Displacement and step measurement method for measurement object by deflectometry, and measurement apparatus therefor

Abstract

To provide a displacement and step measurement method for a measurement object by imaging-type deflectometry and a measurement apparatus therefor.SOLUTION: A measurement apparatus includes: first projection means for projecting a pattern of a first grating; a projection optical system equipped with a tilt optical system for projecting the first grating pattern from a direction inclined with respect to the normal direction of a surface of a measurement object and forming an image on or near the surface of the measurement object; imaging means for capturing an image formed on or near the surface of the measurement object from a reflection direction from the surface of the measurement object inclined with respect to the normal direction of the surface of the measurement object; phase analysis means for performing phase analysis on the image formed on the surface imaged by the imaging means; and calculation means for determining displacement, step, rotation angle, tilt, or shape of the surface of the measurement object on the basis of the analysis result of the phase analysis means.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for measuring the displacement, step, rotation angle, inclination, or shape of a measurement object by deflectometry. [Background technology]

[0002] For products with curved surfaces, such as fress processed products, and products manufactured by combining such products, inspections are conducted to check for displacement such as unevenness on the surface of the curved products and for steps when assembled.

[0003] In particular, when the surface of the curved product is a mirror surface, an inspection method called deflectometry is often used. In this inspection method, a grid pattern placed at a distance from the target is projected onto the mirror surface, and the inspector visually checks the reflected image, or takes a photograph with a camera and analyzes the image, to inspect the deformation of the grid pattern and the condition of the sudden changes in the state of the unevenness and other displacements within the mirror surface of the product and the steps when they are combined. As for the image analysis method, a method has been proposed to improve the measurement accuracy by performing phase analysis.

[0004] When the object is small, an optical system has been proposed for photographing the object with a microscope, in which a stripe pattern is first imaged near the object's surface, reflected by the object's surface, and the image of the reflected stripe pattern is photographed by a camera (see Patent Document 1). Also, a system has been proposed in which projection and photography are performed on a coaxial optical system using a microscope. This optical system forms an image of a grating pattern not on the object's surface but at a different position, and the image is then reflected by the object's surface and photographed by a camera placed on a coaxial optical system. This makes it possible to measure minute changes in the angle of the object (see Non-Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-24737 A [Non-patent literature]

[0006] [Non-Patent Document 1] G. Hausler et al., Microdeflectometry-a novel tool to acquire three-dimensional microtopography with nanometer height resolution, Optics letters Vol. 33, Issue 4, pp. 396-398 (2008). Summary of the Invention [Problem to be solved by the invention]

[0007] Conventional inspection devices that use a method called deflectometry to inspect curved products, such as fress processed products, or products manufactured by combining curved products, have a problem in that the measuring device, including the grating pattern that is reflected by the surface of the product, is large in size. In addition, the grid pattern moves significantly on the imaging side due to changes in the angle of the object. Therefore, the measurement of the displacement or step of the object is significantly affected by the change in the angle of the object, resulting in a decrease in the measurement accuracy of the displacement or step. There is also a problem that the measurement accuracy of the displacement or step decreases when the object has a low degree of specularity on the surface. The change in the angle of the object includes a change in the posture of the object and a partial change in angle due to the deformation of the object.

[0008] In addition, since the grating pattern captured by the imaging means is a mirror image of the surface of the object to be measured, it is highly sensitive to changes in the angle of the surface of the object to be measured. Since the phase difference during deformation of the object to be measured is the sum of the angular change component and the out-of-plane displacement component, it is significantly affected by minute angular changes and cannot separate the out-of-plane displacement component. Therefore, there is a problem that conventional deflectometry is not suitable for measuring the out-of-plane displacement of an object to be measured. In addition, because the focal point of this measurement method is not on the surface of the object, it is difficult to use it in conjunction with 3D shape measurement.

[0009] SUMMARY OF THE PRESENT EMBODIMENT In order to solve the above problems, an object of the present invention is to provide a method and an apparatus for measuring the displacement and step of a measurement object by imaging deflectometry. [Means for solving the problem]

[0010] The invention of claim 1 is a measurement method in which a first grating pattern is imaged on or near the surface of the object to be measured using a projection optical system from a direction tilted from the normal direction of the surface of the object to be measured, the image formed on the surface or near the surface is photographed by an imaging means from a reflection direction from the surface of the object to be measured that is tilted from the normal direction of the surface of the object to be measured, and phase analysis is performed on the image formed on the surface or near the surface, thereby measuring the displacement, step, rotation angle, tilt, and shape of the surface of the object to be measured. The invention according to claim 2 provides the above-mentioned measuring method, wherein the image formed on the surface or in the vicinity of the surface is projected via a tilt optical system. The invention according to claim 3 is the above-mentioned measuring method, in which the image formed on the surface or in the vicinity of the surface is captured via a tilt optical system. According to a fourth aspect of the present invention, in the above-mentioned measuring method, the phase of the grating pattern is changed. The invention of claim 5 is the above-mentioned measurement method, in which a second grating pattern is projected onto the surface of the object to be measured from the normal direction of the surface of the object to be measured, and an image diffusely reflected from the surface of the object to be measured is captured by the imaging means. The invention of claim 6 is the above-mentioned measurement apparatus, comprising a first projection means for projecting a first grating pattern, a projection optical system for projecting the first grating pattern from a direction tilted from the normal direction of the surface of the measurement object and forming an image on the surface or near the surface of the measurement object, an imaging means for photographing the image formed on the surface or near the surface of the measurement object from a reflection direction from the surface of the measurement object that is tilted from the normal direction of the surface of the measurement object, a phase analysis means for performing phase analysis on the image of the image formed on the surface or near the surface photographed by the imaging means, and a calculation means for determining the displacement and change in step of the surface of the measurement object based on the analysis result by the phase analysis means. The invention according to claim 7 is the above-mentioned measuring device, wherein the imaging means captures the image formed on the surface via a tilt optical system. The invention according to claim 8 is the above-mentioned measurement device, further comprising a phase changing means for changing a phase of the pattern of the first grating. The invention of claim 9 relates to the above-mentioned measurement device, which includes a second projection means for projecting a second grating pattern, and the second projection means projects the second grating pattern onto the surface of the object to be measured from the normal direction of the surface of the object to be measured, and the imaging means captures an image of the second grating pattern diffusely reflected from the surface of the object to be measured, and the calculation means calculates the shape of the object to be measured based on the image of the second grating pattern captured by the imaging means. Effect of the Invention

[0011] The present invention can provide a method and an apparatus for measuring the displacement and step of a measurement object by imaging deflectometry. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing the basic configuration of deflectometry. [Diagram 2] 11A and 11B are diagrams illustrating captured images during translation in deflectometry. [Diagram 3] 1A and 1B are diagrams illustrating images captured during rotation in deflectometry. [Figure 4] 1A to 1C are diagrams illustrating the principle of imaging deflectometry according to a first embodiment of the present invention. [Diagram 5] 3A to 3C are diagrams illustrating changes in optical paths during rotation in the imaging deflectometry according to the first embodiment of the present invention. [Figure 6] FIG. 2 is a diagram for explaining an example according to the first embodiment of the present invention. [Figure 7] FIG. 13 is a diagram for explaining a change in phase when a rotation angle is applied. [Figure 8] FIG. 13 is a diagram illustrating the relationship between an applied displacement and a measured displacement. [Figure 9] 11A and 11B are diagrams illustrating the relationship between a given rotation angle and a measured rotation angle. [Figure 10] FIG. 11 is a diagram illustrating a second embodiment of the present invention. [Figure 11] FIG. 11 is a diagram illustrating a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. (1) Deflectometry Principle First, the principle of deflectometry will be explained. Figure 1 is a diagram showing the basic configuration of deflectometry. Here, an object with a mirror surface, such as a product with a curved surface like a fress processed product or a product manufactured by combining them, is taken as the measurement target. A lattice pattern is placed on the same side of the surface of the measurement target as the camera, and the camera is installed in a position where it can capture the mirror image of the lattice pattern. The camera captures the lattice pattern (the mirror image of the lattice pattern shown in Figure 1) reflected on the mirror surface of the measurement target. Here, it is well known that a mirror image appears in a symmetrical position with respect to the mirror surface of an object, so it can be considered that the mirror image of the lattice pattern appears in a symmetrical position with respect to the surface of the measurement target, as shown in Figure 1. In addition, the focus of the camera is adjusted so that it can capture the mirror image of the lattice pattern, not the surface of the measurement target. Here, if we focus on point P on the grid pattern in Figure 1, the mirror image of point P is point A in the mirror image of the grid pattern. In an image captured by a camera, point A is captured as shown diagrammatically in Figure 1. In Figure 1, the dashed line connecting the camera and point A indicates the line of sight of one pixel in the captured image. In other words, the image captured by the pixel in the image where point A is captured is an object or mirror image on this dashed line. This line of sight can be considered to be reflected in the direction of point P by the object to be measured, so it can be considered to capture an image on the dashed line drawn in the direction of point P.

[0014] Next, FIG. 2 shows a schematic diagram of the relationship between the amount of displacement and the captured image when the measurement object is translated in the normal direction of the surface. When the measurement object is translated in the normal direction of the surface, the mirror image of the lattice pattern is displaced toward the measurement object by twice the amount of displacement in the normal direction of the measurement object as shown in FIG. 2. When the measurement object is displaced, the line of sight for photographing the above-mentioned point P also moves in parallel, and the image is captured to the right of point P in the figure on the lattice pattern. Considering the mirror image side, the pixel that photographed point A before the displacement photographs point B on the mirror image of the lattice pattern after the displacement. The mirror image of the lattice pattern is displaced in the normal direction, but since the line of sight of the pixel that photographed point A extends obliquely from the camera direction, point B becomes a point to the right of point A in the mirror image. In the captured image after the displacement shown in FIG. 2, the captured lattice pattern is depicted as having moved to the left, but as the measurement object is translated in this way, the captured lattice pattern moves in the captured image.

[0015] Next, FIG. 3 shows a schematic diagram of the relationship between the amount of rotation and the captured image when the measurement object rotates slightly. When the measurement object rotates counterclockwise in FIG. 3, the mirror image of the lattice pattern rotates counterclockwise in FIG. 3 by twice the amount of rotation of the measurement object. When the measurement object rotates, the line of sight for photographing the above-mentioned point P also rotates, and the image is captured to the left of point P in FIG. 3 on the lattice pattern. Considering the mirror image side, the pixel that photographed point A before the rotation photographs point C on the mirror image of the lattice pattern after the displacement. The mirror image of the lattice pattern is displaced in the normal direction, but the line of sight of the pixel that photographed point A extends obliquely from the camera direction, so point C becomes a point to the left of point A in the mirror image. In the photographed image after rotation shown in FIG. 3, the photographed lattice pattern is depicted as having moved to the right, but as the measurement object rotates in this way, the photographed lattice pattern moves in the photographed image.

[0016] This concludes the explanation of the principle of deflectometry. According to this principle, the amount of movement of the grid pattern in the image due to the displacement caused by the translation in the normal direction of the surface of the measurement object is calculated by multiplying the displacement of the measurement object by a constant determined by the arrangement of the camera. Also, the amount of movement of the grid pattern in the image due to the rotation of the measurement object is calculated by multiplying the rotation angle of the measurement object by the distance between the measurement object and the grid pattern. In a typical deflectometry arrangement, the sensitivity to changes in the rotation angle of the measurement object is very high. Therefore, it can be said to be an excellent method for detecting unevenness such as the rotation angle of the measurement object and minute displacements on the surface of the measurement object. However, on the other hand, when it is desired to measure the out-of-plane displacement of the surface of the object to be measured, the angle change component that occurs during the displacement is significantly included, resulting in a movement of the grid pattern in the image, and the rotation component of the object to be measured will appear extremely larger than the displacement component, which poses a problem in that it may not be possible to measure the desired out-of-plane displacement of the object's surface.

[0017] (2) Embodiment 1 FIG. 4 is a schematic diagram showing the principle of imaging deflectometry according to the present invention. In imaging deflectometry, a specular object is used as a measurement object. The camera is composed of an image sensor and an imaging lens, as in conventional deflectometry. The imaging lens is placed between the grating pattern and the measurement object, and its position is determined so that the grating pattern is imaged on or near the measurement object. By applying illumination light from outside to the grating pattern, the scattered light is imaged by the imaging lens. The real image of the grating pattern thus obtained is reflected by the measurement object, and the resulting mirror image is photographed by the camera. This differs from conventional deflectometry in that the grating pattern is first imaged on or near the measurement object.

[0018] More specifically, of the scattered light emitted from point P on the grid pattern, the light that enters the imaging lens is focused by the imaging lens onto point A on the surface of the measurement target. At point A, the light that entered point A is specularly reflected by the mirror surface and travels while spreading out between the two solid lines drawn in Figure 4. Part of this light enters the imaging lens of the camera and is imaged at point A' on the surface of the image sensor. As a result, point P on the surface of the grid pattern is captured as an image.

[0019] Next, consider point Q on the surface of the grating pattern. As in the case of point P, the scattered light emitted from point Q that enters the imaging lens is focused by the imaging lens on point B on the surface of the measurement target. The light that enters point B is specularly reflected by the mirror surface, and a part of it enters the imaging lens of the camera and is imaged at point B' on the image sensor. The dashed line in Fig. 4 indicates the range of the scattered light that leaves point Q and reaches point B' on the image sensor. In this way, scattered light emitted from points other than point P on the surface of the grating pattern is also imaged on the surface of the measurement target or near the surface by the imaging lens on the grating pattern side, and if there is a component that is specularly reflected by the surface of the measurement target and enters the imaging lens of the camera, it is imaged on the image sensor. By setting the positional relationship as described above, an optical system for imaging deflectometry can be constructed.

[0020] One method for creating this optical positional relationship is to arrange the grating pattern, the principal plane of the imaging lens, and the measurement target so that they are all parallel to one another, as shown in Figure 4. Furthermore, the measurement target, the principal plane of the imaging lens of the camera, and the image sensor are also arranged so that they are all parallel to one another. In other words, by using such a tilt optical system, the image of the grating pattern can be captured without distortion.

[0021] (3) Effects of imaging deflectometry Consider the case where the object to be measured rotates slightly. As shown in Figure 5, the direction of reflection changes due to the rotation of the object to be measured. At this time, the light that was reflected in the direction of the solid line in Figure 5 before the rotation changes to the direction shown by the dashed line due to the rotation. At this time, the direction of reflection changes by a rotation angle twice that of the object to be measured. However, since the imaging lens of the camera is between these two dashed lines, the camera will capture point A. Now, since we are considering a case where the rotation angle of the object to be measured is small, the change in the position of point A before and after the rotation of the object to be measured is also small. For this reason, point A' imaged on the camera's image sensor hardly changes at all. Note that the rotation of the object to be measured does not include rotation around the normal direction of the object to be measured's surface.

[0022] This means that even if the reflected light path changes due to the rotation of the measurement object, as long as a part of it reaches the imaging lens of the camera, the rotation angle has almost no effect. On the other hand, the change in the captured image due to the displacement of the measurement object in the out-of-plane direction is equivalent to the captured image during translation in the above-mentioned conventional deflectometry. For the above reasons, imaging deflectometry reduces sensitivity to changes in the rotation angle of the measurement object, which significantly reduces the problem in conventional deflectometry that the rotation component of the measurement object appears to be significantly larger than the displacement component, making it easier to measure the out-of-plane displacement component of the measurement object.

[0023] (4) Method for separating out-of-plane displacement and rotation components By capturing an image of a grid pattern with a camera, phase analysis of the captured image of the grid pattern can be performed to obtain information on the phase distribution. When the measurement object moves in parallel, the phase value changes uniformly in the vicinity of the point of interest. Furthermore, when a rotation angle occurs in the measurement object, the grid moves in the image in the vicinity of the point of interest, and the tilt of the measurement object changes the grid pitch in the captured image. The movement of the grid is obtained as a change in phase, and the change in the grid pitch is obtained as a change in the differential value of the phase with respect to the spatial direction.

[0024] In other words, two values, the phase change and the change in the phase differential value, correspond to the two values ​​of the displacement and rotation angle of the measurement object. If these relationships are linear, the corresponding relationships can be easily found, and the displacement and rotation angle can be found from the phase change and the change in the phase differential value. Even if these relationships are not linear, it is possible to find the displacement and rotation angle from the phase change and the change in the phase differential value by formulating them or creating a correspondence relationship table.

[0025] Up to this point, we have only considered the rotation of the measurement object in the direction shown in Figure 5, but the mirror surface of an actual measurement object is flat, and there are two rotation components around two rotation axes that are perpendicular to the normal direction of the mirror surface and perpendicular to each other. In other words, there are a total of three components: a displacement component in the normal direction and rotation components around the two axes. These three components can be found from the change in phase, the change in the differential value of the phase difference in one axial direction, and the change in the differential value of the phase difference in another axial direction.

[0026] (5) Examples An example will be described below. An imaging-type deflectometry device was constructed and experiments were performed. Figure 6 shows a schematic diagram of the experimental device. The x-axis is defined as the direction in which an image of the object to be measured is captured horizontally on the plane of the mirror, the y-axis is defined as the direction in which the image is captured vertically, and the z-axis is defined as the normal direction to the object to be measured. The directions of rotation around the x-axis and y-axis are α and β, respectively, as indicated by the arrows in the figure.

[0027] Figure 7 shows the change in phase when a rotation angle β is applied. In Figure 7, the graph with black triangles is obtained by imaging deflectometry, and the graph with black circles is obtained by conventional deflectometry. As shown in Figure 7, with imaging deflectometry, almost no phase change occurs in the vicinity of -2 degrees to +2 degrees, but with conventional deflectometry, it can be confirmed that the phase changes significantly with respect to a small change in angle.

[0028] The phase distribution can be obtained by performing phase analysis on the captured lattice image. The distribution of the difference between the phase distribution obtained from the lattice image captured before the deformation of the measurement object and the phase distribution obtained from the lattice image captured after the deformation is called the phase difference distribution. If the phase difference of a point of interest in the phase difference distribution is Δφx, then the differential value of the phase difference in the i-direction ∂Δφx / ∂i and the differential value of the phase difference in the j-direction ∂Δφx / ∂j can be calculated from the phase distribution near that point. Since there is a relationship between these values ​​and the displacement w and angle α, the relationship can be expressed using several coefficients, for example, in the following equation 1.

[0029]

number

[0030] Here, k1, k2, k3, and k4 are coefficients. The relationship between the differential value ∂Δφx / ∂i of the phase difference in the i-direction, the displacement w, and the angle α can be expressed as in Equation 2.

[0031]

number

[0032] Here, l1, l2, l3, and l4 are coefficients.

[0033] In addition, equations 1 and 2 can be obtained not only as equations having physical meaning, but also as equations obtained simply from the aspects of data obtained from experimental results. Since there are four unknown coefficients each in Equation 1 and Equation 2, the unknown coefficients can be found by changing the displacement w and angle α four or more times, calculating the phase difference Δφ and the differential value of the phase difference ∂Δφx / ∂i obtained from the grating image captured in each case, and inserting these values ​​into Equation 1 and Equation 2. After the coefficients are obtained, Equation 1 and Equation 2 can be used as simultaneous equations to find the displacement w and angle α from the phase difference Δφ and the differential value of the phase difference Δφ, ∂Δφx / ∂i, obtained from the captured grating image.

[0034] In an actual experiment, the coefficients k1, k2, k3, and k4 calculated in this manner were 0.535, -0.112, -0.0145, and -0.233, respectively, and the coefficients l1, l2, l3, and l4 were -0.0003, -0.0056, 0.0001, and -0.0072, respectively. The displacement w and angle α calculated from the experimental data are shown in Figures 8 and 9. Figure 8 shows the relationship between the applied displacement and the displacement measured by this method. Experiments were carried out with the angle α changed in several ways, and it can be seen that it is possible to separate the angle α and the displacement w. In this case, the error in the displacement w was within 0.16 mm.

[0035] Figure 9 shows the relationship between the applied rotation angle α and the measured rotation angle. When α is in the range of -3.5° to -2.5°, almost no difference due to the applied displacement w is observed, and it can be seen that the displacement w and angle α can be separated. The error in angle α is within 0.12° when α is in the range of -3.5° to -2.5°. As shown by the above experiments, the imaging-type deflectometry of the present invention can simultaneously calculate the rotation angle and displacement of the mirror, which is the measurement target, separately by using the phase difference and the differential value of the phase difference.

[0036] (6) Embodiment 2 FIG. 10 is a diagram for explaining the second embodiment of the present invention. (6-1) Measuring equipment The measuring device 100 comprises a first projection means 2 which projects a first grating pattern onto the surface of a measurement object 1, which is a product having a curved surface such as a fress processed product having a mirror-like surface, or a product manufactured by combining these products; a projection optical system with a tilting optical system which projects the first grating pattern from a direction tilted from the normal direction of the surface of the measurement object 1 and forms an image on the surface of the measurement object 1; and an imaging means which photographs the image formed on the surface of the measurement object from a reflection direction from the surface of the measurement object which is tilted from the normal direction of the measurement object.

[0037] The first projection means 2 may be, for example, a plate with a grid pattern drawn on one side, or a liquid crystal plate capable of displaying a grid pattern. The projection optical system is formed by a lens 3, a mirror 4, and a lens 5. The projection optical system includes a tilt optical system. The tilt optical system is formed by the positional relationship between the first projection means 2 and the lens 3. The first projection means 2 is disposed parallel to the lens 3 and offset from the optical axis of the lens 3. A grating pattern by the first projection means 2 is imaged on the surface of the measurement object 1 via a projection optical system having a tilt optical system. Because the projection optical system has a tilt optical system, the grating pattern from the first projection means 2 is imaged without being out of focus at the far point and near point on the surface of the measurement object 1.

[0038] The grid pattern of the first projection means 2 formed on the surface of the measurement object 1 is imaged by a camera 7, which is an imaging means, via a mirror 6. Note that the camera 7 may image the grid pattern of the first light projecting means formed on the surface of the measurement object 1 without using the mirror 6. The measuring device 100 is equipped with a phase analysis means (not shown) that performs phase analysis on the image of the image formed on the surface captured by the camera 7, and a calculation means (not shown) that calculates at least one of the displacement and step on the surface of the object to be measured 1, the rotation angle or inclination of the object to be measured 1, or the shape of the surface of the object to be measured 1 based on the analysis results by the phase analysis means.

[0039] The first projection means 2 is equipped with a phase changing means (not shown) that changes the phase of the grating pattern 2 projected from the first projection means 2. The phase analysis means performs measurements by changing the phase of the sinusoidal intensity distribution of the grating pattern of the first projection means 2 to, for example, 0, π / 2, π, and 3π / 2, and can analyze the image data of the surface light source image captured for each measurement using a phase shift method.

[0040] (6-2) Imaging of a grating pattern on a specular object surface A tilted optical system forms an image of a grid pattern on the surface of the object to be measured, and then captures the reflected image. This means that even if there is a slight change in the angle of the object to be measured, there is almost no change in the image captured by the camera, and the system has low sensitivity to changes in angle. This makes it possible to measure only the components of displacement and steps with high accuracy.

[0041] (6-3) Camera side tilt In the optical system of (6-2), by further providing a tilt on the photographing side, the following advantages are obtained. The range in which phase analysis can be performed in focus can be expanded. The same optical system can be used for capturing images for 3D measurements using grid projection.

[0042] (6-4) A device for projecting grid patterns for 3D measurement In addition to projecting the grating pattern for deflectometry, a device is installed that projects a grating pattern for 3D measurement from a different angle. This makes it possible to capture the scattered reflected light components of the rough surface of the measurement object, and perform 3D measurement of the measurement object from that. This makes it possible to measure displacement and steps even when the specular reflection component is strong or when the scattered reflected light is strong.

[0043] FIG. 11 is a diagram for explaining an embodiment equipped with a three-dimensional measurement projection means for projecting a grid pattern for three-dimensional measurement. By further providing a three-dimensional measurement grid projection means 8 in the measurement device 100 shown in FIG. 10, it is possible to perform a measurement by deflectometry when the surface of the measurement object 1 has a large specular component, and to perform three-dimensional measurement when the surface of the measurement object 1 has a large rough surface component. When measuring the shape of the measurement object using the three-dimensional measurement grid projection means 8, the shape of the measurement object can be obtained using a conventionally known calculation method (for example, JP 2016-170113 A or a light cutting method) based on an image of the grid pattern captured by a camera, which is an imaging means. Both measurement methods can be performed by one measurement device. As described above, the embodiments of the present invention make it possible to miniaturize the measurement device, to reduce the effects of changes in the angle of the object to be measured and the curvature of the object to be measured, thereby improving the measurement accuracy of displacement and step differences, and to measure displacement and step differences even when the specular reflection component of the object to be measured is strong and the scattered reflection component is also strong. [Explanation of symbols]

[0044] 1. Measurement target 2. First Projection Means 3 Lenses 4. Mirror 5 Lenses 6. Mirror 7. Camera 8. 3D measurement grid projection means 100 Measuring Equipment

Claims

1. forming an image of the first grating pattern on or near the surface of the measurement object; The image formed on or near the surface is captured by an imaging means in a reflection direction from the surface of the measurement object that is inclined from a normal direction of the surface of the measurement object; A phase analysis is performed on an image obtained by capturing an image formed on the surface or near the surface, A measurement method for measuring a displacement or step, a rotation angle, a tilt, or a shape of a surface of the measurement object.

2. The grating pattern is imaged on the surface or near the surface of the measurement object via a tilt optical system. The measurement method according to claim 1 .

3. The image formed on the surface or near the surface is photographed via a tilt optical system. The measurement method according to claim 1 .

4. The measurement method according to claim 1 , further comprising changing a phase of the grating pattern.

5. a second grating pattern is projected onto the surface of the measurement object from a normal direction of the surface of the measurement object, and an image diffusely reflected by the surface of the measurement object is captured by the imaging means; The measurement method according to claim 1 .

6. a first projection means for projecting a first grating pattern; a projection optical system that forms an image of the first grating pattern on a surface or near the surface of a measurement object; an imaging means for capturing an image formed on the surface of the object to be measured or an image formed near the surface; a phase analysis means for performing a phase analysis on an image formed on the surface or in the vicinity of the surface, the image being photographed by the imaging means; a calculation means for calculating a displacement or step, a rotation angle, a tilt, and a shape of the surface of the measurement object based on the analysis result by the phase analysis means; A measuring device equipped with

7. The imaging means captures an image formed on the surface via a tilt optical system. The measurement device according to claim 6.

8. 7. The measurement apparatus according to claim 6, further comprising a phase changing means for changing a phase of the pattern of the first grating.

9. a second projection means for projecting a second grating pattern; projecting a second grating pattern onto the surface of the measurement object in a normal direction of the surface by the second projection means; An image of the object to be measured diffusely reflected from the surface of the object is captured by the imaging means; The calculation means calculates a shape of the measurement object based on the image of the second grating pattern captured by the imaging means. The measurement device according to claim 6.

Images