Optical displacement meter and measuring method for measuring the profile of an object

Abstract

Provided is an optical displacement meter and a measurement method of a profile of a measurement object, which can efficiently measure a profile of a measurement object while preventing an increase in manufacturing cost. Reflected light from a measurement object is received by a plurality of pixel columns arranged in an X2 direction in a light-receiving unit (121), and a plurality of light-receiving amount distributions are output. A peak detection unit (1) detects one or more peak candidate positions of light-receiving amounts in a Z2 direction based on the plurality of light-receiving amount distributions for each pixel column. A peak position to be adopted for a profile is selected from the peak candidate positions detected for each pixel column based on a relative positional relationship with a peak position of another pixel column adjacent to the pixel column, and a profile generation unit (3) generates profile data indicating a profile based on the selected peak position.

Description

[0001] (This application is a divisional application of the application filed on August 12, 2019, with application number 201910740724.2 and title "Optical Displacement Meter".) Technical Field

[0002] This invention relates to an optical displacement meter that detects the displacement of a measurement object using triangulation. Background Technology

[0003] In optical displacement gauges using the optical sectioning method, the object to be measured (hereinafter referred to as the workpiece) is illuminated from a light projection unit using a strip of light with a linear cross-section, and the reflected light is received by a two-dimensional light-receiving element. The contour of the workpiece is measured based on the position of the peak of the light intensity distribution obtained by the light-receiving element. Here, the light illuminating the workpiece may undergo multiple reflections on the surface of the workpiece. In this case, because multiple peaks appear in the light intensity distribution due to the multiple reflections of the light incident on the light-receiving element, the accurate contour of the workpiece cannot be measured. The same problem occurs when light from a part other than the light projection unit (interference light) is incident on the light-receiving element, or when light reflected from a part of the workpiece other than the target measurement part is incident on the light-receiving element.

[0004] In the optical displacement meter described in Japanese Patent Application Publication No. 2012-127887, a workpiece is sequentially illuminated by a first light and a second light polarized in directions perpendicular to each other. The first light and the second light reflected from the workpiece are received by a light-receiving element, and first waveform data and second waveform data indicating the light amount distribution of the first light and the second light are generated.

[0005] A peak is selected from the first and second waveform data based on the ratio of corresponding peaks between them. The workpiece profile is then measured based on the position of the selected peak.

[0006] According to the optical displacement meter described in Japanese Patent Application Publication No. 2012-127887, a peak generated by light that is reflected only once on the surface of a workpiece can be selected from multiple peaks in the light intensity distribution. However, since two light projection elements for emitting light polarized in mutually perpendicular directions are required in the optical displacement meter, the manufacturing cost of the optical displacement meter is increased. In addition, since first waveform data and second waveform data need to be acquired and calculations need to be performed on these waveform data, the contour of the workpiece cannot be measured efficiently. Summary of the Invention

[0007] The purpose of this invention is to provide an optical displacement meter that can efficiently measure the contour of a measurement object while preventing increased manufacturing costs.

[0008] (1) The optical displacement meter according to the present invention is an optical displacement meter that uses optical sectioning. The optical displacement meter is used to measure the contour of a measurement object. The optical displacement meter includes: a light projection unit for illuminating the measurement object using slit light diffused along a first direction or point light scanned along the first direction; a light receiving unit for including a plurality of pixels arranged along the first direction and a second direction intersecting the first direction, and for receiving reflected light from each position of the measurement object along the first direction and outputting a light receiving amount distribution; a peak detection unit for detecting one or more peak candidate positions of light receiving amount in the second direction for each pixel column based on a plurality of light receiving amount distributions output from a plurality of pixel columns arranged along the first direction; and a contour generation unit for selecting a peak position to be used for the contour from the peak candidate positions detected by the peak detection unit for each pixel column based on the relative positional relationship of the peak positions of other pixel columns adjacent to the pixel column, and generating contour data for indicating the contour based on the selected peak position.

[0009] In this optical displacement meter, a light projection unit scans slit light or point light diffused along a first direction and illuminates the object being measured. Reflected light from the object is received by a plurality of pixel columns arranged along the first direction in a light-receiving unit, and a light-receiving distribution is output. In each pixel column, multiple pixels are arranged along a second direction. A peak detection unit detects one or more candidate peak positions in the second direction for each pixel column based on the multiple light-receiving distributions output from the multiple pixel columns. A peak position to be used for the contour is selected from the detected candidate peak positions based on the relative positional relationship with the peak positions of adjacent pixel columns, and a contour generation unit generates contour data indicating the contour based on the selected peak position.

[0010] Using this structure, even when multiple peak candidate positions are detected in the light distribution corresponding to any pixel column, the peak position to be used for the contour is selected for each pixel column based on its relative positional relationship with the peak positions of other pixel columns. In this case, it is unnecessary to set up multiple light projection elements with different polarization directions in the optical displacement meter. Furthermore, it is not necessary to obtain multiple light distributions for each pixel column, thus eliminating the need to calculate multiple light distributions. As a result, the contour of the object can be measured efficiently while preventing an increase in manufacturing costs.

[0011] (2) The optical displacement meter may further include: a switching unit for switching the operating mode of the contour generation unit between a first operating mode and a second operating mode. In the first operating mode, when the peak detection unit detects multiple peak candidate positions in the light distribution corresponding to any pixel column, the contour generation unit may select the peak position to be used in the contour from the multiple peak candidate positions based on the continuity between the peak candidate positions in the light distribution corresponding to at least the pixel column adjacent to the pixel column in the first direction and the detected multiple peak candidate positions. In the second operating mode, when the peak detection unit detects multiple peak candidate positions in the light distribution corresponding to the pixel column, the contour generation unit may select the peak position to be used for the contour from the multiple peak candidate positions based on preset conditions.

[0012] In some shapes of the object being measured, the peak position selected based on preset conditions can coincide with the position of the object's surface. In this case, the contour of the object can be measured more efficiently by selecting the second operating mode.

[0013] (3) The preset conditions may include the following: selecting the peak candidate position with the maximum light reception from multiple peak candidate positions in each light reception distribution as the peak position to be used for the contour. Using this structure, when the peak candidate position with the maximum light reception coincides with the position of the surface of the object being measured, the contour of the object being measured can be measured more efficiently by selecting the second operating mode.

[0014] (4) The preset conditions may also include the following: selecting the peak candidate position closest to one end or the other end in the second direction from multiple peak candidate positions in each light-receiving distribution as the peak position to be used for the contour. Using this structure, when the peak candidate position closest to one end or the other end in the second direction coincides with the position of the surface of the object being measured, the contour of the object being measured can be measured more efficiently by selecting the second operation mode.

[0015] (5) The optical displacement meter may further include: a parameter acquisition unit, used to acquire parameters indicating the pattern of peaks in the peak candidate positions detected by the peak detection unit. The contour generation unit may select the peak position to be used for the contour from multiple peak candidate positions in each light-receiving distribution based on the parameters acquired by the parameter acquisition unit.

[0016] In this case, the peak position to be used for the contour is selected based on a comprehensive judgment of the relative positional relationship between the peak candidate positions of multiple pixel columns in the first direction and the peak pattern. As a result, the contour of the object being measured can be measured more accurately.

[0017] (6) The parameters acquired by the parameter acquisition unit may include the amount of light received by the peak or the width of the peak. In this case, parameters indicating the mode of the peak can be easily acquired.

[0018] (7) The optical displacement meter may further include: a cluster generation unit, configured to generate multiple clusters, each comprising one or more peak candidate positions, from multiple peak candidate positions detected by the peak detection unit in a plurality of light-receiving distributions. Each cluster may include one or more peak candidate positions selected such that the distance between adjacent peak candidate positions in the first direction is equal to or less than a predetermined value, and the contour generation unit may determine the relative positional relationship based on the number of peak candidate positions included in each cluster generated by the cluster generation unit. In this case, the relative positional relationship can be easily determined based on the number of peak candidate positions included in each cluster.

[0019] (8) The optical displacement meter may further include a distance calculation unit for calculating the distance between each candidate peak position in the light distribution corresponding to each pixel column and the candidate peak position in the light distribution corresponding to the pixel column adjacent to each pixel column in the first direction. The contour generation unit may determine the relative positional relationship based on the distance calculated by the distance calculation unit. In this case, the relative positional relationship can be easily determined based on the distance between adjacent candidate peak positions.

[0020] (9) The optical displacement meter may further include: a pattern generation unit for generating a geometric pattern based on multiple peak candidate positions detected by the peak detection unit; and a correlation calculation unit for calculating, for each pixel column, a correlation coefficient between the geometric pattern generated by the pattern generation unit and the multiple peak candidate positions detected by the peak detection unit. The contour generation unit may determine the relative positional relationship based on the correlation coefficient calculated by the correlation calculation unit. In this case, the relative positional relationship can be easily determined based on the correlation coefficient between the geometric pattern and the multiple peak candidate positions.

[0021] (10) The optical displacement meter may further include: a filtering processing unit for filtering the contour data such that, in each part of the contour data generated by the contour generation unit, the smoothing effect increases as the value decreases. In this case, the contour portion corresponding to the flat portion of the measured object can be smoothed while maintaining the shape of the stepped and edge portions in the contour.

[0022] According to the present invention, the contour of the object to be measured can be measured efficiently while preventing an increase in manufacturing costs. Attached Figure Description

[0023] Figure 1 This is a block diagram showing the structure of an optical displacement meter according to the first embodiment;

[0024] Figure 2 It is a 3D view of the camera and the workpiece.

[0025] Figure 3 It is a diagram showing the relationship between the light irradiation position on the surface of the workpiece and the light incident position on the light receiving unit;

[0026] Figure 4 It is a diagram showing the relationship between the light irradiation position on the surface of the workpiece and the light incident position on the light receiving unit;

[0027] Figure 5 It is a diagram showing the distribution of light received on the light-receiving surface of the light-receiving unit;

[0028] Figure 6 It is shown Figure 5 A graph showing the distribution of light received in a single pixel column;

[0029] Figure 7 It is shown Figure 5 A diagram showing the positions of all peaks in the light intensity distribution;

[0030] Figure 8 It shows based on Figure 7 A graph of the contour data obtained from the peak position;

[0031] Figure 9A and 9B It is a diagram used to illustrate reflections on the surface of a workpiece;

[0032] Figure 10 This is a diagram showing another example of the distribution of light received in a light-receiving unit;

[0033] Figure 11 It is shown Figure 10 A graph showing the distribution of light received in a single pixel column;

[0034] Figure 12 This is a block diagram showing the structure of the contour acquisition unit;

[0035] Figure 13 This is a diagram used to illustrate the operation of the contour acquisition unit in the first operation mode;

[0036] Figure 14 This is a diagram used to illustrate the operation of the contour acquisition unit in the first operation mode;

[0037] Figure 15 This is a diagram used to illustrate the operation of the contour acquisition unit in the first operation mode;

[0038] Figure 16 This is a block diagram showing the structure of the unit obtained from the contour of the modified example;

[0039] Figures 17A-17C It is used for explanation Figure 12 A diagram illustrating the operation of the filtering unit;

[0040] Figure 18 This is a block diagram illustrating the structure of the contour acquisition unit according to the second embodiment;

[0041] Figure 19 This is a diagram illustrating the operation of the contour acquisition unit in the first operation mode according to the second embodiment;

[0042] Figure 20 This is a block diagram illustrating the structure of the contour acquisition unit according to the third embodiment; and

[0043] Figure 21A and 21B This is a diagram illustrating the operation of the contour acquisition unit in the first operation mode according to the third embodiment. Detailed Implementation

[0044] [1] First embodiment

[0045] (1) Structure of an optical displacement meter

[0046] The following description, with reference to the accompanying drawings, illustrates an optical displacement meter using the optical sectioning method as an embodiment of the present invention. Figure 1 This is a block diagram illustrating the structure of an optical displacement meter according to the first embodiment. Figure 1 As shown, the optical displacement meter 500 includes a camera 100, a processing unit 200, an input unit 300, and a display unit 400. The optical displacement meter 500 may include multiple cameras 100. The cameras 100 are configured to be detachable from the processing unit 200. The cameras 100 and the processing unit 200 may be integrated into one unit.

[0047] The camera 100 includes a light projection unit 110 and an image capture unit 120. The light projection unit 110 is configured to illuminate the measurement object (hereinafter referred to as workpiece W) using a strip of light diffused in one direction (the X1 direction, which will be described later). The light projection unit 110 may be configured to illuminate the workpiece W using light scanned in one direction, instead of using a strip of light diffused in one direction.

[0048] The camera unit 120 includes a light-receiving unit 121 and a light-receiving lens 122. Reflected light from the workpiece W passes through the light-receiving lens 122 and is incident on the light-receiving unit 121. The light-receiving unit 121 includes, for example, a complementary metal-oxide-semiconductor (CMOS) sensor and has a plurality of pixels arranged in a two-dimensional configuration. The light distribution of the light-receiving unit 121 is output as digital data.

[0049] The processing device 200 includes a storage unit 210 and a control unit 220. The processing device 200 also includes a light projection control unit 221, a light receiving control unit 222, an input setting unit 223, a contour acquisition unit 224, a switching unit 225, a measurement processing unit 226, and a display processing unit 227 as functional units.

[0050] Storage unit 210 includes random access memory (RAM), read-only memory (ROM), hard disk, or semiconductor memory, etc., and stores measurement programs. Control unit 220 is, for example, a central processing unit (CPU). Control unit 220 executes the measurement programs stored in storage unit 210, thereby realizing the functional units of processing device 200. Some or all of the functional units of processing device 200 can be implemented by hardware such as electronic circuits.

[0051] The light projection control unit 221 controls the light irradiation timing and light intensity of the light projection unit 110. The light receiving control unit 222 controls the light receiving timing of the light receiving unit 121. The input setting unit 223 provides the command signal given by the input unit 300 to the contour acquisition unit 224, the switching unit 225, and the measurement processing unit 226.

[0052] The contour acquisition unit 224 acquires contour data indicating the contour of the workpiece W based on the light distribution output from the light receiving unit 121 and the command signal given from the input setting unit 223. The switching unit 225 switches the operation mode of the contour acquisition unit 224 between a first operation mode and a second operation mode based on the command signal given by the input setting unit 223. Details of the contour acquisition unit 224 and the operation modes will be described later.

[0053] The measurement processing unit 226 performs measurement processing on the contour data acquired by the contour acquisition unit 224. Here, the measurement processing is used to calculate the dimensions (displacements) of any part on the surface of the workpiece W based on the contour data. The display processing unit 227 generates image data indicating the shape of the workpiece W based on the contour data and the dimensions (displacements) calculated by the measurement processing, and provides the generated image data to the display unit 400.

[0054] The input unit 300 includes a keyboard and a pointing device, and is configured to be operated by a user. A mouse or joystick, etc., can be used as the pointing device. A dedicated console can also be used as the input unit 300. The user operates the input unit 300, thus sending command signals from the input unit 300 to the input setting unit 223 of the processing device 200.

[0055] The display unit 400 is, for example, a liquid crystal display panel or an organic electroluminescent (EL) panel. The display unit 400 displays the contour of the workpiece W and the measurement results of the measurement processing unit 226 based on the image data provided by the display processing unit 227 of the processing device 200.

[0056] (2) Operation summary

[0057] Figure 2 It is a 3D view of the camera 100 and the workpiece W. Figure 3 and 4 This is a diagram showing the relationship between the light irradiation position on the surface of the workpiece W and the light incident position on the light receiving unit 121. Figures 2-4 In this diagram, two directions perpendicular to each other in the horizontal plane are defined as the X1 direction and the Y1 direction, and are represented by arrows X1 and Y1 respectively. The vertical direction is defined as the Z1 direction and is represented by arrow Z1. Figure 3 and 4 In this diagram, two directions perpendicular to each other on the light-receiving surface of the light-receiving unit 121 are defined as the X2 direction and the Z2 direction, and are represented by arrows X2 and Z2, respectively. Here, the light-receiving surface is a surface formed by multiple pixels of the light-receiving unit 121.

[0058] exist Figure 2 In the example, a groove with a trapezoidal cross-section extending along the Y1 direction is formed in the surface of workpiece W. Camera 100 illuminates the surface of workpiece W with a strip of light extending along the X1 direction. In the following text, the linear region on the surface of workpiece W illuminated by the strip of light is referred to as the illuminating region T1. Figure 3 As shown, light reflected from the illumination area T1 passes through the light-receiving lens 122 and is incident on the light-receiving unit 121. In this case, when the reflection position of the light in the illumination area T1 is different in the Z1 direction, the incident position of the reflected light on the light-receiving unit 121 is different in the Z2 direction.

[0059] like Figure 4 As shown, when the reflection position of light in the irradiation area T1 is different in the X1 direction, the incident position of the reflected light onto the light-receiving unit 121 is different in the X2 direction. Therefore, the incident position of light onto the light-receiving unit 121 in the Z2 direction represents the position (height) of the irradiation area T1 in the Z1 direction, and the incident position of light onto the light-receiving unit 121 in the X2 direction represents the position of the irradiation area T1 in the X1 direction.

[0060] Figure 5 This is a diagram showing the light distribution on the light-receiving surface of the light-receiving unit 121. Based on Figure 5 The light-receiving unit 121 generates a light-receiving distribution based on the amount of light received by each pixel p. The plurality of pixels p in the light-receiving unit 121 are arranged two-dimensionally along the X2 and Z2 directions. Each column of the plurality of pixels p along the Z2 direction is referred to as a pixel column SS. Therefore, on the light-receiving surface of the light-receiving unit 121, the plurality of pixel columns SS are arranged along the X2 direction, and each pixel column SS includes the plurality of pixels p along the Z2 direction.

[0061] In this invention, each pixel p is not limited to a single pixel (the smallest unit of a pixel) in an imaging device such as a CMOS sensor, and can include multiple pixels. For example, each pixel p can include four pixels arranged in a 2×2 configuration, or each pixel p can include nine pixels arranged in a 3×3 configuration. Therefore, in the case of binning processing where multiple pixels are combined as a unit, each pixel p can include the multiple pixels included in that unit.

[0062] from Figure 2 The light reflected from the irradiated area T1 is incident on Figure 5 The light-receiving area R1 is shown. As a result, the amount of light received by the light-receiving area R1 increases. For each pixel column SS, Figure 5 The distribution of light received is output as digital data.

[0063] Figure 6 It is shown Figure 5 A graph showing the distribution of light received in a single pixel column SS. Figure 6 In the diagram, the horizontal axis represents the position in the Z2 direction, and the vertical axis represents the amount of light received. For example... Figure 6 As shown, the distribution of light received in a pixel column SS exhibits the same characteristics as... Figure 5 The peak P (local maximum) corresponds to the illuminated area R1. The position of peak P in the Z2 direction (hereinafter referred to as peak position PP) indicates the height of the surface (reflective surface) of the workpiece W in the irradiated area T1.

[0064] Figure 1 The contour acquisition unit 224 detects one or more peak positions PP (in each of the multiple light-receiving distributions corresponding to multiple pixel columns SS) in each of the multiple light-receiving distributions. Figure 6 (One example is shown). The contour acquisition unit 224 acquires contour data indicating the contour (shape of the irradiation area T1) of the workpiece W based on multiple peak positions PP.

[0065] Figure 7 It is shown Figure 5 A graph showing the positions of all peaks in the light-receiving distribution (PP). Figure 8 It shows based on Figure 7 The peak position is obtained from the contour data of PP. (See figure) Figure 7 and 8 As shown, all detected peak positions PP are displayed as continuous lines, thus obtaining contour data indicating the contour of workpiece W.

[0066] As described above, light reflected from the irradiation area T1 is incident on the light-receiving unit 121, thus a peak representing the height of the irradiation area T1 appears in the light-receiving amount distribution. However, light reflected from parts other than the irradiation area T1 may also be incident on the light-receiving unit 121. In this case, a peak (hereinafter referred to as a false peak) appears in the light-receiving amount distribution that is different from the peak indicating the height of the irradiation area T1 (hereinafter referred to as the true peak). Figure 9A and 9B This is a diagram used to illustrate reflections on the surface of workpiece W. Figure 10 This is a diagram showing another example of the light distribution in the light-receiving unit 121. Figure 11 It is shown Figure 10 A graph showing the distribution of light received in a single pixel column SS.

[0067] like Figure 9A As shown, light illuminating the workpiece W undergoes specular reflection and diffuse reflection from the irradiation area T1. Here, specular reflection refers to reflection where the incident angle and reflection angle are equal, and diffuse reflection refers to reflection where the incident angle and reflection angle are different. Typically, the light specularly reflected from the irradiation area T1 does not reach the light-receiving unit 121, while a portion of the light L1 diffusely reflected from the irradiation area T1 reaches the light-receiving unit 121. On the other hand, as... Figure 9B As shown, some other light L2 that is diffusely reflected from the irradiation area T1 may be specularly reflected from other areas on the surface of the workpiece W besides the irradiation area T1 (hereinafter referred to as the pseudo-irradiation area T2) and may be incident on the light receiving unit 121.

[0068] In the case of specular reflection, the intensity of the light does not change significantly before and after the reflection. Therefore, there is no large difference between the intensity of light L1 incident from the irradiation area T1 to the light-receiving unit 121 and the intensity of light L2 incident from the pseudo-irradiation area T2 to the light-receiving unit 121. This embodiment is an example, and such multiple reflections (reflections occurring multiple times) can occur in various situations. For example, when the workpiece W and the camera 100 are configured such that specularly reflected light is received by the light-receiving unit 121 as reflected light from the workpiece W, diffusely reflected light other than specularly reflected light may be further reflected from other areas and may be received by the light-receiving unit 121.

[0069] In this case, such as Figure 10As shown, on the light-receiving surface of the light-receiving unit 121, the amount of light received in areas other than the light-receiving region R1 (hereinafter referred to as the pseudo-light-receiving region R2) increases. Therefore, as Figure 11 As shown, in the light-receiving distribution, in addition to the true peak P1, which corresponds to the light-receiving region R1, there is also a pseudo peak P2, which corresponds to the pseudo light-receiving region R2. That is, the contour acquisition unit 224 detects the positions of the true peak P1 and the pseudo peak P2 as candidate positions for peak P (hereinafter referred to as peak candidate positions). If the position of the pseudo peak P2 is used instead of the position of the true peak P1, accurate contour data cannot be obtained.

[0070] Additionally, light from sources other than the light projection unit 110 (interference light) may be incident on the light receiving unit 121. Alternatively, light illuminating a portion of the workpiece W other than the irradiation area T1 may be reflected and may also be incident on the light receiving unit 121. In these cases, a spurious peak P2 appears in addition to the true peak P1 in the light distribution, thus causing the same problem.

[0071] Therefore, the contour acquisition unit 224 selectively operates in either a first operation mode or a second operation mode. In the first operation mode, based on the peak candidate positions in the light-receiving distribution corresponding to the pixel columns SS adjacent to the same pixel column SS and the relative positional relationship (e.g., continuity) between the detected multiple peak candidate positions, the position of the true peak P1 is selected as the peak position PP instead of the position of the spurious peak P2. In the second operation mode, a peak candidate position is selected as the peak position PP from the multiple peak candidate positions based on preset conditions.

[0072] The operation of the contour acquisition unit 224 will be described in detail below. In the following description, the peak candidate position in the light distribution corresponding to the pixel column SS will be referred to simply as the peak candidate position of the pixel column SS.

[0073] (3) Contour acquisition unit

[0074] Figure 12 This is a block diagram showing the structure of the contour acquisition unit 224. For example... Figure 12 As shown, the contour acquisition unit 224 includes a peak detection unit 1, a cluster generation unit 2, a contour generation unit 3, and a filtering processing unit 4 as functional units. Figure 1 The control unit 220 executes the measurement program stored in the storage unit 210, thereby realizing the functional units of the contour acquisition unit 224. Some or all of the functional units of the contour acquisition unit 224 can be implemented by hardware such as electronic circuits.

[0075] In both the first and second operating modes, peak detection unit 1 detects peaks (including peak candidate positions) of each pixel column SS based on the light distribution output from light receiving unit 121. In the first operating mode, cluster generation unit 2 generates multiple clusters from the multiple peak candidate positions detected by peak detection unit 1. Here, each cluster includes one or more peak candidate positions selected such that the distance between adjacent peak candidate positions in the X2 direction is equal to or less than a predetermined value.

[0076] In the first operating mode, the contour generation unit 3 selects a peak position PP corresponding to the position of the surface of the workpiece W from multiple peak candidate positions in each light-receiving distribution based on the number of peak candidate positions contained in each cluster generated by the cluster generation unit 2. In this embodiment, the peak candidate position included in the largest cluster is selected as the peak position PP. The size of the cluster indicates the number of peak candidate positions included in the cluster.

[0077] In the second operating mode, the contour generation unit 3 selects a peak position PP from multiple candidate peak positions in each light-receiving distribution based on preset conditions. The preset conditions include "Standard (maximum peak)," "Near," and "Far (FAR)." In the "Standard (maximum peak)" case, the peak candidate position with the maximum light-receiving amount is selected as the peak position PP from the multiple candidate peak positions in each light-receiving distribution. Figure 11 In the example, the position of the true peak P1 with the maximum amount of light received is selected from the two peaks P as the peak position PP.

[0078] In the "near" case, the peak candidate position closest to one end (e.g., the left end) in the Z2 direction is selected from multiple peak candidate positions in each light-receiving distribution as the peak position PP. Figure 11 In the example, the position of the leftmost pseudo-peak P2 is selected as the peak position PP from the two peaks P. In the case of "far", the peak candidate position closest to the other end (e.g., the right end) in the Z2 direction is selected as the peak position PP from multiple peak candidate positions in each light-receiving distribution. Figure 11 In the example, the position of the rightmost true peak P1 is selected from the two peaks P as the peak position PP.

[0079] The user operates the input unit 300, and thus the input setting unit 223 can be used to set any of the following: "Standard (Maximum Peak)", "Near", and "Far". In some shapes of the workpiece W, the peak position PP selected based on any condition can coincide with the position of the surface of the workpiece W. Therefore, if the user identifies an appropriate condition corresponding to the shape of the workpiece W, the appropriate peak position PP corresponding to the position of the surface of the workpiece W can be selected more efficiently by setting this condition in the second operating mode.

[0080] Furthermore, the contour generation unit 3 generates contour data indicating the contour of the workpiece W based on the selected peak position PP. The filtering processing unit 4 filters the contour data, making the smoothness effect greater as the value changes in each part of the contour data generated by the contour generation unit 3. Details of the filtering processing unit 4 will be explained later. The contour based on the contour data generated by the contour generation unit 3 is displayed on the display unit 400 by the display processing unit 227.

[0081] Figure 13 , 14 Figures 1 and 15 are used to illustrate the operation of the contour acquisition unit 224 in the first operation mode. As described above, Figure 12 Peak detection unit 1 detects the peak candidate positions of each pixel column SS. Figure 13 In the example, a dot pattern is used to represent the pixel p of the light-receiving unit 121 corresponding to the detected peak candidate position. For example... Figure 13 As shown, multiple peak candidate positions are detected in some pixel columns SS.

[0082] Figure 12 The cluster generation unit 2 generates multiple clusters from the multiple peak candidate positions detected by the peak detection unit 1. Each cluster includes multiple peak candidate positions that are adjacent to each other in the X2 direction. Two peak candidate positions included in the same cluster do not necessarily need to be adjacent to each other in the X2 direction. A predetermined peak candidate position and peak candidate positions within a predetermined distance from that predetermined peak candidate position can be included in the same cluster.

[0083] exist Figure 14 In the example, 14 clusters C1–C14 are generated from multiple peak candidate locations, and these clusters C1–C14 are indicated using different dot patterns or shading patterns. Cluster C1 is the largest cluster, cluster C14 is the second largest cluster, and clusters C2, C3, C5–C7, and C9 are the smallest clusters. Figure 14 In the diagram, multiple pixel columns SS arranged along the X2 direction are sequentially named pixel columns SS1, SS2, SS3, ... from the left side.

[0084] In pixel column SS1, three peak candidate positions were detected, and these three peak candidate positions are included in clusters C1, C2, and C3, respectively. In pixel column SS2, three peak candidate positions were detected, and these three peak candidate positions are included in clusters C1, C4, and C5, respectively. In pixel column SS3, four peak candidate positions were detected, and these four peak candidate positions are included in clusters C1, C4, C6, and C7, respectively. In these cases, Figure 12 The contour generation unit 3 selects the peak candidate position included in the largest cluster C1 as the peak position PP.

[0085] In pixel columns SS4 to SS8, only one peak candidate position included in cluster C1 is detected. In these cases, contour generation unit 3 selects this peak candidate position as the peak position PP.

[0086] Similarly, as Figure 15 As shown, in the pixel column SS of region A1 along the X2 direction of the light-receiving unit 121, the peak candidate position included in cluster C1 is selected as the peak position PP. In the pixel column SS of region A2 along the X2 direction of the light-receiving unit 121, the peak candidate position included in cluster C14 is selected as the peak position PP. Figure 15 In the example, a dot pattern is used to indicate the pixel p of the light-receiving unit 121 corresponding to the selected peak position PP. Figure 12 The contour generation unit 3 generates contour data based on the selected peak position PP.

[0087] (4) Variations

[0088] Although this embodiment has described selecting the peak candidate position PP as the largest cluster, the invention is not limited thereto. The peak position PP can be selected based on a comprehensive judgment of the number of peak candidate positions included in the cluster and other parameters indicating the mode of the peak candidate.

[0089] Figure 16 This is a block diagram showing the structure of unit 224 obtained from the contour of a modified example. It will be explained... Figure 16 Contour acquisition unit 224 and Figure 12 The differences between the contour acquisition units 224. For example... Figure 16 As shown, the contour acquisition unit 224 according to the modified example further includes a parameter acquisition unit 5. In the first operation mode, the parameter acquisition unit 5 acquires multiple parameters that respectively indicate the modes of the multiple candidate peaks P detected by the peak detection unit 1.

[0090] Specifically, the light received by the true peak P1 is often greater than that of the spurious peak P2. Optionally, the width of the true peak P1 is often narrower than the width of the spurious peak P2. Therefore, the parameter acquisition unit 5 acquires, for example, the light received by a candidate peak P or the width of a candidate peak P as the aforementioned parameters.

[0091] The contour generation unit 3 comprehensively judges the number of peak candidate positions included in each cluster generated by the cluster generation unit 2, as well as the light received amount of the candidate peak or the width of the candidate peak obtained by the parameter acquisition unit 5. As a result of this judgment, the contour generation unit 3 selects any cluster and selects the peak candidate positions included in the selected cluster as peak positions PP.

[0092] (5) Filtering unit

[0093] Figures 17A-17CIt is used for explanation Figure 12 A diagram illustrating the operation of the filtering unit 4. Figures 17A-17C In the display unit 400, the outline of workpiece W is displayed. On the screen of display unit 400, symbols corresponding to the outline of workpiece W are defined. Figure 1 The X2 and Z2 directions of the light-receiving unit 121 correspond to the X3 and Z3 directions.

[0094] Even when workpiece W is partially flat, there may be some unevenness in the surface condition or color of workpiece W, such as Figure 17A As shown, the contour of workpiece W based on contour data may also be uneven and jagged. When smoothing filtering is applied to the contour data to smooth the contour of workpiece W, such as... Figure 17B As shown, the stepped or edge portions of the outline disappear, and an accurate outline cannot be obtained.

[0095] Therefore, in this embodiment, the filtering unit 4 calculates the output value f by calculating the following expression (1). i Here, when the multiple pixel columns SS arranged along the X3 direction are sequentially numbered from the left to the i-th (i is an integer greater than or equal to 1), the z in expression (1) i It represents the position (height) of the portion of the contour data corresponding to the i-th pixel column SS in the Z3 direction. α is a weighting parameter in the Z3 direction. k is an integer greater than or equal to 1 and represents the range (core) calculated for pixel number i.

[0096]

[0097] For all numbers i, calculate the output value f of expression (1). i Therefore, the contour data is filtered so that the smoothing effect is greater in the parts of the contour with smaller height changes than in the parts with larger height changes. The result is as follows: Figure 17C As shown, the contours are smoothed while maintaining the shape of the stepped and edge portions.

[0098] The filter processing unit 4 can calculate the output value f by substituting expression (1) into the following expression (2). i Here, x in expression (2) i β is the position of the portion of the contour data corresponding to the i-th pixel column SS in the X3 direction. β is the weighting parameter in the X3 direction. The other parameters are the same as those in expression (1).

[0099]

[0100] For all numbers i, calculate the output value f of expression (2). iTherefore, filtering the contour data results in a smoother texture for areas with smaller height variations than for areas with larger height variations. Furthermore, filtering the contour data ensures a smoother texture between adjacent parts in the X3 direction than between parts spaced apart in the X3 direction.

[0101] Furthermore, the user can specify the range of contour data to be filtered in the Z3 direction by operating the input unit 300. Multiple ranges can also be specified for filtering. Figure 17A This example shows how to specify two ranges F1 and F2 to be filtered using a dot pattern.

[0102] In expression (1) or expression (2), kernel k can be... Figure 1 The input setting unit 223 is set to a Gaussian kernel, or it can be operated by... Figure 1 The user sets the input settings in the input setting unit 223 of the input unit 300. Optionally, in Figure 1 When the measurement processing unit 226 is set to measure a predetermined step portion of the profile, the kernel k can be automatically set in the input setting unit 223 according to the size of the step portion.

[0103] (6) Effect

[0104] In the optical displacement meter 500 according to this embodiment, the light projection unit 110 illuminates the workpiece W with light. The reflected light from the workpiece W is received by a plurality of pixel columns SS arranged along the X2 direction in the light receiving unit 121, and a light receiving amount distribution is output. The peak detection unit 1 detects one or more peak candidate positions of the light receiving amount in the Z2 direction of the plurality of pixels p arranged in the respective pixel column SS in each of the plurality of light receiving amount distributions. From the peak position candidate positions detected for each pixel column SS, a peak position PP to be used for the contour is selected based on the relative positional relationship with the peak positions PP of other pixel columns SS adjacent to that pixel column SS, and the contour generation unit 3 generates contour data indicating the contour of the workpiece W based on the selected peak position PP.

[0105] Using this structure, even when multiple peak candidate positions are detected for any pixel column SS, the peak position PP to be used for the contour can be selected based on the relative positional relationship of the peak positions PP of that pixel column SS with respect to other pixel columns SS. In this case, it is unnecessary to set multiple light projection elements with different polarization directions in the optical displacement meter 500. Furthermore, it is unnecessary to obtain multiple light reception distributions for each pixel column SS. Therefore, it is unnecessary to calculate multiple light reception distributions. As a result, the contour of the workpiece W can be measured efficiently while preventing an increase in manufacturing costs.

[0106] When determining the relative positional relationship, the cluster generation unit 2 generates multiple clusters, each containing one or more peak candidate positions, from multiple peak candidate positions detected in multiple light-receiving distributions. Each cluster includes one or more peak candidate positions selected such that the distance between adjacent peak candidate positions in the X2 direction is equal to or less than a predetermined value. The contour generation unit 3 determines the relative positional relationship based on the number of peak candidate positions included in each generated cluster. In this case, the relative positional relationship can be easily determined.

[0107] [2] Second embodiment

[0108] The differences between the optical displacement meter 500 according to the second embodiment and the optical displacement meter 500 according to the first embodiment will be explained. Figure 18 This is a block diagram illustrating the structure of the contour acquisition unit 224 according to the second embodiment. Figure 18 As shown, in this embodiment, instead of Figure 12 The cluster generation unit 2 and the contour acquisition unit 224 include a distance calculation unit 6.

[0109] In the first operating mode, the distance calculation unit 6 calculates the distance between each peak candidate position of each pixel column SS and the peak position PP of the pixel column SS adjacent to that pixel column SS. The contour generation unit 3 selects the peak position PP from multiple peak candidate positions of each pixel column SS based on the distance calculated by the distance calculation unit 6. In this embodiment, for each pixel column SS, the peak candidate position with the smallest distance to the peak candidate position of the adjacent pixel column SS is selected as the peak position PP.

[0110] Figure 19 This is a diagram illustrating the operation of the contour acquisition unit 224 in the first operation mode according to the second embodiment. Figure 18 Peak detection unit 1 detects the peak candidate positions of each pixel column SS. Figure 19 In the example, a dot pattern is used to indicate the pixel p of the light-receiving unit 121 corresponding to the detected peak candidate position.

[0111] Specifically, in pixel column SS1, one peak candidate position is detected, and the pixel p corresponding to this peak candidate position is pixel p1. In pixel column SS2, two peak candidate positions are detected, and the pixels p corresponding to these peak candidate positions are pixels p2 and p3, respectively. In pixel column SS3, two peak candidate positions are detected, and the pixels p corresponding to these peak candidate positions are pixels p4 and p5, respectively. In pixel column SS4, two peak candidate positions are detected, and the pixels p corresponding to these peak candidate positions are pixels p6 and p7, respectively.

[0112] The following will explain the distance between each peak candidate position of each pixel column SS and the peak position PP of the adjacent pixel column SS as the distance between the pixel corresponding to each peak candidate position and the pixel corresponding to the peak position PP. Since only one peak candidate position corresponding to pixel p1 is detected in pixel column SS1, therefore Figure 18 The contour generation unit 3 selects the peak candidate position corresponding to pixel p1 as the peak position PP.

[0113] Figure 18 The distance calculation unit 6 calculates the distance between each pixel p2 and p3 in pixel column SS2 and pixel p1 in the adjacent pixel column SS1. In this example, the distance between pixels p1 and p3 is shorter than the distance between pixels p1 and p2. Therefore, for pixel column SS2, the contour generation unit 3 selects the peak candidate position PP as the peak position PP, which corresponds to the pixel p3 with the smallest distance to the adjacent pixel p1 in pixel column SS1.

[0114] Similarly, distance calculation unit 6 calculates the distance between each pixel p4 and p5 in pixel column SS3 and pixel p3 in the adjacent pixel column SS2. In this example, the distance between pixels p3 and p5 is shorter than the distance between pixels p3 and p4. Therefore, for pixel column SS3, contour generation unit 3 selects the peak candidate position corresponding to pixel p5 as the peak position PP.

[0115] Distance calculation unit 6 calculates the distance between each pixel p6 and p7 in pixel column SS4 and pixel p5 in the adjacent pixel column SS3. In this example, the distance between pixels p5 and p7 is shorter than the distance between pixels p5 and p6. Therefore, for pixel column SS4, contour generation unit 3 selects the peak candidate position corresponding to pixel p7 as the peak position PP. Figure 18 The contour generation unit 3 generates contour data based on the peak position PP selected for each pixel column SS.

[0116] As described above, in this embodiment, when multiple peaks are detected in any pixel column SS, the contour generation unit 3 determines the relative positional relationship between the peak candidate positions in the pixel column SS adjacent to that pixel column SS in the X2 direction and the detected multiple peak candidate positions. When determining the relative positional relationship, the distance calculation unit 6 calculates the distance between each peak candidate position in each pixel column SS and the peak candidate position in the pixel column SS adjacent to that pixel column SS in the X2 direction. The contour generation unit 3 determines the relative positional relationship between the peak candidate positions based on the calculated distances. In this case, the relative positional relationship can be easily determined.

[0117] Although this embodiment has described selecting the peak candidate position PP with the smallest distance from the peak position PP in the adjacent pixel column SS for each pixel column SS, the present invention is not limited thereto. Figure 16 Similar to the variation, the contour acquisition unit 224 may also include a parameter acquisition unit 5. In this case, the contour generation unit 3 selects the peak position PP based on a comprehensive judgment of the distance to the peak position PP in the adjacent pixel column SS calculated by the distance calculation unit 6 and the parameters acquired by the parameter acquisition unit 5.

[0118] [3] Third embodiment

[0119] The differences between the optical displacement meter 500 according to the third embodiment and the optical displacement meter 500 according to the first embodiment will be explained. Figure 20 This is a block diagram illustrating the structure of the contour acquisition unit 224 according to the third embodiment. Figure 20 As shown, in this embodiment, instead of Figure 12 The cluster generation unit 2 and the contour acquisition unit 224 include a pattern generation unit 7 and a related calculation unit 8.

[0120] In the first operating mode, the pattern generation unit 7 generates a geometric pattern based on multiple peak candidate positions detected by the peak detection unit 1. The geometric pattern includes straight lines and arcs, etc. The correlation calculation unit 8 calculates the correlation coefficient between the geometric pattern generated by the pattern generation unit 7 and the multiple peak candidate positions detected by the peak detection unit 1.

[0121] The contour generation unit 3 selects the peak position PP from multiple peak candidate positions of each pixel column SS based on the correlation coefficient calculated by the correlation calculation unit 8. In this embodiment, for each pixel column SS, the peak candidate position with the largest correlation coefficient with the generated geometric pattern is selected as the peak position PP.

[0122] Figure 21A and 21B This is a diagram illustrating the operation of the contour acquisition unit 224 in the first operation mode according to the third embodiment. Figure 20 Peak detection unit 1 detects the peak candidate positions of each pixel column SS. In this example, the detected peak candidate positions are... Figure 13 The candidate peak positions shown are the same.

[0123] like Figure 21A As shown, Figure 20 The pattern generation unit 7 generates a linear geometric pattern based on multiple peak candidate positions detected by the peak detection unit 1. Figure 21A In the example, isolated peak candidate positions that are discontinuous with other peak candidate positions are excluded (with Figure 14In the state of the candidate peak positions corresponding to clusters C2 to C9, geometric patterns are generated.

[0124] then, Figure 20 The relevant calculation unit 8 calculates the pattern generated by the pattern generation unit 7. Figure 21A The geometric pattern and peak detection unit 1 detected Figure 13 The correlation coefficients between multiple peak candidate positions. For each pixel column SS, Figure 20 The contour generation unit 3 selects the candidate peak position PP as the peak position PP, which has the highest correlation coefficient with the generated geometric pattern. Figure 21B In the example, a dot pattern is used to indicate the pixel p of the light-receiving unit 121 corresponding to the selected peak candidate position.

[0125] As described above, in this embodiment, the contour generation unit 3 determines the relative positional relationship between the peak candidate positions in pixel columns SS that are at least adjacent to pixel column SS in the X2 direction and the detected multiple peak candidate positions. When determining the relative positional relationship, the pattern generation unit 7 generates a geometric pattern based on the detected multiple peak candidate positions. The correlation calculation unit 8 calculates the correlation coefficient between the generated geometric pattern and the detected multiple peak candidate positions for each pixel column SS in the multiple pixel columns SS. The relative positional relationship between the peak candidate positions is determined based on the calculated correlation coefficient. In this case, the relative positional relationship can be easily determined.

[0126] Although this embodiment has described selecting the candidate peak position PP with the highest correlation coefficient to the generated geometric pattern for each pixel column SS, the invention is not limited thereto. Figure 16 Similar to the variation, the contour acquisition unit 224 may also include a parameter acquisition unit 5. In this case, the contour generation unit 3 selects the peak position PP based on a comprehensive judgment of the correlation coefficient calculated by the correlation calculation unit 8 and the parameters acquired by the parameter acquisition unit 5.

[0127] [4] Correspondence between the elements of the claims and the elements of the embodiments

[0128] The following will illustrate examples of the correspondence between the elements of the claims and the elements of the embodiments, but the invention is not limited to these examples. Various other elements having the structure or function described in the claims may be used as elements of the claims.

[0129] Workpiece W is an example of the object being measured, optical displacement meter 500 is an example of an optical displacement meter, light projection unit 110 is an example of a light projection unit, X2 direction is an example of a first direction, and Z2 direction is an example of a second direction. Pixel p is an example of a pixel, pixel column SS is an example of a pixel column, light receiving unit 121 is an example of a light receiving unit, and peak detection unit 1 is an example of a peak detection unit.

[0130] Contour generation unit 3 is an example of a contour generation unit, switching unit 225 is an example of a switching unit, parameter acquisition unit 5 is an example of a parameter acquisition unit, and cluster generation unit 2 is an example of a cluster generation unit. Distance calculation unit 6 is an example of a distance calculation unit, pattern generation unit 7 is an example of a pattern generation unit, correlation calculation unit 8 is an example of a correlation calculation unit, and filtering processing unit 4 is an example of a filtering processing unit.

Claims

1. An optical displacement meter that uses optical sectioning, the optical displacement meter being used to measure the contour of a measurement object, the optical displacement meter comprising: A light projection unit is used to illuminate the measurement object using slit light diffused along a first direction or point light scanned along the first direction; The light-receiving unit includes a plurality of pixels arranged along the first direction and a second direction intersecting the first direction, and is used to receive reflected light from various positions of the measurement object along the first direction and output the light-receiving amount distribution. The peak detection unit is used to detect one or more peak candidate positions of light received in the second direction for each pixel column based on multiple light received distributions output from multiple pixel columns arranged along the first direction. A contour generation unit is configured to select the peak position to be used for the contour from the peak candidate positions detected by the peak detection unit for each pixel column, and generate contour data to indicate the contour based on the selected peak position. as well as The filtering processing unit is used to filter the contour data so that the smoothing effect is greater in the parts of the contour where the height change is small than in the parts where the height change is large.

2. The optical displacement meter according to claim 1, in, The filtering unit performs filtering on each pixel column in the multiple pixel columns based on the peak position of the pixel column in the second direction and the peak position of each pixel column in the second direction within a pre-specified specific range.

3. The optical displacement meter according to claim 1, in, The filtering unit performs filtering on each pixel column among multiple pixel columns based on the position of the pixel column in the first direction and the peak position in the second direction, as well as the position of each pixel column in the first direction and the peak position in the second direction within a pre-specified specific range.

4. The optical displacement meter according to claim 1, further comprising: The input setting unit is used to specify the range of contour data to be filtered. The filtering unit performs filtering on the contour data within the range specified by the input setting unit.

5. The optical displacement meter according to claim 1, further comprising: The parameter acquisition unit is used to acquire parameters that indicate the pattern of peaks in the candidate peak positions detected by the peak detection unit. The contour generation unit selects the peak position to be used for the contour from multiple peak candidate positions in each light-receiving distribution based on the parameters obtained by the parameter acquisition unit.

6. The optical displacement meter according to claim 5, in, The parameters acquired by the parameter acquisition unit include the amount of light received by the peak or the width of the peak.

7. The optical displacement meter according to claim 1, further comprising: A measurement processing unit is used to perform measurement processing on the contour data filtered by the filtering processing unit, and to calculate the size or displacement of the measured object; as well as The display processing unit is used to generate image data that indicates the size or displacement of the measured object calculated by the measurement processing unit.

8. A method for measuring the contour of an object, the method comprising: The object to be measured is illuminated by either slit light diffused along a first direction or point light scanned along the first direction. The light receiving unit receives reflected light from various positions of the measurement object along the first direction, wherein the light receiving unit includes a plurality of pixels arranged along the first direction and a second direction intersecting the first direction; The light-receiving distribution is output based on the light-receiving amount output from the pixel column arranged along the first direction; Based on multiple light-receiving distributions output from multiple pixel columns configured along the first direction, one or more peak candidate positions of light-receiving amount in the second direction are detected for each pixel column; Select the peak position to be used for the contour from the peak candidate positions detected for each pixel column; Generate contour data to indicate the contour based on the selected peak position; and The contour data is filtered so that the smoothing effect is greater in the parts of the contour where the height change is smaller than in the parts where the height change is larger.

9. The method according to claim 8, in, Based on the peak position of the pixel column in the second direction and the peak position of each pixel column in the second direction within a pre-specified specific range, filtering is performed on each pixel column in the multiple pixel columns.

10. The method of claim 8, further comprising: The contour data after filtering is then subjected to measurement processing. Calculate the dimensions or displacement of the object being measured; as well as Displays image data used to indicate the calculated dimensions or displacement of the measured object.

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