JP2008157635A - Optical measurement apparatus and optical measurement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical measurement apparatus having a noncontact probe, and readily measuring the interior of a hole, in a short time. <P>SOLUTION: Three pairs of measurement units 20 are disposed in the inside of a base 16 of the probe 15. Each measurement unit 20 comprises an optical fiber 21 as a light source, an irradiation hole 22, a reflection light guide hole 23 as a transmission section, a condensing lens 24; and a light-receiving element (two-dimensional PSD) 25. If the probe 15 is irradiated with a light from the light source, in a state where the probe 15 is inserted in the hole in an object to be processed, the light is reflected irregularly by the inner wall of the hole. A portion of the scattered light (reflected light) is transmitted through the probe 15 and is imaged on a light-receiving plane 26 of the light-receiving element 25. The inside diameter of the hole is calculated, by obtaining an virtual circle having the circumference as the inner wall of the hole, based on coordinates of an imaging point. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical measurement apparatus and an optical measurement method for measuring the inside of a hole provided in, for example, a casting such as a cylinder block or various machined products.

  Conventionally, for example, the following devices are known as devices for measuring the internal shape (for example, inner diameter, roundness, surface roughness, etc.) of a hole formed in an object to be measured such as castings. (For example, refer to Patent Document 1). The measurement apparatus disclosed in Patent Document 1 receives various tables that allow the object to be measured to move in a predetermined direction, a CCD camera that images the position of the hole of the object to be measured, and the output of the CCD camera. A computer, a microprobe inserted into the hole of the object to be measured, and the like are provided. The microprobe has a pair of contacts at its tip. According to this measuring device, the microprobe (contactor) is brought into contact with the inner wall surface of the hole of the object to be measured, thereby making it possible to perform a desired measurement regarding the inner shape of the hole.

For example, when measuring the inner diameter of the hole, the following steps are performed. That is, the first step of moving the probe toward the inner wall surface of the hole of the object to be measured placed on the table and bringing one contact into contact with the inner wall surface of the hole; And a second step of specifying the position of the contact point when contacting the inner wall surface based on the detection result of the detection means. Next, when the probe is moved in the opposite direction to the first step and the other contact is brought into contact with the inner wall surface of the hole, and the other contact is brought into contact with the inner wall surface of the hole. And a fourth step of specifying the position of the contact point based on the detection result of the detection means. Furthermore, a fifth step of calculating a distance between the contact points, that is, an inner diameter of the hole based on the positions of the two contact points specified by the second step and the fourth step, respectively.
JP 2004-53413 A

  By the way, in the conventional measuring apparatus, it is necessary to repeat the operation of bringing the microprobe into contact with the inner wall surface of the hole a plurality of times. Such an operation is complicated for an operator and takes time. In the step (first step and third step) of bringing the microprobe into contact with the inner wall surface of the hole, the table is moved to bring the microprobe (contactor) into contact with the inner wall surface of the hole. A complicated mechanism such as stopping the table by using a signal of resistance change when the contact) contacts the inner wall surface of the hole as a trigger is required. For this reason, the measurement apparatus becomes complicated and eventually increases in size, and it is difficult to perform a desired measurement in a short time at the manufacturing site of the object to be measured.

  The present invention has been made in view of such a conventional situation, and an object of the invention is to provide an optical measuring device that can easily measure the inside of a hole in a short time by including a non-contact type probe. And providing an optical measurement method.

  In order to achieve the above object, an optical measuring device according to the invention described in claim 1 is an optical measuring device for measuring the inside of a hole provided in a measured object, wherein the hole of the measured object is provided. A light source that irradiates basic light toward the inner wall surface, a transmission part that transmits arbitrary scattered light reflected by the inner wall surface, and a light receiving element that receives the arbitrary scattered light transmitted through the transmission part A virtual circle diameter and center coordinates based on a light receiving position of the arbitrary scattered light on the light receiving element in a state where the probe is inserted into the hole. Thus, the gist is provided with a calculation means for calculating the inner diameter of the hole.

  According to the above configuration, a part of the scattered light reflected by the inner wall surface is received by the light receiving element via the transmission part. Then, based on the light receiving position of the scattered light on the light receiving element, the interval between the reflection position of the basic light on the inner wall surface of the hole and the probe is calculated, and the coordinate value of the reflection position of the basic light is determined. . As a result, the virtual circle diameter and the center coordinate are obtained based on the coordinate value of the reflection position. Then, the inner diameter of the hole is calculated from the coordinate value of the reflection position and the center coordinate value of the virtual circle. As described above, in this configuration, it is not necessary to bring the probe into contact with the inner wall surface of the hole, and a desired measurement regarding the inner shape of the hole, that is, the inner diameter of the hole can be performed by an extremely simple operation such as inserting the probe into the hole. Can be measured. Therefore, the inside of the hole can be easily measured in a short time without complicating the device structure.

  An optical measuring device according to a second aspect of the present invention is an optical measuring device that measures the inside of a hole provided in a measured object, and emits basic light toward the inner wall surface of the hole of the measured object. A non-contact type comprising a light source for irradiation, a transmission part for transmitting arbitrary scattered light reflected by the inner wall surface, and a light receiving element for receiving the arbitrary scattered light transmitted through the transmission part A virtual circle diameter and a center based on a light receiving position of the arbitrary scattered light on the light receiving element in at least two places along the depth direction of the probe in a state where the probe is inserted into the hole. The gist of the present invention is that it comprises computing means for calculating the inclination angle of the hole by obtaining the coordinates.

  According to the above configuration, a part of the scattered light reflected by the inner wall surface is received by the light receiving element via the transmission part. Based on the light receiving position of the scattered light on the light receiving element, the interval between the reflection position of the basic light on the inner wall surface of the hole and the probe is calculated, and the coordinate value of the reflection position of the basic light is determined. . As a result, one virtual circle diameter and center coordinates are obtained based on the coordinate values of such reflection positions. Subsequently, in another place along the depth direction of the hole, another virtual circle diameter and center coordinates are obtained based on the light receiving position of the scattered light on the light receiving element in the same manner as described above. Thereby, a virtual circle diameter and center coordinates are separately identified at two locations along the depth direction of the hole, and the inclination angle of the hole is calculated based on the respective center coordinates.

  As described above, in this configuration, it is not necessary to bring the probe into contact with the inner wall surface of the hole, and a desired measurement regarding the inner shape of the hole, that is, the inclination of the hole can be performed by a very simple operation such as inserting the probe into the hole. The angle can be measured. Therefore, the inside of the hole can be easily measured in a short time without complicating the device structure.

  According to a third aspect of the present invention, there is provided the optical measuring device according to the first or second aspect, wherein a plurality of the light sources are provided on the same circumference having a center on the axis of the probe. This is the gist. According to the above configuration, since two or more coordinate values of the reflection position are obtained by one measurement, it becomes easy to identify a virtual circle necessary for measuring the inclination angle of the hole. That is, the inside of the hole can be easily measured.

  The optical measurement device according to claim 4 is the invention according to any one of claims 1 to 3, wherein the light receiving element is a two-dimensional position detection element, and the light receiving surface of the two-dimensional position detection element is The gist is that the probe is disposed on a plane orthogonal to the axis of the probe. According to this, even if it is a case where a several light source is used, a light receiving element can be shared.

  The optical measurement method according to claim 5 is an optical measurement method for measuring the inside of a hole provided in the object to be measured, toward at least three different locations on the inner wall surface of the hole of the object to be measured. Irradiating basic light to specify the coordinates of each location, and calculating the inner diameter of the hole by obtaining a virtual circle based on the coordinates of at least three different locations of the inner wall surface obtained in the step. This is the gist. According to this, it is not necessary to bring the probe into contact with the inner wall surface of the hole, and a desired measurement regarding the inner shape of the hole, that is, the measurement of the inner diameter of the hole can be performed by an extremely simple operation such as inserting the probe into the hole. It becomes possible.

  According to the optical measuring device and the method of the present invention, the inside of the hole can be easily measured in a short time by including the non-contact type probe.

Hereinafter, an embodiment (first embodiment) in which an optical measuring device of the present invention and a method for measuring the inside of a hole using the device will be described with reference to the drawings.
As shown in FIG. 1, the optical measuring device 10 includes a base 11 and an arm portion 12 that is pivotally supported by the base 11. The arm portion 12 includes a plurality of arm portions 12. The three arm members 13 (in this embodiment) are pivotally supported with respect to each other. A non-contact type probe (hereinafter simply referred to as a probe) 15 is provided on the arm member 13 disposed on the most distal side among the plurality of arm members 13 (see FIG. 2). The optical measuring device 10 includes a computer as a control unit and a calculation unit, and a motor as a driving unit that is electrically connected to the computer and moves the probe 15 in a three-dimensional direction and rotates around the axis (both are both). (Not shown). Then, the probe 15 is moved in a predetermined direction inside the hole 51 (cylinder) of the DUT 50 such as a cylinder block, thereby measuring the internal shape of the hole (in this embodiment, the inclination angle of the hole). can do. Hereinafter, the probe 15 of this embodiment will be described with reference to FIG.

  The probe 15 includes a base body 16 formed of a metal material and having a hollow cylindrical shape. The base body 16 has a base body 17 formed in a bottomed cylindrical shape having a bottom portion 17a at the tip, and a base tip portion formed in a bottomed cylindrical shape having the same diameter as the base body body 17 and having a bottom portion 18a at the base end. 18 (FIG. 3). The base body 17 and the base end portion 18 are fixed so as not to move relative to each other by a fastening member (not shown) in a state where the bottom portions 17a and 18a are overlapped. The base 16 has a cross section formed as a perfect circle. The center of the cross section of the base 16 is an axis g (see FIG. 4), and an imaginary line extending through the axis g in the axial direction of the base 16 is an axis h. The direction in which the axis h extends (the extending direction of the base body 16) is referred to as the axis direction. Further, since the axial center g, the axial line h, and the axial direction of the probe 15 coincide with those of the base 16, the probe 15 is also used synonymously.

  The probe 15 includes three sets of measurement units 20. Each measurement unit 20 includes an optical fiber 21 as a light source, an irradiation hole 22, a reflected light introduction hole 23 as a transmission part, a condensing lens 24, and a light receiving element 25. The Of these configurations, the optical fiber 21, the irradiation hole 22, the reflected light introducing hole 23, and the condenser lens 24 are configurations that each measurement unit 20 has individually, but only the light receiving element 25 is shared by all the measurement units 20. Yes. These three sets of measurement units 20 are provided at equal intervals (120 degree intervals) on the same circumference around the axis h of the base 16 (see FIGS. 4 and 5). For convenience of explanation, the three measurement units 20 shown in the upper part of FIGS. 3 and 4 are the second measurement unit 20a and the first measurement unit 20a in FIG. It is assumed that the measurement unit 20b and the third measurement unit 20c are arranged. Hereinafter, the configuration and operation of the measurement unit 20 and each member will be described with respect to the first measurement unit 20a. However, the second measurement unit 20b and the third measurement unit 20c are different only in position. Since it is the same structure, description is abbreviate | omitted.

About the optical fiber 21 The optical fiber 21 as a light source is a unit composed of a cover 21a covering the periphery and an optical fiber 21b housed in the cover 21a. A window 21c facing outward in the radial direction is formed on the side surface on the distal end side of the optical fiber 21 (FIG. 3), and light (infrared light) transmitted through the optical fiber 21b is converged from the window 21c. Irradiation is performed toward the outside in the radial direction of the substrate 16 on an imaginary line k passing through the axis h of the substrate 16 and orthogonal to the axis h. Hereinafter, the light emitted from the optical fiber 21 is referred to as “basic light α”, and it is assumed that the optical axis of the basic light α coincides with the virtual line k. 3 and 4, the imaginary line k is illustrated only for the optical fiber 21 constituting the first measurement unit 20a. An existing product may be used for the optical fiber 21. For example, there is a model name E32-T24 of OMRON Corporation.

Irradiation hole 22 and reflected light introduction hole 23 An irradiation hole 22 that is a through hole is formed at the intersection of the base 16 with the virtual line k. Further, a reflected light introducing hole 23 cut out in a rectangular shape is formed in the base body 17 on the tip end side in the axial direction from the irradiation hole 22 (FIGS. 3 and 4).

Condensing Lens 24 Circular holes 17b and 18b are formed in the bottom portion 17a at the tip of the base body 17 and the bottom portion 18a of the base tip portion 18, respectively, and the circular holes are sandwiched between the bottom portions. The condensing lens 24 is fixed to (FIGS. 3 and 5). The condenser lens 24 is a convex lens, and is installed so that the optical axis thereof is parallel to the axis h of the base body 16. The optical center point 24 a of the condenser lens 24 (the radial direction and thickness direction of the condenser lens 24). Is located on the imaginary line 1 obtained by translating the imaginary line k by the distance a along the axis h of the substrate 16 toward the tip of the substrate 16. In FIG. 5, the imaginary line 1 is shown only for the condenser lens 24 constituting the first measurement unit 20 a.

Regarding the Light Receiving Element 25 The light receiving element 25 is a two-dimensional position detecting element (Position Sensitive Detector = PSD), and includes a base portion 25a and a light receiving surface 26 arranged facing the condenser lens 24 side (FIG. 3). . The light receiving element 25 is attached to the base end 18 so that the light receiving surface 26 is parallel to a surface orthogonal to the axis h of the base 16, and the light receiving surface 26 extends in the axial direction from the center point 24 a of the condenser lens 24. The distance b is separated. The light receiving element 25 converts the gravity center position (light receiving position) of infrared light imaged on the light receiving surface 26 into an electric signal as coordinates (x, y) on the x axis and the y axis orthogonal thereto, and outputs the electric signal. be able to. The light receiving element 25 may be an existing product as a two-dimensional PSD, for example, model name S7848 of Hamamatsu Photonics Co., Ltd.

  The origin (x0, y0) 26a of the coordinates on the light receiving surface 26 is set on the axis h of the base 16, and the y axis of the light receiving surface 26 is set in parallel with the virtual line k and the virtual line l. (FIG. 6). The electric signal output from the light receiving element 25 is input to the computer via a terminal pin (not shown), and the distance s from the origin 26a to the light receiving position is calculated. The distance s is calculated as a positive value (+) when the image is formed on the condenser lens 24 side with the origin 26 a of the light receiving surface 26 as the center, and the image is formed on the opposite side of the condenser lens 24. If it is, it is calculated as a negative value (−).

  As described above, the light receiving element 25 outputs the coordinates of the barycentric position of the light imaged on the light receiving surface 26 as an electric signal. Therefore, when the image is formed as diffused light, an error occurs in specifying the coordinates. It becomes easy. Therefore, it is preferable that the light imaged on the light receiving element 25 has a small area, and for that purpose, it is preferable to use a condensing lens 24 having a focal length focused on the light receiving element 25. .

  Specifically, the focal length f is 1 / f = 1 / a + 1 / b (a is the distance from the virtual line k in the axial direction to the center point 24a (virtual line 1) of the condenser lens 24, and b is the axial direction. The distance from the center point 24a (imaginary line 1) of the condenser lens 24 to the light receiving surface 26) can be specified, so that the focal length f can be determined based on the values of a and b.

Regarding the path of light emitted from the measurement unit 20 Hereinafter, in the measurement unit 20 of the present embodiment, the light emitted from the optical fiber 21 strikes the inner wall surface 52 of the hole 51, and the generated scattered light forms an image on the light receiving element 25. The route to be performed will be described with reference to FIG. 7 illustrates only the first measurement unit 20a among the three sets of measurement units 20 for convenience of explanation, the same applies to the second measurement unit 20b and the third measurement unit 20c.

  The light transmitted through the optical fiber 21 is irradiated from the window 21c at the tip of the optical fiber 21 to the outside. The basic light α emitted from the optical fiber 21 passes through the irradiation hole 22 along the virtual line k, exits the probe 15, and then reaches the inner wall surface 52 of the hole 51. In addition, the location where the basic light α is reflected by hitting the inner wall surface 52 of the hole 51 is also on the imaginary line k, and this location is referred to as a reflection position 52a. Here, the inner wall surface 52 of the hole 51 including the reflection position 52a is formed by boring or the like, and the surface thereof appears flat to the naked eye, but has microscopic unevenness. . Accordingly, the basic light α is irregularly reflected at the reflection position 52a and becomes scattered light. Of the scattered light, light directed in a specific direction (this light is referred to as “reflected light β”) passes through the reflected light introduction hole 23 and is introduced into the probe 15, and a part thereof is a condenser lens. An image is formed on the light receiving surface 26 through 24. The light receiving position at which the reflected light β is collected by the condenser lens 24 and imaged on the light receiving surface 26 is referred to as an imaging point 26b.

  For convenience of understanding, the reflected light β shown in FIG. 7 represents only the scattered light reflected at the reflection position 52a, in particular, the light passing through the center point 24a of the condenser lens 24, and from the reflection position 52a. The image formation point 26b is connected by a straight line. That is, the imaging point 26b is formed on an extension of a line obtained by connecting the reflection position 52a and the central point 24a of the condenser lens 24.

  Since the reflection position 52a and the central point 24a of the condenser lens 24 are respectively formed on the virtual line k and the virtual line l that pass through the axis h and are parallel to each other, the imaging point 26b also passes through the axis h and these virtual lines k. And formed at any one point on the virtual line m parallel to the virtual line l. That is, in the first measurement unit 20a, the locus of the imaging point 26b formed on the light receiving surface 26 when the distance between the probe 15 and the reflection position 52a is different (hereinafter simply referred to as “imaging point 26b”). Of the light receiving surface 26 coincides with the y axis (x = 0). In FIG. 6, the locus of the imaging point 26b when the first measurement unit 20a is used is indicated by a one-dot chain line.

  On the other hand, FIG. 6 shows an approximate position of the imaging point 26b formed on the light receiving surface 26 by the reflection position 52a shown in FIG. 7, but the reflection position 52a is a probe rather than the position shown in FIG. If the position is away from 15, the optical axis of the reflected light β passes through the condenser lens 24 with a larger angle difference with respect to the axis h. For this reason, the image forming point 26b in that case is formed at a position where the y coordinate value is smaller than the image forming point 26b shown in FIG. 7 (the image forming point 26b of the probe 15 indicated by a two-dot difference line in FIG. 9). See).

  Next, a measurement procedure of the inclination angle (inclination angle with respect to the axial direction of the probe 15) θ of the hole 51 using the optical measurement apparatus 10 according to the above embodiment will be described. The outline of the measurement procedure is shown in the flowchart of FIG. 8, and the computer includes a ROM (not shown) in which data for executing each step of the flowchart is stored. Hereinafter, a description will be given with reference to the flowchart of FIG. 8 and FIG. 9. The measurement inside the hole 51 is performed by obtaining an equation of a virtual circle having the inner wall surface 52 of the hole 51 at the specific position (position where the basic light α is irradiated in the probe 15) as a circumference.

Step 1 (S1)
First, the computer drives the driving means to move the probe 15 to the first measurement position 30 inside the hole 51 (position indicated by a solid line in FIG. 9). The hole 51 to be measured has a depth, an inner diameter, and the like set based on the processing data. In order to accurately measure the shape of the hole 51, the axial direction of the probe 15 is at the first measurement position 30. It is preferable to keep it substantially parallel to the forming direction. The depth of the first measurement position 30 is not limited as long as it is inside the hole 51. However, if the first measurement position 30 is close to the lower end of the hole 51, the probe 15 cannot further move.

Step 2 (S2)
After moving to the first measurement position 30, coordinate measurement for calculating the shape (inner diameter) of the hole 51 is performed. At the stage of measuring the inner diameter of the hole 51, neither the center nor the radius of the hole 51 is known. For this reason, at the first measurement position 30, the axial center g at the position where the basic light α is irradiated among the probes 15 at the same position is the coordinate origin (X = 0, Y = 0). Three different coordinates on the circumference of the inner wall surface 52 of the hole 51 are measured. In this case, the same map as the coordinates of the light receiving surface 26 may be used as the coordinates, or a different map may be used. The coordinates of the three points to be measured are obtained by sequentially operating the first measurement unit 20a, the second measurement unit 20b, and the third measurement unit 20c. Hereinafter, a measurement method using the first measurement unit 20a will be described as an example.

  First, an imaginary line n passing through the center point 24a of the condenser lens 24 and parallel to the axis h of the base body 16 is assumed (FIG. 7). Since both the virtual line k and the virtual line 1 are orthogonal to the axis h of the base body 16, the virtual line k and the virtual line 1 are also orthogonal to the virtual line n. The basic light α that has reached the inner wall surface 52 of the hole 51 is diffusely reflected as scattered light at the reflection position 52 a, and a part of the scattered light forms an image on the light receiving surface 26 through the condenser lens 24 as reflected light β. An optical axis passing through the central point 24a of the condenser lens 24 in the reflected light β is defined as a virtual line p.

  Here, in FIG. 7, the intersection of the virtual line k and the virtual line n is a point O, and the intersection of the virtual line n and the virtual line m on the light receiving surface 26 is a point D. When the reflection position 52a of the basic light α is a point A, the central point 24a of the condenser lens 24 is a point B, and the imaging point 26b on the light receiving surface 26 of the reflected light β is a point C, a triangle OAB on the same plane. And two right triangles of the triangle DBC.

  Since the interior angles of the triangle OAB and the triangle DBC with the point B as the vertex are diagonal, they are the same angle, and the interior angles with the point O and the point D as the vertex are both at right angles. Are equal triangles, and the triangle OAB and the triangle DBC are similar. Further, since the side OB is set to the distance a and the side DB is set to the distance b, the relationship of the distance of the side OA: the distance of the side CD = the distance a: the distance b is established according to the similarity condition.

  On the other hand, since the side OA is a part of the virtual line k, the distance from the surface of the base 16 to the reflection position 52a (point A) is L, and the distance from the axis h to the surface of the base 16 (base radius) is the distance r. If the distance from the axis h to the center point 24a (point B) of the condenser lens 24 is a distance c, the distance of the side OA can be expressed by L + rc. Among these, the distance r and the distance c are specified in advance. On the other hand, the side DC is a part on the imaginary line m parallel to the imaginary line k, and the distance from the axis h to the point D on the light receiving surface 26 is the distance from the axis h to the center point 24a of the condenser lens 24. (= Distance c). The distance of the side DC is the distance c from the axis h to the center point 24a of the condenser lens 24, and the distance s from the axis h to the point C is divided, so the distance of the side DC = distance c−. It can be represented by a distance s.

  And the relationship of L + rc: cs = a: b is established from the similarity condition of the triangle. When this expression is expanded, the following expression (1) is obtained.

  In the right side of this equation, the distance a, distance b, distance c, and distance r are all known values, and only the distance s changes. Therefore, by obtaining the distance s, the distance L can be obtained using the above formula. Here, since the relationship between the distance L and the distance s is a linear straight line as shown in the above equation (1), a minute change ds of the distance s obtained by differentiating the equation (1) with the distance s. The ratio of the minute change dL of the distance L to the distance, that is, the detection sensitivity in the light receiving element 25 is constant as dL / ds = −a / b and does not depend on the distance L and the distance s.

  The distance s is the distance from the origin 26a on the light receiving surface 26 to the imaging point 26b (point C) (however, when the y coordinate is negative, the distance s is a negative value), and the imaging point 26b (point C). Is specified by coordinates (0, y1), and therefore can be specified as s = y1. By substituting the value of s thus obtained into the above equation, the distance L from the surface of the probe 15 to the reflection position 52a which is the inner wall surface 52 of the hole 51, and further the coordinate values (X11, Y11) of the reflection position 52a are obtained. Can be measured. The coordinates (X11, Y11) of the reflection position 52a obtained by the measurement by the first measurement unit 20a are stored in a RAM (not shown) of the computer.

  Since three different coordinates are required to obtain the formula of the first virtual circle 31 that is a virtual circle at the first measurement position 30, the second measurement unit 20b and the third measurement unit 20c are operated in the same procedure. Thus, coordinate values (X12, Y12) (X13, Y13) of two different reflection positions are obtained. Among these, the second measurement unit 20b is disposed at a position rotated 120 degrees clockwise in FIG. 3 about the axis h with respect to the first measurement unit 20a. For this reason, the locus of the imaging point 26b on the light receiving surface 26 by the second measuring unit 20b is formed on a straight line (y = −1 / √3x) that passes through the origin 26a and is tilted 120 degrees clockwise with respect to the y axis. (Indicated by a two-dot chain line in FIG. 6).

  Further, since the third measurement unit 20c is disposed at a position rotated 120 degrees counterclockwise in FIG. 4 with respect to the first measurement unit 20a with the axis h as the center, light reception by the third measurement unit 20c is performed. The locus of the imaging point 26b on the surface 26 is formed on a straight line (y = 1 / √3x) that passes through the origin 26a and is tilted 120 degrees counterclockwise with respect to the y-axis (indicated by a broken line in FIG. 6). ). The coordinate values (x12, y12) and (x13, y13) of the imaging point 26b (point C) on the light receiving surface 26 measured using the second measurement unit 20b and the third measurement unit 20c, respectively. When the reflection position 52a is close to the probe 15, the y coordinate value is small and the y coordinate value is increased as the reflection position is separated.

  Accordingly, the distances s based on the coordinate values of the imaging point 26b (point C) of the second measurement unit 20b and the third measurement unit 20c can be obtained by the following formula (2) or formula (3). .

  By substituting the distance s obtained by the above equation into the equation (1), the distances L from the surface of the substrate 16 to the respective reflection positions 52a in the second measurement unit 20b and the third measurement unit 20c can be obtained. Further, the coordinate values (X12, Y12) (X13, Y13) of each reflection position can be obtained. This coordinate value is also stored in a RAM (not shown) of the computer.

Step 3 (S3)
The formula of the first virtual circle 31 is calculated based on the three coordinate values of the inner wall surface 52 of the hole 51 obtained in step 2 above. First, the coordinate values (X _i , Y _i ), (X _{i + 1} , Y) of arbitrary two points among the coordinate values (X11, Y11) (X12, Y12) (X13, Y13) of the already obtained three reflection positions 52a. _{i + 1} ) is substituted into the circle equation of the following equation (4). In the present embodiment, it is assumed that the cross-sectional shape of the hole 51 is a substantially perfect circle.

Then, by subtracting both equations obtained after substituting each coordinate value and arranging Cx and Cy, the following equation (5) is obtained. It should be noted that (n-1) Equations (5) are obtained from the measurement results of n points (3 points in the present embodiment).

  Here, when the equation (5) is set as the following equations (6) to (8),

The above formula (5) is expressed as the following formula (9).

Note that (n-1) Equations (9) are obtained from the measurement results of n points (three points in the present embodiment). From this result, when Cx and Cy are obtained using the least square method, the following equations (10) and (11) are obtained.

However, the range of Σ is 1 ≦ i ≦ n−1. Thereby, the center coordinates 31a of the first virtual circle 31 are obtained. And after determining this center coordinate 31a, Ri corresponding to the coordinate value of each reflection position is calculated | required by following formula (12), and let the average value be the measured value R of the radius of a virtual circle.

However, the range of Σ is 1 ≦ i ≦ n. By calculating the radius of the virtual circle in this way, the inner diameter of the hole (the diameter of the virtual circle) is calculated. Therefore, if three different coordinates on the circumference can be obtained, the three constants of the circle equation can be calculated. The calculated formula of the first virtual circle 31 is stored in the RAM of the computer.

Step 4 (S4)
In step 4, the computer drives the driving means to move the probe 15 to the second measurement position 40 (position indicated by a two-dot chain line in FIG. 9). The second measurement position 40 is a position where the probe 15 at the first measurement position 30 is moved by a predetermined distance t in the depth direction F of the hole 51 on the axis h.

Step 5 (S5)
After the probe 15 is moved to the second measurement position 40, the shape of the hole 51 at the same position is measured. This measurement method is the same as the measurement method in Step 2, and the first measurement unit 20a, the second measurement unit 20b, and the third measurement unit 20c are operated sequentially, and the inner wall surface 52 of the hole 51 at this second measurement position is different. Three coordinate values (X21, Y21) (X22, Y22) (X23, Y23) are measured.

Step 6 (S6)
The formula of the second virtual circle 41 is calculated based on the three coordinate values of the inner wall surface 52 of the hole 51 at the second measurement position 40 obtained in step 5 above. The calculation method is the same as in step 3, and the calculated expression of the second virtual circle 41 is stored in the RAM (not shown) of the computer.

Step 7 (S7)
The computer reads the equations of the first virtual circle 31 obtained in step 3 and the second virtual circle 41 obtained in step 6 from the RAM, and calculates the inclination angle θ of the hole 51. That is, the inclination angle θ of the hole 51 with respect to the axial direction of the probe 15 can be obtained by a line connecting the center coordinates 31a of the first virtual circle 31 and the center coordinates 41a of the second virtual circle 41 (FIG. 10). Here, when the inclination angle θ of the hole 51 is zero and the inner wall surface 52 coincides with the axial direction of the probe 15, the central coordinates 31 a of the first virtual circle 31 and the central coordinates 41 a of the second virtual circle 41 coincide. Should do. On the other hand, when the central coordinates 41a of the second virtual circle 41 do not coincide with the central coordinates 31a of the first virtual circle 31 (the state shown in FIG. 10), the hole 51 is inclined with respect to the axial direction of the probe 15. Therefore, the inclination angle θ of the hole 51 can be calculated from the relationship between the center coordinate 31a of the first virtual circle 31, the center coordinate 41a of the second virtual circle 41, and the distance t of the probe 15.

According to the optical measurement device 10 of the above embodiment, the following effects can be obtained.
* According to the optical measurement apparatus 10 of the present embodiment, the coordinate value of each reflection position 52a is obtained by irradiating the inner surface 52 of the hole 51 with the basic light α from each measurement unit 20 (20a, 20b, 20c). The inner diameter of the hole 51 is measured by identifying one virtual circle at an arbitrary location inside the hole 51. In addition, the inclination angle θ of the hole 51 is measured by identifying virtual circles at two locations in the axial direction of the probe 15 inside the hole 51. That is, the inside of the hole 51 can be measured without bringing the probe 15 into contact with the inner wall surface 52 of the hole 51. Thereby, in this embodiment, a complicated mechanism for bringing the probe 15 into contact with the inner wall surface 52 of the hole 51 is not required, the configuration can be simplified, and the enlargement of the apparatus can be avoided. A desired measurement can be performed by an extremely simple operation such as inserting the probe 15 into the hole 51. Therefore, according to the optical measuring apparatus 10 of the present embodiment, the inside of the hole 51 can be easily measured in a short time at the manufacturing site of the measurement object 50.

  * In this embodiment, an arbitrary light of the scattered light scattered at the reflection position 52a of the inner wall surface 52 is imaged on the light receiving element 25 as reflected light β, and the coordinates of the imaging point 26b are measured. . For this reason, in the present embodiment, it is not necessary to strictly adjust the angle of light, the installation location of the light receiving element 25 inside the base body 16 and the like so that the reflected light β is accurately imaged on the light receiving element 25. Therefore, according to the optical measuring device 10 of the present embodiment, the structure can be simplified.

  * In the optical measuring device 10 of this embodiment, three optical fibers 21 as light sources are provided in the circumferential direction as a unit. Here, at least three coordinate values are required to identify the virtual circle. According to the present embodiment, such three coordinate values can be instantaneously calculated in one measurement. Thereby, identification of a virtual circle diameter and center coordinates can be performed easily. The optical fibers 21 are provided at equal intervals in the circumferential direction. That is, the coordinate values of the reflection positions 52a are obtained at equal intervals in the circumferential direction. This makes it possible to identify a virtual circle that reflects the internal shape of the hole 51 with high accuracy, so that the inclination angle of the inner wall surface 52 of the hole 51 and the inner diameter of the hole 51 can be accurately measured.

* By using the optical fiber 21 as a light source, it is possible to reliably irradiate a predetermined portion of the inner wall surface 52 of the hole 51 with the basic light α.
* The coordinate value of the inner wall surface 52 of the hole 51 is calculated by obtaining the distance s from the origin 26a of the light receiving surface 26 to the imaging point 26b on the light receiving surface 26 of the reflected light β. Therefore, the coordinate value of the inner wall surface 52 of the hole 51 can be easily measured.

  * A light receiving element (two-dimensional PSD) 25 is arranged as a light receiving means so that its light receiving surface 26 is on a plane orthogonal to the axis h, and is shared by each measurement unit 20. For this reason, it is not necessary to prepare light receiving means according to the number of measurement units 20.

  * The reflected light β is condensed by the condenser lens 24 and imaged on the light receiving surface 26. For this reason, the spot area of the imaging point 26b on the light receiving surface 26 is reduced, and the PSD measurement error for obtaining the position of the center of gravity of the light is reduced.

* Since the reflected light β is condensed by the condensing lens 24 to form an image on the light receiving element 25, the amount of light at the image forming point 26b on the light receiving element 25 also increases, and the detection sensitivity is improved.
* Since the relationship between the distance L and the distance s is a linear line (formula (1)), the detection sensitivity in the light receiving element 25 is constant as dL / ds = −a / b, and the distance L and the distance s are Stable sensitivity can be obtained without dependence.

In addition, you may change and apply the said embodiment as follows.
If the light receiving element (two-dimensional PSD) 25 is provided with a filter that allows only light having the wavelength used for measurement to pass through, noise such as disturbance light can be further reduced.

  ○ Without using the condensing lens 24 arranged in the above embodiment, by forming a fine hole at the position where the condensing lens 24 was arranged, the fine hole functions as a pinhole to reflect light. β may be imaged or irradiated on the light receiving surface 26. In this case, since the imaging (irradiation) point 26b is formed on the light receiving surface 26 only by the reflected light β that has passed through the pores, the imaging (irradiation) point 26b is compared with the case where the condenser lens 24 is used. The amount of light may be insufficient. For this reason, it is necessary to use, as the basic light α, light capable of obtaining an amount of light that allows the reflected light β to be detected by the light receiving element 25 without using the condenser lens 24.

  In the above embodiment, three sets of measurement units 20 are provided at equal intervals in the circumferential direction, but one or two sets of measurement units 20 may be provided. When the measurement unit 20 is one set, the probe 15 is allowed to rotate around the axis h, and is rotated by a predetermined angle every time the coordinates of the inner wall surface 52 of the hole 51 are measured, and the holes 51 at three different positions are measured. By measuring the coordinates of the inner wall surface 52, the shape of the hole 51 can be measured. In the case of two sets, it is only necessary to measure the coordinates of the inner wall surface 52 of the hole 51 in at least three different places.

  The light receiving means may be replaced with the two-dimensional PSD 25 of the above embodiment, and a color CCD capable of identifying colors may be used. In this case, the light colors of the light sources of the three sets of measurement units 20 are made different (for example, green, blue, red), so that even if the reflected light from the plurality of measurement units 20 is sequentially received by the light receiving means That is, the coordinates of each imaging point 26b can be specified for each reflected light β from the reflection position 52a of each measurement unit 20.

In the above embodiment, the optical fiber 21 is used as the light source. However, instead of this, another light source such as an LED or a laser diode may be used.
In the present embodiment, the three optical fibers 21 are provided at equal intervals in the circumferential direction, but the intervals between adjacent optical fibers 21 may be different from each other.

  A configuration in which one set of the measurement unit 20 in the probe 15 of the present embodiment is further provided on the distal end side of the probe 15 may be employed. That is, the probe 15 is provided with 3 sets × 2 stages of measurement units 20. When configured in this way, the first virtual circle and the second virtual circle can be measured at different locations in the depth direction of the hole 51 without moving the probe 15 in the axial direction inside the hole 51. It becomes possible. Therefore, according to this configuration, since the operation of moving the probe 15 from the first measurement position 30 to the second measurement position 40 in the hole 51 is not required, it is easier to measure the inside of the hole 51. Become.

  In this embodiment, virtual circles are identified at two locations (first measurement position 30 and second measurement position 40) in the depth direction inside the hole 51, and the inner diameter of the hole is individually determined from the radius of the virtual circle. However, the virtual circles may be identified at three or more locations inside the hole 51, and the average value of the diameters of the virtual circles may be used as the inner diameter of the hole.

  In the present embodiment, it is assumed that the cross-sectional shape of the hole 51 is a substantially perfect circle. However, when the cross-sectional shape is an ellipse, an elliptic formula is adopted instead of the circle equation. In this case, when the virtual circle is obtained as described above, at least four coordinate values of the reflection position on the inner wall surface of the hole 51 are required. In such a case, in order to simplify and speed up the measurement, a configuration in which four or more measurement units 20 are provided on the same circumference having the center on the axis h of the base 16 is preferable.

In the present embodiment, the inclination angle θ of the inner wall surface 52 of the hole 51 is measured by obtaining the first virtual circle 31 and the second virtual circle 41 inside the hole 51, but this is changed to the following method. Also good. That is, after calculating the distance (L) L ₂ inside the distance in the first measurement position 30 in the same manner as the embodiment in two places (L) L ₁ and the second measurement position 40 of the hole 51, The inclination angle θ _i is obtained by the following equation (13).

The inclination angle θ _i is obtained by this equation (13), and the average value is used as the measured value of the inclination angle θ of the inner wall surface.
In the present embodiment, the light receiving element 25 is disposed at a position that is located closer to the distal end side of the base body 16 than the optical fiber 21, but the position where the light receiving element 25 is disposed is not limited thereto. In other words, the light receiving element 25 may be disposed at a location located on the base end side of the base body 16 with respect to the optical fiber 21. Even in such a configuration, any light out of the scattered light reflected by the inner wall surface 52 of the hole 51 is imaged on the light receiving element 25, so that a desired measurement regarding the internal shape of the hole 51 is possible. It becomes.

  In this embodiment, after identifying the first virtual circle 31, the probe 15 is moved to the bottom side in the depth direction F of the hole 51 to identify the second virtual circle 41. A method of identifying the second virtual circle 41 by moving the probe 15 to the opening side) may be employed.

  In this embodiment, the first virtual circle 31 is identified, and then the second virtual circle 41 is identified to determine the inclination of the hole. Without being limited thereto, a predetermined number of coordinates of the inner wall surface 52 of the hole 51 at the first measurement position 30 are measured, and then a predetermined number of coordinates of the inner wall surface 52 of the hole 51 at the second measurement position 40 are measured. You may employ | adopt the process of identifying the 1 virtual circle 31 and the 2nd virtual circle 41, and calculating | requiring the inclination of the hole 51. FIG.

  Next, an embodiment (second embodiment) of the optical measurement apparatus of the present invention, which is different from the embodiment (first embodiment) already shown, will be described. This embodiment is characterized in that the condensing lens 124 is inclined and arranged as compared with the first embodiment, and the description of the same configuration as the first embodiment is omitted and will be described. Even in this case, the same reference numerals are used for the same configurations as those in the first embodiment.

  As shown in FIG. 11, the bottom of the base body 117 constituting the base 16 of the probe 15 is not formed at the bottom but is opened, while the bottom 118a of the base top 118 is centered with respect to the outer periphery 118b. The portion 118c is formed in a convex cross section projecting toward the base body 117 side. An inclined portion 118d is formed between the outer peripheral portion 118b and the central portion 118c, and a circular hole penetrating the bottom portion 118a is formed so as to straddle between the outer peripheral portion 118b and the central portion 118c. A holding frame (not shown) is formed around the inner side of the circular hole, and the condenser lens 124 is fixed in the holding frame.

  FIG. 12 shows the positional relationship of the condenser lens 124 in detail. The optical center point 124a of the condensing lens 124 is located on an imaginary line 1 obtained by translating the imaginary line k along the axis h of the substrate 16 to the tip side of the substrate 16 by a distance a. On the other hand, the condensing lens 124 is disposed such that its optical axis coincides with a line q connecting the origin 26 a of the light receiving surface 26 and the center point 124 a of the condensing lens 124. In this embodiment as well, three sets of measurement units are provided, and the condensing lenses constituting the other measurement units are similarly inclined and arranged in each measurement unit, as in the first embodiment. It is. Moreover, since the measuring method of the inside of a hole using the optical measuring device 10 which concerns on this 2nd Embodiment is the same as 1st Embodiment, description is abbreviate | omitted. According to the optical measurement device 10 of the second embodiment, the following effects can be obtained in addition to the first embodiment.

  That is, in the first embodiment, the optical axis of the condensing lens 24 is parallel to the probe axis h, and the reflected light that is reflected by the reflection position 52 a of the inner wall surface 52 of the hole 51 and passes through the condensing lens 24. Since β connects the reflection position 52 a of the hole 51 and the center point 24 a of the condenser lens 24, there is always a certain angle difference between the reflected light β and the optical axis of the condenser lens 24. When there is such an angle difference, the shape of the image forming point formed on the light receiving surface 26 is an elliptical shape, more specifically, a shape like a comet with a tail. This phenomenon is referred to as a coma aberration phenomenon, and becomes more noticeable as the angle difference of the reflected light β with respect to the condenser lens 24 increases, and the tail becomes longer. The two-dimensional PSD 25, which is a light receiving element, obtains the center of gravity of the image forming point on the light receiving surface 26. Therefore, the position of the center of gravity determined by the light receiving element 25 is shifted with the deformation of the shape of the image forming point 26b due to the above phenomenon. There is also a possibility that a detection error occurs.

  On the other hand, the detection error by the light receiving element 25 due to the coma aberration phenomenon is reduced by arranging the optical axis of the condenser lens 124 so as to be inclined corresponding to the reflected light β in advance as in the second embodiment. Can be made. In this case, since it is difficult to eliminate the angle difference between the reflected light β and the optical axis of the condensing lens 124, the reflected light β can be received on the light receiving surface 26 at an intermediate position within the range where the reflected light β can be received (see FIG. 6). By aligning the optical axis of the condenser lens 124 with a certain origin 26a, it is possible to suppress the occurrence of an extreme detection error.

  Further, the angle when the optical axis of the condenser lens 124 is inclined is not limited to that shown in the above embodiment, and at least the optical axis of the condenser lens 124 is directed toward the tip of the probe 15. What is necessary is just to incline to the axis line h side. The specific angle can be set according to the effective detection range of the light receiving element 25, the diameter of the assumed hole, and the like.

The technical idea that can be grasped from the above-described embodiment is shown below.
(1) The optical system according to claim 1 or 2, wherein the probe is provided with a condensing lens for condensing arbitrary scattered light transmitted through the transmission part and causing the light receiving element to receive the light. Type measuring device.
(2) The optical measuring device according to the technical idea 1, wherein the condensing lens is disposed such that an optical axis thereof is inclined toward the probe axis toward the tip of the probe.

Schematic which shows the optical measuring device of this embodiment (1st Embodiment). The partial expansion schematic which shows the same optical measuring device. Sectional drawing inside the probe of this embodiment. FIG. 4 is an end view taken along line AA in FIG. 3. FIG. 4 is an end view taken along line BB in FIG. 3. The schematic diagram which shows the locus | trajectory of the image formation point on a light-receiving surface. Schematic which shows the measuring method inside a hole. The flowchart which shows the measuring method inside a hole. Explanatory drawing which shows the measuring method inside a hole. The explanatory schematic diagram which shows the measuring method of the inside of a hole. Sectional drawing inside the probe of 2nd Embodiment. Explanatory drawing which shows the optical axis of the condensing lens of 2nd Embodiment.

Explanation of symbols

α: basic light, θ, θ _i ... inclination angle, F: depth direction, h: axis, 10 ... optical measuring device, 15 ... probe, 20 (20a, 20b, 20c) ... measuring unit, 21 ... optical fiber, DESCRIPTION OF SYMBOLS 23 ... Reflected light introduction hole as a transmission part, 24, 124 ... Condensing lens, 25 ... Light receiving element (two-dimensional PSD), 26 ... Light receiving surface, 30 ... First measurement position, 31 ... First virtual circle, 40 ... Second measurement position, 41 ... second virtual circle, 50 ... measurement object, 51 ... hole, 52 ... inner wall surface, 52a ... reflection position.

Claims (5)

An optical measuring device for measuring the inside of a hole provided in a measured object,
A light source for irradiating basic light toward the inner wall surface of the hole of the object to be measured, a transmission part for transmitting arbitrary scattered light reflected by the inner wall surface, and the arbitrary scattering transmitted through the transmission part A non-contact type probe comprising a light receiving element for receiving light;
Calculation means for calculating an inner diameter of the hole by obtaining a virtual circle diameter and a center coordinate based on a light receiving position of the arbitrary scattered light on the light receiving element in a state where the probe is inserted into the hole. An optical measuring device comprising: An optical measuring device for measuring the inside of a hole provided in a measured object,
A light source for irradiating basic light toward the inner wall surface of the hole of the object to be measured, a transmission part for transmitting arbitrary scattered light reflected by the inner wall surface, and the arbitrary scattering transmitted through the transmission part A non-contact type probe comprising a light receiving element for receiving light;
In a state where the probe is inserted into the hole, the virtual circle diameter and the center coordinate are obtained based on the light receiving position of the arbitrary scattered light on the light receiving element in at least two places along the depth direction of the hole. Thus, the optical measuring device is provided with a calculating means for calculating the inclination angle of the hole. The optical measuring device according to claim 1 or 2,
An optical measurement apparatus, wherein a plurality of the light sources are provided on the same circumference having a center on the axis of the probe. It is an optical measuring device according to any one of claims 1 to 3,
The optical measurement apparatus, wherein the light receiving element is a two-dimensional position detecting element, and a light receiving surface of the two-dimensional position detecting element is disposed on a plane orthogonal to the axis of the probe. An optical measurement method for measuring the inside of a hole provided in an object to be measured,
Irradiating basic light toward at least three different locations on the inner wall surface of the hole of the object to be measured, and specifying the coordinates of each location;
An optical measurement method comprising a step of calculating an inner diameter of the hole by obtaining a virtual circle based on at least three different coordinates of the inner wall surface obtained in the step.

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