JP6362058B2 - Test object measuring apparatus and article manufacturing method - Google Patents

Description

The present invention measures the test object, the dimensions of the object, a method of manufacturing a measuring device Contact and articles to calculate the shape information such as tolerance and angle.

  An image measuring device is one of devices for measuring the dimensions of a test object. The image measuring device captures the test object, acquires an image of the test object, detects the edge (edge) of the test object from the intensity change data of the image, and determines the distance between the detected multiple edges. By calculating, the size of the test object is measured. In the method of detecting the edge from the intensity change data of the image of the entire test object, there is a possibility that the inside of the chamfered portion of the test object or the surface texture (surface unevenness) is erroneously detected as an edge. For this reason, the possibility of erroneous detection can be reduced by setting the range (edge detection range) for edge detection from the intensity change data of the image to a narrow range around the true edge. In the conventional measuring apparatus, in order to accurately detect the edge of the object to be detected, it is necessary for the operator to determine from the image a portion that is supposed to be an edge and manually set the edge detection range.

  Therefore, in order to reduce the labor of such workers, methods of Patent Documents 1 and 2 have been proposed. In Patent Document 1, a two-dimensional image of the entire test object is binarized to extract a contour line (provisional edge), and an edge detection range is automatically set around the contour line, and more accurately within that range. A measuring device that detects the position of an edge has been proposed. Patent Document 2 proposes a measuring device that performs three-dimensional measurement of a test object and extracts an edge of the test object from three-dimensional point cloud data of the test object.

JP 2012-42324 A Japanese Patent No. 4400594

  As described above, in the method of detecting an edge from the intensity change data of the entire image, there is a possibility that a part other than the edge is erroneously detected as an edge. For this reason, in the method described in Patent Document 1, even if a two-dimensional image of the entire test object is binarized when the test object has a surface texture, a contour line (provisional edge) is erroneously detected in the surface texture portion. The subsequent edge detection range cannot be set correctly.

  Further, since the method described in Patent Document 2 uses three-dimensional data, the influence of the surface texture on edge detection is small. However, since there is a trade-off relationship between the data amount of 3D point cloud data and measurement time, it is difficult to obtain high resolution (high density) 3D point cloud data in practice. This is because even if high-resolution 3D point cloud data is obtained, it takes a long time to perform image processing on a large amount of 3D point cloud data. On the other hand, when low-resolution three-dimensional point cloud data is acquired, the accuracy is low, and the position of the edge cannot be detected with high accuracy.

  Therefore, an object of the present invention is to detect the edge of a test object with high accuracy.

A measuring apparatus according to one aspect of the present invention for solving the above-described problems is a measuring apparatus for measuring a test object, the image sensor for imaging the test object, and light from the test object for the image sensor. A two-dimensional measurement unit that acquires a first image of the test object using an optical system that guides to the test object, and projects light onto the test object, and reflects the light reflected by the test object through the optical system A three-dimensional measuring unit that acquires three-dimensional data of the test object from a second image that is detected by being guided to an image sensor, and a temporary edge of the test object is detected using the three-dimensional data, and is detected An edge detection range in the first image is set by superimposing a temporary edge on the first image, and the test object is detected by detecting an edge of the test object in the edge detection range using the first image. and possess a calculation unit that calculates shape information of the object, Serial first image is characterized by a higher resolution than the 3-dimensional data.

  According to the present invention, the edge of the test object can be detected with high accuracy.

It is the schematic of the measuring device in 1st Embodiment. 5 is a flowchart showing a calculation process by a calculation unit 140. FIG. It is a figure which shows measurement data, calculation data, and an edge detection range. It is the schematic of the measuring device in 2nd Embodiment. It is the schematic of the measuring device in 3rd Embodiment. It is the schematic of the measuring device in 4th Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a schematic diagram of a measuring apparatus 10 that measures a test object 170 in the first embodiment. The measurement apparatus 10 includes a three-dimensional measurement unit 120 that performs three-dimensional measurement of the test object 170 and outputs three-dimensional data including height (z) data and vertical and horizontal (x, y) two-dimensional data. The three-dimensional measurement unit 120 of the measurement apparatus 10 is a measurement unit that uses the principle of the light cutting method. The three-dimensional measurement unit 120 includes a line illumination unit 101 that illuminates the test object 170 in a line shape, an imaging unit (light detection unit) 102, and a calculation unit 108. The line illumination unit 101 illuminates the test object 170 in a line shape, the distortion of the illumination line caused by the shape of the test object 170 is measured by the imaging unit 102, and the calculation unit 108 calculates the test object 170 from the measurement data. The three-dimensional shape is calculated.

  The line illumination unit 101 can scan a line-shaped illumination position with a galvanometer mirror (not shown), and thereby it is possible to sequentially illuminate the entire test object 170 and its periphery. Further, the mounting table 106 that supports the object 170 can be rotated by a rotary stage (not shown). The object 170 is rotated relative to the line illumination unit 101 and the imaging unit 102 by the rotation stage, and images are sequentially acquired by the imaging unit 102. Thereby, the test object 170 can be measured from all directions. Data of the image captured by the imaging unit 102 is transmitted to the calculation unit 108. The calculation unit 108 includes a calculation unit that performs calculation processing using the transmitted image. The calculation unit calculates a distortion amount of the line from the acquired image, and calculates three-dimensional point cloud data of the test object 170 using known information regarding the arrangement of the line illumination unit 101 and the imaging unit 102. The three-dimensional point cloud data includes data on the height (z direction in FIG. 1) of the test object 170 and two-dimensional data in the vertical and horizontal directions (x and y directions).

  The measuring apparatus 10 includes a two-dimensional measurement unit 130 that performs two-dimensional measurement of the test object 170 in the x and y directions and outputs two-dimensional image data in the x and y directions. The two-dimensional measuring unit 130 includes an incoherent light source 103, an optical system 104, and an imaging unit 110.

  The incoherent light source 103 is composed of a plurality of light source elements, and the plurality of light source elements are arranged in a ring shape so as to surround a place where the test object 170 is arranged. Each light source element can control lighting individually, and can thereby illuminate the test object 170 from a desired direction.

  The light illuminated on the test object 170 from the incoherent light source 103 is reflected or scattered by the test object 170 and collected by the optical system 104. The optical system 104 connects the test object 170 and the light receiving surface of the imaging unit 110 in a conjugate relationship, and the imaging unit 110 captures the test object 170 and outputs two-dimensional image data of the test object 170. The two-dimensional image data is data representing numerically the light intensity distribution on the imaging surface of the imaging unit 110 onto which light from the test object 170 and its periphery is projected. The two-dimensional image data may be monochrome data or color data. The optical system 104 includes a lens 104a and a lens 104b, and an iris diaphragm 105 disposed between the lens 104a and the lens 104b. Therefore, the resolving power of the optical system 104 can be adjusted by changing the aperture diameter of the iris diaphragm 105. Since the dimension measurement accuracy in the horizontal direction (x, y direction) depends on the resolution of the imaging unit 110, it is desirable that the number of pixels of the imaging unit 110 is large. The data of the two-dimensional image output by the imaging unit 110 is transmitted to the calculation unit 140.

  There is no restriction on the difference in resolution between the 3D point cloud data and the 2D image data. However, if the resolution of the 3D point cloud data is high, the processing time becomes long, so the resolution of the 3D point cloud data is as low as possible. Thus, it is desirable to use a two-dimensional image for edge detection with higher accuracy. Further, in the three-dimensional measurement, measurement may be performed with a relatively high resolution in a region around the edge assumed in advance, and with a relatively low resolution in a region far from the edge. Here, the resolution (density) is expressed by how many pixels and pixel data are arranged in a unit length (for example, 1 inch), and is expressed by a unit of ppi (pixels per inch), for example.

  The measuring apparatus 10 automatically measures the edge position of the test object 170 with high accuracy using the three-dimensional point cloud data and the two-dimensional image data, and the dimension, tolerance, angle, etc. of the test object 170 from the measured edge position. A calculation unit (calculation device) 140 for calculating the shape information. This calculation process will be described with reference to FIGS. FIG. 2 is a flowchart showing a calculation process by the calculation unit 140. The calculation process includes steps S101 to S109. FIG. 3 is a diagram showing measurement data, calculation data obtained by applying this calculation process, and an edge detection range.

  The acquisition unit of the calculation unit 140 first acquires the three-dimensional point cloud data of the test object 170 output from the three-dimensional measurement unit 120 (S101). FIG. 3A shows three-dimensional point group data 181 obtained by measuring a specimen having a rectangular parallelepiped shape. The three-dimensional measurement data at each point of the test object is shown in black or gray. The dotted line is the edge of the test object that is supplementarily shown from the viewpoint of visibility. This dotted line data is not included in the three-dimensional point cloud data. In the measurement apparatus 10 of the present embodiment, the three-dimensional point cloud data can be obtained for the four side surfaces of the test object 170 by rotating the test object 170 relative to the imaging unit 102. ing. Note that if there is 3D point cloud data on the side surface of the test object, the edge can be accurately detected as the data amount increases. However, three-dimensional point cloud data on the side surface of the test object is not necessarily required, and the measuring apparatus to which the present invention can be applied is not limited to such conditions.

  The calculation unit 140 detects the temporary edge of the test object 170 using the three-dimensional point cloud data (S102). FIG. 3B shows temporary edges 182 (solid line and dotted line) detected from the three-dimensional point group data 181 shown in FIG. An arbitrary algorithm can be used as a method for detecting the temporary edge 182 from the three-dimensional point cloud data 181. For example, a method for detecting an edge based on a change in depth (height) and normal of 3D point cloud data, or a method for generating a triangular polygon from 3D point cloud data, and a method for determining the continuity and method of adjacent polygons A method for detecting an edge based on the direction and distance of a line is known. Since these methods use information on the depth (height) of the test object, it is possible to identify the surface texture, not to be affected by the surface texture, and to detect the true edge with high accuracy. is there. However, since the density of the data in the horizontal direction (x, y direction) orthogonal to the optical axis of the optical system 104 in the three-dimensional point group data 181 is lower than that in the two-dimensional image data, the edge position detection accuracy is high. There is no. Therefore, as described later, the edge position is obtained with higher accuracy using the two-dimensional image data.

  Next, the calculation unit 140 calculates an optimum focus position in the measurement by the two-dimensional measurement unit from the three-dimensional point cloud data 181 (S103). Then, the control unit (not shown) adjusts the focus position by moving the Z-axis stage 150 that moves while holding the mounting table 106 in the Z direction. The focus position is determined by the imaging unit 110 so that the edge of the test object 170 is imaged most clearly. The calculation unit 140 calculates height information for each temporary edge from the three-dimensional point cloud data 181. Then, a focus position that is in focus is calculated for each temporary edge from the information on the height of each temporary edge. By moving the test object 170 to the optimum focus position by the Z-axis stage 150 and sequentially imaging the test object 170 by the imaging unit 110, it is possible to acquire a clear image for each temporary edge. . Although the Z-axis stage 150 is used as the focus adjustment unit, the focus position may be adjusted by changing the focal position of the optical system 104. This step can be omitted if the optical system 104 is telecentric and the depth of focus is wide. On the other hand, when the aperture diameter of the iris diaphragm 105 is increased in order to increase the resolving power of the optical system 104, it is desirable to adjust the focus because the depth of focus becomes shallow.

  Next, the acquisition unit of the calculation unit 140 acquires two-dimensional image data of the test object 170 imaged by the imaging unit 110 (S104). FIG. 3C is a two-dimensional image 183 of the above-described rectangular parallelepiped test object. The intensity of light in the two-dimensional image 183 is represented by color shading. Since this test object has a striped texture on the surface, a simple method such as binarization may erroneously detect the stripe as an edge.

  Next, the calculation unit 140 performs alignment between the two-dimensional image data and the three-dimensional point cloud data (S105). The correspondence relationship between the orientations and magnifications of the two images is grasped by, for example, capturing a known reference object with both imaging units in advance, and alignment is executed based on the correspondence relationship. This step can be omitted if the positions of the three-dimensional point cloud data and the two-dimensional image data are associated with each other by hardware, such as accurately aligning the imaging unit and the optical system.

  Next, in a state where the two-dimensional image data and the three-dimensional point cloud data are aligned, the temporary edge detected in S102 is superimposed on the two-dimensional image (S106). As described above, it is necessary to set an edge detection range (window region) in a two-dimensional image in order to reduce the possibility of erroneous edge detection and detect a true edge from two-dimensional image data with high accuracy. is there. Therefore, next, an edge detection range in the two-dimensional image is set.

  The calculation unit 140 automatically sets the edge detection range so that the edge detection range is set around the temporary edge projected in the two-dimensional image data (S107). In this way, by setting the edge detection range to a limited narrow range around the temporary edge, the possibility of erroneous detection of the edge is reduced, and the edge position is detected with high accuracy. FIG. 3D is a diagram showing a temporary edge 184 (black solid line) superimposed on a two-dimensional image 183 of a rectangular parallelepiped test object, and an edge detection range 185 (black dotted line) set in the vicinity thereof. is there.

  Next, the calculation unit 140 detects an edge from the two-dimensional image inside the set edge detection range 185 (S108). FIG. 3E is a diagram showing a detected edge 186 (black solid line) in the two-dimensional image 183 of the rectangular parallelepiped test object. Since the edge detection range is limited, the possibility of erroneously detecting an edge due to the texture of the test object is smaller than detecting an edge in the entire two-dimensional image. Therefore, the measuring device 10 can measure the true position of the edge of the test object to be measured with higher accuracy. Further, since the edge detection range is limited, the calculation time for edge detection is shortened.

  In addition, when the test object has a chamfered part, the edge detection range is set only to the chamfered part, so that the chamfered part can be detected at a more detailed position and the chamfered object to be measured. The true position of the edge in the part can be specified with high accuracy.

  Next, the calculation unit 140 uses the two-dimensional image data to calculate the shape, geometric tolerance, angle, orthogonality, roundness, and the like of the test object 170 from the positions of a plurality of edges measured with high accuracy. Information is calculated (S109). Since shape information is obtained from two-dimensional image data, it relates to two-dimensional information. Since the edge position is measured with high accuracy in the measuring apparatus 10, values such as dimensions and geometrical tolerances of the test object 170 can be obtained more accurately.

  As described above, according to the measurement apparatus 10 of the present embodiment, since the information on the depth (height) of the test object included in the three-dimensional data obtained by the three-dimensional measurement unit is used, the influence of the surface texture is reduced. The true edge can be detected without receiving it, and the erroneous detection of the edge can be prevented. Furthermore, by setting the edge detection range within a limited range including the true edge position, the edge position of the test object can be specified with high accuracy.

  In the present embodiment, the test object 170 is irradiated by the incoherent light source 103, and the reflected light or scattered light is measured by the imaging unit 110. However, the present invention is limited to such a configuration. Not. For example, the mounting base 106 is made of a transparent material such as a glass plate, and the test object 170 is illuminated from the back (lower side), and a shadow formed by the test object 170 being dimmed or shielded is imaged by the imaging unit 110. Any configuration may be used.

  In addition, an imaging element such as a CCD can be used for the imaging unit, and a line sensor or a photosensor can also be used. In the case of a line sensor or a photo sensor, an image is acquired by scanning them.

(Second Embodiment)
FIG. 4 is a schematic diagram of the measuring apparatus 20 according to the second embodiment. The description of the same members as those in the first embodiment is omitted.

  The three-dimensional measuring unit 220 of the measuring device 20 includes a TOF (Time-OF-FLIGHT: Time of Flight) camera 210 as an imaging unit. The TOF camera measures the flight time (Time-OF-FLIGHT) until light reaches the object after the light emitted from the light source reaches the object and is reflected by the object. Is a camera using the time-of-flight method calculated by

  There are several types of TOF cameras. The light pulse method is to illuminate a test object with a pulsed light source such as an LED, measure the time until the light pulse reaches the camera, and calculate the distance from the time. In the phase difference method, the light intensity is modulated in a sine wave shape, the phase change of the light reaching the camera is measured by the camera, and the distance is calculated from the phase change. Although the three-dimensional measurement unit 220 of this embodiment uses the optical pulse method, the method of the TOF camera is not limited.

  The three-dimensional measuring unit 220 includes a pulse light source 203 and a driver 204 that synchronizes the pulse light source 203 and the TOF camera 210. A light pulse is applied to the test object 170 by the pulse light source 203, and the light pulse reflected and scattered by the test object 170 is collected by the optical system 104. Since the pulse light source 203 emits a light pulse having a wavelength in the near-infrared region, only the near-infrared light is guided to the TOF camera 210 by providing a wavelength filter 211 that transmits near-infrared light and reflects visible light. be able to.

  The test object 170 and the TOF camera 210 are in a conjugate relationship by the optical system 104. The TOF camera 210 images a light pulse reflected or scattered by the test object 170 and calculates a distance from the time difference between pulses (time from emission to arrival). The TOF camera 210 outputs distance data calculated for each position of the test object to the calculation unit 140 as 3D point cloud data of the test object 170.

  Since the TOF camera is composed of complex sensors, there is currently a limit to increasing the number of pixels. For this reason, since the density of the three-dimensional point cloud data acquired by the TOF camera is lower than the two-dimensional image data obtained by the two-dimensional measuring unit, the edge position detection accuracy is not high. Therefore, as described later, the edge position is obtained with higher accuracy using a two-dimensional image.

  In addition to the incoherent light source 103, the two-dimensional measuring unit 230 of the measuring device 20 includes an illuminating unit 200 that transmits and illuminates the object 170 from the back (lower side). The illumination unit 200 includes a light source 201 for illumination and a beam expander 202 including lenses 202a and 202b. The light source 201 is, for example, a green or red LED. The light emitted from the light source 201 is enlarged in beam diameter by the beam expander 202, passes through the mounting table 205, and illuminates the test object 170. Since the mounting table 205 is made of a transparent material such as glass or sapphire, it transmits light. When the test object 170 is a light-shielding material, a shadow formed by the test object 170 blocking light is imaged on the imaging unit 110 by the optical system 104. Transmitted illumination is particularly suitable for measuring the contour of a test object because an image with higher contrast than reflected illumination is obtained.

  The two-dimensional measuring unit 230 also has an incoherent light source 103 as in the first embodiment in order to realize reflected illumination. The two-dimensional measuring unit 230 can select and use either reflected illumination or transmitted illumination.

  The data of the two-dimensional image captured by the imaging unit 110 of the two-dimensional measurement unit 230 is output to the calculation unit 140. Similar to the first embodiment, the calculation unit 140 detects the edge of the test object using the 3D point cloud data and the 2D image data according to the calculation flow of FIG. Is calculated.

  According to the measurement apparatus of the present embodiment, the edge of the test object can be detected with high accuracy.

  Note that in the case of the measuring apparatus 20 of the second embodiment, the TOF camera 210 and the imaging unit 110 share a straight line passing through the optical axis of the optical system 104 indicated by a one-dot chain line in FIG. The three-dimensional point cloud data for the side face is not acquired.

(Third embodiment)
FIG. 5 is a schematic view of a measuring apparatus 30 according to the third embodiment. The description of the same members as those in the above embodiment is omitted.

  The three-dimensional measurement unit of the measurement device 30 is a measurement unit using a pattern projection method. A measurement unit based on the pattern projection method includes a projector for projecting a light pattern, a photodetector, and the like. Projecting a known light pattern onto a test object, detecting distortion of the light pattern caused by the shape of the test object with a photodetector, and calculating three-dimensional point cloud data of the test object from the detection data This is the principle of the pattern projection method.

  There are several methods for pattern projection. The lattice pattern projection method calculates a three-dimensional point group data by projecting a large number of lattice patterns onto a test object to acquire a large number of images and analyzing fringes. The random pattern projection method calculates the three-dimensional point cloud data by analyzing the distortion of the pattern of one image captured by projecting a known random pattern. In the case of the lattice pattern projection method, since it is necessary to acquire a large number of images, a camera capable of high-speed shooting is necessary for measuring in a short time. However, since there is a trade-off relationship between the number of pixels of the camera and the frame rate, if the measurement time is to be shortened, the number of pixels used for measurement of the image sensor must be reduced. In this case, the density of the acquired three-dimensional point cloud data decreases. In the random pattern projection method, since coordinate data can be obtained only at a position where a pattern is present, only low-density three-dimensional point group data can be obtained. The measurement apparatus 30 of the third embodiment is based on the principle of the random pattern projection method, but the pattern projection method is not limited.

  The three-dimensional measuring unit of the measuring device 30 has a projector 301. The projector 301 projects a known random pattern onto the test object 170. The pattern distorted by the shape of the test object 170 is imaged on the imaging unit (photodetector) 110 by the optical system 104. Data of the image captured by the imaging unit 110 is transmitted to the calculation unit 140. The calculation unit 140 calculates a pattern distortion amount from the acquired image data, and calculates three-dimensional point cloud data of the test object 170 using information on a known random pattern.

  The measuring device 30 also has an incoherent light source 103 in the same way as the above-described embodiment in order to realize reflected illumination. The test object 170 is illuminated by the incoherent light source 103, and the light reflected or scattered by the test object 170 is imaged on the imaging unit 110 by the optical system 104. The captured two-dimensional image data is transmitted to the calculation unit 140. Similar to the first embodiment, the calculation unit 140 detects the edge of the test object using the 3D point cloud data and the 2D image data according to the calculation flow of FIG. Is calculated.

  According to the measurement apparatus of the present embodiment, the edge of the test object can be detected with high accuracy.

  In the case of the measurement apparatus 30 of the third embodiment, since the 3D point cloud data and the 2D image data are obtained by the same imaging unit 110, the 3D point cloud data for the side surface of the test object 170 is not acquired. .

(Fourth embodiment)
FIG. 6 is a schematic diagram of a measuring apparatus 40 according to the fourth embodiment. The description of the same members as those in the above embodiment is omitted.

  The three-dimensional measuring unit of the measuring device 40 has a frequency scanning interferometer. The frequency scanning interferometer includes a coherent variable frequency light source 401, interference optical systems (405 to 409, 416, 420) for generating interference light, a photodetector 440 that receives the interference light, and the like. While scanning the frequency emitted from the light source, the interference light of the test light and the reference light is acquired, and the distance (position of the test surface) is calculated from the phase change of the interference signal. Is the principle.

  The variable frequency light source 401 is a coherent light source capable of scanning a frequency in a constant frequency region. As the variable frequency light source 401, for example, a semiconductor laser (ECDL) using an external resonator or a full-band tunable DFB laser can be used. The variable frequency light source 401 is connected to a digital / analog converter 402. By adjusting the current value sent from the digital / analog converter 402 to the variable frequency light source 401, the frequency of light emitted from the light source is controlled.

  The light emitted from the variable frequency light source 401 is guided to the beam splitter 403. One of the lights branched by the beam splitter 403 is guided to the frequency measurement unit 404. The frequency of the light emitted from the variable frequency light source 401 can be measured by the frequency measurement unit 404. Data of the frequency measured by the frequency measurement unit 404 is transmitted to the control unit 411. The control unit 411 sends a control signal to the digital / analog converter 402 so that the measured frequency becomes a predetermined frequency. If the frequency variable light source 401 can be set to a predetermined frequency with high accuracy, the frequency measurement unit 404 can be omitted.

  The other light branched by the beam splitter 403 is guided to the λ / 2 wavelength plate 407 after the beam diameter is expanded by the lenses 405 to 406. The λ / 2 wavelength plate 407 can be rotated by a rotation mechanism (not shown). Linearly polarized light is emitted from the variable frequency light source 401. Depending on the rotation angle of the λ / 2 wavelength plate 407, the polarization direction of the light transmitted through the λ / 2 wavelength plate 407 can be controlled to an arbitrary direction. A polarizing beam splitter 408 is disposed behind the λ / 2 wavelength plate 407, and the light branching ratio by the polarizing beam splitter 408 can be changed by the rotation angle of the λ / 2 wavelength plate 407.

  The light incident on the polarization beam splitter 408 is branched into reference light 421 and test light 422 having polarization directions orthogonal to each other. The reference light 421 is guided to the reference mirror 410 after passing through the λ / 4 wavelength plate 409a. The test light 422 is guided to the test object 170 after passing through the λ / 4 wavelength plate 409b. The test object 170 is placed on the mounting table 106.

  The light reflected or scattered by the test object 170 passes through the λ / 4 wave plate 409b again and is then guided to the polarization beam splitter 408. Similarly, the light reflected by the reference mirror 410 passes through the λ / 4 wavelength plate 409a again and is guided to the polarization beam splitter 408. By passing through the λ / 4 wavelength plate twice, the polarization directions of the reference light 421 and the test light 422 are both rotated by 90 °. The reference light 421 is reflected by the polarization beam splitter 408, and the test light 422 passes through the polarization beam splitter 408, whereby both the reference light and the test light are guided in the direction of the optical system 104. As a result, the reference light 421 and the test light 422 are spatially superimposed.

  The light superimposed by the beam splitter 408 is collected by the lens 104a. It is desirable to set the front focal point of the lens 104a so as to be in the vicinity of the surface of the object 170 to be measured. As a result, the surface of the test object 170 is imaged without blurring the imaging unit 110 and the photodetector 440.

  An iris diaphragm 105 is disposed in the vicinity of the rear focal point of the lens 104a. Depending on the size of the aperture diameter of the iris diaphragm 105, the amount of light, the depth of field, and the size of speckle in the interference light can be adjusted.

  The light that has passed through the iris diaphragm 105 is collected by the lens 104 b, reflected by the wavelength filter 420, and guided to the polarizer 416. The transmission axis of the polarizer 416 is arranged to be 45 ° with respect to the polarization direction of the reference light and the test light. Thereby, the reference light and the test light interfere with each other, and interference light is generated.

  The reference light and the test light are reflected by the wavelength filter 420 and guided to the light detector 440, and the light intensity (light quantity) of the interference light is measured by the light detector 440. The photodetector 440 is, for example, a CCD or a CMOS. The interference light image (interference signal) measured by the photodetector 440 is transmitted to the calculation unit 140.

  When the total scanning amount of frequency is ΔF, the speed of light is c, and the phase change amount of the interference signal is ΔΦ, the optical path length difference between the reference surface 410 and the test object 170 is expressed by the following equation (1).

  In the frequency scanning interferometer, the optical path length difference can be obtained by scanning the frequency of the light emitted from the light source, measuring the interference signal, and calculating the change amount of the phase of the interference signal. In the measuring device 40, a plurality of images are acquired by the photodetector 440 while scanning the frequency of light emitted from the frequency variable light source 401. The acquired image is transmitted to the calculation unit 140, and the calculation unit 140 analyzes the interference signal to calculate the optical path length difference. Since the photodetector 440 is an area sensor, three-dimensional point cloud data in the XYZ directions of the test object can be acquired by processing the interference signal for each pixel.

  In the frequency scanning interferometer, it is necessary to acquire a plurality of images in order to obtain information on the optical path length difference. In order to shorten the image acquisition time and the time required for measurement, it is desirable to use a camera capable of high-speed shooting. However, since there is a trade-off relationship between the number of pixels of the camera and the frame rate, if an attempt is made to shorten the measurement time, an image sensor with a small number of pixels must be used. In this case, the density of the acquired three-dimensional point cloud data decreases.

  Further, when the surface roughness of the test object 170 is large, speckles are generated when the coherent light is irradiated. When the frequency is scanned, the phase correlation decreases at the portion where the speckle light intensity is low, and the measurement error increases. In order to avoid a decrease in the reliability of measurement, the reliability of the measurement can be improved by removing the data from the three-dimensional point cloud data for the portion where the light intensity of the speckle is low. However, in this case, the density of the three-dimensional point cloud data decreases according to the threshold value of speckle light intensity.

  As described above, if the measurement time is shortened or speckles are present, it is difficult to obtain a high-resolution image, and the density of 3D point cloud data is lower than that of 2D image data. The accuracy is not high. Therefore, the edge position is obtained with higher accuracy using the data of the two-dimensional image measured by the two-dimensional measuring unit.

  An incoherent light source 103 is also configured in the measuring device 40. The dimension in the horizontal direction (x, y direction) of the test object is calculated using an image obtained by irradiating the test object with light from the incoherent light source 103. The incoherent light source 103 is composed of a plurality of light source elements, and the plurality of light source elements are arranged in a ring shape. Each light source element can individually control lighting, thereby realizing illumination from a desired direction.

  The incoherent light source 103 and the variable frequency light source 401 emit light having different wavelengths. The wavelength filter 420 is designed to transmit light from the incoherent light source 103 and reflect light from the variable frequency light source 401. The light illuminated by the incoherent light source 103 and reflected or scattered by the test object 170 passes through the wavelength filter 420 and forms an image on the imaging surface of the imaging unit 110. The imaging unit 110 images the test object 170 and outputs a two-dimensional image of the test object 170. Since the dimension measurement accuracy in the horizontal direction (x, y direction) of the test object depends on the resolution of the imaging unit 110, the imaging unit 110 preferably has an imaging element with a high number of pixels.

  The data of the two-dimensional image captured by the imaging unit 110 of the two-dimensional measurement unit is transmitted to the calculation unit 140. Similar to the above-described embodiment, the calculation unit 140 detects the edge of the test object using the 3D point cloud data and the 2D image data according to the calculation flow of FIG. Is calculated.

  According to the measurement apparatus of the present embodiment, the edge of the test object can be detected with high accuracy.

  Note that, in the case of the measurement device 40 of the fourth embodiment, the photodetector 440 and the imaging unit 110 share a straight line passing through the optical axis of the optical system 104, and thus a three-dimensional point on the side surface of the test object 170. Group data is not acquired.

<Embodiment of Method for Manufacturing Article>
The method for manufacturing an article in the present embodiment is used, for example, to manufacture an article such as a metal part such as a gear or an optical element. The method for manufacturing an article according to this embodiment uses the above-described measuring device to measure shape information such as the dimensions of the specimen that is the article, and processes the specimen based on the measurement result in the process. Including the step of. For example, the shape of the test object is measured using a measuring device, and the test object is processed based on the measurement result so that the shape of the test object becomes a desired shape such as a design value. Since the shape of the test object can be measured with high accuracy by the measuring device, the article manufacturing method of the present embodiment is advantageous in at least the processing accuracy of the article as compared with the conventional method.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

Claims (10)

A measuring device for measuring a test object,
A two-dimensional measuring unit that acquires a first image of the test object using an image sensor that images the test object and an optical system that guides light from the test object to the image sensor;
Three-dimensional measurement for projecting light onto the test object and obtaining three-dimensional data of the test object from a second image detected by guiding the light reflected by the test object to the image sensor by the optical system And
A temporary edge of the test object is detected using the three-dimensional data, an edge detection range in the first image is set by superimposing the detected temporary edge on the first image, and the first image is used and have a a calculation unit that calculates shape information of the test object by detecting the edge of the test object in said edge detection range,
Here, the first image has a higher resolution than the three-dimensional data .   The measurement apparatus according to claim 1, wherein the image sensor of the two-dimensional measurement unit and the image sensor of the three-dimensional measurement unit are the same. The image sensor of the two-dimensional measurement unit is different from the image sensor of the three-dimensional measurement unit,
The two-dimensional measuring unit and the three-dimensional measuring unit emit light having different wavelengths,
The wavelength filter guides the light having the wavelength of the two-dimensional measurement unit to the image sensor of the two-dimensional measurement unit, and guides the light of the wavelength of the three-dimensional measurement unit to the image sensor of the three-dimensional measurement unit. The measuring device according to claim 1. The three-dimensional measuring unit measures the test object using a pattern projection method in which a light pattern is projected onto the test object and distortion of the light pattern generated by the test object is measured. measurement apparatus according to any one of claims 1 to 3, characterized. The calculation unit sets an edge detection range in the two-dimensional image by aligning the two-dimensional image data and the three-dimensional data and then superimposing a temporary edge of the test object on the two-dimensional image. The measuring apparatus according to any one of claims 1 to 4 , wherein the measuring apparatus includes: The calculation unit performs alignment between the two-dimensional image data and the three-dimensional data based on a correspondence relationship between the two-dimensional image data and the three-dimensional data obtained in advance. 5. The measuring device according to 5 . The calculating unit, the measurement device according to any one of claims 1 to 6, characterized in that to set the edge detection range in the two-dimensional image so as to surround the provisional edge. A focus adjustment unit for adjusting a focus position in measurement by the two-dimensional measurement unit;
The focus adjustment unit, the measuring device according to any one of claims 1 to 7, wherein the adjusting the focus position using the focus position calculated using the 3-dimensional data. Wherein the shape information of the object, the measurement device according to any one of claims 1 to 8, characterized in that the a size of the test object. A measuring step of measuring the shape information of the article by using the measuring device according to claim 1 to 9,
And a step of processing the article based on a measurement result of the measurement step.

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