Displacement sensor, manufacturing system, and article manufacturing method

Abstract

In order to provide a displacement sensor that can easily change an object displacement-direction which is to be measured, this displacement sensor is characterized by including: an illumination unit that illuminates the object by causing illumination light to be incident on the object; an imaging unit that includes an optical element that guides first light from the object so as to cause an image of the object to rotate and that captures images of the object by receiving the first light via the optical element; and a computation unit that, on the basis of a first image captured at a first time and a second image captured at a second time by the imaging unit, calculates the amount of displacement of the object between the first time and the second time. The invention is also characterized in that the optical element guides at least a portion of the incident illumination light from the illumination unit to the object.

Description

Displacement meter, manufacturing system, and method for manufacturing an article

[0001] The present invention relates to a displacement meter that measures the amount of displacement of an object.

[0002] Conventionally, there has been known a displacement meter that measures the amount of displacement of an object in a non-contact manner by receiving light from the object that is generated by irradiating the object with a laser beam before and after the object is displaced. Patent Document 1 discloses a displacement meter that measures the amount of displacement of an object in a predetermined direction by using a one-dimensional image sensor formed from a plurality of pixels arranged in the predetermined direction.

[0003] Japanese Patent Application Publication No. 3-235007

[0004] In the displacement meter disclosed in Patent Document 1, when an object is displaced in a predetermined direction that forms an angle θ with respect to the arrangement direction of the plurality of pixels in the one-dimensional image sensor, the displacement meter measures an amount of displacement that is cos θ times the amount of displacement of the object in the predetermined direction. In other words, when the direction of displacement of the object and the arrangement direction of the plurality of pixels in the one-dimensional image sensor are orthogonal to each other, the one-dimensional image sensor cannot measure the amount of displacement of the object.

[0005] Therefore, in order to accurately measure the displacement of an object using the displacement meter disclosed in Patent Document 1, it is necessary to change the orientation of the housing to align the array direction of multiple pixels in the one-dimensional image sensor housed in the housing with the direction of displacement of the object. This complicates the measurement process. Therefore, an object of the present invention is to provide a displacement meter that can easily change the direction of displacement of the object being measured.

[0006] The displacement meter according to the present invention comprises an illumination unit that illuminates an object by irradiating the object with illumination light; an imaging unit that includes an optical element that guides first light from the object so as to rotate an image of the object and captures an image of the object by receiving the first light through the optical element; and a calculation unit that calculates the amount of displacement of the object between the first time and the second time from the first image captured by the imaging unit at the first time and the second image captured at the second time, wherein the optical element guides at least a portion of the illumination light incident from the illumination unit to the object.

[0007] According to the present invention, it is possible to provide a displacement meter that can easily change the direction of displacement of an object to be measured.

[0008] 1 is a schematic partial YZ cross-sectional projection view of a displacement meter according to the first embodiment. FIG. 2 is a schematic partial YZ cross-sectional projection view of a displacement meter according to the first embodiment. FIG. 3 is a schematic partial perspective view of a displacement meter according to the second embodiment. FIG. 4 is a diagram showing how the direction of displacement of an object measured by the displacement meter according to the second embodiment changes. FIG. 5 is a schematic partial YZ cross-sectional projection view of a displacement meter according to the third embodiment. FIG. 6 is a schematic partial YZ cross-sectional projection view of a displacement meter according to the first embodiment. FIG. 7 is a schematic partial YZ cross-sectional projection view of a displacement meter according to the fourth embodiment.

[0009] The displacement meter according to this embodiment will be described in detail below with reference to the accompanying drawings. Note that the drawings shown below may be drawn at a scale different from the actual scale in order to facilitate understanding of this embodiment. In the following, the direction in which the photoelectric conversion elements are arranged in the line sensor 6 is defined as the Y direction (second direction), the direction perpendicular to the Y direction and parallel to the optical axis of the light receiving optical system is defined as the Z direction (first direction), and the direction perpendicular to the Y direction and the Z direction is defined as the X direction.

[0010] [First Embodiment] Conventionally, a displacement meter is known that acquires a speckle distribution by irradiating a laser beam onto an object before and after displacement of the object, and then photoelectrically converts the speckle distribution to obtain an amount of displacement of the object by calculating an extremum of a cross-correlation function between the acquired signals. Among such displacement meter, a one-dimensional image sensor formed from a plurality of pixels arranged in a predetermined direction is known to accurately measure the amount of displacement of the object in the predetermined direction.

[0011] However, in such conventional displacement meters, if the arrangement direction of the multiple pixels in the one-dimensional image sensor differs from the direction of the object's displacement, measurement errors will occur. For example, if the object displaces in a predetermined direction that forms an angle θ with the arrangement direction, the one-dimensional image sensor will measure a displacement that is cos θ times the actual displacement of the object in the predetermined direction.

[0012] In other words, if the direction of displacement of an object and the direction of arrangement of the multiple pixels in the one-dimensional image sensor are perpendicular to each other, the one-dimensional image sensor will be unable to measure the amount of displacement of the object. Therefore, in order to accurately measure the amount of displacement of an object using such a conventional displacement meter, it is necessary to change the orientation of the housing to align the direction of arrangement of the multiple pixels in the one-dimensional image sensor housed in the housing with the direction of displacement of the object. This makes the measurement process complicated.

[0013] Furthermore, among the above-mentioned conventional displacement meters, there is also known a type that uses a two-dimensional image sensor to measure the displacement of an object in a predetermined plane with high accuracy. That is, such conventional displacement meters can measure the displacement of an object with high accuracy even if the direction of the object's displacement in the predetermined plane changes, but the cost of providing the two-dimensional image sensor and peripheral circuits increases.

[0014] Furthermore, since the amount of image data acquired with a two-dimensional image sensor is greater than that with a one-dimensional image sensor, the time required to acquire the image data, transfer the data, and calculate the amount of displacement of an object by processing the data increases. In other words, conventional displacement meters using such two-dimensional image sensors result in higher costs and lower throughput.

[0015] Therefore, the present embodiment aims to provide a non-contact displacement meter that can measure the amount of displacement of an object while suppressing a decrease in throughput and an increase in cost by simply changing the direction of the displacement of the object. Fig. 1 shows a partial schematic projection view in the YZ cross section of a displacement meter 50 (length measuring meter) according to the first embodiment.

[0016] The displacement meter 50 according to this embodiment can measure the displacement of an object 2 arranged opposite to it in a non-contact manner. The displacement meter 50 according to this embodiment includes a light source 3, a first focusing optical element 4, a second focusing optical element 5, a line sensor 6 (image pickup element), an aperture 7, an image rotator 8 (optical element), an image rotator holder 9 ( FIG. 3 ), a signal processing unit 11, and a control unit 12. In the displacement meter 50 according to this embodiment, the above components are housed in a housing 40.

[0017] In the displacement meter 50 according to this embodiment, the first focusing optical element 4 and the image rotator 8 form an illumination optical system, and the image rotator 8, the second focusing optical element 5, and the diaphragm 7 form a light-receiving optical system. In addition, in the displacement meter 50 according to this embodiment, the light source 3, the first focusing optical element 4, and the image rotator 8 form an illumination unit that illuminates a predetermined area (illumination area) on a predetermined surface of the object 2 by making illumination light incident on the object 2. In addition, in the displacement meter 50 according to this embodiment, the image rotator 8, the second focusing optical element 5, the diaphragm 7, and the line sensor 6 form an imaging unit that captures an image of the object 2 by receiving light (first light), for example, diffusely reflected light, from the object 2.

[0018] The light source 3 is an incoherent light source such as an LED or halogen lamp that emits white light, and can be appropriately selected from a plurality of such incoherent light sources. The first focusing optical element 4 is formed by at least one lens (refractive optical element) appropriately selected depending on the size and shape of the illumination area on the object 2. The second focusing optical element 5 is formed by at least one lens (refractive optical element) appropriately selected depending on the resolution set in the light receiving optical system.

[0019] The diaphragm 7 is disposed between the second focusing optical element 5 and the line sensor 6 at a position spaced apart from the second focusing optical element 5 by the focal length of the second focusing optical element 5. In the displacement meter 50 according to this embodiment, by providing the diaphragm 7 in this manner, a telecentric light receiving optical system can be formed on the object 2 side.

[0020] That is, in the displacement meter 50 according to this embodiment, by forming such an object-side telecentric optical system, it is possible to form a robust measurement system that can measure the displacement amount of the object 2 at a constant magnification even if the distance to the object 2 changes. Furthermore, by forming an object-side telecentric optical system, it is possible to set the optical magnification according to the position of the line sensor 6 relative to the diaphragm 7.

[0021] It is also possible to form a double-telecentric optical system by appropriately arranging a condensing optical element between the diaphragm 7 and the line sensor 6. When a double-telecentric optical system is formed in the displacement meter 50 according to this embodiment, the magnification of the light-receiving optical system is determined according to the ratio between the focal lengths of the second condensing optical element 5 and the condensing optical element. The determined magnification is constant regardless of the position of the line sensor 6.

[0022] The line sensor 6 is a photoelectric conversion element array that extends in a one-dimensional direction, specifically in the Y direction, with a plurality of photoelectric conversion elements (pixels) arranged in the Y direction. In the displacement meter 50 according to this embodiment, by using the line sensor 6, the amount of data that is transferred and used for calculations is reduced compared to when an area sensor is used, enabling high-speed measurement and improving throughput.

[0023] In the displacement meter 50 according to this embodiment, the light beam received by the line sensor 6 is photoelectrically converted to generate an image signal, and the generated image signal is input to a signal processing unit 11 (arithmetic unit). The signal processing unit 11 is formed by an FPGA (Field Programmable Gate Array), a microcomputer, or the like, and calculates the amount of displacement of the object 2 by processing the image signal output from the line sensor 6.

[0024] For example, the signal processing unit 11 calculates a cross-correlation function between an image signal (first signal) acquired at a predetermined timing (first time) and an image signal (second signal) acquired at another predetermined timing (second time). More specifically, for example, the signal processing unit 11 acquires a first image signal generated by photoelectrically converting a luminance distribution in an image (first image) captured at a predetermined timing. Next, the signal processing unit 11 acquires a second image signal generated by photoelectrically converting a luminance distribution in an image (second image) captured at another predetermined timing, and calculates a cross-correlation function between the acquired first image signal and second image signal.

[0025] Then, the amount of displacement of the object 2 between the predetermined timing and the other predetermined timing can be calculated from the position of the peak (extreme value) in the calculated cross-correlation function. Note that the signal processing unit 11 can calculate the amount of displacement of the object 2 with a resolution of one pixel or less from information on the position of the peak in the calculated cross-correlation function and information on positions before and after the position of the peak.

[0026] In the displacement meter 50 according to this embodiment, a light beam emitted from the light source 3 is collected by the first collecting optical element 4 and then guided to the object 2, thereby illuminating the object 2. Furthermore, at least a portion of the light beam collected by the first collecting optical element 4 passes through the image rotator 8 and is then guided to the object 2.

[0027] The light diffusely reflected by the object 2 passes through the image rotator 8, is collected by the second collecting optical element 5, passes through the diaphragm 7, and is then guided to the line sensor 6. As a result, an image reflecting the pattern on the illuminated predetermined surface of the object 2 is formed in the line sensor 6.

[0028] In the displacement meter 50 according to this embodiment, an image rotator 8 that guides light from the object 2 so as to rotate the image of the object 2 around the Z direction is provided between the object 2 and the second focusing optical element 5. By providing the image rotator 8 in this manner, the displacement meter 50 according to this embodiment can adjust (change, decide, select) the direction of the displacement of the object 2 to be measured.

[0029] 1, a plurality of light source conversion elements are arranged in the Y direction in the line sensor 6. In this case, a conventional displacement meter having the same configuration as the displacement meter 50 according to this embodiment except that it does not include the image rotator 8 can measure the displacement amount of the object 2 in the Y direction. On the other hand, the displacement meter 50 according to this embodiment can measure the displacement amount of the object 2 in a predetermined direction other than the Y direction according to the predetermined angle by rotating the image rotator 8 provided around the Z direction.

[0030] 2A shows a perspective view of the image rotator 8 provided in the displacement meter 50 according to this embodiment. As shown in FIG. 2A, the image rotator 8 provided in the displacement meter 50 according to this embodiment is formed by a Dove prism.

[0031] Specifically, the image rotator 8 formed by a Dove prism has an object-side slope 8a facing the object 2, a sensor-side slope 8b facing the line sensor 6, a bottom surface 8c, a top surface 8d, an illumination-side side surface 8e, and an anti-illumination-side side surface 8f. As shown in Fig. 2A, light that enters the image rotator 8 from the object-side slope 8a while being refracted is reflected by the bottom surface 8c, and then exits the image rotator 8 from the sensor-side slope 8b while being refracted.

[0032] 2A, when light from a portion of the object 2 extending in a predetermined direction in the XY plane passes through the image rotator 8, an image of that portion is formed by rotating around the Z direction in which the bottom surface 8c of the image rotator 8 extends. Specifically, the image of that portion of the object 2 is formed by rotating around the Z axis (the axis of rotation of the image of the object 2 by the image rotator 8) by twice the angle between the predetermined direction in which that portion extends in the XY plane and the bottom surface 8c.

[0033] That is, in the displacement meter 50 according to this embodiment, by rotating the image rotator 8 by a predetermined angle around the Z axis, an image of the object 2 rotated by twice the predetermined angle is formed. In other words, by rotating the image rotator 8, which is disposed so that the bottom surface 8 c is parallel to the YZ plane, by a predetermined angle around the Z axis, it is possible to measure the amount of displacement of the object 2 in a direction that forms an angle twice the predetermined angle with respect to the Y direction in which the line sensor 6 extends.

[0034] 1, when the image rotator 8, which is disposed so that the bottom surface 8c is parallel to the YZ plane, is rotated by 45 degrees around the Z axis, the line sensor 6 can measure the displacement amount of the object 2 in the X direction. That is, in the displacement meter 50 according to this embodiment, the provision of the image rotator 8 makes it possible to measure the displacement amount of the object 2 in a predetermined direction in the XY plane (first plane) perpendicular to the Z direction.

[0035] Furthermore, if an attempt is made to reduce the size of the displacement meter 50 according to this embodiment in the Z direction, the illumination light from the light source 3 will interfere with the image rotator 8. For example, the measurement center is set to the working distance from the end face 40 e of the housing 40, specifically, a position 70 mm away from the end face 40 e in the Z direction on the optical axis of the light-receiving optical system, and the measurable range from the measurement center in the Y direction is set to ±15 mm.

[0036] Furthermore, when the size of the field of view of the displacement meter 50 according to this embodiment is 10 mm and the angle of incidence of the illumination light on the object 2 is 20 degrees, the width of the illumination light needs to be 20 mm or more to sufficiently illuminate the measurable range of the object 2. If the width of the illumination light is set to 20 mm, the illumination light and the field of view will interfere with each other at a position about 30 mm away from the object 2.

[0037] 1, in the displacement meter 50 according to this embodiment, at least a portion of the illumination light from the first focusing optical element 4 passes through the image rotator 8 and is then guided to the object 2. When a Dove prism is used as the image rotator 8 provided in the displacement meter 50 according to this embodiment, optical polishing is performed on each surface of the Dove prism, so that the illumination light can be guided toward the object 2 regardless of the direction from which the illumination light is incident on the image rotator 8.

[0038] At least a part of the illumination light from the first focusing optical element 4 enters the image rotator 8 from, for example, the illumination-side side surface 8 e, and then exits from the object-side inclined surface 8 a or the anti-illumination-side side surface 8 f, thereby being guided to the object 2. That is, in the displacement meter 50 according to this embodiment, the image rotator 8 also serves as a light guide that guides the illumination light from the light source 3 to the object 2.

[0039] 1, in the displacement meter 50 according to this embodiment, the area illuminated by the illumination light on the object 2 is sufficiently larger than the measurement area of ​​the object 2 measured by the line sensor 6. In addition, in the above configuration, there is a risk that part of the illumination light incident on the image rotator 8 will travel as stray light toward the line sensor 6, but such stray light can be blocked by the diaphragm 7.

[0040] 3 shows a projection view in the YZ cross section of the image rotator 8 and the image rotator holder 9 provided in the displacement meter 50 according to this embodiment. In the displacement meter 50 according to this embodiment, the image rotator holder 9 is provided to hold the image rotator 8, and therefore the range in which the illumination light interferes with the field of view becomes even wider.

[0041] 3, in the displacement meter 50 according to this embodiment, an opening 9a (first opening) is formed in the image rotator holding portion 9 at a portion facing the illumination-side side surface 8e of the image rotator 8. Then, at least a portion of the illumination light from the light source 3 passes through the opening 9a formed in the image rotator holding portion 9, and then enters the inside of the image rotator 8 from the illumination-side side surface 8e.

[0042] That is, in the displacement meter 50 according to this embodiment, at least a part of the illumination light from the light source 3 passes through an opening 9a formed in the image rotator holding portion 9 and is incident on the image rotator 8. Then, the illumination light emitted from the image rotator 8 passes through an opening 9b (second opening) formed in the image rotator holding portion 9 so as to face the object-side inclined surface 8a of the image rotator 8, and is incident on the object 2.

[0043] Next, the light from the object 2 passes through the opening 9b and enters the image rotator 8. The light that has passed through the inside of the image rotator 8 then exits from the sensor-side slope 8b of the image rotator 8 and passes through an opening 9c (third opening) formed in the image rotator holding part 9 so as to face the sensor-side slope 8b. In this way, the light from the object 2 is guided to the line sensor 6.

[0044] As described above, in the displacement meter 50 according to this embodiment, illumination light is obliquely incident on the object 2 so that the optical axis of the illumination optical system and the optical axis of the light-receiving optical system are non-parallel to each other in the YZ plane (second plane), but this is not limited to this. That is, in the displacement meter 50 according to this embodiment, illumination light may be incident on the object 2 so that the optical axis of the illumination optical system and the optical axis of the light-receiving optical system are approximately parallel to each other when projected onto the YZ plane. In this case, it is sufficient to form the openings 9b and 9c in the image rotator holding unit 9, and there is no need to form the opening 9a.

[0045] The image rotator holding portion 9 can hold the image rotator 8 by, for example, bonding the anti-illumination side surface 8f to a portion facing the anti-illumination side surface 8f of the image rotator 8. Then, in the image rotator holding portion 9, if only the portion to which the anti-illumination side surface 8f of the image rotator 8 is bonded is provided, that is, if the portion facing the illumination side surface 8e of the image rotator 8 is left open, there is no need to form the opening 9a.

[0046] As described above, the displacement meter 50 according to this embodiment is provided with the image rotator 8 that guides light from the object 2 so as to rotate the image of the object 2 around the Z direction. This allows the user to change the direction of the displacement of the object 2 to be measured without changing the installation direction of the housing 40 of the displacement meter 50 according to this embodiment.

[0047] Furthermore, in the displacement meter 50 according to this embodiment, an image rotator 8 is provided so as to guide at least a part of the illumination light incident from the illumination unit to the object 2. This allows the size of the displacement meter 50 according to this embodiment in the Z direction to be reduced.

[0048] Although the displacement meter 50 according to this embodiment uses a Dove prism as the image rotator 8, the present invention is not limited to this. For example, the image rotator 8 may be a combination 8' of three reflecting surfaces as shown in Fig. 2B, or a single optical element having the three reflecting surfaces.

[0049] [Second embodiment] Fig. 4A shows a schematic perspective view of an image rotator holder 19 provided in a displacement meter 60 according to a second embodiment. Fig. 4B is a diagram showing how the direction of displacement measured by the displacement meter 60 according to the second embodiment changes. Note that the displacement meter 60 according to this embodiment has the same configuration as the displacement meter 50 according to the first embodiment, except that the image rotator holder 19 is provided instead of the image rotator holder 9. Therefore, the same components are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0050] The image rotator holder 19 provided in the displacement meter 60 according to this embodiment is configured to be rotatable around the Z axis parallel to the extension direction of the Dove prism while holding the Dove prism as the image rotator 8. As shown in Fig. 4B, by rotating the image rotator holder 19 around the Z axis, the angle of the image rotator 8 around the Z axis is changed, and the direction of the displacement of the object 2 to be measured can be changed.

[0051] Specifically, by rotating the image rotator 8 by a predetermined angle around the Z axis from a state where θ = 0 degrees, it is possible to measure the amount of displacement of the object 2 in a direction that forms an angle twice the predetermined angle with respect to the Y direction in which the line sensor 6 extends. As shown in Figure 4B, the state where the image rotator 8 is at θ = 0 degrees is a state where the bottom surface 8c of the image rotator 8 is parallel to the YZ plane, that is, a state where the angle (90 - θ) formed by the normal to the bottom surface 8c with respect to the Y axis is 90 degrees. In this case, it is possible to measure the amount of displacement of the object 2 in the Y direction.

[0052] When the image rotator 8 is rotated to θ = 22.5 degrees, the amount of displacement of the object 2 in a direction that forms 45 degrees with respect to the Y direction in the XY plane can be measured. When the image rotator 8 is rotated to θ = 45 degrees, the amount of displacement of the object 2 in the X direction that forms 90 degrees with respect to the Y direction in the XY plane can be measured. When the image rotator 8 is rotated to θ = 90 degrees, the amount of displacement of the object 2 in the Y direction that forms 180 degrees with respect to the Y direction in the XY plane can be measured.

[0053] As described above, in the displacement meter 60 according to this embodiment, the direction of the displacement of the object 2 to be measured can be adjusted by rotating the image rotator 8 by rotating the image rotator holding unit 19 without changing the mounting direction of the housing 40 with respect to the object 2. Specifically, if the direction of displacement in the image of the object 2 rotated by the image rotator 8 forms an angle θ with respect to the Y direction in which the line sensor 6 extends, and the amount of displacement in that direction of displacement is L, the amount of displacement of the object 2 to be measured is L cos θ.

[0054] Therefore, in the displacement meter 60 according to this embodiment, the direction of displacement of the object 2 can be determined by rotating the image rotator 8 so as to maximize the amount of displacement of the object 2 to be measured. In other words, in the displacement meter 60 according to this embodiment, the object 2 is driven at a constant speed, and the image rotator 8 is rotated so as to maximize the output speed, thereby determining the direction of displacement of the object 2.

[0055] That is, in the displacement meter 60 according to this embodiment, the control unit 12 causes the imaging unit to capture images of the object 2 at different times while the image rotator 8 is positioned at each of a plurality of angles θ around the Z axis. Next, the signal processing unit 11 calculates the amount of displacement of the object 2 per unit time from the images of the object 2 captured at the different times. Then, the direction of displacement of the object 2 can be determined from the angle θ at which the calculated amount of displacement per unit time is greatest.

[0056] Furthermore, the displacement meter 60 according to this embodiment calculates a cross-correlation function between image signals acquired at different times, and calculates the displacement amount of the object 2 from the position of the peak in the calculated cross-correlation function. In this case, it is possible to obtain both the displacement amount on the positive side and the displacement amount on the negative side in a predetermined direction. In other words, the displacement meter 60 according to this embodiment can obtain both the displacement amount on the positive side and the displacement amount on the negative side in the Y direction of the object 2 when the image rotator 8 shown in FIG. 4B is at θ = 0 degrees.

[0057] That is, the displacement meter 60 according to this embodiment can acquire both the amount of displacement on the positive side and the amount of displacement on the negative side in the Y direction of the object 2 when the image rotator 8 is at θ = 0 degrees and when the image rotator 8 is at θ = 90 degrees. Therefore, the displacement meter 60 according to this embodiment can acquire the amount of displacement of the object 2 in a predetermined direction and a predetermined orientation in the XY plane by rotating the image rotator 8 by an angle θ between 0 degrees and 90 degrees. Therefore, in the cylindrical surface of the image rotator holder 19 provided in the displacement meter 60 according to this embodiment, the opening 9a for allowing at least a portion of the illumination light to enter the image rotator 8 does not need to be formed over the entire circumferential direction.

[0058] As described above, the displacement meter 60 according to this embodiment is provided with the image rotator 8 that guides light from the object 2 so as to rotate the image of the object 2 around the Z direction. This allows the user to change the direction of the displacement of the object 2 to be measured without changing the installation orientation of the housing 40 of the displacement meter 60 according to this embodiment. Furthermore, the displacement meter 60 according to this embodiment is provided with an image rotator holder 19 that rotatably holds the image rotator 8, thereby making it possible to determine the direction of displacement of the object 2.

[0059] 5 shows a schematic perspective view of a displacement meter 70 according to a third embodiment. Note that the displacement meter 70 according to this embodiment has the same configuration as the displacement meter 50 according to the first embodiment, except that an image rotator holding unit 29 is provided instead of the image rotator holding unit 9. Therefore, the same components are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0060] In the displacement meter 70 according to this embodiment, the image rotator holding portion 29 that holds the image rotator 8 is provided so as to be detachable from the housing 40 that houses other optical elements. In other words, in the displacement meter 70 according to this embodiment, the image rotator 8 is provided so as to be insertable into and detachable from the optical path of the illumination light from the light source 3 and the optical path of the light from the object 2.

[0061] For example, the image rotator holding unit 29 can be fixed to the housing 40 by a screw fastening unit (not shown). Note that the image rotator holding unit 29 may also be fixed to the housing 40 via a magnet, a leaf spring, or the like.

[0062] In the displacement meter 70 according to this embodiment, when measuring the amount of displacement of the object 2 in an unknown direction, an image rotator holding unit 29 that holds the image rotator 8 in order to determine the unknown direction is attached to the housing 40. On the other hand, when measuring the amount of displacement of the object 2 in a known direction, the image rotator holding unit 29 is detached from the housing 40 because it is not necessary to rotate the image of the object 2 by the image rotator 8 by adjusting the orientation of the housing 40 to match the known direction.

[0063] In the displacement meter 70 according to this embodiment, if the image rotator holding unit 29 is attached to the housing 40, the operating distance to the object 2 becomes shorter, and there is a risk of interference with the object 2 due to the influence of vibrations, etc. Therefore, in the displacement meter 70 according to this embodiment, by providing the image rotator holding unit 29 that is detachable from the housing 40, it is possible to select an optimum configuration depending on the usage situation and environment.

[0064] As described above, the displacement meter 70 according to this embodiment is provided with the image rotator 8 that guides light from the object 2 so as to rotate the image of the object 2 around the Z direction. This allows the user to change the direction of the displacement of the object 2 to be measured without changing the installation orientation of the housing 40 of the displacement meter 70 according to this embodiment. Furthermore, the displacement meter 70 according to this embodiment is provided with an image rotator holding unit 29 that is detachable from the housing 40, so that it is possible to select whether to use the image rotator 8 depending on the usage situation and environment.

[0065] 6A and 6B respectively show partial schematic YZ cross-sectional projection views of a displacement meter 50 according to the first embodiment and a displacement meter 80 according to a fourth embodiment. Note that the displacement meter 80 according to this embodiment has the same configuration as the displacement meter 50 according to the first embodiment except that it is further provided with a focusing optical element 10. Therefore, the same components are denoted by the same reference numerals and descriptions thereof will be omitted.

[0066] As shown in Fig. 6B, in the displacement meter 80 according to this embodiment, an additional focusing optical element 10 formed by at least one lens (refractive optical element) is provided between the object 2 and the image rotator 8. This makes it possible to increase the working distance to the object 2 so as to ensure a sufficient distance, compared to the displacement meter 50 according to the first embodiment shown in Fig. 6A. Note that in the displacement meter 80 according to this embodiment, two lenses are provided as the additional focusing optical element 10 as shown in Fig. 6B in order to form an object-side telecentric optical system.

[0067] As described above, the displacement meter 80 according to this embodiment is provided with the image rotator 8 that guides light from the object 2 so as to rotate the image of the object 2 around the Z direction. This allows the user to change the direction of the displacement of the object 2 to be measured without changing the installation direction of the housing 40 of the displacement meter 80 according to this embodiment.

[0068] Furthermore, the displacement meter 80 according to this embodiment is provided with an additional focusing optical element 10 that guides light from the object 2 to the image rotator 8. This allows the working distance to the object 2 to be increased.

[0069] [Method for manufacturing an article] The method for manufacturing an article according to this embodiment includes a step of measuring the amount of displacement of the object 2 using a displacement meter according to any one of the first to fourth embodiments, and a step of manufacturing an article by performing processing such as cutting, bending, or machining on the object 2 based on the measured amount of displacement. In other words, the displacement meter according to any one of the first to fourth embodiments makes it possible to accurately measure the distance that the object 2 has actually moved, and it becomes possible to manufacture articles with small variation in length.

[0070] Furthermore, by reducing the variation in length of manufactured articles, it becomes possible to omit, for example, a subsequent process of inspecting the length of the manufactured articles, thereby improving throughput. Furthermore, by reducing the variation in length of manufactured articles, it becomes possible to improve the reliability of other devices, such as automobiles, into which the articles are incorporated. Furthermore, by providing a manufacturing system including a displacement meter according to any one of the first to fourth embodiments and a processing unit that processes the object 2 based on the displacement amount of the object 2 measured by the displacement meter, it becomes possible to improve the reliability of articles manufactured by the manufacturing system.

[0071] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0072] This application claims priority based on Japanese Patent Application No. 2023-220581, filed on December 27, 2023, the entire contents of which are incorporated herein by reference.

[0073] 2 Object 3 Light source (illumination unit) 4 First condensing optical element (illumination unit) 5 Second condensing optical element (imaging unit) 6 Line sensor (imaging unit) 7 Aperture (imaging unit) 8 Image rotator (optical element) 11 Calculation unit 50 Displacement meter

Claims

1. A displacement meter comprising: an illumination unit that illuminates an object by causing illumination light to be incident on the object; an optical element that guides first light from the object so as to rotate an image of the object, and an imaging unit that captures an image of the object by receiving the first light that has passed through the optical element, and a calculation unit that calculates a displacement amount of the object between a first time and a second time from the first image captured at the first time by the imaging unit and the second image captured at the second time, wherein the optical element guides at least a part of the illumination light incident from the illumination unit to the object.

2. The displacement meter according to claim 1, further comprising a holding unit that holds the optical element, the holding unit having a first opening through which at least a part of the illumination light from the illumination unit passes.

3. The displacement meter according to claim 2, wherein the holding unit has a second opening through which the illumination light from the optical element passes and through which the first light from the object passes, and a third opening through which the first light from the optical element passes.

4. The displacement meter according to any one of claims 1 to 3, wherein the imaging unit includes an imaging element having a plurality of pixels arranged in a one-dimensional direction.

5. The displacement meter according to claim 4, wherein a direction parallel to a rotation axis of the image of the object by the optical element and an arrangement direction of the plurality of pixels are perpendicular to each other.

6. The displacement meter according to any one of claims 1 to 5, wherein the calculation unit calculates the displacement amount of the object in a predetermined direction in a first plane perpendicular to a rotation axis of the image of the object by the optical element.

7. The displacement meter according to any one of claims 1 to 6, wherein the illumination unit illuminates a predetermined region on a predetermined surface of the object, and the imaging unit receives diffusely reflected light from the predetermined region.

8. The displacement meter according to any one of claims 1 to 7, wherein the calculation unit calculates the displacement amount using a cross-correlation function between the first image and the second image.

9. The arithmetic unit acquires a first signal by photoelectrically converting the luminance distribution in the first image, acquires a second signal by photoelectrically converting the luminance distribution in the second image, and calculates the displacement amount by calculating an extreme value of the cross-correlation function between the first signal and the second signal. The displacement meter according to claim 8, characterized in that.

10. The imaging unit includes an image sensor having a plurality of pixels arranged in a one-dimensional direction. In a second plane parallel to the rotation axis of the image of the object formed by the optical element and the arrangement direction of the plurality of pixels, the optical axis of the illumination unit and the optical axis of the imaging unit are non-parallel to each other. The displacement meter according to any one of claims 1 to 9, characterized in that.

11. The imaging unit includes an image sensor and a light receiving optical system that is telecentric on the object side and guides the first light from the object to the image sensor. The displacement meter according to any one of claims 1 to 10, characterized in that.

12. The optical element is rotatable about the rotation axis of the image of the object formed by the optical element. The displacement meter according to any one of claims 1 to 11, characterized in that.

13. A step of causing the imaging unit to image the images at different times while the optical element is arranged at each of a plurality of angles around the rotation axis of the image of the object formed by the optical element, and calculating the displacement amount per unit time from the images imaged at different times by the arithmetic unit; And a step of causing the arithmetic unit to determine the angle at which the calculated displacement amount per unit time is the largest. The displacement meter according to any one of claims 1 to 12, characterized in that it comprises a control unit that performs the steps.

14. The optical element is detachably provided in the optical path of the illumination light from the illumination unit and in the optical path of the first light from the object. The displacement meter according to any one of claims 1 to 13, characterized in that.

15. The displacement meter according to any one of claims 1 to 14, further comprising at least one refractive optical element that guides the first light from the object to the optical element.

16. The optical element is a double prism. The displacement meter according to any one of claims 1 to 15, characterized in that.

17. The optical element has three reflecting surfaces. The displacement meter according to any one of claims 1 to 15, characterized in that.

18. The displacement meter according to any one of claims 1 to 17, wherein the illumination unit includes an incoherent light source that emits the illumination light.

19. A manufacturing system comprising: the displacement meter according to any one of claims 1 to 18; and a processing unit that processes the object based on the amount of displacement of the object measured by the displacement meter.

20. A method for manufacturing an article, comprising: a step of measuring the amount of displacement of the object using the displacement meter according to any one of claims 1 to 18; and a step of manufacturing an article by processing the object based on the measured amount of displacement.

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