Grating projection device and shape measuring apparatus including the same

Abstract

To provide a grating projection device and the like capable of measuring a shape with high accuracy and at high speed.SOLUTION: A grating projection device 10 includes: a light source 22 that emits coherent light; an expander 13 that converts the emitted light into a plane wave; a first beam splitter 14 that splits the converted light into first light that is transmitted light and second light that is reflected light; a first mirror 15 that reflects the first light; a second mirror 16 that reflects the second light toward an object and causes it to intersect the first light; and a second beam splitter that reflects the first light toward the object and transmits the second light to generate interference fringe light for irradiation in which the first light and the second light are superimposed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a grating projection device that irradiates measurement light having a grating-shaped interference fringe, and a shape measurement device including the same.

Background Art

[0002] Conventionally, in the field of measuring the shape of an object to be measured, a three-dimensional shape measurement device using structured light has been proposed. This three-dimensional shape measurement device projects spot light, linear light, grating light, etc. onto the object to be measured, observes this with a camera, and measures the three-dimensional shape of the object to be measured using the principle of triangulation. There are methods such as the light section method and the slit light projection method.

[0003] In these projection methods, since the projected pattern is enlarged with respect to the depth direction of the object to be measured, correction is required. Further, in the slit light projection method, as the distance to the object to be measured increases, the contrast of the image captured by the camera decreases, and thus the resolution of shape measurement decreases as the distance to the object to be measured increases. The light section method also has the same characteristic regarding the enlargement of the projected pattern with respect to the depth direction of the object to be measured, and also has the characteristic that the resolution of shape measurement depends on the beam diameter.

[0004] Patent Document 1 below discloses a technique for measuring the shape of an object to be measured by the slit light projection method. From a light emission structure, linear patterns are emitted at equal angular intervals and projected onto a reference surface. The accurate shape of the object to be measured is calculated from the image acquired by the image sensor and the angle of the beam emitted from the light emission structure, taking into account the difference with respect to the reference surface and the expansion of the emitted beam.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, the technology related to three-dimensional shape measurement using a conventional structured light measures the shape information of a relatively large object to be measured, ranging from several hundred millimeters to several tens of meters, at high speed in a batch within the measurement plane, and the measurement accuracy is also on the order of several tens of micrometers to several millimeters.

[0007] In this way, the conventional three-dimensional shape measurement technology using structured light cannot be said to be appropriate as a technology for measuring an object to be measured with a size of several millimeters to several hundred millimeters with high accuracy of less than ten micrometers. For this reason, in such a high-precision measurement field, generally, pinpoint non-contact measurement by a focus method equipped with a high-magnification objective lens or a three-dimensional coordinate measuring machine that contacts the bead at the tip of a probe is used, but there is a drawback that the number of measurement points is small despite the time required for measurement.

[0008] An object of the present invention is to provide a grating projection device capable of improving the measurement resolution and performing high-speed shape measurement with high accuracy of less than several micrometers in the field of shape measurement using a conventional structured light, and a shape measurement device equipped with the same. More specifically, an object of the present invention is to provide a grating projection device capable of stably projecting grating light with an extremely fine pitch without changing the pitch of the grating light in the depth direction of the object to be measured, and a shape measurement device equipped with the same.

Means for Solving the Problems

[0009] The present invention for solving the above problems is a device that irradiates an object with grating-shaped light, a light source that emits coherent light, an expander provided on the optical path of the light emitted from the light source, which converts the incident light into a plane wave and transmits it, A first beam splitter that is provided on the optical path of the light transmitted through the expander and splits the light into a first light that is transmitted light and a second light that is reflected light; A first mirror that is provided on the optical path of the first light transmitted through the first beam splitter and reflects the first light; A second mirror that is provided on the optical path of the second light reflected by the first beam splitter, reflects the second light toward the object, and intersects the first light reflected by the first mirror; A second beam splitter that is provided at a position where the first light reflected by the first mirror and the second light reflected by the second mirror intersect, reflects the first light toward the object, and generates interference fringe light for irradiation that superimposes the first light and the second light by transmitting the second light, related to a grating projection device.

[0010] According to this displacement detection head, the coherent light emitted from the light source is expanded by the expander and converted into a plane wave, and is split into a first light and a second light by the first beam splitter. Then, the first light passes through the first mirror and reaches the second beam splitter, and the second light passes through the second mirror and reaches the second beam splitter. The first light and the second light, which are plane waves that have reached the second beam splitter, are superimposed on each other at the second beam splitter to become interference fringe light for irradiation (measurement) toward the object. Then, the irradiated interference fringe light is projected onto the object.

[0011] The interference fringe light for irradiation formed as described above is formed by the first light and the second light, which are plane waves, intersecting at a predetermined angle. Therefore, the range in which interference fringes are generated within the interference fringe light extends over a wide range in the optical axis direction, and the interference fringes have a fine pitch and no change in pitch in the optical axis direction. Therefore, in shape measurement using this interference fringe light, shape measurement can be performed with high resolution and high accuracy.

Effect of the Invention

[0012] As described above, according to the lattice projection device of the present invention, since the first light and the second light, which are plane waves, intersect at a predetermined angle to form interference light for irradiation, the range in which interference fringes are generated within the interference fringe light extends over a wide range in the optical axis direction. Further, the interference fringes have a fine pitch and no change in pitch in the optical axis direction. Therefore, in shape measurement using this interference fringe light, shape measurement can be performed with high resolution and high accuracy.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0014] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the three-dimensional shape measurement device 1 of this example is composed of a lattice projection device 10 and a shape detection device 30.

[0015] As shown in Fig. 1, the lattice projection device 10 is composed of: a) a case 11; b) a light source 12, an expander 13, a first beam splitter 14, a first mirror 15, a second mirror 16, an adjustment mechanism 17, a second beam splitter 18, and an image sensor 19 as a reference light imaging unit, which are arranged in the case 11; and c) a control device 20.

[0016] The case 11 is composed of a housing-shaped member, and an opening 11a for emitting interference fringe light for irradiation (measurement) toward the object to be measured (target object) 100 is formed on the surface facing the shape detection device 30. The opening 11a has a sufficient size through which the interference fringe light for irradiation can pass.

[0017] The light source 12 emits coherent light. Examples of coherent light include single-mode semiconductor lasers, multi-mode semiconductor lasers, gas lasers such as HeNe lasers, and superluminescent diodes. As shown in Fig. 1, hereinafter, for convenience, the direction along the optical axis of the light emitted from the light source 12 and along the optical axis of the interference fringe light irradiated from the lattice projection device 10 is referred to as the Z-axis direction, the direction orthogonal to this Z-axis is referred to as the X-axis direction, and the direction orthogonal to the X-axis and Z-axis and orthogonal to the paper surface in Fig. 1 is referred to as the Y-axis direction.

[0018] The expander 13 is provided on the optical path of the light emitted from the light source 12. In the process of the coherent light emitted from the light source 12 passing through, the coherent light is expanded and converted into a plane wave. To increase the allowable range of the distance between the lattice projection device 10 and the object to be measured 100, it is necessary to improve the wavefront accuracy of the plane wave generated by the expander 13, and preferably, the wavefront accuracy is λ (= wavelength of the coherent light) or less within the beam diameter of the coherent light.

[0019] The first beam splitter 14 is provided on the optical path of the light transmitted through the expander 13, and splits the light into a first light (hereinafter referred to as "plane wave L") that is transmitted light in the Z-axis direction and a second light (hereinafter referred to as "plane wave R") that is reflected light in the X-axis direction. It is preferable that the light quantity ratio between the plane wave L and the plane wave R is 1:1.

[0020] The first mirror 15 is provided on the optical path of the plane wave L transmitted through the first beam splitter 14, and reflects the plane wave L in the X-axis direction.

[0021] The second mirror 16 is provided on the optical path of the plane wave R reflected by the first beam splitter 14, and reflects the plane wave R in the Z-axis direction toward the opening 11a of the case 11, in other words, toward the object 100 to be measured arranged at the measurement position, and intersects with the plane wave L reflected by the first mirror 15.

[0022] The second beam splitter 18 is provided at the position where the plane wave L reflected by the first mirror 15 and the plane wave R reflected by the second mirror 16 intersect. The second beam splitter 18 reflects the plane wave L in the Z-axis direction toward the opening 11a of the case 11, that is, toward the object 100 to be measured, and at the same time, transmits the plane wave R, thereby superimposing the plane wave L and the plane wave R, and generating interference fringe light for irradiation, that is, measurement interference fringe light with interference fringes formed at a predetermined pitch in the radial X-axis direction.

[0023] Similarly, the plane wave L passes through the second beam splitter 18, and the plane wave R is reflected in the X-axis direction by the second beam splitter 18, so that the plane wave L and the plane wave R are superimposed, and reference interference fringe light with interference fringes formed at a predetermined pitch in the radial direction is generated. The interference fringes included in this reference interference fringe light are the same as the interference fringes included in the irradiation interference fringe light.

[0024] At this time, it is preferable that the optical path length (R1 + R2) of the plane wave R from the first beam splitter 14 to the second beam splitter 18 and the optical path length (L1 + L2) of the plane wave L from the first beam splitter 14 to the second beam splitter 18 are equal at the level of several micrometers. This is because if the difference between the optical path length (R1 + R2) of the plane wave R and the optical path length (L1 + L2) of the plane wave L is large, the interference fringes formed will drift due to environmental changes such as air pressure. Therefore, in this example, an adjustment mechanism 17 for adjusting the position and orientation of the second mirror 16 is provided, and the optical path length (R1 + R2) of the plane wave R can be adjusted by this adjustment mechanism 17. In this example, the adjustment mechanism 17 is configured to be able to translate the second mirror 27 in the directions along the X-axis, Y-axis, and Z-axis, and also to be able to rotate around each of the X-axis, Y-axis, and Z-axis. Incidentally, this adjustment mechanism 28 may be provided on the first mirror 15, or may be provided on both the first mirror 15 and the second mirror 16. Further, the adjustment mechanism 17 does not necessarily need to be configured to be able to perform translational movement and rotational movement for all axes, and the axes for translational movement and the rotation axis can be set as needed, and at least one axis is set in the translational movement and rotational movement.

[0025] The plane wave R and the plane wave L are superimposed by the second beam splitter 18, thereby forming interference fringes with a predetermined pitch in the radial direction. FIG. 3 shows the mode of the interference fringes formed by superimposing the plane wave R and the plane wave L. The relationship between the incident angles θ1 and θ2 of the two plane waves R and L and the pitch d of the interference fringes is shown by the following formula. sinθ1 + sinθ2 = λ / d λ is the wavelength of the coherent light. For example, when λ = 655 nm and θ1 = θ2 = 0.4°, the pitch d of the interference fringes becomes 47 μm.

[0026] As can be seen from the explanatory diagram shown in FIG. 3, in order to form interference fringes in a wide range with respect to the distance direction between the grating projection device 10 and the object 100 to be measured, it is preferable that the incident angles θ1 and θ2 are small. On the other hand, when the incident angles θ1 and θ2 are made small, the pitch d of the interference fringes becomes large, resulting in a trade-off with the required resolution.

[0027] Regarding the stability in the atmosphere, by housing the optical path from the first beam splitter 14 to the second beam splitter 18 in the case 11, the influence of air fluctuations can be suppressed. On the other hand, in the optical path from the grating projection device 10 to the object 100 to be measured, since the plane wave R and the plane wave L overlap, the influence of air fluctuations is canceled. However, when the pitch d of the interference fringes is greatly enlarged, the influence of air fluctuations is also enlarged. Therefore, it is preferable to set the optimal pitch d according to the purpose of use. The adjustment of the pitch d of the interference fringes can be executed, for example, by rotating the second mirror 16 around the Y axis by the adjustment mechanism 17.

[0028] The range G in which the interference fringes shown in FIG. 3 are formed is expressed by the following formula. G = (beam radius of plane wave R and plane wave L) / tan(θ1 + θ2) Here, for example, when the beam radii of the plane wave R and the plane wave L are 50 mm and θ1 = θ2 = 0.4°, G becomes 7 m, and interference fringes are formed in a sufficiently wide range. Since the actual effective diameter is about half of the beam diameter, the distance from the grating projection device 10 to the object 100 to be measured is about G / 2.

[0029] The interference fringes formed by the plane wave R and the plane wave L are not necessarily formed perpendicular to the object 100 to be measured. However, at any position within the range G / 2 where the interference fringes are formed, the interference fringes are formed with the same pitch d. Therefore, the distance from the grating projection device 10 to the object 100 to be measured at which the interference fringes can be projected onto the object 100 to be measured is approximately G / 2, which is 7 m / 2 = 3.5 m in the above example.

[0030] The coherence distance required for the coherent light source 12 is 2 × beam radius of the plane wave × tan(θ1 + θ2) or more in the optical path from the first beam splitter 14 to the second beam splitter 18 when the optical path length difference between the plane wave R and the plane wave L is zero. In this case, it holds if it is 0.7 mm or more.

[0031] In this way, the pitch d of the stable interference fringes projected onto the object 100 to be measured can be easily formed in the range from several micrometers to several millimeters.

[0032] On the other hand, the reference interference fringe light is incident on the image sensor 19, and the image thereof is captured by this image sensor 19. Note that various types capable of capturing images, such as a CMOS image sensor and a CCD image sensor, can be applied to the image sensor 19.

[0033] As shown in FIG. 2, the control device 20 is composed of an image input unit 21, an interference fringe pitch measurement unit 22, an interference fringe direction measurement unit 23, a comparison processing unit 24, a target value storage unit 25, and a position / angle control unit 26. Note that the control device 20 is composed of a computer including, for example, a CPU, a RAM, a ROM, etc. The functions of the image input unit 21, the interference fringe pitch measurement unit 22, the interference fringe direction measurement unit 23, the comparison processing unit 24, and the position / angle control unit 26 are realized by a computer program, and execute the processes described later. The target value storage unit 25 is composed of an appropriate storage medium such as a RAM.

[0034] The image input unit 21 is a functional unit that inputs the image data of the reference interference fringe light captured by the image sensor 19. As described above, the reference interference fringe light has the same interference fringes as the irradiation interference fringe light. Therefore, the image acquired by the image input unit 21 is equivalent to the image of the irradiation interference fringe light.

[0035] The interference fringe pitch measurement unit 22 is a functional unit that analyzes the image data of the reference interference fringe light acquired by the image input unit 21 to measure the pitch d of the interference fringes. The interference fringe orientation measurement unit 23 is also a functional unit that analyzes the image data of the reference interference fringe light acquired by the image input unit 21 to measure the orientation of the interference fringes, or in other words, the rotation angle of the interference fringes. This rotation angle is the rotation angle around the normal to the image. Note that the processing of the interference fringe pitch measurement unit 22 and the interference fringe orientation measurement unit 23 does not have to be in this order, and it can be in the reverse order or in a mode where both are processed in parallel.

[0036] The target value storage unit 25 stores data of the target interference fringes, including data regarding the preset pitch d and orientation of the interference fringes.

[0037] Also, the comparison processing unit 24 is a functional unit that compares the data regarding the pitch d and orientation of the target interference fringes stored in the target value storage unit 25 with the pitch d and orientation of the reference interference fringes calculated by the interference fringe pitch measurement unit 22 and the interference fringe orientation measurement unit 23, calculates the difference value, determines that it is acceptable if the difference value is within the allowable range, and gives an instruction to the image input unit 21 to capture an image. On the other hand, if the difference value is outside the allowable range, the comparison processing unit 24 determines it as defective, calculates the correction data, performs the process of transmitting the calculated correction data to the position / angle control unit 26, and then gives an instruction to the image input unit 21 to capture an image.

[0038] The position / angle control unit 26 is a functional unit that controls the operation of the adjustment mechanism 17, and controls the operations related to the translational movements of the second mirror 16 in the X-axis, Y-axis, and Z-axis directions and the rotational movements around each axis by the adjustment mechanism unit 17. In particular, when receiving the correction data from the comparison processing unit 24, it operates the adjustment mechanism 17 according to the correction data to control the posture of the second mirror 16 so that the reference interference fringes acquired by the image sensor 19 become the target interference fringes.

[0039] The series of processes in the image input unit 21, the interference fringe pitch measurement unit 22, the interference fringe orientation measurement unit 23, and the comparison processing unit 24 can be executed at a predetermined time interval (for example, an appropriately set sampling interval), but it is not limited thereto, and it may be executed each time new data related to the target interference fringe is stored in the target value storage unit 25. By this series of processes, the reference interference fringe (equivalent to the measurement (irradiation) interference fringe) is controlled to become the target interference fringe, and after the adjustment is completed, this process can be terminated.

[0040] Also, the operation of matching the reference interference fringe with the target interference fringe is performed by translating the second mirror 16 in a direction selected from the X-axis, Y-axis, and Z-axis, and by rotating the second mirror 16 around the selected axis. The correction data calculated by the comparison processing unit 24 are the movement amount Xd in the X-axis direction, the movement amount Yd in the Y-axis direction, the movement amount Zd in the Z-axis direction, the rotation angle Tx around the X-axis, the rotation angle Ty around the Y-axis, and the rotation angle Tz around the Z-axis. Based on these data, the adjustment mechanism 17 is controlled by the position / angle control unit 26.

[0041] For example, as shown in FIG. 4, by rotating the second mirror 16 around the Y-axis, the pitch (interference fringe pitch) d of the interference fringe can be adjusted. As shown in FIG. 5, by rotating the second mirror 16 around the X-axis, the interference fringe pitch d and the orientation can be adjusted. Also, as shown in FIG. 6, by rotating the second mirror 16 around the X-axis, the orientation and the pitch d of the interference fringe can be changed. As shown in FIG. 7, by translating the second mirror 16 in the X-axis direction and the Y-axis direction, the phase of the interference fringe can be shifted. FIG. 7 shows a state where the phase is shifted from the upper interference fringe to the lower interference fringe. Also, in FIGS. 4 to 7, the mirror 2 corresponds to the second mirror 16.

[0042] In shape measurement by the structured light method, it is necessary to rotate the direction of the interference fringes projected onto the object 100 according to the shape and inclination of the object 100 to be measured. At this time, the control device 20 controls the posture of the second mirror 16 while checking the image captured by the image sensor 19, so that the direction of the interference fringes can be changed to an arbitrary direction.

[0043] Furthermore, according to the size of the step of the object 100 to be measured, the pitch of the interference fringes can be zoomed without interruption, and the processing time for stitching together a plurality of captured images by image processing as in the conventional technique can also be shortened.

[0044] In addition, in the structured light method, a technique of measuring the shape of the object 100 to be measured with higher accuracy by shifting the phase of the projected interference fringes is adopted. Also in this example, under the control of the control device 20, the adjustment mechanism 17 can easily shift the phase of the interference fringes by causing the second mirror 16 to move in a combined translational motion along the X-axis direction and the Z-axis direction.

[0045] Note that the adjustment modes shown in FIGS. 4 to 7 are merely examples and are not limited thereto. By adjusting the position and posture of the second mirror 16 in various modes, the direction and pitch d of the interference fringes can be adjusted. Similarly, by adjusting the position and posture of the first mirror 15, or by adjusting the positions and postures of both the first mirror 15 and the second mirror 16, the direction and pitch d of the interference fringes can be adjusted.

[0046] The shape detection device 30 includes a case 31 arranged in parallel so as to face the case 11 of the grating projection device 10, image sensors 32 and 33 as measurement image imaging units provided in the case 31, a shape calculation unit 35 that analyzes the images captured by the image sensors 32 and 33 and calculates the shape of the measurement object 100, and a moving mechanism 34 that moves the case 31 in the Z-axis direction along the optical axis of the interference fringe light for measurement.

[0047] The case 31 is composed of a housing-shaped member. An opening 31a is formed on the surface facing the case 11 at a position facing the opening 11a of the case 11, and an opening 31b is formed at a position facing the opening 31a on the surface opposite to the case 11. Similar to the opening 11a, the opening 31a has a sufficient size to allow the interference fringe light for irradiation (measurement) to pass through.

[0048] The object to be measured 100 is arranged at a measurement position set outside the opening 31b. The interference fringe light for irradiation irradiated through the opening 11a of the grating projection device 10 is irradiated onto the object to be measured 100 through the openings 31a and 31b of the case 31. Then, the reflected light of the interference fringe light for irradiation reflected by the object to be measured 100 is received by the image sensors 32 and 33, respectively. Note that the angles θa and θb of the respective imaging optical axes of the image sensors 32 and 33 with respect to the optical axis of the interference fringe light for irradiation are appropriately set according to the part of the object to be measured 100 whose shape is to be detected. Also, the opening 31b is set to have a sufficient size for the image sensors 32 and 33 to receive the reflected light from the object to be measured 100, respectively.

[0049] Also, for the image sensors 32 and 33, similar to the image sensor 19, various image sensors capable of imaging an image, such as a CMOS image sensor or a CCD image sensor, can be applied. Note that in recent years, the pixels of image sensors have become very dense, and depending on the magnification of the objective lens attached to the image sensors 32 and 33, the pitch of the interference fringes projected onto the object to be measured 100 can be imaged with a fineness of several micrometers.

[0050] The shape calculation unit 35 analyzes the images captured by the image sensors 32 and 33, and performs a process of calculating the shape of the object to be measured 100. There are various methods for detecting the shape of the object to be measured 100, such as those using the principle of triangulation or the principle of the light section method. In this example, the shape calculation unit 35 calculates depth information (three-dimensional information) by analyzing, for example, the distortion of the interference fringes projected onto the object to be measured 100. Note that the number and arrangement of the image sensors 32 and 33 are determined according to the method of shape detection and the part of the object to be measured 100 for which the shape is detected. Therefore, one or more image sensors are arranged.

[0051] The movement mechanism 34 includes a position detection sensor or a displacement sensor, and moves the case 31 and the image sensors 32 and 32 provided in the case 31 in the Z-axis direction along the optical axis of the interference fringe light for irradiation under the control of the control device 20 based on the position information detected by this position detection sensor or displacement sensor. In other words, the movement mechanism 34 moves the case 31 and the image sensors 32 and 32 provided in the case 31 forward and backward in the Z-axis direction with respect to the object to be measured 100 arranged at the measurement position.

[0052] In the conventional structured light method, since it is configured to measure the shape of the object to be measured 100 that is relatively far away, the depth of focus of the objective lens attached to the image sensors 32 and 33 is deep. In contrast, in this example, since the purpose is to measure the shape of the object to be measured 100 from several millimeters to several hundred millimeters with high accuracy of ten micrometers or less, the magnification of the objective lens attached to the image sensors 32 and 33 is high and the depth of focus is shallow.

[0053] For this reason, even if interference fringes are projected onto the entire object to be measured 100, depending on the depth of focus of the image sensors 32 and 33, it is expected that only partial interference fringes can be photographed. Therefore, in order to eliminate such inconveniences, under the control of the control device 20, while moving the image sensors 32 and 33 in the Z-axis direction along the optical axis of the interference fringe light by the movement mechanism 34, the image sensors 32 and 33 may continuously capture images and the captured images may be connected.

[0054] For example, when the pitch d of the interference fringes projected onto the object 100 to be measured is about 50 μm, it is easy to capture the projected interference fringes with high precision by the image sensors 32 and 33 in view of the resolution of recent image sensors. Also, although it depends on the angle of the imaging optical axes of the image sensors 32 and 33, generally when measuring the shape of the object 100 with an accuracy corresponding to 1% of 50 μm per cycle in image analysis, sub-micron measurement becomes possible.

[0055] According to the grating projection apparatus 10 of this example having the above configuration, since the irradiation (measurement) interference fringe light is formed by crossing the plane wave R and the plane wave L at a predetermined angle, the range in which interference fringes are generated in the interference fringe light extends over a wide range in the optical axis direction. Also, the interference fringes have a fine pitch and no pitch change in the optical axis direction. Therefore, in the shape measurement using this interference fringe light, the degree of freedom regarding the distance between the three-dimensional shape measurement apparatus 1 and the object 100 to be measured is high, and shape measurement can be performed with high resolution and high precision.

[0056] Also, the reference interference fringe light equivalent to the measurement interference fringe light is observed by the image sensor 19, and under the control of the control device 20, the position and orientation of the second mirror 16 are adjusted by the adjustment mechanism 17 so that the irradiation interference fringe light becomes the target interference fringes. Therefore, the generated irradiation interference fringe light can be accurately matched with the interference fringe light required for shape measurement.

[0057] Also, the three-dimensional shape measurement apparatus 1 of this example can be applied to various fields where shape measurement is performed. For example, when the three-dimensional shape measurement apparatus 1 of this example is mounted on a machine tool, the shape of the workpiece can be instantaneously measured on the machine, and by feeding back the measurement result to the machining, high-precision machining can be realized. Or, it can be used as a measurement apparatus for measuring dimensional changes in the cutting edge shape of a cutting tool used in a machine tool at the sub-micron level. Furthermore, it can also be used for semiconductor defect inspection, measurement of polishing marks and flatness of optical components.

[0058] The specific embodiments of the present invention have been described above. However, the descriptions of the above-described embodiments are illustrative in all respects and not restrictive. Modifications and changes can be appropriately made by those skilled in the art. The scope of the present invention is indicated not by the above-described embodiments but by the scope of the claims. Furthermore, the scope of the present invention includes changes from the embodiments within the scope equivalent to the scope of the claims.

Explanation of Reference Numerals

[0059] 1 Three-dimensional shape measuring device 10 Grid projection device 11 Case 12 Light source 13 Expander 14 First beam splitter 15 First mirror 16 Second mirror 17 Adjustment mechanism 18 Second beam splitter 19 Image sensor (reference light imaging unit) 20 Control device 21 Image input unit 22 Interference fringe pitch measurement unit 23 Interference fringe direction measurement unit 24 Comparison processing unit 25 Target value storage unit 26 Position / angle control unit 30 Shape detection device 31 Case 32 Image sensor (measurement image imaging unit) 33 Image sensor (measurement image imaging unit) 34 Moving mechanism 35 Shape calculation unit

Claims

1. An apparatus for irradiating an object with grid-shaped light, comprising: a light source that emits coherent light; an expander provided on the optical path of the light emitted from the light source, which converts the incident light into a plane wave and transmits it; a first beam splitter provided on the optical path of the light transmitted through the expander, which splits the transmitted light into a first light that is transmitted light and a second light that is reflected light; a first mirror provided on the optical path of the first light transmitted through the first beam splitter, which reflects the first light; a second mirror provided on the optical path of the second light reflected by the first beam splitter, which reflects the second light toward the object and intersects the first light reflected by the first mirror; a second beam splitter provided at a position where the first light reflected by the first mirror and the second light reflected by the second mirror intersect, which reflects the first light toward the object and generates interference fringe light for irradiation by superposing the first light and the second light by transmitting the second light.

2. The grid projection apparatus according to claim 1, wherein a first optical path length from which the first light reaches the second beam splitter from the first beam splitter and a second optical path length from which the second light reaches the second beam splitter from the first beam splitter are set to the same length.

3. The second beam splitter is further configured to generate reference interference fringe light by transmitting the first light and reflecting the second light to superpose the first light and the second light; further, a reference light imaging unit provided on the optical path of the reference interference fringe light generated by the second beam splitter, which receives the reference interference fringe light and images its image; and an adjustment mechanism for adjusting at least one of the position and angle of at least one of the first mirror and the second mirror.

4. The grid projection apparatus according to claim 3, further comprising a control device for controlling the operation of the adjustment mechanism.

5. The grid projection apparatus according to claim 4, wherein the control device compares an imaging image of the reference interference fringe light imaged by the reference light imaging unit with a target image, and controls the adjustment mechanism so that the imaging image matches the target image.

6. The adjustment mechanism according to claim 3 of the grating projection device is configured to adjust the position in the axial direction of any one of at least a first axis along the optical axis of the interference fringe light for irradiation, a second axis orthogonal to the first axis and along the optical axis of the reference interference fringe light, and a third axis orthogonal to the first axis and the second axis, and to adjust at least any one of the rotation angles around the first axis, the rotation angle around the second axis, and the rotation angle around the third axis.

7. The grating projection device according to claim 6, further comprising a control device configured to control the operation of the adjustment mechanism.

8. The control device according to claim 7 of the grating projection device is configured to compare a captured image of the reference interference fringe light captured by the reference light imaging unit with a target image, and to control the adjustment mechanism so that the captured image matches the target image.

9. The grating projection device according to any one of claims 1 to 8, a measurement image imaging unit configured to receive measurement interference fringe light irradiated from the grating projection device and reflected by the object, and to capture an image of the interference fringe light; a shape detection unit configured to detect the shape of the object based on the image captured by the measurement image imaging unit. A shape measurement device comprising:

10. The shape measurement device according to claim 9, further comprising a moving mechanism configured to move the measurement image imaging unit along the optical axis of the measurement interference fringe light.

Images