62 in the laser rangefinder 60, for example, the light source 80 having the configuration shown in FIG. 10 is used.

That is, in this light source 80, the laser light emitted from one single frequency oscillation laser light source 81 is split by the beam splitter 82 and input to the two optical frequency comb generators (OFCG1, OFCG2) 86A, 86B. It is supposed to be done.

The two optical frequency comb generators 86A and 86B are driven by oscillators 83A and 83B that oscillate at different frequencies fm + Δfm and frequency fm. The respective oscillators 83A and 83B are phase-locked by the common reference oscillator 84, so that the relative frequencies of fm + Δfm and fm become stable. In front of the optical frequency comb generator (OFCG1) 86A, a frequency shifter 85 such as an acoustic optical frequency shifter (AOFS) is provided, and the input laser beam is given an optical frequency shift of frequency fa by this frequency shifter 85. It has become like. As a result, the beat frequency between the carrier frequencies becomes an AC signal having a frequency fa instead of a DC signal. As a result, the beat signal of the high frequency side band of the carrier frequency and the beat signal of the low frequency side side band are generated in the opposite frequency regions with the beat frequency fa between the carrier frequencies of the beat signal, which is convenient for phase comparison. ..

In the present embodiment, the signal processing unit 67 of the laser rangefinder 60 executes the inclined surface boundary position identification program, but the laser rangefinder 60 only measures the height and the reflected light intensity (step S1 in FIG. 3). The boundary can be identified by executing the inclined surface boundary position identification program that performs the processing of steps ST2 to ST9 in FIG. 3 on another device, for example, a personal computer, and analyzing the measurement result by the laser range finder 60. can. That is, the present invention is a device provided with means for executing each process of the boundary position identification method, a computer program for causing a computer to execute each process of the boundary position identification method, in addition to the method of identifying the boundary position of an inclined surface. It can also be implemented as a computer-readable storage medium that stores a computer program.

Further, the laser rangefinder 60 is an example of a rangefinder, and if the height of the measurement point and the reflection intensity of the measurement light can be measured using light, another type of rangefinder may be used. You can also.

In this method, an integrated luminance-virtual plane position graph is created, and the position of the boundary plane is identified by finding the inflection point of this graph. Therefore, even when the reflection intensity of the measurement light is weak and the measurement accuracy of the measurement point height is poor, the boundary surface position can be identified with high accuracy. In a type such as the laser rangefinder 60 shown as an example of a rangefinder, in which the irradiation of the measurement light and the detection of the reflected light are performed coaxially, the incident angle of the measurement light on one inclined surface is often small. In particular, the present invention is useful.

10 valve seat, 11 valve contact surface, 12 outer peripheral surface, 13 boundary, 15 boundary surface, 16 valve sliding shaft, 17 measurement point, 20 measurement light, 21 reference surface, 22 virtual surface, 60 laser rangefinder, 61st 1 light source, 62 2nd light source, 63 reference light detector, 66 measurement light detector, 67 signal processing unit

Claims (9)

A measurement light of a virtual surface of a boundary surface which is a plane including a boundary between the first surface and the second surface of a measurement object having a first surface and a second surface having different inclinations and having known design dimensions. the set with the inclination given in advance based on the design dimensions, while changing the virtual surface height is the distance between the virtual plane and the reference plane relative to a reference plane orthogonal to the measurement area including the boundary An extraction step of extracting those whose measurement point height, which is the distance from the reference plane optically measured, is smaller than the virtual plane height, among the measurement points in the
For the measurement point extracted in the extraction step, the measurement point brightness, which is the brightness of the reflected light from the first surface or the second surface of the measurement light used for measuring the measurement point height, is logarithmically converted. The integrated brightness calculation process that totals and calculates the integrated brightness, and
A method for identifying an inclined surface boundary position, which comprises an identification step of identifying the position of the boundary surface by specifying an inflection point of a curve showing a relationship between the integrated luminance and the virtual surface height. The method for identifying an inclined surface boundary position according to claim 1, further comprising a measurement step of optically measuring the height of the measurement point and measuring the brightness of the measurement point prior to the extraction step. The method for identifying an inclined surface boundary position according to claim 2, wherein the measurement step is performed by a range finder that irradiates the measurement light and detects the reflected light coaxially. The identification step is characterized in that a curve showing the relationship between the integrated luminance and the virtual surface height is differentiated, and the virtual surface height at which the differential value is a predetermined threshold value is set as the boundary position. The method for identifying an inclined surface boundary position according to any one of 1 to 3. The method for identifying an inclined surface boundary position according to any one of claims 1 to 4, wherein the boundary is a closed figure. The measurement object is a valve seat, said first surface is a surface per valve, said second surface Ri smaller outer circumference der inclination than the surface per valve provided on an outer periphery of surface per said valve the inclination of the imaginary plane inclined surface boundary localization method according to claim 5, wherein the inclination der Rukoto face the outer circumferential surface of the surface per valve and the valve contact surface make. The inclined boundary position identification method according to any one of claims 1 to 4, wherein the boundary is an open figure. A measurement light of a virtual surface of a boundary surface which is a plane including a boundary between the first surface and the second surface of a measurement object having a first surface and a second surface having different inclinations and having known design dimensions. the set with the inclination given in advance based on the design dimensions, while changing the virtual surface height is the distance between the virtual plane and the reference plane relative to a reference plane orthogonal to the measurement area including the boundary An extraction means for extracting those whose measurement point height, which is the distance from the optically measured reference plane, is smaller than the virtual plane height, among the measurement points in the
For the measurement point extracted by the extraction means, the measurement point brightness, which is the brightness of the reflected light from the first surface or the second surface of the measurement light used for measuring the measurement point height, is logarithmically converted. An integrated brightness calculation means that totals and calculates the integrated brightness,
An inclined surface boundary position identification device including an identification means for identifying the position of the boundary surface by specifying an inflection point of a curve showing a relationship between the integrated luminance and the virtual surface height. On the computer
A measurement light of a virtual surface of a boundary surface which is a plane including a boundary between the first surface and the second surface of a measurement object having a first surface and a second surface having different inclinations and having known design dimensions. the set with the inclination given in advance based on the design dimensions, while changing the virtual surface height is the distance between the virtual plane and the reference plane relative to a reference plane orthogonal to the measurement area including the boundary Extraction processing for extracting those whose measurement point height, which is the distance from the reference plane optically measured, is smaller than the virtual plane height, among the measurement points in the
For the measurement point extracted by the extraction process, the measurement point brightness, which is the brightness of the reflected light from the first surface or the second surface of the measurement light used for measuring the measurement point height, is logarithmically converted. The integrated brightness calculation process that totals and calculates the integrated brightness,
An inclined surface boundary position identification program that executes an identification process for identifying the position of the boundary surface by specifying an inflection point of a curve showing the relationship between the integrated luminance and the virtual surface height.

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