Contactless distance measurement machine

Abstract

A contactless distance measurement machine (1) irradiates a stylus (20) from a distal end part to a side thereof with measurement light from an interferometer (30). The contactless distance measurement machine comprises: a cylindrical light generation unit (21) that converts measurement light from the interferometer (30) into cylindrical light; an optical element group that changes the cylindrical light from the cylindrical light generation unit (21) into light along an extension axis (E) of the stylus (20); a planar light generation unit (24) that converts the light along the extension axis (E) into light oriented outward around the extension axis (E), and that converts light which is reflected off the surface of a measurement object W and returns inward around the extension axis (E) into light along the extension axis (E); an azimuth detection unit (28) that detects an azimuth at which the light returning to the planar light generation unit (24) reaches a maximum intensity; and a spatial light modulation unit (25) that restricts the light which has returned to the planar light generation unit (24) to light of the azimuth detected by the azimuth detection unit (28).

Description

Non-contact distance measuring device

[0001] The present invention relates to a non-contact distance measuring device.

[0002] In a shape measuring instrument, a laser interferometer, a non-contact distance measuring device, is moved along the surface of the object to scan the surface with the laser interferometer's measurement light, and the surface shape is measured from the variation in distance along the scanning path (see Patent Document 1). To measure the inner shape of a recess or hole, a point sensor is used that irradiates the interferometer's measurement light laterally from the tip of a stylus (see Patent Document 2). In this point sensor, the measurement light passes along the central axis of the stylus, is bent at a right angle by a mirror at the tip of the stylus, and is emitted laterally from the stylus. The emitted measurement light is reflected by the surface of the object and returned to the stylus, where it interferes with a reference light to measure distance. When measuring the inner shape of the object, the stylus is introduced inside the object and the measurement light is irradiated perpendicularly onto the inner surface of the object. The stylus is then moved in a circular motion along the inner surface of the object while maintaining an orientation such that the reflected light from the object returns to the stylus, thereby scanning the inner surface of the object with the measurement light. Such a point sensor, which irradiates measurement light laterally from the tip of the stylus, can be used not only to measure the inner shape of the object, but also for non-contact measurement of the outer shape of the object to be measured, such as a turbine blade.

[0003] JP 2013-250152 A JP 2021-148769 A

[0004] When using a point sensor that irradiates the measurement light laterally from the tip of a stylus to measure the internal shape of an object, the direction of the measurement light from the stylus must be adjusted so that the optical axis of the measurement light is normal to the surface of the object, so that the measurement light reflects off the surface of the object and returns to the stylus. For this reason, when measuring shape using the point sensor, a rotation mechanism is used to orient the stylus at an arbitrary angular position, in addition to a movement mechanism that moves the stylus along the surface of the object. The mechanical rotation of the stylus presents the following problems: The mechanical rotation affects the measurement accuracy, and maintenance of the mechanical moving parts is required, resulting in increased equipment and maintenance costs. Furthermore, controlling the stylus rotation complicates the measurement program, and the rotation takes time, reducing measurement efficiency. Therefore, a non-contact distance sensor that can measure distance in any direction while eliminating these disadvantages was needed.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a non-contact distance measuring instrument that irradiates measuring light laterally from the tip of a stylus and is capable of changing the direction of the measuring light without rotating the stylus.

[0006] The non-contact distance measuring device of the present invention is a non-contact distance measuring device that irradiates measurement light from an interferometer laterally from the tip of a stylus, and has a planar light generating unit that converts light along the extension axis of the stylus into light that is perpendicular to the extension axis and directed outward from the extension axis, and a spatial light modulator that limits the outwardly spreading light to light in a specified direction from the extension axis.

[0007] In this invention, a stylus is supported along the surface of the workpiece using a three-dimensional movement mechanism or the like, and while maintaining the extension direction of the stylus parallel to the surface of the workpiece, the stylus is moved along the surface of the workpiece, and the surface of the workpiece is scanned with measurement light from the tip of the stylus. The measurement light from the tip of the stylus is converted by the planar light generator into outward light (planar light perpendicular to the extension direction of the stylus) and becomes light that extends all around the stylus extension direction. Therefore, there is no need to control the orientation of the stylus when scanning the surface of the workpiece. In other words, although the measurement light from the stylus is light that extends all around the stylus extension direction, the component reflected by the surface of the workpiece and returning to the stylus is mainly perpendicular to the surface of the workpiece. Note that this narrowing of the light components is premised on the fact that the surface of the workpiece is nearly a mirror surface, that the specular reflection component is dominant in the reflected light, and that the numerical aperture of the optical system on the workpiece side is small. In the present invention, limiting the light to a specified direction means narrowing down the light so that the light component in a specific direction is the main component. Therefore, the light with the greatest intensity among the light reflected by the surface of the workpiece and returning to the stylus is used as the return light, and by detecting its interference with the reference light, the distance from the current position of the stylus to the surface of the workpiece can be measured. As a result, a non-contact distance measuring instrument can be achieved that can change the direction of the measurement light without rotating the stylus.

[0008] In the non-contact distance measuring instrument of the present invention, the planar light generating unit is preferably one of a prism, mirror, or lens having a conical, spherical, parabolic, ellipsoidal, or other aspherical reflective surface, a prism, mirror, or lens having a conical, spherical, parabolic, ellipsoidal, or other aspherical refractive surface, or a prism, mirror, or lens having a conical, spherical, parabolic, ellipsoidal, or other aspherical refractive and reflective surface, or a combination thereof, and the stylus is preferably transparent around the periphery of the planar light generating unit. In the present invention, the planar light generating unit can convert light along the extension axis of the stylus into outward light centered on the extension axis, and can convert light reflected by the surface of the object and returning inward centered on the extension axis into light along the extension axis of the stylus. In the present invention, the prism, mirror, or lens having a conical, spherical, or aspherical (parabolic, ellipsoidal, or other aspherical) reflecting or refracting surface is not limited to a single optical element, but may be, for example, a combination of multiple lenses. Furthermore, the shape of the refracting surface can be a lens having a spherical or aspherical refracting surface (such as a fisheye lens), or a prism using a combination of a parabolic or ellipsoidal reflecting and refracting surface. Examples of prisms with such refracting surfaces include a combination of a parabolic surface and a flat surface (utilizing parabolic refraction and reflection), an ellipsoidal surface and a convex surface (utilizing ellipsoidal refraction and reflection and refraction by a convex surface), and an ellipsoidal surface and a concave surface (utilizing ellipsoidal refraction and reflection and refraction by a concave surface).

[0009] The non-contact distance measuring instrument of the present invention preferably includes a cylindrical light generating unit that converts the measurement light from the interferometer into cylindrical light of a predetermined radius. In the present invention, an axicon lens or a conical prism can be used as the cylindrical light generating unit. For example, light emitted from an end face of an optical fiber connected to the interferometer is converted into parallel light by a collimating lens, and this parallel light is then incident on an axicon lens to generate light that spreads in a conical shape. When this light is incident on a lens with the apex of the cone as its focal point, cylindrical light with a ring-shaped light distribution is generated at the focal point on the exit side. In the present invention, the cylindrical light generating unit converts light from the end face of the optical fiber into cylindrical light, and can narrow this light and introduce it into the end face of the optical fiber by injecting cylindrical light or a portion of the cylindrical light in the opposite direction. In the present invention, by converting the measurement light from the interferometer into cylindrical light of a predetermined radius by the cylindrical light generating unit, the cylindrical light is converted into planar light perpendicular to the extension direction of the stylus without waste in the planar light generating unit, thereby ensuring the amount of measurement light returning to the interferometer.

[0010] In the non-contact distance measuring device of the present invention, the spatial light modulation unit is preferably an optical filter that transmits only light in a direction specified relative to a predetermined center position on a plane perpendicular to the optical axis, or a mirror that reflects only light in a direction specified relative to the center position. In the present invention, the optical filter that transmits only light in a specific direction can be, for example, a liquid crystal shutter or a rotating shutter with a pinhole. The mirror that reflects only light in a specific direction can be a rotating mirror with only specific portions designated as reflective areas, or an element in which DMD (digital micromirror device) or MEMS (microelectromechanical system) mirrors are arranged in a two-dimensional matrix. In the present invention, the spatial light modulation unit can be located anywhere on the optical path relative to the planar light generation unit. That is, it may act on light incident on the planar light generation unit or on light emitted from the planar light generation unit.

[0011] The non-contact distance measuring device of the present invention preferably includes an orientation detection unit that detects the orientation to be assigned to the spatial light modulation unit, and the orientation detection unit detects the orientation of the light reflected by the surface of the object to be measured and returned to the planar light generation unit at the maximum intensity. In the present invention, the orientation detection unit can be an image sensor with a two-dimensional array of multiple light-receiving elements, such as a CCD (solid-state image sensor) camera. When cylindrical light is incident on the image sensor, a circular image is obtained on the surface of the image sensor. By using image processing software that detects the area with the maximum light intensity in the obtained image, the orientation at which the light intensity is maximum relative to the center of the circular shape can be detected, and this orientation can be assigned to the spatial light modulation unit.

[0012] The non-contact distance measuring device of the present invention is a non-contact distance measuring device that irradiates measurement light from an interferometer laterally from the tip of a stylus, and includes: a cylindrical light generating unit that converts the measurement light from the interferometer into cylindrical light of a predetermined radius; a group of optical elements that convert the cylindrical light from the cylindrical light generating unit into light along the extension axis of the stylus; a planar light generating unit that converts the light along the extension axis into light that is perpendicular to the extension axis and directed outward from the extension axis, and converts light that is reflected by the surface of the object to return inward from the extension axis into light along the extension axis; an orientation detecting unit that detects the orientation of the light that is reflected by the surface of the object to return to the planar light generating unit with the maximum intensity; and a spatial light modulating unit that limits the light that is reflected by the surface of the object to return to the planar light generating unit to light in the orientation detected by the orientation detecting unit.

[0013] In this invention, the measurement light from the interferometer is converted into cylindrical light of a predetermined radius by the cylindrical light generating unit, which is then converted into light along the extension axis of the stylus by a group of optical elements. The planar light generating unit then converts this cylindrical light into outward light centered on the extension axis, and this outward light is emitted laterally from the tip of the stylus over the entire circumference. The stylus is supported along the surface of the object to be measured by a three-dimensional movement mechanism or the like, and while maintaining the extension direction of the stylus parallel to the surface of the object, the stylus is moved along the surface of the object to scan the surface of the object with the measurement light from the tip of the stylus. During this scanning, the measurement light from the stylus is reflected by the surface of the object and returns to the stylus. Of the measurement light that travels over the entire circumference, the component that returns to the stylus is mainly the component perpendicular to the surface of the object. Therefore, the direction of maximum intensity of the light reflected by the surface of the workpiece and returning to the stylus is detected by the direction detection unit, and only the light in the direction detected by the spatial light modulation unit is returned to the interferometer, and interference with the reference light is detected, thereby making it possible to measure the distance from the current position of the stylus to the surface of the workpiece.This makes it possible to create a non-contact distance measuring device that can change the direction of the measurement light without rotating the stylus.

[0014] In the present invention, the orientation detection unit detects the orientation of the maximum intensity among the light reflected by the surface of the object being measured and returning to the stylus, and the spatial light modulation unit returns only the light in the orientation detected by the spatial light modulation unit to the interferometer. Therefore, similar to existing point sensors, the interferometer simply detects the interference between the returned light and the reference light. Note that the orientation detection unit must detect the orientation on the optical path after reflection by the surface of the object being measured, but the spatial light modulation unit may limit the orientation before or after reflection by the surface of the object being measured. When the spatial light modulation unit limits the orientation before reflection by the surface of the object being measured, the orientation detection mode is first performed by disabling the spatial light modulation unit and performing only orientation detection by the orientation detection unit. In this case, the light emitted to the side of the stylus becomes a continuous planar light around the entire circumference. Next, the measurement mode is performed by enabling the spatial light modulation unit, and limiting the orientation of the light returned to the interferometer to the orientation detected in the orientation detection mode. In other words, the light returning to the interferometer becomes a spot light with a limited orientation, and this spot light can be used to measure the distance to the surface of the workpiece. If the orientation is limited by the spatial light modulator after reflection from the surface of the workpiece, the mode switching described above is not necessary, and orientation can be limited following orientation detection at any time. The light emitted to the side of the stylus always becomes a planar light that is continuous all around, but the light returned to the interferometer mainly consists of light with a limited orientation component.

[0015] The non-contact distance measuring device of the present invention is a non-contact distance measuring device that irradiates measurement light from an interferometer sideways from the tip of a stylus, and includes: a cylindrical light generating unit that converts the measurement light from the interferometer into cylindrical light of a predetermined radius; an optical element group that converts the cylindrical light from the cylindrical light generating unit into light along the extension axis of the stylus; a planar light generating unit that converts the light along the extension axis into light perpendicular to the extension axis and directed outward from the extension axis, and converts light reflected by the surface of the object to return inward from the extension axis into light along the extension axis; and a spatial light modulation unit that is installed on the optical path of the optical element group and limits the light passing through the optical element group to light in a specified direction centered on the optical axis of the optical path.

[0016] In this invention, the measurement light from the interferometer is converted into cylindrical light of a predetermined radius by the cylindrical light generating unit, which is then converted into light along the extension axis of the stylus by a group of optical elements. The planar light generating unit then converts this cylindrical light into outward light centered on the extension axis, and this outward light is emitted laterally from the tip of the stylus over the entire circumference. The stylus is supported along the surface of the object to be measured by a three-dimensional movement mechanism or the like, and while maintaining the extension direction of the stylus parallel to the surface of the object, the stylus is moved along the surface of the object to scan the surface of the object with the measurement light from the tip of the stylus. During this scanning, the measurement light from the stylus is reflected by the surface of the object and returns to the stylus. Of the measurement light that travels over the entire circumference, the component that returns to the stylus is mainly the component perpendicular to the surface of the object. Therefore, by detecting the interference between the reference light and the light with the greatest intensity reflected by the surface of the workpiece and returning to the stylus, the distance from the current position of the stylus to the surface of the workpiece can be measured.

[0017] In the present invention, an interferometer control device is used to control the movement of the stylus by the three-dimensional movement mechanism or the scanning of the object to be measured with the measurement light, and also to specify the orientation of the measurement light for the spatial light modulator. Specifically, when scanning the surface of the object to be measured, the orientation of one revolution around the optical axis is continuously specified for the spatial light modulator at each location on the surface. When the orientation is specified by the spatial light modulator before reflection on the surface of the object to be measured, the light emitted laterally from the stylus becomes a spot light in the specified orientation, and as this light circulates around the stylus, the returned light is returned to the interferometer. The intensity of this returned light peaks in the orientation perpendicular to the surface of the object to be measured, and the intensity of the light is low in other orientations. Therefore, by using the peak component of the returned light, distance measurement using the interferometer can be performed without controlling the orientation specification according to the stylus position. When the spatial light modulator limits the direction after reflection from the surface of the workpiece, the light emitted laterally from the stylus becomes continuous light around the entire circumference of the stylus, but is then limited to the direction specified by the spatial light modulator, and this light is returned to the interferometer as returned light. This returned light has a peak in light intensity in a direction perpendicular to the surface of the workpiece, and is weak in other directions. Therefore, by using the component of the peak portion of the returned light, distance measurement using an interferometer can be performed without controlling the direction specification according to the stylus position.

[0018] FIG. 1 is a diagram showing a non-contact distance measuring device according to a first embodiment of the present invention. FIG. 2 is a diagram showing the shape of a surface perpendicular to the optical axis of measurement light according to the first embodiment. FIG. 3 is a diagram showing planar light in the orientation detection mode of the first embodiment. FIG. 4 is a diagram showing planar light in the measurement mode of the first embodiment. FIG. 5 is a diagram showing the path of measurement light in the orientation detection mode of the first embodiment. FIG. 6 is a diagram showing the path of measurement light in the measurement mode of the first embodiment. FIG. 7 is a diagram showing the operation of measuring the inner surface of a measured object by a non-contact distance measuring device of the present invention. FIG. 8 is a diagram showing the operation of measuring the outer surface of a measured object by a non-contact distance measuring device of the present invention. FIG. 9 is a diagram showing a non-contact distance measuring device according to a second embodiment of the present invention. FIG. 10 is a diagram showing the path of measurement light in the second embodiment. FIG. 11 is a diagram showing a non-contact distance measuring device according to a third embodiment of the present invention. FIG. 12 is a diagram showing the path of measurement light in the third embodiment. FIG. 13 is a diagram showing a non-contact distance measuring device according to a fourth embodiment of the present invention. FIG. 14 is a diagram showing the path of measurement light in the fourth embodiment. FIG. 15 is a diagram showing a non-contact distance measuring device according to a fifth embodiment of the present invention. FIG. 16 is a diagram showing the path of measurement light in the fifth embodiment. FIG. 17 is a diagram showing a non-contact distance measuring device according to a sixth embodiment of the present invention. FIG. 18 is a diagram showing a non-contact distance measuring device according to a seventh embodiment of the present invention. FIG. 19 is a diagram showing the path of measurement light in the seventh embodiment. 10 is a diagram showing a non-contact distance measuring device according to an eighth embodiment of the present invention, a diagram showing a non-contact distance measuring device according to a ninth embodiment of the present invention, and a diagram showing a front measurement mode of the ninth embodiment.

[0019] 1 shows a non-contact distance measuring device 1 according to the present invention. The non-contact distance measuring device 1 has a probe 20 supported by a three-dimensional movement mechanism 10, and an interferometer 30 is connected to the probe 20.

[0020] The three-dimensional movement mechanism 10 has a table 11 on which the workpiece W is placed and a column 12 adjacent to the table 11, and supports a probe 20 by an arm 13 extending from the column 12. The three-dimensional movement mechanism 10 can move the probe 20 to any position along the X, Y, and Z axes relative to the table 11 by using a movement mechanism (not shown) installed on the table 11, column 12, and arm 13. In FIG. 1 , a cylindrical workpiece W is placed on the table 11, and the tip of the probe 20 is inserted inside the workpiece W. By moving the probe 20 by the three-dimensional movement mechanism 10, the tip of the probe 20 can be moved along the inner surface of the workpiece W, and the inner surface can be scanned with measurement light.

[0021] The interferometer 30 performs high-precision distance measurement by interfering laser light, and includes a laser light source 31 and a photodetector 32. The laser light from the light source 31 is introduced as measurement light into the probe 20 via an optical fiber 311, an optical branching / coupling device 312, and an optical fiber 313. Return light from the probe 20 is returned to the photodetector 32 via an optical fiber 323, an optical branching / coupling device 322, and an optical fiber 321. A reference optical path 330 corresponding to the optical path length of the measurement light returning from the optical fiber 313 to the optical fiber 323 via the probe 20 is formed between the optical branching / coupling device 312 and the optical branching / coupling device 322. The reference optical path 330 includes a corner cube 332 connected to the optical branching / coupling device 312 and the optical branching / coupling device 322 via a pair of optical fibers and an optical branching / coupling device 331. The corner cube 332 can be adjusted to expand or contract the inner and outer diameters of the effective range (see the shaded area in FIG. 3 ) of the planar light L13, which will be described later. The interferometer 30 has a control unit 39, which can measure the distance between the probe 20 and the object to be measured W based on interference between the return light reflected by the probe 20 on the object to be measured W and the reference light from the reference light path 330. The control unit 39 incorporates software for performing measurement calculations and control in the interferometer 30, as well as software for controlling the operation of the probe 20 and the three-dimensional movement mechanism 10.

[0022] The probe 20 has a main pipe 201, which is a stylus, and branch pipes 202 and 203 are connected to the middle of the main pipe 201. The central axis of the main pipe 201 is the extension axis E, and the central axes of the branch pipes 202 and 203 are arranged perpendicular to the extension axis E. A cylindrical light generating unit 21 is installed inside the branch pipe 202. An optical fiber 313 extending from the interferometer 30 is connected to the end of the branch pipe 202. A return light sending unit 29 is installed inside the branch pipe 203. An optical fiber 323 continuing to the interferometer 30 is connected to the end of the branch pipe 203.

[0023] Inside the main pipe 201, a first beam splitter 22 is installed at the connection point with the branch pipe 202, and a second beam splitter 26 is installed at the connection point with the branch pipe 203. A spatial light modulation unit 25 is installed between the first beam splitter 22 and the second beam splitter 26. A planar light generation unit 24 is installed at the lower end of the main pipe 201 in the figure. An imaging lens group 23 is installed between the first beam splitter 22 and the planar light generation unit 24. An orientation detection unit 28 is installed at the upper end of the main pipe 201 in the figure. An imaging lens group 27 is installed between the second beam splitter 26 and the orientation detection unit 28.

[0024] Each part of the probe 20 will be described in detail below. In the following description, the relationship between each part will be explained with reference to FIG. 1, and the measurement light in the probe 20 will be explained with reference to FIGS. 2, 3, and 4. The cylindrical light generating unit 21 has a collimating lens 211, an axicon lens 212, and an illumination lens 213. The measurement light L11 emitted from the end face of the optical fiber 313 has a point-like beam profile (shape on a plane perpendicular to the optical axis) (see FIG. 2A). The measurement light L11 is incident from the collimating lens 211 side, converted into parallel light distributed in a circle, and then incident on the axicon lens 212. The axicon lens 212 is a conical prism that converts the incident parallel light into light that spreads in a cone shape. The focal position on the incident side of the illumination lens 213 is aligned with the apex of the cone shape of the light that has exited the axicon lens 212, and the light that spreads in a cone shape from the axicon lens 212 passes through the illumination lens 213 to generate cylindrical light L12 with a ring-shaped beam profile (see FIG. 2B ) on the exit side.

[0025] The first beam splitter 22 is arranged at the connection between the main tube 201 and the branch tube 202, and is inclined at 45 degrees with respect to the axis of the main tube 201 and the axis of the branch tube 202, and bends the cylindrical light L12 from the cylindrical light generating unit 21 at a right angle to make it light along the extension axis E, and sends it to the imaging lens group 23.

[0026] The imaging lens group 23 has a pair of imaging lenses 231, 232 whose optical axis is the extension axis E, and an aperture 233 placed therebetween, and sends the cylindrical light L12 from the first beam splitter 22 to the planar light generating unit 24.

[0027] The planar light generating unit 24 has a spherical mirror 241, and a transparent window 242 is provided in the main tube 201 around the spherical mirror 241, extending continuously around the entire circumference. The spherical mirror 241 has a spherical reflecting surface whose center of curvature is located on the extension axis E. The spherical mirror 241 receives the cylindrical light L12 sent from the imaging lens group 23 in an annular region that is at an angle of 45 degrees with respect to the extension axis E, based on the center of curvature, thereby generating planar light L13 (see FIG. 2C) that spreads radially outward over the entire circumference, i.e., perpendicular to the extension axis E and outward. The planar light L13 spreading outward from the spherical mirror 241 passes through the transparent window 242, is irradiated onto the inner surface of the workpiece W, is reflected, and returns inward. It is then reflected by the spherical mirror 241 and converted again into cylindrical light (cylindrical light L14, see FIG. 2D), and returns to the imaging lens group 23. The planar light L13 spreading outward from the spherical mirror 241 is not all light within the same plane perpendicular to the extension axis E, but the light reflected on the inner surface of the object W and returning inward becomes planar light L13 that passes exclusively within a plane perpendicular to the extension axis E. The planar light generating unit 24 is not limited to the spherical mirror 241 having a spherical reflecting surface, but may have a conical or parabolic reflecting surface, and may be a prism rather than a mirror.

[0028] The spatial light modulation unit 25 is composed of a panel-shaped optical filter arranged in a direction perpendicular to the stretching axis E, and this optical filter has tiny liquid crystal shutters arranged two-dimensionally. This optical filter can transmit light only in any direction around the intersection with the stretching axis E, and block light transmission in other areas, using an external control signal. External control can be performed, for example, by the control unit 39 of the interferometer 30. The spatial light modulation unit 25 can be switched between two modes, an orientation detection mode and a measurement mode, under the control of the control unit 39.

[0029] In the orientation detection mode, the spatial light modulation unit 25 transmits all of the cylindrical light L14 sent from the first beam splitter 22 along the extension axis E, and sends it to the second beam splitter 26 as transmitted light L15 (see FIG. 2D). In the measurement mode, the spatial light modulation unit 25 transmits only the light in a specified orientation DL out of the cylindrical light L14 sent from the first beam splitter 22 along the extension axis E, and sends it to the second beam splitter 26 as modulated light L16 (see FIG. 2E). This allows the spatial light modulation unit 25 to limit the modulated light L16 to a component of the planar light L13 that spreads outward in the planar light generation unit 24 and is oriented in the specified orientation DL around the extension axis E.

[0030] The second beam splitter 26 is disposed at the connection between the main tube 201 and the branch tube 203, and is inclined at 45 degrees with respect to the axis of the main tube 201 and the axis of the branch tube 203, respectively, and transmits a portion of the transmitted light L15 or modulated light L16 from the spatial light modulation unit 25 along the extension axis E and sends it to the imaging lens group 27, while bending the other portion at a right angle and sending it to the branch tube 203 and the return light sending unit 29.

[0031] The imaging lens group 27 has a pair of imaging lenses 271, 272 whose optical axis is the extension axis E, and sends another portion of the transmitted light L15 or modulated light L16 along the extension axis E from the second beam splitter 26 to the orientation detection unit 28.

[0032] The orientation detection unit 28 is composed of a CCD image sensor in which a large number of light-receiving elements are two-dimensionally arranged, and is disposed at the end of the main pipe 201 so as to be perpendicular to the extension axis E. When the spatial light modulation unit 25 is in orientation detection mode, the orientation detection unit 28 obtains an annular image on the surface of the image sensor using cylindrical transmitted light L15 from the imaging lens group 27. For example, image processing software incorporated in the control unit 39 of the interferometer 30 can be used to detect the area with the greatest light intensity in the annular image, thereby detecting the orientation DL where the light intensity is greatest relative to the center of the annular shape. The detected orientation DL can be specified as a specific orientation DL when limiting the transmission area in the spatial light modulation unit 25.

[0033] 3 , when the center of the probe 20 is in the direction DL relative to the center of the workpiece W and planar light L13 is emitted from the probe 20 in the entire circumference, the planar light L13 reflected from the inner surface S of the workpiece W returns to the probe 20 mainly as components L131 and L132 that are incident perpendicularly to the inner surface S. Component L131 is in the direction DL relative to the center of the probe 20 and is the portion of the inner surface S closest to the probe 20. Component L132 is on the opposite side of the direction DL relative to the center of the probe 20 and is the portion of the inner surface S farthest from the probe 20. Therefore, of the planar light L13 emitted in the entire circumference, the component L131 in the direction DL is the component with the greatest light intensity reflected from the inner surface S. Therefore, by detecting the direction of maximum light intensity using the direction detection unit 28, the direction DL of the inner surface S closest to the probe 20 can be detected.

[0034] 4, when the center of the probe 20 is in the direction DL relative to the center of the workpiece W and planar light L13 is emitted from the probe 20 in the entire circumference, the direction detection unit 28 detects the direction of maximum light intensity, thereby making it possible to detect the direction DL of the inner surface S closest to the probe 20. Although the planar light L13 emitted from the probe 20 is directed in the entire circumference, by limiting it to modulated light L16 directed in the direction DL by the spatial light modulation unit 25, it is possible to select only the light corresponding to the component L131 in FIG.

[0035] The return light sending unit 29 has an illumination lens 291, an axicon lens 292, and a collimator lens 293. These have a configuration in which the above-mentioned cylindrical light generating unit 21 is arranged in an inverted manner, and converge the transmitted light L15 or modulated light L16 from the second beam splitter 26 into a point shape, and make it incident on the end face of the optical fiber 313 as return light L19.

[0036] By the above-described probe 20, the measurement light L11 incident from the optical fiber 313 scans the inner surface of the workpiece W as planar light L13 and is returned to the interferometer 30 from the optical fiber 323 as return light L19. In the interferometer 30, the return light L19 interferes with the reference light from the reference light path 330, thereby sequentially measuring the distance to the inner surface of the workpiece W and performing shape measurement along the scanning path. Here, when measuring the distance at each point along the scanning path, as described above, the spatial light modulator 25 is set to the orientation detection mode to detect the orientation DL, and the spatial light modulator 25 is set to the measurement mode to limit the light to the orientation DL, and the operation is repeated.

[0037] 5 shows the path of the measurement light in the probe 20 in the orientation detection mode. In the orientation detection mode, the measurement light L11 is converted into cylindrical light L12 by the cylindrical light generator 21, and passes through the first beam splitter 22, the imaging lens group 23, and the planar light generator 24 to become planar light L13. The planar light L13 is reflected by the inner surface of the object W and returns to the planar light generator 24, where it is converted into cylindrical light L14, which passes through the imaging lens group 23 and the first beam splitter 22 and reaches the spatial light modulator 25. In the orientation detection mode, all directions are specified to the spatial light modulator 25 by the control unit 39 as orientation specification information Dc, for example, and the cylindrical light L14 passes directly through the spatial light modulator 25 to become transmitted light L15. The transmitted light L15 is split into two by the second beam splitter 26. One of the split beams passes through an imaging lens group 27 and is introduced into an orientation detection unit 28, which detects orientation information Dd indicating the orientation DL. The other split beam is converted into return light L19 by a return light sending unit 29 and returned to the interferometer 30.

[0038] FIG. 6 shows the path of the measurement light in the probe 20 in the measurement mode. In the measurement mode, the measurement light L11 is converted into cylindrical light L12 by the cylindrical light generator 21, and passes through the first beam splitter 22, the imaging lens group 23, and the planar light generator 24 to become planar light L13. The planar light L13 is reflected by the inner surface of the object W and returns to the planar light generator 24, where it is converted into cylindrical light L14, which passes through the imaging lens group 23 and the first beam splitter 22 and reaches the spatial light modulator 25. Up to this point, the process is the same as in the orientation detection mode. In the measurement mode, the spatial light modulator 25 is assigned orientation designation information Dc from the control unit 39, for example, indicating the orientation DL indicated by the orientation information Dd previously detected in the orientation detection mode. The cylindrical light L14 is then limited to the component of the orientation DL by the spatial light modulator 25 to become modulated light L16. The modulated light L16 is then split into two by the second beam splitter 26. One of the split beams is guided to the orientation detection unit 28 via the imaging lens group 27, but orientation detection is omitted in the measurement mode. The other split beam is converted into return beam L19 by the return beam transmitter 29 and returned to the interferometer 30.

[0039] FIG. 7 shows the operation of measuring the inner surface of the workpiece W using the probe 20. First, as shown in FIG. 7A, the three-dimensional movement mechanism 10 is operated under the control of the control unit 39, and the probe 20 is introduced into the inside of the workpiece W and positioned close to the surface in an arbitrary direction. The positioned probe 20 emits planar light L13 under the control of the control unit 39, detects the orientation DL of the approaching probe 20 in orientation detection mode, and then measures distance in measurement mode using the component of the orientation DL as modulated light L16. Next, as shown in FIGS. 7B to 7G, the probe 20 is moved along the inner surface of the workpiece W under the control of the control unit 39, and the orientation detection mode and measurement mode are repeatedly executed at each predetermined position. In this case, the direction of the modulated light L16 used to measure the distance is automatically selected to be the normal direction that is closest to the inner surface of the workpiece W by detecting the orientation DL at each position, and no special orientation control is required. Furthermore, the direction of the modulated light L16 is optically changed in the probe 20, and no mechanical rotation operation is required. The three-dimensional movement mechanism 10 only needs to perform two-dimensional coordinated operation of the X and Y axes to move the probe 20 along the inner surface of the workpiece W.

[0040] FIG. 8 shows the operation of measuring the outer surface of the workpiece W using the probe 20. First, as shown in FIG. 8A, the three-dimensional movement mechanism 10 is operated under the control of the control unit 39, and the probe 20 is positioned close to the outer surface of the workpiece W. The positioned probe 20 emits planar light L13 under the control of the control unit 39, detects the orientation DL of the approaching probe 20 in orientation detection mode, and then performs distance measurement in measurement mode using the component of the orientation DL as modulated light L16. Next, as shown in FIGS. 8B to 8F, the probe 20 is moved along the outer surface of the workpiece W under the control of the control unit 39, and the orientation detection mode and measurement mode are repeatedly executed at each predetermined position. Even in such outer surface measurement, the direction of the modulated light L16 used to measure the distance is automatically selected as the normal direction that is closest to the surface of the workpiece W by detecting the orientation DL at each position, and no special orientation control is required. Furthermore, the direction of the modulated light L16 is optically changed in the probe 20, and no mechanical rotation operation is required. The three-dimensional movement mechanism 10 only needs to perform two-dimensional coordinated operation of the X and Y axes to move the probe 20 along the outer surface of the workpiece W.

[0041] 9 shows a non-contact distance measuring device 2 according to the present invention. The non-contact distance measuring device 2 has a probe 20A supported by a three-dimensional movement mechanism 10, and an interferometer 30A is connected to the probe 20A.

[0042] The three-dimensional movement mechanism 10 is the same as that of the first embodiment described above. The interferometer 30A is the same as that of the first embodiment described above. However, in the interferometer 30A shown in FIG. 9 , the light source 31 and optical fibers 311 and 313 are shown in the upper part of the figure, and the photodetector 32 and optical fibers 321 and 323 are shown in the lower part of the figure. The probe 20A basically has the same configuration as that of the first embodiment described above, but the cylindrical light generation unit 21 and the return light transmission unit 29 are arranged in reverse, and the spatial light modulation unit 25A is arranged on the incident side of the return light transmission unit 29 of the branch pipe 202.

[0043] 10 shows the path of the measurement light in the probe 20A. In the probe 20A, the measurement light L21 from the interferometer 30A is converted into cylindrical light L22 by the cylindrical light generating unit 21, and then passes through the second beam splitter 26, the first beam splitter 22, the imaging lens group 23, and the planar light generating unit 24 to become planar light L23. The planar light L23 is reflected by the inner surface of the object W and returns to the planar light generating unit 24, where it is converted into cylindrical light L24 and passed through the imaging lens group 23 to the first beam splitter 22, where it is split into two. One of the split light beams passes through the second beam splitter 26 and the imaging lens group 27 to become cylindrical light L25 and is introduced into the orientation detecting unit 28, where orientation information Dd indicating the orientation DL is detected. The other split light beam is introduced into the spatial light modulating unit 25A. The spatial light modulator 25A is assigned the orientation DL indicated by the orientation information Dd detected by the orientation detector 28 as the orientation designation information Dc, and the cylindrical light L24 is limited to the component of the orientation DL by the spatial light modulator 25A to become modulated light L26. The modulated light L26 is sent to the return light transmitter 29, where it is converted into return light L27 and returned to the interferometer 30A.

[0044] The non-contact distance measuring device 2 of the second embodiment can also achieve the same effects as the non-contact distance measuring device 1 of the first embodiment. Furthermore, in the non-contact distance measuring device 2, the detection of the direction DL by the direction detection unit 28 and the limitation of the component of the direction DL by the spatial light modulation unit 25A can be performed continuously, eliminating the need to repeatedly switch between the direction detection mode and the measurement mode as in the non-contact distance measuring device 1 of the first embodiment, and allowing for simple and efficient processing.

[0045] 11 shows a non-contact distance measuring device 3 according to the present invention. The non-contact distance measuring device 3 has a probe 20B supported by a three-dimensional movement mechanism 10, and an interferometer 30B is connected to the probe 20B.

[0046] The three-dimensional movement mechanism 10 is the same as that of the first embodiment. The interferometer 30B has the same light source 31, photodetector 32, and control unit 39 as the interferometer 30 of the first embodiment, but the optical fiber connections are different. In FIG. 11 , an optical fiber 311, an optical branching / coupling unit 312, and an optical fiber 313 leading to the probe 20B are connected to the light source 31. The optical fiber 313 is used both to send measurement light and to receive return light. A corner cube 332 is connected to the optical branching / coupling unit 312 via an optical fiber 333 to form a reference light path 330, and an optical fiber 321 is connected to the photodetector 32 to send mixed light of the reference light from the reference light path 330 and the return light from the optical fiber 313.

[0047] Probe 20B has a main pipe 201, which is a stylus, and one branch pipe 202. A mirror 22B is installed in main pipe 201 at the branch point with branch pipe 202. An imaging lens group 23 and a planar light generating unit 24, similar to those in the first embodiment, are installed on the tip side of main pipe 201 below mirror 22B in the figure. A cylindrical light generating unit 21B and a spatial light modulating unit 25B, similar to those in the first embodiment, are installed in branch pipe 202.

[0048] 12 shows the path of the measurement light in the probe 20B. In the probe 20B, the measurement light L31 from the interferometer 30B is converted into cylindrical light L32 by the cylindrical light generator 21B and introduced into the spatial light modulator 25B. The orientation DL is specified in the spatial light modulator 25B by the orientation designation information Dc from the control unit 39, and the cylindrical light L32 is limited to the component of the orientation DL by the spatial light modulator 25B and converted into modulated light L33. The modulated light L33 passes through the mirror 22B, the imaging lens group 23, and the planar light generator 24 to become planar light L34. The planar light L34 is reflected by the inner surface of the workpiece W and returns to the planar light generator 24, where it is converted into modulated light L35 and sent to the cylindrical light generator 21B via the imaging lens group 23, the mirror 22B, and the spatial light modulator 25B, where it is converted into returned light L36 and returned to the interferometer 30B.

[0049] The non-contact distance measuring device 3 of the third embodiment also provides the same effects as the non-contact distance measuring device 1 of the first embodiment. Furthermore, in the probe 20B of the third embodiment, the measurement light L31 and the return light L36 share the same path, making the configuration simpler than those of the first and second embodiments. Furthermore, since the direction DL is not detected as in the first and second embodiments, the direction detector can be omitted, thereby simplifying the configuration and improving the processing efficiency of the measurement.

[0050] Furthermore, in the probe 20B of the third embodiment, the control unit 39 uses the orientation DL calculated from the position control information of the probe 20B as the orientation designation information Dc for the spatial light modulation unit 25B. For example, the orientation of the center position of the probe 20B relative to the center of the workpiece W can be used as this orientation DL. Therefore, by periodically repeating the process of sequentially designating orientations from 0 to 360 degrees at predetermined angular intervals as the orientation designation information Dc and detecting the orientation in which the distance measured by the interferometer 30B is shortest, the orientation DL at the current position of the probe 20B and the distance to the inner surface of the workpiece W can be measured. Here, by setting the angular range of the orientation designation information Dc to a specific range from 0 to 360 degrees, it is possible to narrow down the measurement target area on the inner surface of the workpiece W and measure the closest point within that range. Furthermore, in the probe 20B of the third embodiment, when measuring the inner surface of the object W to be measured, if the inner diameter of the object W to be measured is small and the entire inside of the object W to be measured is within the effective range of the planar light L13 (see Figure 3), by positioning the probe 20 along the central axis of the object W to be measured, it is possible to measure the distance along the entire inner surface of the object W to be measured without moving the probe 20B.

[0051] 13 shows a non-contact distance measuring device 4 according to the present invention. The non-contact distance measuring device 4 has a probe 20C supported by a three-dimensional movement mechanism 10, and an interferometer 30C is connected to the probe 20C.

[0052] The three-dimensional movement mechanism 10 is the same as that of the first embodiment. The interferometer 30C is the same as that of the third embodiment. The probe 20C has a main tube 201, which is a stylus, and one branch tube 202. An extension section 204 is formed at the connection between the branch tube 202 and the main tube 201. A cylindrical light generating unit 21C is installed from the branch tube 202 to the extension section 204. The cylindrical light generating unit 21C has a collimating lens 211 and an axicon lens 212 similar to those of the first embodiment, and also has an illumination lens 213C with a larger diameter than the illumination lens 213 of the first embodiment. A mirror 214 is installed between the axicon lens 212 and the illumination lens 213C to bend the optical axis and to transmit a portion of the illumination lens 213C that is biased relative to the center.

[0053] A spatial light modulation unit 25C is provided at the upper end of the main tube 201 in the drawing. The spatial light modulation unit 25C is configured as a DMD (digital micromirror device) in which MEMS (microelectromechanical systems) mirrors are arranged in a two-dimensional matrix, and the reflection state of any region of the surface can be selected under the control of the control unit 39. For example, of the cylindrical light L42 sent from the illumination lens 213C, only the light in a direction DL specified with respect to the center position of the surface of the spatial light modulation unit 25C can be reflected to produce modulated light L43 along the extension axis E of the main tube 201. A group of imaging lenses 23 and a planar light generating unit 24 similar to those in the first embodiment are provided at the tip side of the main tube 201 in the drawing.

[0054] 14 shows the path of the measurement light in the probe 20C. In the probe 20C, the measurement light L41 from the interferometer 30C is converted into cylindrical light L42 by the cylindrical light generating unit 21C and introduced into the spatial light modulating unit 25C. The orientation DL is specified in the spatial light modulating unit 25C by the orientation specifying information Dc from the control unit 39, and the cylindrical light L42 is limited to the component of the orientation DL by the spatial light modulating unit 25C and converted into modulated light L43. The modulated light L43 passes through the imaging lens group 23 and the planar light generating unit 24 to become planar light L44. The planar light L44 is reflected by the inner surface of the workpiece W and returns to the planar light generating unit 24, where it is converted into modulated light L45 and sent to the cylindrical light generating unit 21C via the imaging lens group 23 and the spatial light modulating unit 25C, where it is converted into return light L46 and returned to the interferometer 30C.

[0055] The non-contact distance measuring device 4 of the fourth embodiment also provides the same effects as the non-contact distance measuring device 1 of the first embodiment. Furthermore, the probe 20C of the fourth embodiment also provides the same effects as the third embodiment. Furthermore, the probe 20C of the fourth embodiment uses a DMD as the spatial light modulation unit 25C, thereby enabling faster operation than when a liquid crystal shutter is used.

[0056] 15 shows a non-contact distance measuring device 5 according to the present invention. The non-contact distance measuring device 5 has a probe 20D supported by a three-dimensional movement mechanism 10, and an interferometer 30D is connected to the probe 20D.

[0057] The three-dimensional movement mechanism 10 is the same as that of the first embodiment. The interferometer 30D is the same as that of the interferometer 30B of the third embodiment. The probe 20D has, in the main pipe 201, a mirror 22D, an imaging lens group 23, and a planar light generating unit 24, which are the same as those of the third embodiment. On the other hand, in the branch pipe 202, the cylindrical light generating unit 21B and the spatial light modulating unit 25B of the third embodiment are omitted, and instead a modulated light generating unit 21D is installed.

[0058] The modulated light generation unit 21D has a rotating prism 215 between the collimator lens 211 and the illumination lens 213. The rotating prism 215 is arranged with its output surface tilted with respect to the optical axis, and is rotatable around the optical axis direction of the modulated light generation unit 21D by a motor (not shown). This rotation causes a virtual conical surface to be formed by the trajectory of the output surface of the rotating prism 215, and the apex position of the virtual conical surface is aligned with the focal position of the illumination lens 213. As a result, the rotating prism 215 can replace the function of the axicon lens 212 in the cylindrical light generation unit 21B of the third embodiment, and can also replace the function of the spatial light modulation unit 25B of the third embodiment.

[0059] 16 shows the path of the measurement light in the probe 20D. In the probe 20D, the measurement light L51 from the interferometer 30D is introduced into the modulated light generator 21D, which generates modulated light L52. The orientation DL of the modulated light generator 21D is specified by orientation specification information Dc from the control unit 39, and the modulated light L52 travels along the cylindrical path in the specified orientation DL. The modulated light L52 passes through the mirror 22D, the imaging lens group 23, and the planar light generator 24 to become planar light L53. The planar light L53 is reflected by the inner surface of the workpiece W and returns to the planar light generator 24, where it is converted into modulated light L54 and sent to the modulated light generator 21D via the imaging lens group 23 and the mirror 22D, where it is converted into return light L55 and returned to the interferometer 30D.

[0060] The non-contact distance measuring device 5 of the fifth embodiment also provides the same effects as the non-contact distance measuring device 1 of the first embodiment. Furthermore, the probe 20D of the fifth embodiment also provides the same effects as the third embodiment. Furthermore, the probe 20D of the fifth embodiment uses a modulated light generating unit 21D instead of the cylindrical light generating unit 21B and spatial light modulating unit 25B of the third embodiment. Therefore, the amount of light can be increased compared to when light is limited by a filter such as the spatial light modulating unit 25B, thereby improving the utilization efficiency of the light incident as the measurement light L51. The modulated light generating unit 21D of the probe 20D of the fifth embodiment requires mechanical rotation of the rotating prism 215. However, the rotating prism 215 is lightweight and compact, and therefore, the burden on the device or the reduction in accuracy that would be caused by a mechanism for rotating the probe 20D itself can be avoided.

[0061] 17 shows a non-contact distance measuring device 6 according to the present invention. The non-contact distance measuring device 6 has a probe 20E supported by a three-dimensional movement mechanism 10, and an interferometer 30E is connected to the probe 20E.

[0062] The three-dimensional movement mechanism 10 is the same as that of the first embodiment. The interferometer 30E is the same as that of the interferometer 30B of the third embodiment. The probe 20E is substantially the same as that of the probe 20D of the fifth embodiment (see FIG. 15 ), except that the modulated light generation unit 21E is different from that of the modulated light generation unit 21D.

[0063] The modulated light generation unit 21D of the fifth embodiment uses a rotating prism 215 to deflect the light beam into a cone shape. In contrast, the modulated light generation unit 21E of this embodiment uses a spatial light phase modulator 216 that does not require mechanical operation. The spatial light phase modulator 216 is an optical element that can form a hologram image, deflect a light beam, deform the beam shape, and so on by performing two-dimensional phase manipulation on an optical signal of a certain wavelength λ. For example, an LCOS-SLM X15213 series manufactured by Hamamatsu Photonics KK can be used as a transmissive spatial light phase modulator.

[0064] The path of the measurement light in the non-contact distance measuring device 6 of this embodiment is the same as that in the fifth embodiment (see FIG. 16 ). The non-contact distance measuring device 6 of this sixth embodiment also provides the same effects as the non-contact distance measuring device 1 of the first embodiment. Furthermore, the probe 20E of the sixth embodiment also provides the same effects as those in the third embodiment and the fifth embodiment. Furthermore, the probe 20E of the sixth embodiment uses a spatial light phase modulator 216 in the modulated light generating unit 21E, which eliminates mechanical operations such as prism rotation, improving maintainability and reducing operating costs. Although the present embodiment uses a transmissive spatial light phase modulator 216, a reflective spatial light phase modulator may also be used.

[0065] 18 shows a non-contact distance measuring device 7 according to the present invention. The non-contact distance measuring device 7 has a probe 20F supported by a three-dimensional movement mechanism 10, and an interferometer 30F is connected to the probe 20F.

[0066] The three-dimensional movement mechanism 10 is the same as that of the first embodiment. The interferometer 30F is the same as that of the interferometer 30B of the third embodiment. Like the probe 20E of the sixth embodiment (see FIG. 17 ), the probe 20F uses a spatial light phase modulator 216 as the modulated light generation unit 21F, but omits the structure between the modulated light generation unit 21F and the imaging lens 232, and further omits the branch pipe 202, leaving only the main pipe 201.

[0067] 18, in probe 20F, optical fiber 313 of interferometer 30F is connected to the upper end of main tube 201 in the figure, and a collimating lens 211, a spatial light phase modulator 216, and an imaging lens 232 are arranged in this order downward in the figure, with planar light generating unit 24 (spherical mirror 241 and transparent window 242) installed at the lower end in the figure. In probe 20F, parallel light from collimating lens 211 is deflected by spatial light phase modulator 216 to form a spot light, and the spot light is incident on planar light generating unit 24 via imaging lens 232 while rotating within an imaginary conical surface by controlling the deflection direction.

[0068] 19 shows the path of the measurement light in the probe 20F. In the probe 20F, the measurement light L51 from the interferometer 30F is introduced into the modulated light generator 21F, and the modulated light L52 is generated by the spatial light phase modulator 216. The orientation DL of the spatial light phase modulator 216 is specified between 0 and 360 degrees by orientation specification information Dc from the control unit 39, and the modulated light L52 circulates in a conical path. The modulated light L52 passes through the imaging lens 232 and is introduced into the planar light generator 24, where it is converted into planar light L53. The planar light L53 is reflected by the inner surface of the workpiece W, returns to the planar light generator 24, converted into modulated light L54, and passes through the imaging lens 232 and the modulated light generator 21F as return light L55, which is returned to the interferometer 30F.

[0069] The non-contact distance measuring device 7 of the seventh embodiment also provides the same effects as the non-contact distance measuring device 1 of the first embodiment. Furthermore, the probe 20F of the seventh embodiment also provides the same effects as the third embodiment, the fifth embodiment, and the sixth embodiment. Furthermore, the probe 20F of the seventh embodiment only includes the spatial light phase modulator 216 as the modulated light generating unit 21F, and the mirror 22D and the imaging lens group 23 (see FIG. 15 ) of the probe 20D are omitted, leaving only the imaging lens 232. This significantly simplifies the optical path configuration and prevents attenuation of the light beam. Furthermore, the probe 20F also omits the branch pipe 202 and has a linear configuration consisting of only the main pipe 201, making it easier to handle during measurement.

[0070] In this embodiment, a transmissive spatial light phase modulator 216 with no mechanical operation is used, but it may be replaced with an element with mechanical operation, such as a rotating prism. However, in order to obtain the effects of improved maintainability and reduced operating costs as in the sixth embodiment, it is preferable to use a spatial light phase modulator 216 with no mechanical operation.

[0071] 20 shows a non-contact distance measuring device 8 according to the present invention. The non-contact distance measuring device 8 has a probe 20G supported by a three-dimensional movement mechanism 10, and an interferometer 30G is connected to the probe 20G.

[0072] The three-dimensional movement mechanism 10 is the same as that of the first embodiment. The interferometer 30G is the same as that of the interferometer 30B of the third embodiment. The probe 20G is substantially the same as the probe 20E of the sixth embodiment (see FIG. 17 ), except that a reflective spatial light phase modulator 217 is used instead of the transmissive spatial light phase modulator 216, and a collimating lens 211 is disposed in the branch pipe 202 that intersects with the main pipe 201, and an optical fiber 313 of the interferometer 30G is connected to the branch pipe 202.

[0073] In the probe 20G, the parallel light from the collimator lens 211 is reflected by the spatial light phase modulator 217 to become deflected spot light (modulated light L52), and the spot light rotates within a virtual conical surface by controlling the deflection direction, and is then incident on the planar light generating unit 24 via the imaging lens 232. The path of the measurement light in the probe 20G is similar to the path of the measurement light in the probe 20F of the seventh embodiment (see FIG. 19 ) except that the optical path is bent by the spatial light phase modulator 217.

[0074] The non-contact distance measuring device 8 of the eighth embodiment also provides the same effects as the non-contact distance measuring device 1 of the first embodiment. Furthermore, the probe 20G of the eighth embodiment also provides the same effects as the third embodiment, the fifth embodiment, the sixth embodiment, and the seventh embodiment.

[0075] In this embodiment, a reflective spatial light phase modulator 217 that does not have a mechanical operation is used, but it may be replaced with an element that performs a mechanical operation, such as a rotating mirror. However, in order to obtain the effects of improving maintainability and reducing operating costs as in the seventh embodiment, it is preferable to use a spatial light phase modulator 217 that does not have a mechanical operation.

[0076] 21 and 22 show a non-contact distance measuring device 9 according to the present invention. The non-contact distance measuring device 9 has a probe 20H supported by a three-dimensional movement mechanism 10, and an interferometer 30H is connected to the probe 20H.

[0077] The three-dimensional movement mechanism 10 is the same as that of the first embodiment. The interferometer 30H is the same as the interferometer 30B of the third embodiment. The probe 20H is substantially the same as the probe 20G of the eighth embodiment, except that a light guide hole 243 is formed in the spherical mirror 241 of the planar light generating unit 24. The light guide hole 243 is a through-hole formed in the spherical mirror 241, and extends along the extension axis E, which is the central axis of the main tube 201.

[0078] In the probe 20H, the parallel light from the collimator lens 211 is reflected to form spot light (modulated light L52). Here, the spatial light phase modulator 217 of the modulated light generation unit 21H is switched between a side measurement mode and a front measurement mode under the control of the control unit 39.

[0079] 21, in the side measurement mode, the spot light reflected by the spatial light phase modulator 217 is deflected with respect to the extension axis E and passes through a virtual conical surface that reaches the inclined surface of the spherical mirror 241. Then, the spot light circulates along a conical path according to the orientation designation information from the control unit 39, is converted into planar light L53 by the spherical mirror 241, is reflected by the inner surface of the workpiece W, and is returned in the opposite direction along the same path as modulated light 54 (the same optical path as in the eighth embodiment shown in FIG. 20). This makes it possible to measure the inner surface of the workpiece W.

[0080] 22, in the front measurement mode, the spot light (modulated light L52) reflected by the spatial light phase modulator 217 is guided along the extension axis E, passes through the light guiding hole 243 at the center of the spherical mirror 241, is reflected by the inner surface of the object W to be measured, and is returned in the opposite direction along the same path as modulated light L54. This makes it possible to measure the bottom surface of the object W to be measured.

[0081] The non-contact distance measuring device 9 of the ninth embodiment also provides the same effects as the non-contact distance measuring device 1 of the first embodiment. Furthermore, the probe 20H of the ninth embodiment can measure the inner surface of the object W similar to the eighth embodiment described above. Furthermore, the probe 20H of the ninth embodiment can measure the inner surface of the object W described above in the side measurement mode (see FIG. 21), and can also measure the bottom surface of the object W by switching to the front measurement mode (see FIG. 21).

[0082] [Other Embodiments] The present invention is not limited to the above-described embodiments, and modifications within the scope of achieving the object of the present invention are included in the present invention. In each of the above-described embodiments, the main pipe 201 is used as the stylus, and branch pipes 202 and 203 are connected to the main pipe 201 to install the cylindrical light generating unit 21, the return light transmitting unit 29, or, depending on the embodiment, the spatial light modulating unit 25A, etc. However, the mechanical arrangement of each of these functional elements can be appropriately selected so as to realize the measurement light path of each embodiment. Furthermore, other optical elements may be used for the spatial light modulating unit 25 and the orientation detecting unit 28 as long as similar functions are obtained, and the optical elements used in the cylindrical light generating unit 21, the return light transmitting unit 29, and the imaging lens groups 23 and 27 may also be appropriately changed.

[0083] 1 to 9: Non-contact distance measuring device, 10: Three-dimensional movement mechanism, 11: Table, 12: Column, 13: Arm, 20 to 20H: Probe, 201: Main pipe, 202: Branch pipe, 203: Branch pipe, 204: Extension section, 21: Cylindrical light generating section, 211: Collimating lens, 212: Axicon lens, 213, 213C: Irradiation lens, 214: Mirror, 215: Rotating prism, 21B, 21C: Cylindrical light generating section, 21D 21H...modulated light generating unit, 22...first beam splitter, 22B, 22D...mirror, 23...imaging lens group, 231, 232...imaging lens, 233...diaphragm, 24...planar light generating unit, 241...spherical mirror, 242...transparent window, 243...light guiding hole, 25, 25A, 25B, 25C...spatial light modulating unit, 26...second beam splitter, 27...imaging lens group, 271, 272...imaging lens, 28...orientation detection Output unit, 29... Return light output unit, 291... Irradiation lens, 292... Axicon lens, 293... Collimator lens, 30 to 30H... Interferometer, 31... Light source, 311, 313, 321, 323... Optical fiber, 312, 322, 331... Optical branching coupler, 32... Photodetector, 330... Reference light path, 332... Corner cube, 39... Control unit, Dc... Orientation designation information, Dd... Orientation information, DL... Orientation, E... Extension axis, L11, L21, L31, L41, L51...measurement light, L12, L22, L32, L42...cylindrical light, L13, L23, L34, L44, L53...planar light, L131, L132...component, L14, L24...cylindrical light, L15...transmitted light, L16, L26, L33, L35, L43, L45, L52, L54...modulated light, L19, L27, L36, L46, L55...return light, S...inner surface, W...object to be measured.

Claims

1. A non-contact distance measuring device that irradiates measurement light from an interferometer laterally from the tip of a stylus, comprising: a planar light generating unit that converts light along the extension axis of the stylus into light perpendicular to the extension axis and directed outward from the extension axis; and a spatial light modulator that limits the outwardly spreading light to light in a specified direction from the extension axis.

2. A non-contact distance measuring device as claimed in claim 1, wherein the planar light generating unit is either a prism, mirror or lens having a conical, spherical, parabolic, ellipsoidal or other aspherical reflecting surface, a prism, mirror or lens having a conical, spherical, parabolic, ellipsoidal or other aspherical refracting surface, or a prism, mirror or lens having a conical, spherical, parabolic, ellipsoidal or other aspherical refracting and reflecting surface, or a combination of these, and the stylus is transparent around the planar light generating unit.

3. A non-contact distance measuring device according to claim 1 or 2, further comprising a cylindrical light generating section for converting the measurement light from the interferometer into cylindrical light of a predetermined radius.

4. A non-contact distance measuring device as claimed in claim 1 or 2, wherein the spatial light modulation unit is an optical filter that transmits only light in a specified direction relative to a predetermined central position on a plane perpendicular to the optical axis, or a mirror that reflects only light in a specified direction relative to the central position.

5. A non-contact distance measuring device as claimed in claim 4, further comprising an orientation detection unit which detects an orientation to be specified to said spatial light modulation unit, said orientation detection unit detecting the orientation in which the intensity of light reflected by the surface of the object to be measured and returned to said planar light generation unit is maximum.

6. A non-contact distance measuring device which irradiates measuring light from an interferometer laterally from the tip of a stylus, comprising: a cylindrical light generating unit which converts the measuring light from the interferometer into cylindrical light of a predetermined radius; a group of optical elements which convert the cylindrical light from the cylindrical light generating unit into light along the extension axis of the stylus; a planar light generating unit which converts the light along the extension axis into light perpendicular to the extension axis and outwardly directed about the extension axis, and converts light reflected by the surface of the object to return inwardly directed about the extension axis into light along the extension axis; an orientation detecting unit which detects the orientation of the light reflected by the surface of the object to return to the planar light generating unit in which the intensity is maximum; and a spatial light modulating unit which limits the light reflected by the surface of the object to return to the planar light generating unit to light in the orientation detected by the orientation detecting unit.

7. A non-contact distance measuring device which irradiates measuring light from an interferometer laterally from the tip of a stylus, comprising: a cylindrical light generating unit which converts the measuring light from the interferometer into cylindrical light of a predetermined radius; a group of optical elements which convert the cylindrical light from the cylindrical light generating unit into light along the extension axis of the stylus; a planar light generating unit which converts the light along the extension axis into light perpendicular to the extension axis and directed outward from the extension axis, and converts light which is reflected by the surface of the object to be measured and returns inward from the extension axis into light along the extension axis; and a spatial light modulator which is installed on the optical path of the group of optical elements and limits the light which passes through the group of optical elements to light in a specified direction centered on the optical axis of the optical path.

Images