Probe and shape measurement device

Abstract

To provide a probe and a shape measurement device that can execute a shape measurement of a measurement object highly precisely regardless of kinds of measurement objects.SOLUTION: A probe comprises: a light incidence / outgoing part (a cable tip surface 33a) which emits measurement light LA, and upon which reflection light LB thereof is incident; a light split element (a beam splitter 44) that has a first surface 44a, a second surface 44b and a third surface 44c, splits the measurement light LA incident upon the first surface 44a from the light incidence / outgoing part, emits a part of the split measurement light from the second surface 44b, splits the reflection light LB incident upon the second surface 44b, emits a part of the split reflection light toward the light incidence / outgoing part from the first surface 44a, and emits the remaining reflection light from the third surface 44c; a light reception element 45 that receives the reflection light LB emitted from the third surface 44c; a tip attachment part (attachment shaft 46) that enables selectively attaching a non-contact measurement-purpose first probe tip part 50, and a contact measurement-purpose second probe tip part 60.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a probe used for detecting the position coordinates of a measurement point, and a shape measuring instrument including the probe. [Background technology]

[0002] As a shape measuring device that measures the shape of a measurement object, for example, a three-dimensional coordinate measuring machine is known, which obtains the shape of the measurement object by detecting the position coordinates (three-dimensional coordinates) of various measurement points of the measurement object (workpiece) using a probe.

[0003] For example, the three-dimensional coordinate measuring machine described in Patent Document 1 measures the shape of an object by contacting the probing ball of a contact measurement probe with each measurement point on the object and obtaining the position coordinates of the measurement point when the probing ball comes into contact with the measurement point.

[0004] In addition, the three-dimensional coordinate measuring machine described in Patent Document 2 measures the shape of the object non-contact by emitting measurement light to the measurement point by an optical probe for non-contact measurement, receiving reflected light at the measurement point, and calculating the distance from the optical probe to the measurement point by a known measurement method using an interferometer, for each measurement point of the object. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-075431 A [Patent Document 2] JP 2020-098180 A Summary of the Invention [Problem to be solved by the invention]

[0006] Fig. 15 is an explanatory diagram for explaining the problems of a conventional contact measurement probe. As shown in Fig. 15, a contact measurement probe 200 includes a stylus 201, a probing ball 202 provided at the tip of the stylus 201, a fulcrum part 203 provided at the base end of the stylus 201, and a sensor 204. The sensor 204 is a strain gauge or the like that detects contact of the probing ball 202 with each measurement point of a workpiece W that is a measurement object.

[0007] In such a probe 200, there is a distance between the probing ball 202 (point of force) and the fulcrum part 203 and sensor 204 (point of action). For this reason, when the probing ball 202 is brought into contact with each measurement point of the workpiece W to detect the position coordinates of each measurement point, as in the three-dimensional coordinate measuring machine described in Patent Document 1, an error may occur due to the bending of the stylus 201. Furthermore, when detecting the three-dimensional coordinates of a fine edge shape and a free curved surface, a radius correction error of the probing ball 202 may occur. Furthermore, a special device is required for the fulcrum part 203, which increases the cost.

[0008] On the other hand, when an optical probe for non-contact measurement is used, as in the three-dimensional coordinate measuring machine described in Patent Document 2, the problem does not occur as when the probe 200 for contact measurement is used. However, when an optical probe is used, the sensitivity of the optical probe becomes unstable for a measurement object with small roughness (e.g., a mirror surface), making it difficult to measure the shape of the measurement object. This problem becomes prominent particularly when measuring the shape of a free-form surface.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a probe and a shape measuring device that are capable of performing shape measurement with high accuracy regardless of the type of measurement object. [Means for solving the problem]

[0010] A probe for achieving the object of the present invention includes a light entrance / exit section which emits measurement light and into which reflected light of the measurement light is incident, a light dividing element having a first surface, a second surface, and a third surface, which optically divides the measurement light incident on the first surface from the light entrance / exit section, and emits a portion of the measurement light from the second surface, and reflected light of the measurement light emitted from the second surface is incident on the second surface, and optically divides the reflected light incident on the second surface, and emits a portion of the reflected light from the first surface towards the light entrance / exit section and emits the remainder of the reflected light from the third surface, a light receiving element which receives the reflected light emitted from the third surface, and a tip attachment section which has an optical path for the measurement light emitted from the second surface and the reflected light incident on the second surface, and which is capable of selectively attaching a first probe tip for non-contact measurement and a second probe tip for contact measurement, The first probe tip has a first tip and a first base end, and comprises a hollow first shaft that forms an optical path when the first base end is detachably attached to the tip attachment portion, and an optical element that is provided at the first tip and emits measurement light that has entered through the inside of the first shaft from the second surface toward the measurement object and emits reflected light reflected by the measurement object toward the second surface.The second probe tip has a second tip and a second base end, and comprises a hollow second shaft that forms an optical path when the second base end is detachably attached to the tip attachment portion, a tip sphere that is provided at the second tip and contacts the measurement object, and a retroreflective element that retroreflects the measurement light that has entered through the inside of the second shaft from the second surface and causes the reflected light to enter the second surface.

[0011] According to this probe, a first probe tip for non-contact measurement and a second probe tip for contact measurement can be selectively attached to the tip attachment section depending on the object to be measured.

[0012] In a probe according to another aspect of the present invention, the optical element is a reflective element that reflects measurement light incident from the second surface through the inside of the first shaft toward the measurement object and reflects the reflected light from the measurement object toward the second surface.

[0013] In a probe according to another aspect of the present invention, a retroreflective element is provided inside the second tip portion.

[0014] In a probe according to another aspect of the present invention, the tip ball is a retroreflective ball lens that functions as a retroreflective element, which reduces the number of parts in the tip of the second probe and reduces costs.

[0015] In a probe according to another aspect of the present invention, the refractive index of the retroreflective ball lens is 2. This makes it possible to make the back focal length of the retroreflective ball lens zero.

[0016] In a probe according to another aspect of the present invention, the light receiving element is a position detection sensor or a two-dimensional image sensor, which makes it possible to detect the coordinates of the incident position of the reflected light with respect to the light receiving surface of the light receiving element.

[0017] A probe according to another aspect of the present invention includes a collimator lens provided between the light incident / exit portion and the first surface.

[0018] In a probe according to another aspect of the present invention, a rotation mechanism is provided that rotates the tip attachment part and the first probe tip part in an axial direction centered on the optical axis of the optical path when the first probe tip part is attached to the tip attachment part, thereby allowing the measurement light to perform rotational scanning on the measurement surface of the measurement object.

[0019] A shape measuring device for achieving the object of the present invention is a shape measuring device for measuring the shape of a measured object, and is equipped with the above-mentioned probe, a displacement mechanism capable of displacing the probe, a light source of measurement light optically connected to the light input / output section, and an interference signal detection section optically connected to the light input / output section for detecting an interference signal between reflected light incident on the light input / output section and reference light which is a part of the measurement light reflected at a reflecting surface other than the measured object and the retroreflective element.

[0020] In a shape measuring device according to another aspect of the present invention, when the second probe tip is attached to the tip attachment section, the device includes an incident position coordinate acquisition section that continuously acquires incident position coordinates of reflected light with respect to the light receiving surface of the light receiving element, a distance calculation section that continuously calculates a distance from a predetermined reference position to the retroreflective element based on an interference signal detected by the interference signal detection section, and a contact detection section that detects contact of the tip ball with the measurement object based on the incident position coordinates continuously acquired by the incident position coordinate acquisition section and the distance continuously calculated by the distance calculation section while the displacement mechanism is being driven. This makes it possible to easily detect contact of the tip ball with the measurement object.

[0021] In a shape measuring device according to another aspect of the present invention, a contact displacement mechanism of the tip ball with respect to the measurement object is capable of displacing the probe at least in the X, Y and Z directions of a machine coordinate system of the shape measuring device, and the device includes an XYZ coordinate acquisition unit that acquires the XYZ coordinates of the probe in the machine coordinate system, and a tip ball coordinate calculation unit that calculates the XYZ coordinates of the tip ball in the machine coordinate system based on the XYZ coordinates of the probe acquired by the XYZ coordinate acquisition unit, the incident position coordinates acquired by the incident position coordinate acquisition unit, and the distance calculated by the distance calculation unit when the contact detection unit detects contact of the tip ball with the measurement object, thereby obtaining the XYZ coordinates of the tip ball in the machine coordinate system.

[0022] In a shape measuring device according to another aspect of the present invention, a tip sphere coordinate calculation unit obtains information indicating the relationship between the XYZ directions of the machine coordinate system, the two-dimensional directions of the light receiving surface, and the emission direction of the measurement light from the second surface in advance, and calculates the XYZ coordinates of the tip sphere based on the XYZ coordinates of the probe, the incident position coordinate, the distance, and the information, thereby obtaining the XYZ coordinates of the tip sphere in the machine coordinate system. Effect of the Invention

[0023] The present invention is capable of performing highly accurate shape measurement of an object regardless of its type. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic diagram of a three-dimensional coordinate measuring machine. [Diagram 2] FIG. 2 is an enlarged perspective view of a probe head and a probe. [Diagram 3] FIG. 2 is a cross-sectional view of a probe equipped with a first probe tip for non-contact measurement. [Figure 4] 5A and 5B are explanatory diagrams for explaining a mounting structure of a first probe tip portion and a second probe tip portion relative to a mounting shaft. [Diagram 5] FIG. 13 is a cross-sectional view of a probe fitted with a second probe tip for contact measurement. [Figure 6] 6 is an enlarged cross-sectional view of the tip of the second probe shown in FIG. 5. [Figure 7] FIG. 13 is an enlarged cross-sectional view of a modified example of the tip of the second probe. [Figure 8] 5 is an explanatory diagram for explaining the relationship between the refractive index of a probing sphere and a back focal length. FIG. [Figure 9] FIG. 11 is an explanatory diagram for explaining detection of an interference signal by a photodetector when a first probe tip portion is attached to a probe. [Figure 10] FIG. 13 is an explanatory diagram for explaining detection of an interference signal by a photodetector when a second probe tip portion is attached to a probe. [Figure 11] FIG. 2 is an explanatory diagram for explaining functions of a controller and a control device. [Figure 12] 4 is an explanatory diagram for explaining a function of a contact detection unit and related information acquired by an information acquisition unit; FIG. [Figure 13] FIG. 11 is an explanatory diagram for explaining an example of a method for generating relationship information. [Figure 14] 4 is a flowchart showing a process for measuring the shape of a measurement surface of a workpiece by a three-dimensional coordinate measuring machine. [Figure 15] 1A and 1B are explanatory diagrams for explaining problems with a conventional contact measurement probe. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] [Configuration of 3D coordinate measuring machine] Fig. 1 is a schematic diagram of a three-dimensional coordinate measuring machine 10 corresponding to the shape measuring device of the present invention. Note that mutually orthogonal X, Y and Z axes in Fig. 1 indicate the X, Y and Z directions of a machine coordinate system determined based on the machine coordinate origin specific to the three-dimensional coordinate measuring machine 10.

[0026] 1, a three-dimensional coordinate measuring machine 10 uses a probe 26 that supports both non-contact and contact measurements to perform shape measurement of a workpiece W, which is a measurement object of the present invention. Note that the shape of the workpiece W referred to here includes various dimensional shapes such as length and diameter, in addition to the three-dimensional shape, two-dimensional shape, surface shape, and contour shape of the workpiece W. Also, the shape and type of the workpiece W to be measured are not particularly limited.

[0027] The three-dimensional coordinate measuring machine 10 includes a stand 12, a table 14 (base plate) provided on the stand 12, a right Y carriage 16R and a left Y carriage 16L provided upright at both ends of the table 14, and an X guide 18 connecting the upper parts of the right Y carriage 16R and the left Y carriage 16L. A gate-shaped frame 19 is formed by the right Y carriage 16R, the left Y carriage 16L, and the X guide 18.

[0028] Sliding surfaces along which the right Y carriage 16R and the left Y carriage 16L slide in the Y direction are formed on the upper surface and side surfaces of both ends in the X direction of the table 14. The right Y carriage 16R and the left Y carriage 16L are provided with air bearings (not shown) at positions facing the sliding surfaces of the table 14. This allows the right Y carriage 16R and the left Y carriage 16L to move freely in the Y direction together with the X guide 18.

[0029] An X-carriage 20 is attached to the X-guide 18. A sliding surface along the X-direction along which the X-carriage 20 slides is formed on this X-guide 18. Also, an air bearing (not shown) is provided on the X-carriage 20 at a position facing the sliding surface of the X-guide 18. This allows the X-carriage 20 to move freely in the X-direction.

[0030] A Z carriage 22 (also called a Z spindle) is attached to the X carriage 20. The X carriage 20 is also provided with a Z-direction guide air bearing (not shown) that guides the Z carriage 22 in the Z direction. This allows the Z carriage 22 to be held by the X carriage 20 so as to be movable in the Z direction. A probe head 24 that selectively holds various probes including the probe 26 of the present invention is provided at the lower end of the Z carriage 22.

[0031] 11, the three-dimensional coordinate measuring machine 10 is provided with a Y drive unit 27Y that moves the gate-shaped frame 19 in the Y direction, an X drive unit 27X that moves the X carriage 20 in the X direction, and a Z drive unit 27Z that moves the Z carriage 22 in the Z direction. This allows the probe head 24 (probe 26) to move in the X, Y, and Z directions.

[0032] Furthermore, although not shown, a Y linear scale is provided at the end of table 14 on the right Y carriage 16R side, an X linear scale is provided on X guide 18, and a Z linear scale is provided on Z carriage 22. Furthermore, three-dimensional coordinate measuring machine 10 is provided with XYZ detection unit 29A (see FIG. 11) which is a detection unit that reads the XYZ linear scales. The detection result of XYZ detection unit 29A is output to control device 72 via controller 70.

[0033] Fig. 2 is an enlarged perspective view of the probe 26 to which the probe head 24 and the second probe tip 60 are attached. As shown in Fig. 2, the probe head 24 is, for example, a five-axis simultaneous control head equipped with a stepless positioning mechanism. The probe head 24 is provided with a head rotation drive unit 27R (see Fig. 11) such as a motor that rotates the probe 26 in a direction θ1 around a rotation axis parallel to the Z direction and in a direction θ2 around a rotation axis perpendicular to the Z direction. The head rotation drive unit 27R, together with the above-mentioned drive units 27X, 27Y, and 27Z, constitutes a displacement mechanism of the present invention.

[0034] The probe head 24 is also provided with a rotation angle detection unit 29B (see FIG. 11) such as a rotary encoder that detects the rotation angles θ1 and θ2 of the probe 26 around its axis. The detection result of the rotation angle detection unit 29B is output to the control device 72 via the controller 70.

[0035] The probe 26 is detachably attached to the probe head 24. A first probe tip 50 for non-contact measurement and a second probe tip 60 for contact measurement can be selectively attached to the tip of the probe 26, as shown in Fig. 1. This makes it possible to selectively perform non-contact measurement or contact measurement of the shape of the workpiece W by attaching the first probe tip 50 or the second probe tip 60 to the tip of the probe 26.

[0036] When the first probe tip 50 is attached to the tip of the probe 26, the probe 26 emits measurement light LA ​​input from the wavelength swept light source 28 via the optical fiber cable 30, the fiber circulator 32, and the optical fiber cable 33 toward the measurement surface of the workpiece W. The probe 26 also receives reflected light LB reflected by the measurement surface of the workpiece W, and outputs this reflected light LB and reference light LC (see FIG. 9), which will be described later, to the photodetector 36 via the optical fiber cable 33, the fiber circulator 32, and the optical fiber cable 34.

[0037] The second probe tip portion 60, which will be described in detail later, is formed to be hollow, and has a probing sphere 65 provided at its tip portion.

[0038] Fig. 3 is a cross-sectional view of probe 26 to which a first probe tip 50 for non-contact measurement is attached. As shown in Fig. 3, probe 26 has a longitudinal axis MA, and first probe tip 50 is rotatable in a direction θ3 around this longitudinal axis MA (the optical axis of an optical path LP described later). In addition to a probe main body 40, an optical fiber connection part 42, an attachment shaft 46, and a hollow motor 47, probe 26 includes a first probe tip 50 and a second probe tip 60 (see Fig. 5) that can be selectively attached to the attachment shaft 46.

[0039] The probe main body 40 is formed in a generally cylindrical shape extending in the direction of the longitudinal axis MA, and includes a main body base end 40a and a main body tip end 40b having a smaller diameter than the main body base end 40a. An optical fiber connection part 42 protrudes from the side surface of the main body base end 40a in a direction perpendicular to the longitudinal axis MA. A beam splitter holder 41, a beam splitter 44, a light receiving element 45, a mounting shaft 46, and a hollow motor 47 are provided inside the main body base end 40a.

[0040] The optical fiber connection part 42 has one end connected to the tip of the optical fiber cable 33, and the other end holding the collimator lens 43. The base end of the optical fiber cable 33 opposite to the tip is inserted into the probe head 24 and the Z carriage 22, etc., and is connected to the fiber circulator 32.

[0041] A cable tip surface 33a, which is the tip surface of the tip of the optical fiber cable 33, corresponds to the light incident / emitting portion of the present invention. This cable tip surface 33a functions as an exit surface that outputs the measurement light LA ​​input from the wavelength swept light source 28 through the fiber circulator 32 and the like to the optical fiber cable 33 in a direction perpendicular to the longitudinal axis, and also functions as an entrance surface onto which reflected light LB of the measurement light LA ​​is incident.

[0042] The collimator lens 43 collimates the measurement light LA ​​(diffused light) emitted from the cable tip surface 33a, and then emits the parallel light to a beam splitter 44 described below. The collimator lens 43 also converges the reflected light LB incident from the beam splitter 44, and makes the reflected light LB incident on the cable tip surface 33a.

[0043] The beam splitter holding part 41 holds the beam splitter 44 at a position where the optical axis of the collimator lens 43 intersects with an extension of the longitudinal axis MA. The beam splitter holding part 41 also holds a light receiving element 45 at a position facing a third surface 44c (described later) of the beam splitter 44.

[0044] The beam splitter 44 corresponds to the light dividing element of the present invention, and divides the light (measurement light LA, reflected light LB) incident on the beam splitter 44 and outputs the light in different directions. The beam splitter 44 is formed in a substantially cubic shape and has a first surface 44a, and a second surface 44b and a third surface 44c that are connected to the first surface 44a and perpendicular to the first surface 44a.

[0045] The first surface 44a is a surface that is perpendicular to the optical axis of the collimator lens 43 and faces the collimator lens 43. The second surface 44b is a surface that is perpendicular to the longitudinal axis MA and faces the tip side of the longitudinal axis MA. The third surface 44c is a surface that is perpendicular to the longitudinal axis MA and is located on the opposite side of the beam splitter 44 from the second surface 44b.

[0046] The beam splitter 44 splits the measurement light LA ​​that has entered the first surface 44a from the cable tip surface 33a via the collimator lens 43, and emits a part of the measurement light LA ​​from the second surface 44b. Reflected light LB of the measurement light LA ​​that has been emitted from the second surface 44b along the longitudinal axis MA is incident on the second surface 44b. The symbol LP in the figure indicates the optical path of the measurement light LA ​​that exits from the second surface 44b and the reflected light LB that enters the second surface 44b.

[0047] In addition, the beam splitter 44 splits the reflected light LB incident on the second surface 44b, and emits a portion of the reflected light LB from the first surface 44a to the collimator lens 43 (cable tip surface 33a), and emits the remainder of the reflected light LB from the third surface 44c to the light receiving element 45.

[0048] The light receiving element 45 is, for example, a position sensitive detector (PSD) or a two-dimensional image sensor, and is held at a position facing the third surface 44c by the beam splitter holding part 41. The light receiving element 45 has a light receiving surface that receives the reflected light LB emitted from the third surface 44c. The light receiving element 45 outputs incident position coordinates that indicate the incident position of the reflected light LB with respect to the light receiving surface to the control device 72 via the controller 70.

[0049] The mounting shaft 46 corresponds to the tip mounting portion of the present invention. The mounting shaft 46 is a cylinder that extends from inside the main body base end 40a through the main body tip end 40b along the longitudinal axis MA and has an inner surface that surrounds the optical path LP. The opening on the base end side of the mounting shaft 46 faces the second surface 44b. Meanwhile, a substantially annular tip flange F1 is formed on the periphery of the opening on the tip side of the mounting shaft 46.

[0050] The mounting shaft 46 is held rotatably in the axial direction θ3 by the probe main body 40. Specifically, the base end of the mounting shaft 46 is held rotatably in the axial direction θ3 by a hollow motor 47 (described later) inside the main body base end 40a. The tip end of the mounting shaft 46 is held rotatably in the axial direction θ3 via a bearing 49 inside the main body tip end 40b.

[0051] FIG. 4 is an explanatory diagram for explaining the mounting structure of the first probe tip portion 50 and the second probe tip portion 60 to the mounting shaft 46. As shown in FIG. 4, the base end flange F2 formed on the base end side of the first probe tip portion 50 and the second probe tip portion 60 described later is selectively connected to the tip flange F1. For example, one of the tip flange F1 and the base end flange F2 is formed of a magnet and the other is formed of a metal, so that the base end flange F2 is detachably connected to the tip flange F1. Alternatively, the base end flange F2 may be connected to the tip flange F1 by a screw or the like. In addition, positioning grooves and protrusions are formed on the mutually facing surfaces of the tip flange F1 and the base end flange F2. This makes it possible to selectively mount the first probe tip portion 50 and the second probe tip portion 60 to the mounting shaft 46.

[0052] Returning to FIG. 3, the hollow motor 47 corresponds to the rotation mechanism of the present invention, and rotates the mounting shaft 46 in the axial direction θ3. The hollow motor 47 includes a hollow stator 47a (also called a stator) and a hollow rotor 47b (also called a rotor). The stator 47a is fixed to the inner wall surface of the base end portion 40a of the main body. The rotor 47b is provided in the internal space of the stator 47a, and is further fitted and fixed to the outer circumferential surface of the mounting shaft 46. This rotor 47b rotates integrally with the mounting shaft 46 in the axial direction θ3. Note that the detailed structure of the hollow motor 47 is a known technique, and therefore a detailed description thereof will be omitted.

[0053] The first probe tip portion 50 includes a hollow first shaft 51, an optical system holding portion 53, an imaging lens 54, and a right-angle prism mirror 55. The base end flange F2 (corresponding to the first base end portion of the present invention) is formed on the opening periphery on the base end side of the first shaft 51, and the optical system holding portion 53 (corresponding to the first tip portion of the present invention) is provided on the tip side of the first shaft 51. When the base end flange F2 is connected to the tip flange F1, that is, when the first probe tip portion 50 is attached to the mounting shaft 46, the first shaft 51 is a cylinder that forms the optical path LP (surrounds the optical path LP).

[0054] The optical system holding part 53 holds an imaging lens 54 and a right-angle prism mirror 55 therein. The imaging lens 54 is disposed at a position where its optical axis coincides with the optical axis (center line) of the optical path LP. This imaging lens 54 images the measurement light LA ​​incident from the second surface 44b through the inside of the mounting shaft 46 and the first shaft 51, onto the measurement surface of the workpiece W through the right-angle prism mirror 55. The imaging lens 54 also emits the reflected light LB from the workpiece W incident through the right-angle prism mirror 55 toward the second surface 44b.

[0055] The right-angle prism mirror 55 corresponds to the optical element and the reflecting element of the present invention, and reflects the measurement light LA ​​incident thereon from the imaging lens 54 toward the measurement surface of the workpiece W. Specifically, the right-angle prism mirror 55 refracts the measurement light LA ​​incident thereon from the imaging lens 54 by 90° (including approximately 90°) and emits it toward the measurement surface of the workpiece W.

[0056] Further, the right-angle prism mirror 55 reflects the reflected light LB incident from the measurement surface of the workpiece W toward the imaging lens 54. As a result, the reflected light LB passes from the right-angle prism mirror 55 through the imaging lens 54, the inside of the first shaft 51, and the inside of the mounting shaft 46, and is incident on the second surface 44b, and is further split by the beam splitter 44 to be emitted from the first surface 44a and the third surface 44c, respectively. As a result, the reflected light LB is incident on the collimator lens 43 (cable tip surface 33a) and the light receiving surface of the light receiving element 45, respectively.

[0057] The right-angle prism mirror 55 is rotated in the axial direction θ3 together with the mounting shaft 46 and the first shaft 51 by the hollow motor 47 described above. This makes it possible to rotate and scan the measurement light LA ​​along the measurement surface of the workpiece W.

[0058] Instead of the right-angle prism mirror 55, various known reflecting elements such as a mirror may be used.

[0059] Fig. 5 is a cross-sectional view of probe 26 to which a second probe tip 60 for contact measurement is attached. Fig. 6 is an enlarged cross-sectional view of the second probe tip 60 shown in Fig. 5. As shown in Figs. 5 and 6, the second probe tip 60 includes a hollow second shaft 61, a probing sphere holder 63 (see Fig. 6), a corner cube prism 64, and a probing sphere 65.

[0060] The second shaft 61 has an opening periphery on the base end side formed with the base end flange F2 (corresponding to the second base end of the present invention), and a probing sphere holding portion 63 (corresponding to the second tip portion of the present invention) provided on the tip side of the second shaft 61. The second shaft 61 is a cylinder that forms the optical path LP (surrounds the optical path LP) when the base end flange F2 is connected to the tip flange F1, i.e., when the second probe tip portion 60 is attached to the mounting shaft 46.

[0061] The probing sphere holder 63 is formed in a substantially cylindrical shape, holds a corner cube prism 64 therein, and holds a probing sphere 65 at its tip.

[0062] The corner cube prism 64 corresponds to the retroreflective element of the present invention. The corner cube prism 64 retroreflects the measurement light LA ​​that enters through the inside of the mounting shaft 46 and the second shaft 61 from the second surface 44b, and causes the reflected light LB to enter the second surface 44b. Note that various retroreflective elements other than the corner cube prism 64 may be used as long as they are capable of retroreflecting the measurement light LA.

[0063] The probing ball 65 corresponds to the tip ball of the present invention, and comes into contact with the measurement surface of the workpiece W during contact measurement of the workpiece W.

[0064] Fig. 7 is an enlarged cross-sectional view of a modified example of the second probe tip portion 60. In the examples shown in Figs. 5 and 6, the measurement light LA ​​is retroreflected by the corner cube prism 64, but the measurement light LA ​​may be retroreflected by other methods. For example, as shown in Fig. 7, instead of providing the corner cube prism 64 and the probing sphere 65 in the probing sphere holding portion 63, a probing sphere 65A may be provided in the probing sphere holding portion 63.

[0065] The probing sphere 65A is a retroreflective ball lens formed of, for example, a glass material (or various optical materials other than glass material are also acceptable) and functions as a retroreflective element. As a result, the probing sphere 65A retroreflects the measurement light LA ​​that has entered through the inside of the mounting shaft 46 and the first shaft 51 from the second surface 44b, and causes the reflected light LB to enter the second surface 44b. This allows the number of parts of the second probe tip portion 60 to be reduced compared to the examples shown in Figures 5 and 6, thereby reducing the cost of the second probe tip portion 60.

[0066] 8 is a diagram illustrating the relationship between the refractive index of the probing sphere 65A and the back focal length BFL. Note that the symbol P in the figure is a straight line that passes through the center of the probing sphere 65A and is perpendicular to the optical path LP (longitudinal axis MA).

[0067] As shown by symbol 8A in Figure 8, if the outer diameter (diameter) of the probing sphere 65A is "D" and the refractive index of the glass material forming the probing sphere 65A is "n", the focal length EFL of the probing sphere 65A is expressed by the following equation [Equation 1], and the back focal length BFL of the probing sphere 65A is expressed by the following equation [Equation 2].

[0068]

number

[0069]

number

[0070] Here, when the refractive index n of the glass material forming the probing sphere 65A is n=2, the focal length EFL is EFL=D / 2 based on the above formula [1]. And, when the focal length EFL is EFL=D / 2, the back focal length BFL is BFL=0 based on the above formula [2].

[0071] 8, by setting the refractive index n of the probing sphere 65A to n=2, the back focal length BFL can be set to "0". This allows the measurement light LA ​​incident on the probing sphere 65A to be retroreflected at the apex TP (including its vicinity) on the tip side of the probing sphere 65A. As a result, it becomes easy to detect the position coordinates of the probing sphere 65A when the probing sphere 65A is brought into contact with the measurement surface of the workpiece W.

[0072] Fig. 9 is an explanatory diagram for explaining detection of an interference signal SG by the photodetector 36 when the first probe tip 50 is attached to the probe 26. Fig. 10 is an explanatory diagram for explaining detection of an interference signal SG by the photodetector 36 when the second probe tip 60 is attached to the probe 26. Note that in Fig. 10, it is assumed that a probing sphere 65A is provided at the second probe tip 60 as shown in Fig. 7 described above.

[0073] 9 and 10, the swept light source 28 corresponds to the light source of the present invention. Under the control of the control device 72, the swept light source 28 emits measurement light LA ​​to the fiber circulator 32 via the optical fiber cable 30. The measurement light LA ​​is swept light whose wavelength changes sinusoidally in a fixed wavelength band at a fixed wavelength sweep period (fixed wavelength sweep frequency).

[0074] Fiber circulator 32 is optically connected to swept-wavelength light source 28 via fiber optic cable 30, to photodetector 36 via fiber optic cable 34, and to probe 26 via fiber optic cable 33.

[0075] The fiber circulator 32 is, for example, a non-reciprocating, one-way device having three ports, and outputs the measurement light LA ​​input from the wavelength swept light source 28 via the optical fiber cable 30 to the optical fiber cable 33. This causes the measurement light LA ​​from the wavelength swept light source 28 to be input to the probe 26. As a result, when the first probe tip 50 is attached to the probe 26, the reflected light LB reflected from the measurement surface of the workpiece W and the reference light LC reflected from the cable tip surface 33a (corresponding to the reflecting surface of the present invention) are input to the fiber circulator 32 via the optical fiber cable 33 (see FIG. 9).

[0076] On the other hand, when the second probe tip 60 is attached to the probe 26, the reflected light LB reflected back by the probing sphere 65A (or the corner cube prism 64) and the reference light LC reflected by the cable tip surface 33a are input to the fiber circulator 32 via the optical fiber cable 33 (see Figure 10).

[0077] The fiber circulator 32 outputs an interference signal SG of the reflected light LB and the reference light LC input from the probe 26 to a photodetector 36 via an optical fiber cable 34 .

[0078] The photodetector 36 corresponds to the interference signal detection unit of the present invention, and may be, for example, a silicon photodiode, an InGaAs (indium gallium arsenide) photodiode, a phototube, a photomultiplier tube, etc. Under the control of the control device 72, the photodetector 36 converts the interference signal SG input from the fiber circulator 32 via the optical fiber cable 34 into an electric signal, amplifies it, and outputs it to the control device 72. In this way, the control device 72 calculates the distance from the cable tip surface 33a to the reflecting surface of the reflected light LB based on the detection result of the interference signal SG by the photodetector 36.

[0079] Specifically, when the first probe tip 50 is attached to the probe 26, the control device 72 calculates the total distance value of the distance L1 from the cable tip surface 33a to the beam splitter 44, the distance L2 from the beam splitter 44 to the right-angle prism mirror 55, and the distance L3 from the right-angle prism mirror 55 to the measurement surface of the workpiece W (see FIG. 9). On the other hand, when the second probe tip 60 is attached to the probe 26, the control device 72 calculates the total distance value of the distance L1 and the distance L2A from the beam splitter 44 to the probing sphere 65A (or the corner cube prism 64) (see FIG. 10). Note that a specific method of calculating the distance is a publicly known technique (for example, JP 2016-024086 A and JP 2018-084434 A), so a specific description will be omitted here.

[0080] In this embodiment, distance measurement is performed by optical interference using the wavelength swept light source 28, but distance measurement may be performed by using other known optical interference methods.

[0081] Fig. 11 is an explanatory diagram for explaining the functions of the controller 70 and the control device 72. As shown in Fig. 11, when the three-dimensional coordinate measuring machine 10 is in the manual measurement mode, the controller 70 drives each of the driving units 27X, 27Y, 27Z, and 27R in response to an operation input from an operator, and displaces the probe 26 to a position and posture that allows non-contact measurement or contact measurement of the position coordinates of the measurement point for each of a plurality of measurement points in the measurement surface of the workpiece W. When the three-dimensional coordinate measuring machine 10 is in the automatic measurement mode, the controller 70 drives each of the driving units 27X, 27Y, 27Z, and 27R under the control of the control device 72, and displaces the probe 26 to a position and posture that allows non-contact measurement or contact measurement of the position coordinates of the measurement point for each of a plurality of measurement points.

[0082] Furthermore, when performing rotational scanning of the measurement light LA ​​on the measurement surface of the workpiece W during non-contact measurement of each measurement point, the controller 70 drives the hollow motor 47 to rotate the first probe tip 50 in the axial direction θ3.

[0083] Furthermore, the controller 70 continuously outputs to the control device 72 the XYZ coordinates of the probe 26 detected by the XYZ detection unit 29A, the rotation angles θ1, θ2 around the axis of the probe 26 detected by the rotation angle detection unit 29B, and the incident position coordinates of the reflected light LB relative to the light receiving surface detected by the light receiving element 45.

[0084] The control device 72 comprehensively controls the operation of each part of the three-dimensional coordinate measuring machine 10. The control device 72 includes an arithmetic circuit configured with various processors and memories. The various processors include a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), and a programmable logic device (e.g., simple programmable logic devices (SPLD), complex programmable logic devices (CPLD), and field programmable gate arrays (FPGA)). The various functions of the control device 72 may be realized by one processor, or may be realized by multiple processors of the same or different types.

[0085] In addition to the above-mentioned wavelength swept light source 28, photodetector 36, controller 70, etc., a storage unit 74 is connected to the control device 72. In addition to a control program (not shown) for the three-dimensional coordinate measuring machine 10, a measurement program 75, related information 76, etc. are stored in the storage unit 74.

[0086] The measurement program 75 represents the measurement path of the probe 26 when measuring the shape of the workpiece W (for example, the measurement order of each measurement point, the coordinate values ​​of each measurement point, and the coordinate values ​​of intermediate points which are points on the movement path of the probe 26). The relationship information 76 will be described later.

[0087] The control device 72 functions as a drive control unit 80, an XYZ coordinate acquisition unit 81, an incident position coordinate acquisition unit 82, a rotation angle acquisition unit 83, a distance calculation unit 84, a first shape calculation unit 85, and a second shape calculation unit 90 by executing a control program (not shown) in the memory unit 74.

[0088] The drive control unit 80 operates when an automatic measurement mode (non-contact measurement, contact measurement) is selected. Based on a measurement program 75 in the storage unit 74, the drive control unit 80 drives each of the drive units 27X, 27Y, 27Z, and 27R via the controller 70 to displace the position and orientation of the probe 26 for each measurement point on the measurement surface of the workpiece W. This makes it possible to displace the probe 26 to a position and orientation that allows non-contact or contact measurement of the position coordinates of each measurement point.

[0089] The XYZ coordinate acquisition unit 81 continuously acquires the detection results of the XYZ coordinates of the probe 26 (probe head 24) from the XYZ detection unit 29A via the controller .

[0090] The incident position coordinate acquisition unit 82 continuously acquires, via the controller 70, from the light receiving element 45, the detection results of the incident position coordinates of the reflected light LB with respect to the light receiving surface thereof.

[0091] The rotation angle acquisition unit 83 continuously acquires the detection results of the rotation angles of the probe 26 in the directions θ1 and θ2 around the axis from the rotation angle detection unit 29B via the controller 70.

[0092] The distance calculation unit 84 continuously acquires the detection result of the interference signal SG from the photodetector 36 and calculates the distance from an arbitrary reference position (the cable tip surface 33a or the second surface 44b) to the reflection surface of the reflected light LB based on the interference signal SG.

[0093] For example, when the aforementioned reference position is the cable tip surface 33a, the distance calculation unit 84 continuously calculates the distance total value (L1+L2+L3) shown in Fig. 9 during non-contact measurement, and continuously calculates the distance total value (L1+L2A) shown in Fig. 10 during contact measurement. When the aforementioned reference position is the second surface 44b, the distance calculation unit 84 subtracts the known distance from the cable tip surface 33a to the second surface 44b from the aforementioned distance total value.

[0094] The first shape calculation unit 85 operates when non-contact measurement is selected in both the automatic measurement mode and the manual measurement mode. Each time non-contact measurement of each measurement point is performed, the first shape calculation unit 85 calculates the position coordinates (XYZ coordinates) of the measurement point based on at least the XYZ coordinates of the probe 26 acquired by the XYZ coordinate acquisition unit 81, the rotation angles in the axial directions θ1 and θ2 acquired by the rotation angle acquisition unit 83, and the distance calculated by the distance calculation unit 84. As a result, the first shape calculation unit 85 calculates the shape of the measurement surface of the workpiece W based on the calculation results of the position coordinates for each measurement point. Note that the method of calculating the shape of the measurement surface of the workpiece W by non-contact measurement is a publicly known technology (see Patent Document 2 above), so a detailed description will be omitted here.

[0095] The second shape calculation unit 90 operates when contact measurement is selected in both measurement modes. This second shape calculation unit 90 functions as a contact detection unit 91, an information acquisition unit 92, a probing sphere coordinate calculation unit 93, and a shape calculation unit 94.

[0096] FIG. 12 is an explanatory diagram for explaining the function of the contact detection unit 91 and the related information 76 acquired by the information acquisition unit 92. W Y W Z W The axes are the same as the X, Y and Z axes shown in FIG. 1 and the like, and indicate a machine coordinate system determined based on the machine coordinate origin specific to the three-dimensional coordinate measuring machine 10. P Y P Z P The X axis is the probe coordinate system based on the probe 26. P Y PThe direction of the axis indicates the two-dimensional direction of the light receiving surface of the light receiving element 45, and the Z P The direction of the axis indicates the direction of the longitudinal axis MA (the emission direction of the measuring light LA ​​from the second surface 44b).

[0097] Furthermore, the reference symbol V1 in the figure indicates the position coordinate (x w ,y w , z w Furthermore, the reference symbol V2 in the figure indicates the incident position coordinate (x p ,y p Furthermore, the symbol V3 in the figure indicates the distance calculation result V3(z p ) is shown.

[0098] As shown in FIG. 12 and the above-described FIG. 11, the contact detection unit 91 operates while the driving units 27X, 27Y, 27Z, and 27R are being driven (while the position or posture of the probe 26 is being displaced). p ,y p ), and the distance calculation result V3(z p ) and detects whether or not the probing spheres 65, 65A are in contact with each measurement point.

[0099] For example, the contact detection unit 91 detects the incident position coordinate V2(x p ,y p ) and the distance calculation result V3(z p ) and set the threshold range to the incident position coordinate V2(x p ,y p ) and the distance calculation result V3(z p ) falls outside the threshold range, the presence or absence of contact of the probing spheres 65, 65A with the measurement points is detected.

[0100] In addition, the contact detection unit 91 detects the incident position coordinate V2(x p ,y p ) and the distance calculation result V3(z p) is set to a threshold range for the time differential value, and the incident position coordinate V2(x p ,y p ) and the distance calculation result V3(z p The contact of the probing spheres 65, 65A with the measurement points may be detected based on whether the time differential value of the measured value falls outside a threshold range.

[0101] Furthermore, when scanning measurement of the measurement surface of the workpiece W is being performed with the second probe tip 60, the incident position coordinate V2 (x p ,y p ) and the distance calculation result V3(z p ) is set as a threshold value. Then, the contact detection unit 91 detects the incident position coordinate V2(x p ,y p ) and the distance calculation result V3(z p ) is equal to or greater than a threshold value, and the presence or absence of contact of the probing spheres 65, 65A with the measurement points may be detected based on the results of the time sampling.

[0102] The information acquisition unit 92 acquires the related information 76 in advance from the storage unit 74. The related information 76 is the X coordinate system of the machine coordinate system of the three-dimensional coordinate measuring machine 10. W Y W Z W direction and X of the probe coordinate system relative to probe 26 P Y P Z P The relationship information 76 is information indicating the relationship between the direction and, for example, a mathematical formula (determinant). This relationship information 76 is generated in advance and stored in the storage unit 74 (or an external server).

[0103] Fig. 13 is an explanatory diagram for explaining an example of a method for generating the relationship information 76. In Fig. 13, a probing sphere 65A is provided at the second probe tip 60 as shown in Fig. 7 described above.

[0104] 13, first, the probing sphere 65A or the corner cube prism 64 is removed from the probe 26. Then, the probing sphere 65A or the corner cube prism 64 removed from the probe 26, or an object identical to these, is set on the table 14.

[0105] Next, while displacing the position and orientation of the probe 26 with the second probe tip 60 removed N times (N is a natural number equal to or greater than 4), non-contact measurement (irradiation of the measurement light LA ​​and reception of the reflected light LB) of the probing sphere 65A or the corner cube prism 64 by the probe 26 is performed at the N positions. As a result, the position coordinate V1 (x w ,y w , z w ), incident position coordinate V2(x p ,y p ) and the distance calculation result V3(z p ) is obtained (sampled).

[0106] N position coordinates V1(x w ,y w , z w ), incident position coordinate V2(x p ,y p ) and the distance calculation result V3(z p If one of the sets of (n=0) is taken as the reference, then the following equation (3) holds for n=1 to N.

[0107]

number

[0108] If we solve the above formula [3] by the least squares method using the sampling values ​​of n = 1 to N, we get X W Y W Z W Direction and X of the probe coordinate system P Y P Z P As the relationship information 76 indicating the relationship with the direction, "R" in the formula (3) is obtained.

[0109] In addition, the above formula [3] can be replaced with the following formula [4] in order to reduce the influence of errors superimposed on the reference n=0, and this formula [4] can be solved using the least squares method for all combinations of n=0 to N, m=0 to N (where n≠m).

[0110]

number

[0111] Returning to FIG. 11, the probing sphere coordinate calculation unit 93 corresponds to the tip sphere coordinate calculation unit of the present invention, and acquires the relationship information 76 in advance from the information acquisition unit 92. In addition, the probing sphere coordinate calculation unit 93 acquires the position coordinate V1 (xYZ coordinate acquisition unit 81) from the XYZ coordinate acquisition unit 81 each time the contact detection unit 91 detects the contact of the probing spheres 65, 65A with each measurement point. w ,y w , z w ) and the incident position coordinate V2(x p ,y p ) and the distance calculation result V3(z p ) and execute.

[0112] Then, the probing sphere coordinate calculation unit 93 calculates the position coordinate V1(x w ,y w , z w ), incident position coordinate V2(x p ,y p ), distance calculation result V3(z p ) and the relational information 76(R), the position coordinates (x, y, z) of the probing spheres 65, 65A in the machine coordinate system are calculated using the following [Equation 5]. Note that [x0, y0, z0] in [Equation 5] T are offset coordinates from the origin of the machine coordinate system to the probing spheres 65, 65A during non-contact measurement. In addition, when the probe head 24 or the multi-stylus capable of changing the attitude of the probe 26 is not used, [x0, y0, z0] T is [0,0,0] T may be also possible.

[0113]

number

[0114] The shape calculation unit 94 calculates the shape of the measurement surface of the workpiece W based on the calculation results of the position coordinates (x, y, z) of the probing spheres 65, 65A for each measurement point by the probing sphere coordinate calculation unit 93.

[0115] [Functions of 3D measuring machines] Fig. 14 is a flowchart showing the flow of the shape measurement process of the measurement surface of the workpiece W by the three-dimensional coordinate measuring machine 10 configured as described above. As shown in Fig. 14, when the examiner selects non-contact measurement of the measurement surface of the workpiece W, the first probe tip 50 is attached to the probe 26 (NO in step S1, step S2, step S3). Next, non-contact measurement is performed for each of a plurality of measurement points in the measurement surface of the workpiece W by a known method (step S4), and the shape of the measurement surface of the workpiece W is calculated by the first shape calculation unit 85 (step S5).

[0116] On the other hand, if the examiner selects contact measurement of the measurement surface of the workpiece W, the examiner attaches the second probe tip portion 60 to the probe 26 (YES in step S1, step S6).

[0117] Next, the emission of the measurement light LA ​​from the wavelength swept light source 28 is started (step S7), whereby the light receiving element 45 receives the reflected light LB and the incident position coordinate V2 (x p ,y p At the same time, the detection of the interference signal SG by the photodetector 36 and the distance calculation result V3(z p ) and the calculation of is started (step S9).

[0118] Next, each of the drive units 27X, 27Y, 27Z, and 27R is driven based on an input operation to the controller 70 (manual measurement mode), or the drive control unit 80 drives each of the drive units 27X, 27Y, 27Z, and 27R based on a measurement program (automatic measurement mode), and the probe 26 is displaced to a position and orientation that allows contact measurement of the first measurement point (step S10).

[0119] In addition, when the displacement of the probe 26 is started, the contact detection unit 91 detects the incident position coordinate V2 (x p ,y p ), and the distance calculation result V3(z p ), and based on this, the presence or absence of contact of the probing spheres 65, 65A with the initial measurement point is detected (NO in step S11). This makes it possible to optically detect the presence or absence of contact of the probing spheres 65, 65A with the measurement point without using a sensor 204 (see FIG. 15) such as a conventional strain gauge or providing a complex separate detection device.

[0120] When the contact detection unit 91 detects the contact of the probing sphere 65, 65A with the first measurement point (YES in step S11), the probing sphere coordinate calculation unit 93 is activated. The probing sphere coordinate calculation unit 93 has previously acquired the relationship information 76 from the storage unit 74. The probing sphere coordinate calculation unit 93 then calculates the position coordinate V1 (x w ,y w , z w ) and the incident position coordinate V2(x p ,y p ) and the distance calculation result V3(z p ) and execute.

[0121] Next, the probing sphere coordinate calculation unit 93 calculates the position coordinate V1(x w ,y w , z w ), incident position coordinate V2(x p ,y p ), distance calculation result V3(z p) and the relational information 76(R), the position coordinates (x, y, z) of the probing spheres 65, 65A are calculated using the above [Equation 5] (step S12). This completes the contact measurement of the first measurement point.

[0122] Thereafter, for each remaining measurement point, the following steps are repeatedly executed (step S10): displacement of the position and posture of the probe 26 corresponding to the measurement point, detection of contact of the probing spheres 65, 65A with the measurement point by the contact detection unit 91 (step S11), and calculation of the position coordinates (x, y, z) by the probing sphere coordinate calculation unit 93 (step S12) (YES in step S13).

[0123] When the probing sphere coordinate calculation unit 93 has completed calculation of the position coordinates (x, y, z) for all measurement points (NO in step S13), the shape calculation unit 94 calculates the shape of the measurement surface of the workpiece W based on the calculation results of the position coordinates (x, y, z) for each measurement point (step S14).

[0124] As described above, in the three-dimensional coordinate measuring machine 10 of this embodiment, the first probe tip 50 for non-contact measurement and the second probe tip 60 for contact measurement can be selectively attached to the probe 26, making it possible to selectively perform non-contact measurement and contact measurement of the measurement surface of the workpiece W. When non-contact measurement is selected, problems that occur in conventional contact measurement (deflection of the probe and radius correction error of the probing sphere) do not occur, so that shape measurement of the measurement surface can be performed with high precision.

[0125] In addition, in the three-dimensional coordinate measuring machine 10 of this embodiment, when the measurement surface of the workpiece W is a mirror surface with a small roughness that is unsuitable for non-contact measurement, contact measurement can be selected to perform shape measurement of the measurement surface. Furthermore, when contact measurement is selected, that is, when the second probe tip 60 is attached to the probe 26, the position coordinates of the measurement point can be acquired based on the position coordinate V1 of the probe 26 acquired by the XYZ coordinate acquisition unit 81, the incident position coordinate V2 of the reflected light LB acquired by the incident position coordinate acquisition unit 82, and the distance calculation result V3 of the distance calculation unit 84. Therefore, in the contact measurement of this embodiment, it is not necessary to consider the bending of the probe 26 and the occurrence of radius correction errors of the probing spheres 65, 65A, and it is possible to perform shape measurement of the measurement surface with high accuracy, and further, a special device such as the fulcrum part 203 shown in FIG. 15 is not required.

[0126] Therefore, in the three-dimensional coordinate measuring machine 10 of this embodiment, by selecting the first probe tip 50 or the second probe tip 60 depending on the type of workpiece W, it is possible to perform shape measurement of the workpiece W with high accuracy regardless of the type of workpiece W.

[0127] [others] In the above embodiment, the right-angle prism mirror 55 is held by the optical system holding part 53 of the first probe tip part 50, but the right-angle prism mirror 55 may be omitted and the measurement light LA ​​may be emitted from the imaging lens 54 along the longitudinal axis MA to the front side thereof, and the reflected light LB reflected by the measurement surface of the workpiece W may be made incident on the imaging lens 54. In this case, the imaging lens 54 corresponds to the optical element of the present invention.

[0128] In the above embodiment, the hollow motor 47 and the bearing 49 are provided in the probe 26, but the hollow motor 47 and the bearing 49 may be omitted.

[0129] In the above embodiment, the first probe tip 50 for non-contact measurement and the second probe tip 60 for contact measurement can be selectively attached to the probe 26, but the probe 26 may be adapted to only non-contact measurement or only contact measurement. For example, when the probe 26 is adapted to only non-contact measurement, the mounting shaft 46 and the first probe tip 50 are integrated, or the mounting shaft 46 and the hollow motor 47 are omitted and only the first probe tip 50 is fixed and arranged on the front side of the second surface 44b. When the probe 26 is adapted to only contact measurement, the mounting shaft 46 and the second probe tip 60 are integrated, or the mounting shaft 46 and the hollow motor 47 are omitted and only the second probe tip 60 is fixed and arranged on the front side of the second surface 44b.

[0130] In the above embodiment, the three-dimensional coordinate measuring machine 10 is taken as an example of the shape measuring device of the present invention, but the present invention can also be applied to shape measuring devices that use the probe 26 to measure the shapes of various measurement objects. [Explanation of symbols]

[0131] 10...3D coordinate measuring machine, 12...frame, 14...table, 16L...left Y carriage, 16R...right Y carriage, 18...X guide, 19...gantry frame, 20...X carriage, 22...Z carriage, 24...probe head, 26...probe, 27R...head rotation drive unit, 27X...X drive unit, 27Y...Y drive unit, 27Z...Z drive unit, 28...wavelength sweep light source, 29A...XYZ detection unit, 29B...rotation angle detection unit, 30...optical fiber cable, 32...fiber circulator, 33...optical fiber cable, 33a ...cable tip surface, 34...optical fiber cable, 36...photodetector, 40...probe main body, 40a...main body base end, 40b...main body tip, 41...beam splitter holding portion, 42...optical fiber connection portion, 43...collimator lens, 44...beam splitter, 44a...first surface, 44b...second surface, 44c...third surface, 45...light receiving element, 46...mounting shaft, 47...hollow motor, 47a...stator, 47b...rotor, 49...bearing, 50...first probe tip, 51...first shaft, 53...optical system holding portion, 54 ...imaging lens, 55...right-angle prism mirror, 60...second probe tip, 61...second shaft, 63...probing sphere holder, 64...corner cube prism, 65,65A...probing sphere, 70...controller, 72...control device, 74...storage unit, 75...measurement program, 76...related information, 80...drive control unit, 81...XYZ coordinate acquisition unit, 82...incident position coordinate acquisition unit, 83...rotation angle acquisition unit, 84...distance calculation unit, 85...first shape calculation unit, 90...second shape calculation unit, 91...contact detection unit, 92...information acquisition unit, 93 ...probing sphere coordinate calculation unit, 94...shape calculation unit, 200...probe, 201...stylus, 202...probing sphere, 203...fulcrum unit, 204...sensor, BFL...back focus length, EFL...focal length, F1...tip flange, F2...base flange, L1, L2, L2A, L3...distance, LA...measurement light, LB...reflected light, LC...reference light, LP...optical path, MA...longitudinal axis, SG...interference signal, TP...vertex, V1...position coordinate, V2...incident position coordinate, V3...distance calculation result, W...work, n...refractive index, θ1 to θ3...direction around axis

Claims

1. a light incident / exit section for emitting measurement light and receiving reflected light of the measurement light; a light dividing element having a first surface, a second surface, and a third surface, which optically divides the measurement light incident on the first surface from the light incident / emitting portion, and outputs a part of the measurement light from the second surface, and the reflected light of the measurement light output from the second surface is input to the second surface, and the reflected light incident on the second surface is optically divided, and outputs a part of the reflected light from the first surface toward the light incident / emitting portion, and outputs the remainder of the reflected light from the third surface; a light receiving element that receives the reflected light emitted from the third surface; a tip attachment portion having optical paths for the measurement light emitted from the second surface and the reflected light incident on the second surface, the tip attachment portion being capable of selectively attaching a first probe tip portion for non-contact measurement and a second probe tip portion for contact measurement; Equipped with The first probe tip is a hollow first shaft having a first tip portion and a first base end portion, the hollow first shaft forming the optical path when the first base end portion is detachably attached to the tip portion attachment portion; an optical element provided at the first tip portion, emitting the measurement light incident from the second surface through the inside of the first shaft toward a measurement object and emitting the reflected light reflected by the measurement object toward the second surface, The second probe tip is a hollow second shaft having a second tip portion and a second base portion, the hollow second shaft forming the optical path when the second base portion is detachably attached to the tip portion attachment portion; A tip ball provided at the second tip portion and contacting the object to be measured; A probe comprising: a retroreflective element that retroreflects the measurement light that has entered from the second surface through the inside of the second shaft, and causes the reflected light to enter the second surface.

2. The probe according to claim 1 , wherein the optical element is a reflective element that reflects the measurement light incident from the second surface through the inside of the first shaft toward the object to be measured and reflects the reflected light from the object to be measured toward the second surface.

3. The probe of claim 1 , wherein the retroreflective element is disposed within the second tip.

4. The probe of claim 1 , wherein the tip ball is a retroreflective ball lens that functions as the retroreflective element.

5. The probe of claim 4, wherein the refractive index of the retroreflective ball lens is 2.

6. 2. The probe according to claim 1, wherein the light receiving element is a position detection sensor or a two-dimensional image sensor.

7. The probe according to claim 1 , further comprising a collimator lens provided between the light incident / exit portion and the first surface.

8. 7. The probe according to claim 1, further comprising a rotation mechanism that rotates the tip attachment portion and the first probe tip portion in an axis direction centered on an optical axis of the optical path when the first probe tip portion is attached to the tip attachment portion.

9. In a shape measuring apparatus for measuring a shape of a measurement object, A probe according to any one of claims 1 to 6; A displacement mechanism capable of displacing the probe; a light source of the measurement light optically connected to the light incident / exit unit; An interference signal detection unit that is optically connected to the light incident / exit unit and detects an interference signal between the reflected light incident on the light incident / exit unit and a reference light that is a part of the measurement light reflected on a reflection surface other than the measurement object and the retroreflective element; A shape measuring device comprising:

10. When the second probe tip is attached to the tip attachment portion, an incident position coordinate acquisition unit that continuously acquires incident position coordinates of the reflected light with respect to a light receiving surface of the light receiving element; A distance calculation unit that continuously calculates a distance from a predetermined reference position to the retroreflective element based on the interference signal detected by the interference signal detection unit; a contact detection unit that detects contact of the tip ball with the measurement object based on the incident position coordinates continuously acquired by the incident position coordinate acquisition unit and the distance continuously calculated by the distance calculation unit while the displacement mechanism is being driven; The shape measuring apparatus according to claim 9 .

11. the displacement mechanism is capable of displacing the probe at least in X, Y and Z directions of a machine coordinate system of the shape measuring device; an XYZ coordinate acquisition unit for acquiring XYZ coordinates of the probe in the machine coordinate system; a tip sphere coordinate calculation unit that calculates, when the contact detection unit detects contact of the tip sphere with the measurement object, XYZ coordinates of the probe acquired by the XYZ coordinate acquisition unit, the incident position coordinates acquired by the incident position coordinate acquisition unit, and the distance calculated by the distance calculation unit, and The shape measuring apparatus according to claim 10 ,

12. 12. The shape measuring device according to claim 11, wherein the tip sphere coordinate calculation unit acquires in advance information indicating the relationship between the X, Y and Z directions of the machine coordinate system, the two-dimensional directions of the light receiving surface, and the emission direction of the measurement light from the second surface, and calculates the X, Y and Z coordinates of the tip sphere based on the X, Y and Z coordinates of the probe, the incident position coordinates, the distance, and the information.

Images