JP2018197683A - Surface shape distortion measurement device - Google Patents

Abstract

To provide a surface shape distortion measurement device that can measure distortion of a surface shape by fine concavity and convexity, and is less likely to be affected by a change in installation distance of a measured object, too.SOLUTION: A surface shape distortion measurement device comprises: an illumination light source 3 that irradiate slit-like diffusion light; a camera 4 that takes pictures of reflection images upon a measured surface 2 of the diffusion light; image processing means that detects a relative inclination of each reflection point; and a movement mechanism 6 that moves, loading the illumination light source 3 and the camera 4. The image processing means comprises: means that calculates an inclination angle from a reference surface in each point in the reflection image to prepare inclination angle-versus-luminance data associated with luminance of the reflection image of a coordinate determined on the measured surface; move the camera to sequentially take the picture, thereby acquires the inclination angle-versus-luminance data in each coordinate in a measurement area, determines an inclination angle having maximum luminance in each coordinate as a positive reflection inclination angle, and calculates a curvature in each coordinate from a change in the positive reflection inclination angle of each coordinate; and means that displays a distribution of the calculated curvature in the measurement area of the measured surface.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a surface shape distortion measuring apparatus that measures surface shape distortion.

  Conventionally, when measuring distortion of a surface shape of an object in an inspection of an industrial product or the like, for example, the surface shape of the object is measured by a method described in Patent Document 1, and the displacement from the surrounding surface shape is measured as distortion. The method to do is common. However, if the surface has a gradual shape change or inclination, a minute strain is buried in the surrounding shape and cannot be measured accurately. In addition, three-dimensional measurement using the principle of triangulation is known, but since measurement accuracy depends on the pixel resolution and shooting angle of the camera, the measurement range and measurement accuracy are in a trade-off relationship, and within a wide range. It is impossible to measure the distortion of the minute surface shape.

  As a conventional method for measuring distortion of a minute surface shape, a specular reflection image is obtained by irradiating an object to be measured with a lattice pattern in which a plurality of stripes are arranged in parallel in a plane as described in Patent Documents 2 and 3. There is known a method of obtaining a distortion of a surface shape from a change in pitch between lines of the lattice image.

  FIG. 9 is a schematic layout diagram of a measurement system and an example of a lattice pattern in a method for detecting distortion from a regular reflection image of a conventional lattice pattern. An illuminating device 91 irradiates a measurement object 92 with a lattice pattern 90 configured by arranging a plurality of stripes extending in the y direction in parallel in a plane at equal intervals, and the lattice pattern 90 formed by the surface of the measurement object 92 is irradiated. A reflection image 93 obtained by regular reflection is captured by a camera 94 and distortion is measured. When the planar shape is distorted, the lattice pattern of the reflected image 93 is distorted and the line interval d changes, so the change in the interval is read to calculate the distortion of the surface. However, in this conventional measuring apparatus, since the distortion of the lattice pattern displayed on the display is measured, the measurement range of the surface to be measured is limited by the size of the display screen of the display. Further, when the installation position of the object to be measured 92 is shifted in the z direction as shown in the figure, the position of the reflected image 93 changes like the reflected image 95, and when this is photographed with a camera, it becomes a lattice pattern 96. The line interval d changes. For this reason, a large error has occurred in the calculated magnitude of distortion.

  As described above, the conventional method of detecting distortion from a regular reflection image of a lattice pattern requires a large display when measuring a minute distortion over a wide range, and the measurement range is limited due to the limitation of the size. It was. Further, when the installation distance of the object to be measured with respect to the camera fluctuates, the pitch between the lines of the regular reflection image changes and a large error occurs in the calculated inclination.

  Therefore, in order to solve this problem, Patent Document 4 describes a surface shape distortion measuring apparatus that is not easily affected by fluctuations in the installation distance of an object to be measured. In the measuring apparatus, the surface to be measured is irradiated with linear diffused light having a certain length and a certain width, a regular reflection image by the surface to be measured is photographed by a camera, and image processing means is obtained from the photographed image. Thus, the relative inclination of the reflection point on the surface to be measured is detected. By sequentially taking pictures while moving the illumination light source and the camera in the width direction of the diffused light, the inclination of each reflection point in the measurement area of the measurement surface is sequentially detected, and the curvature at each reflection point is determined from the change in the inclination. The curvature is calculated and displayed in the measurement area.

JP 2003-4425 A JP 2011-89981 A JP 2012-215486 A Japanese Unexamined Patent Publication No. 2016-200396

  Conventionally, inspections of unevenness due to minute scratches on various products, point-like protrusions due to adhesion of foreign matters during painting, so-called coating solids, etc. have often been performed visually, and such inspections are efficient. There is a need for a measuring instrument that can be performed.

  In the conventional surface shape distortion measuring apparatus described in Patent Document 4, the specular reflection image of diffused light is divided in the width direction to obtain the luminance of each divided pixel, and the center of gravity in the width direction is obtained from the luminance. The center of gravity was used as the coordinates of the regular reflection image of the measurement surface of the linear diffused light. For this reason, conventionally, it is difficult to make the measurement resolution in the width direction in the inspection of the surface to be measured smaller than the width of the diffused light, and the width of the unevenness of the detectable surface shape depends on the width of the diffused light. It was restricted. Therefore, it was difficult to detect minute irregularities such as coatings.

  The present invention has been made to solve such a problem, and is capable of measuring distortion of a surface shape due to minute unevenness, and is not easily affected by fluctuations in the installation distance of an object to be measured. The purpose is to provide.

  In a first aspect, the surface shape distortion measuring apparatus of the present invention is installed with an illumination light source that irradiates a surface to be measured with slit-shaped diffused light extending in the y-axis direction and a relative position with respect to the illumination light source. A camera that captures a reflected image of the diffused light by the surface to be measured; an image processing means that detects a relative inclination of each reflection point of the surface to be measured that produces the reflected image by the captured reflected image; A moving mechanism that mounts an illumination light source and an object to be measured having the camera or the surface to be measured, and moves in the width direction (x-axis direction) of the slit of the diffused light irradiated on the surface to be measured; An encoder that outputs an electrical signal corresponding to the amount of movement of the moving mechanism, and the image processing means is configured such that the measured surface is inclined with respect to a reference surface that is a reference centered on an axis parallel to the y axis. Of the surface to be measured by the diffused light. Assuming that the specular reflection image of the point has been picked up by shifting in the x-axis direction, an inclination angle, which is an inclination angle from the reference plane, is calculated at each point in the reflection image and determined on the surface to be measured. Inclination angle vs. luminance data is generated by associating the inclination angle with the luminance of the reflected image of the coordinates with respect to the coordinates, and the illumination light source and the camera or the surface to be measured are arranged at predetermined intervals by the moving mechanism. By sequentially performing the imaging while moving in the axial direction, the tilt angle versus luminance data at each coordinate in the measurement area of the surface to be measured is acquired, and based on the tilt angle versus luminance data, the maximum at each coordinate is obtained. Is determined as a specular reflection tilt angle that causes specular reflection at the coordinates, and each coordinate is determined from the change in the specular reflection tilt angle of each coordinate in the measurement area of the measurement target surface. Means for calculating that curvature, characterized in that it comprises means for displaying the distribution of the curvature at the calculated out the measurement surface of the measurement region.

  In the present invention, since the slit-like diffused light is measured by moving the moving mechanism, the moving direction of the moving mechanism can be measured up to its driving range, and a minute surface shape can be measured over a wide range. Certainly, since the slit-shaped diffused light is moved for shooting and measurement, the influence on the calculated curvature value is much greater than that of other types of devices even if the installation distance of the object to be measured varies. It is the same as the conventional measuring apparatus described in Patent Document 4 that it has advantages such as being small.

  However, in the image processing of the present invention, for each pixel in the image of the reflected image of the slit-like diffused light, an inclination angle from the reference plane corresponding to the coordinates is obtained and the inclination angle pair corresponding to the luminance of the pixel is obtained. Brightness data is created, and the above-mentioned tilt angle vs. brightness data is obtained for each coordinate in the measurement area of the measurement surface by sequentially performing imaging while moving the illumination light source and the camera or measurement surface in the x-axis direction by the moving mechanism. Save while adding. At this time, for each coordinate, the inclination angle having the maximum luminance is determined from the stored inclination angle versus luminance data as the specular reflection inclination angle that caused specular reflection at the coordinates, and is determined as that of the measured surface. This is the inclination in coordinates. That is, the resolution of the inclination distribution of the surface to be measured is determined by the resolution of the pixels of the captured image. On the other hand, in the image processing described in Patent Document 4, the coordinate of the slit-like diffused light is represented by one point of the center of gravity in the width direction, that is, the x direction, and the inclination of the reflection point of the measured surface is obtained. That is, the resolution of the inclination distribution of the surface to be measured is the slit width of the diffused light. As a result, in the present invention, it is possible to measure the distortion of the surface shape due to finer unevenness as compared with the method described in Patent Document 4.

  In a second aspect, the present invention relates to the surface shape distortion measuring apparatus according to the first aspect, wherein each point in the measurement area of the surface to be measured is based on the specular reflection inclination angle and luminance data at each coordinate. And a means for displaying a luminance distribution with respect to an arbitrary regular reflection inclination angle. In the invention of this aspect, since the points having the same inclination angle with respect to the reference plane are displayed as the luminance distribution in the measurement area of the surface to be measured, the distribution of the curvature can be obtained by displaying the distribution at various inclination angles. As with the distribution display, it is easy to visually grasp a point having a distortion having a specific slope in the measurement region. It is also easy to grasp when there is a region inclined with respect to the reference plane in the measurement region.

  In a third aspect, the present invention relates to a surface shape distortion measuring apparatus according to the first or second aspect, wherein the surface includes a measurement point perpendicular to the y axis and where the optical axis of the camera and the measurement surface intersect. The angle formed by the straight line connecting the light emitting point of the diffused light and the point to be measured and the optical axis of the camera is within 30 degrees.

In the measuring apparatus of the present invention, the inclination of the measurement surface at the reflection point is calculated based on the deviation of the reflected image of the slit-shaped diffused light. The deviation is the depth direction of the measurement surface in addition to the inclination of the measurement surface. In order to reduce the influence, it is necessary to set the illumination light source and the camera so that they face each other as perpendicular to the surface to be measured as possible. For example, in many conventional measuring devices, the illumination light source and the camera are placed apart from each other, and diffused light from the illumination light source is incident on the surface to be measured at an incident angle of 45 degrees or more, is reflected at the same angle, and is incident on the camera and reflected. Although an image is set to be taken, in such a case, if the position of the surface to be measured is displaced in the depth direction, the influence becomes large, and it is difficult to accurately calculate the inclination of the surface.
On the other hand, in the invention of this aspect, by setting the arrangement of the illumination light source, the camera, and the measured surface as described above, the incident angle and the reflection angle of the diffused light of the illumination light source to the measured surface are within about 15 degrees. Since the reflected image is taken by the camera, the influence of the positional deviation in the depth direction of the surface to be measured can be reduced. In order to further reduce the influence, in the invention of the present aspect, the angle between the straight line connecting the light emitting point of the diffused light and the point to be measured and the optical axis of the camera is within 30 degrees. It is desirable that a reflected image with an incident angle and a reflection angle within about 7 degrees is taken with a camera.

  In a fourth aspect, the present invention relates to the surface shape distortion measuring apparatus according to any one of the first to third aspects, wherein the relative displacement in the x-axis direction of the measured surface is determined from the calculated curvature or inclination of the measured surface. It has a means for calculating and a means for displaying the calculated relative displacement. In the surface shape distortion measuring apparatus of the present invention, the curvature and inclination at each reflection point of the surface to be measured are calculated, and these are integrated by double integration or integration in the moving direction of diffused light, that is, the x-axis direction. A continuous displacement in the direction can be calculated. Further, the surface shape of the object to be measured can be visually observed by displaying the change of the relative displacement on a display or the like.

  As described above, according to the present invention, it is possible to obtain a surface shape distortion measuring apparatus that can measure surface shape distortion due to minute unevenness and is not easily affected by fluctuations in the installation distance of an object to be measured.

1 is a schematic configuration diagram of a surface shape strain measuring apparatus according to Embodiment 1. FIG. FIG. 3 is a perspective view of an illumination light source, a camera, and a movement mechanism in Embodiment 1. The figure explaining the measurement principle of the surface shape distortion measuring apparatus of this invention. 3 is a flowchart showing a measurement procedure of the surface shape distortion measuring apparatus according to the first embodiment. The figure which shows the coordinate of a reflected image when an illumination light source and a camera are moved to a x-axis direction at predetermined intervals, and the reflected image was image | photographed. It is a figure which shows an example of the measurement result by the surface shape distortion measuring apparatus of Example 1, and is a figure which shows the curvature distribution displayed on the display. The figure which shows the curvature distribution displayed by magnifying a part of display screen of FIG. It is a figure which shows an example of the measurement result of Example 2, and is a figure which shows distribution of the regular reflection inclination angle displayed on the display. The figure which shows the example of a typical layout of the measuring system of the method of detecting distortion from the regular reflection image of the conventional lattice pattern, and an example of a lattice pattern.

  Hereinafter, the surface shape distortion measuring apparatus of the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description thereof is omitted.

  FIG. 1 is a schematic configuration diagram of the surface shape distortion measuring apparatus according to the first embodiment. In FIG. 1, in the surface shape distortion measuring device 10 of the present embodiment, the illumination light source 3 irradiates the measurement surface 2 of the object 1 to be measured with slit-like diffused light extending in the y-axis direction, and the relative to the illumination light source 3 A reflected image of the diffused light reflected by the surface to be measured 2 is photographed by a camera 4 installed at a fixed position. Data of the reflected image taken by the camera 4 is input to a personal computer 5 having a built-in image processing means, and the relative inclination of each reflection point on the measured surface 2 is detected. The illumination light source 3 and the camera 4 are mounted and fixed on a moving mechanism 6 that moves on an axis parallel to the x-axis direction. The moving mechanism 6 is driven and controlled by the controller 7. The controller 7 includes an encoder that outputs an electrical signal corresponding to the amount of movement of the moving mechanism 6, and the output of the encoder is input to the camera 4 to apply a shooting trigger. While the illumination light source 3 and the camera 4 are moved by the moving mechanism 6, the reflected images are sequentially taken by the camera 4, whereby the inclination of each reflection point in the measurement area of the measurement surface 2 is sequentially detected by the image processing means. The personal computer 5 includes curvature calculating means for calculating the curvature at each reflection point from the change in the inclination of the reflection point, and the calculated distribution of curvature in the measurement region of the measured surface 2 is on the display screen of the personal computer 5. Is displayed. The illumination light source 3 is controlled by the illumination controller 8.

  FIG. 2 is a perspective view of an illumination light source, a camera, and a moving mechanism in this embodiment, and FIG. 3 is a diagram for explaining the measurement principle of the surface shape distortion measuring apparatus of the present invention. As shown in FIG. 2, in this embodiment, the illumination light source 3 and the camera 4 are arranged in a direction as perpendicular as possible to the measurement surface 2 in order to suppress the influence of the positional deviation in the depth direction of the measurement surface. I am doing so. FIG. 3 schematically shows a positional relationship in a plane that is perpendicular to the y-axis and includes the measurement point 14 where the optical axis 13 of the camera 4 and the measurement surface 2 intersect, and the light emission point of the diffused light of the illumination light source 3 The angle α formed by the straight line 16 connecting 15 and the measured point 14 and the optical axis 13 of the camera 4 is desirably as small as possible in order to suppress the influence of the positional deviation in the depth direction of the measured surface. The value of α is preferably 30 degrees or less, and is set to 14 degrees or less for high-accuracy measurement. In FIG. 3, the optical axis 13 of the camera 4 is in the plane shown in FIG. 3, that is, in the plane perpendicular to the y-axis, but the angle between the optical axis of the camera and the straight line 16 satisfies the condition of α. The optical axis of the camera may not be in this plane as long as it is within the range to be satisfied.

  FIG. 4 is a flowchart showing the measurement procedure of the surface shape distortion measuring apparatus of this embodiment. FIG. 5 is a diagram showing the coordinates of the reflected image when the illumination light source and the camera are moved in the x-axis direction at a predetermined interval to capture the reflected image. Hereinafter, the measurement procedure of this embodiment will be described with reference to FIGS. 3, 4, and 5. Basically, the following steps are performed by commands from the personal computer 5.

First, before moving and imaging, the relationship between the coordinates of each pixel in the reflected image and the inclination angle from the reference plane is calculated to create a coordinate-to-angle correspondence table. At this time, the coordinates of each pixel due to the tilt of the surface to be measured are corrected. Specifically, in FIG. 3, when the measured surface 2 is parallel to the x-axis, the reflected image by the regular reflection of the measured point 14 becomes a reflected image 9, but the measured surface is inclined by an angle θ, and the measured surface In the case of 2a, the reflected image by regular reflection becomes a reflected image 9a. At this time, the position of the measurement point due to the occurrence of the inclination θ of the measurement surface may be corrected. That is, the measurement point at the position of the reflected image 9 a becomes the measurement point 17 because the measurement surface is inclined by θ. In this way, the inclination angle corresponds to the coordinates of the pixel in the reflected image of the captured slit. For example, in FIG. 5, in the reflected image of the slit taken at the i-th time, the width of the pixel in the x direction is Δx, the coordinate corresponding to the reflected image 9 of the measurement point 14 parallel to the reference plane is x _i , and the inclination angle θ Assuming that the coordinate of the reflected image 9a corresponding to the tilted measurement point 17 is x _i −nΔx (where n is an integer equal to or greater than 1), the coordinate x _i has an inclination angle of 0, and the coordinate x _i −nΔx has an inclination angle. θ corresponds. For coordinates corresponding to each ± n value in the slit reflection image, an inclination angle corresponding to the coordinates is calculated, and a coordinate-to-angle correspondence table is created. By repeating the imaging while moving in the x-axis direction at a predetermined interval d, an inclination angle corresponding to the coordinates of the pixel in the captured slit is input to each coordinate in the measured region. Note that the reflected image of the slit actually photographed includes not only regular reflection from the surface to be measured but also a scattered and reflected image.

  In FIG. 4, as the first step S1, the movement of the moving mechanism 6 is started by the controller 7 and set to the first position. In step S2, a shooting trigger is input to the camera 4, and a reflected image of the surface to be measured 2 is shot. In step S3, the lens distortion of the camera 4 is corrected by polynomial approximation, and the position coordinates of the reflected image on the screen are corrected.

  Next, in step S4, the reflected image corrected for lens distortion is converted into a rectangular pixel having a pixel width of the photographed image in the x direction, or a width of the set unit image and a width of the unit image size set in the y direction. Divide and extract the luminance in each pixel. Further, as step S5, tilt angle vs. luminance data for the coordinates of each pixel in the reflected image is created from the extracted luminance and coordinate vs. angle correspondence table, and stored in a two-dimensional array on the memory.

  In step S6, it is determined whether or not the moving distance of the moving mechanism 6 has reached the end of the measurement range. If not, the above steps S1 to S5 are repeated. If it has reached, the movement is ended as step S7.

  Next, as step S8, based on the tilt angle versus brightness data for each coordinate stored on the two-dimensional array in the memory, the tilt angle having the maximum brightness is extracted as the specular reflection tilt angle of that coordinate.

  As step S9, the curvature of each point in the measurement area is calculated using the regular reflection inclination angle of each coordinate in the measurement area.

  Finally, in step S 10, the calculated distribution of curvature of the measured surface is processed so as to be color-coded according to the magnitude of the curvature, and displayed on the display screen of the personal computer 5.

  FIG. 6 is a diagram showing an example of a measurement result obtained by the surface shape distortion measuring apparatus of the present embodiment, and shows a curvature distribution displayed on the display. FIG. 7 shows a curvature distribution displayed by enlarging a part of the display screen of FIG. In this example, the painted surface of the product is measured as the surface to be measured, and the curvature distribution of the surface is measured. In FIG. 6, on an actual screen, colors are shown in order of red (R), yellow (Y), green (G), and blue (B) depending on the magnitude of curvature. Red (R) has a curvature of about 9.0 / m to 10.0 / m, yellow (Y) has a curvature of about 5.0 / m, and the convex portion has a green color (G) has a curvature of about 0 / m. As for the part, blue (B) is a curvature -0.7 / m--0.8 / m vicinity, and shows a recessed part, respectively. By this display, the measurer can clearly recognize the state of distortion of the surface shape of the surface to be measured. This color-coded range can be changed by operating the personal computer 5.

  In the curvature distribution display screen of FIG. 6, the whole is green (G) indicating a plane, but a point-like distortion having a center of red (R) and a periphery of blue (B) is seen in part. This is a small dot-like projection called a coating spot. On the display screen of FIG. 6, the presence of such small paint spots can be clearly grasped visually. In the present embodiment, the polarity is inverted with respect to the calculation result of the curvature so that the protrusion is displayed as a positive curvature.

  FIG. 7 shows the coordinate x in FIG. 6 = 18.5 mm. The periphery of one coating point in the vicinity of y = 100 mm is enlarged and displayed. Thereby, it can be seen that one coating is a distortion having a shape of about 1 to 2 mm formed from a convex center portion and a concave peripheral portion. Furthermore, in this embodiment, the changes in the x-axis direction and the y-axis direction of the calculated curvature at each reflection point are enlarged and displayed on the display screen. The change in curvature in the x-axis direction on the straight line with y = 100 mm is displayed below the x-axis, and the change in curvature in the y-axis direction on the straight line with x = 18.5 mm is displayed on the left side of the y-axis. . As a result, the surface shape of the object to be measured and the shape of the coating can be visually observed. It should be noted that a continuous displacement in the direction may be calculated by double integration of the calculated curvature at each reflection point in the x-axis direction, and a change in the relative displacement may be displayed on the display screen. In this case, the relative displacement may be calculated by integrating the inclination of the surface to be measured.

  In the measurement, a device in which the illumination light source 3, the camera 4, and the moving mechanism 6 shown in FIG. 2 are integrated is mounted on a tripod, a rack, or the like, and is installed at an optimum position with respect to the object to be measured.

  Next, a second embodiment of the surface shape distortion measuring apparatus of the present invention will be described. The basic configuration and function of the surface shape distortion measuring apparatus used in the second embodiment are the same as those in the first embodiment shown in FIG. FIG. 8 is a diagram illustrating an example of the measurement result of the present example, and is a diagram illustrating a distribution of specular reflection inclination angles displayed on the display. In the present embodiment, the result of measuring the surface shape of an object having a slightly curved surface shape is shown. As shown in FIG. 8, the regular reflection inclination angle of each coordinate is processed and displayed as color-coded according to its size. Red (R) has an inclination angle of 1.4 to 1.5 degrees, yellow (Y) has an inclination angle of 1.1 to 1.2 degrees, green (G) has an inclination angle of 0.8 degrees, blue (B ) Indicates the vicinity of an inclination angle of 2.0 to 3.0 degrees. From this, it is possible to visually grasp the inclination of the surface shape.

  As described above, it has been confirmed that the present invention can provide a surface shape distortion measuring apparatus that can measure surface shape distortion due to minute unevenness and is less susceptible to fluctuations in the installation distance of the object to be measured.

  Needless to say, the present invention is not limited to the above-described embodiments, and the design can be changed according to the purpose and application. For example, functions other than those shown in the above embodiments may be added to the personal computer. Alternatively, some or all of the functions shown in the above embodiments may be realized by an electronic device other than a personal computer. The type, shape, and function of the illumination light source and camera can be selected according to the purpose. Further, the moving mechanism may be capable of moving more than two axes.

DESCRIPTION OF SYMBOLS 1,92 Measured object 2, 2a Measured surface 3 Illumination light source 4, 94 Camera 5 Personal computer 6 Moving mechanism 7 Controller 8 Illumination controller
9, 9a, 93, 95 Reflected image 10 Surface shape distortion measuring device 13 Optical axis 14, 17 Measurement point 15 Light emitting point 16 Straight line 90, 96 Lattice pattern 91 Illumination device

Claims (4)

An illumination light source that irradiates a surface to be measured with slit-shaped diffused light extending in the y-axis direction, a camera that is installed with a fixed relative position to the illumination light source and that captures a reflected image of the diffused light by the surface to be measured; An image processing means for detecting a relative inclination of each reflection point of the surface to be measured that generates the reflected image by the photographed reflected image; and an object to be measured having the illumination light source and the camera or the surface to be measured. A moving mechanism that is mounted and moves in the width direction (x-axis direction) of the slit of the diffused light irradiated on the surface to be measured, and an encoder that outputs an electrical signal corresponding to the amount of movement of the moving mechanism Prepared,
The image processing means is configured such that the specular reflection image of each point of the measurement surface by the diffused light is x-axis because the measurement surface is inclined with respect to a reference surface that is a reference around an axis parallel to the y-axis. An inclination angle, which is an angle of inclination from the reference plane, is calculated at each point in the reflected image as having been imaged with a change in direction, and the inclination angle is calculated with respect to coordinates determined on the measurement target surface. Create tilt angle versus brightness data corresponding to the brightness of the reflected image at that coordinate,
By sequentially performing the imaging while moving the illumination light source and the camera or the measured surface in the x-axis direction at a predetermined interval by the moving mechanism, the tilt angle pair at each coordinate in the measurement area of the measured surface. Luminance data is acquired, and based on the tilt angle versus brightness data, the tilt angle having the maximum brightness at each coordinate is determined as the regular reflection tilt angle that caused specular reflection at the coordinates;
Means for calculating a curvature at each coordinate from a change in the regular reflection inclination angle of each coordinate within the measurement area of the surface to be measured; and means for displaying a distribution of the curvature within the measurement area of the surface to be measured. A surface shape distortion measuring apparatus comprising:   The apparatus according to claim 1, further comprising means for displaying a luminance distribution with respect to an arbitrary specular reflection inclination angle at each point in the measurement region of the measurement target surface based on data of the specular reflection inclination angle and the luminance at each coordinate. 2. The surface shape distortion measuring apparatus according to 1.   A straight line connecting the light emission point of the diffused light and the measurement point in a plane including a measurement point perpendicular to the y-axis and where the optical axis of the camera intersects the measurement surface and the optical axis of the camera The surface shape distortion measuring apparatus according to claim 1 or 2, wherein the angle is within 30 degrees.   4. The apparatus according to claim 1, further comprising means for calculating a relative displacement in the x-axis direction of the surface to be measured from the calculated curvature of the surface to be measured, and means for displaying the calculated relative displacement. The surface shape distortion measuring apparatus according to any one of the above.