JP2017161291A - Height data processing device, surface shape measurement device, height data correction method, and program - Google Patents

Abstract

Provided is a technique for appropriately determining a reference plane for tilt correction processing without imposing an excessive burden on an operator. A height data processing device includes a plane extracting means and an inclination correcting means. The plane extracting means 72 extracts one or more planes constituting the surface of the test object 14 based on the height data of the test object 14 which is a measurement target. The inclination correction unit 74 corrects the height data so that the height axis direction matches the normal direction of a reference plane selected from one or more planes extracted by the plane extraction unit 72. [Selection diagram] FIG.

Description

  The present invention relates to a height data processing device, a surface shape measuring device, a height data correction method, and a program.

  Conventionally, a laser scanning confocal microscope apparatus, an apparatus using a fringe projection method, and the like are known as apparatuses for measuring the surface shape of a three-dimensional object in a non-contact manner (hereinafter referred to as a surface shape measuring apparatus).

  When measuring the surface shape of the test object with the laser scanning confocal microscope apparatus, the shallow depth of focus realized by the laser scanning confocal microscope apparatus is used. Specifically, a plurality of confocal images having a shallow depth of focus are acquired while changing the relative distance between the objective lens and the test object in the optical axis direction (also referred to as the Z direction). Then, the surface shape of the entire surface of the test object is measured by obtaining a Z position (that is, a focus position) that gives the maximum luminance at each pixel position from a plurality of confocal images. The surface shape measurement data is also referred to as height data. Even in an apparatus using the fringe projection method, height data is generated from a plurality of images acquired by changing the shooting conditions.

  When analyzing the height data acquired by the surface shape measuring apparatus, an inclination correction process is often performed on the height data before the analysis. This process is a process of correcting the entire height data so that the reference plane is parallel to the XY plane orthogonal to the optical axis of the objective lens. For example, if the height data before correction represents a cross-sectional profile as shown in FIG. 1A, the inclination correction processing is performed as shown in FIG. 1B so that the reference plane RP1 is horizontal. Height data representing a correct cross-sectional profile is generated. By using the height data after correction, the step ST generated between the reference plane RP1 and the plane P2 can be easily analyzed as compared with the case of using the height data before correction. In addition, there are various merits such that it is possible to easily perform a binarization process in which only a portion whose height from the reference plane RP1 is equal to or greater than the threshold Th is extracted from the image.

  Furthermore, the inclination correction process not only facilitates various analyzes performed using the height data, but also contributes to improving the accuracy of the analysis. For this reason, it is particularly effective when high accuracy is required as in the measurement of the surface shape using a laser scanning confocal microscope apparatus.

Japanese Patent No. 3847422

  By the way, in order to perform the inclination correction process, it is necessary to determine a reference plane. As a method for determining the reference plane, the operator of the apparatus designates three or more points from the height data, calculates the least square plane based on the specified points, and uses the calculated least square plane as the reference plane. The method of determining is known.

  In this method, the smaller the number of points specified by the operator, the more easily the results are varied. Depending on the operator's selection, the reference plane may be greatly deviated from the surface of the measurement object. Although it is possible to suppress variation in results by causing the operator to specify more points, the operation of specifying many points is not desirable because it places an excessive burden on the operator.

  In view of the above circumstances, an object of the present invention is to provide a technique for appropriately determining a reference plane for tilt correction processing without excessively burdening an operator.

  One aspect of the present invention is a plane extraction unit that extracts one or more planes constituting a surface of the measurement object based on height data of the measurement object, a height axis direction, and the plane extraction unit. There is provided a height data processing device comprising: inclination correction means for correcting the height data so that the normal direction of the reference plane selected from the one or more planes extracted in step 1 matches.

  In another aspect of the present invention, one or more planes constituting the surface of the measurement object are extracted based on height data of the measurement object, and selected from the height axis direction and the one or more planes. Provided is a height data correction method for correcting the height data so that the normal direction of the reference plane matches.

  According to still another aspect of the present invention, a computer of a surface shape measuring apparatus that measures a surface shape of a measurement object is configured to include at least one of the surfaces of the measurement object based on height data of the measurement object. And a program for functioning as a means for correcting the height data so that a height axis direction matches a normal direction of a reference plane selected from the one or more planes. .

  ADVANTAGE OF THE INVENTION According to this invention, the technique which determines appropriately the reference plane of an inclination correction process can be provided, without imposing an excessive burden on an operator.

It is the figure which illustrated the cross-sectional profile represented by the height data before and behind inclination correction processing. It is the figure which illustrated the composition of confocal microscope device 100 concerning a 1st embodiment. 4 is a diagram illustrating image data of a plurality of confocal images acquired by the confocal microscope apparatus 100. FIG. 6 is a diagram illustrating a luminance change curve generated by the confocal microscope apparatus 100. FIG. It is a functional block diagram of the height data correction device 70 according to the first embodiment. 7 is a flowchart of height data correction processing performed by the height data correction device 70. 5 is a flowchart of plane extraction processing performed by the height data correction device 70. It is the figure which illustrated the omnifocal image. It is the figure which illustrated height histograss. It is the figure which showed the example of a display of the candidate of a reference plane. It is the figure which showed another example of a display of the candidate of a reference plane. It is a figure for demonstrating inclination correction processing. 10 is a flowchart of another plane extraction process performed by the height data correction device 70. It is a functional block diagram of height data amendment device 80 concerning a 2nd embodiment. 7 is a flowchart of height data correction processing performed by the height data correction device 80. 10 is a flowchart of plane selection processing performed by the height data correction device 80. 10 is a flowchart of another plane selection process performed by the height data correction device 80.

[First Embodiment]
FIG. 2 is a diagram illustrating the configuration of the confocal microscope apparatus 100 according to this embodiment. The confocal microscope apparatus 100 is a laser scanning confocal microscope apparatus including the laser 1 and is a surface shape measuring apparatus that measures the three-dimensional shape of the test object 14 in a non-contact manner. The test object 14 is, for example, a semiconductor substrate. First, the configuration of the confocal microscope apparatus 100 will be described with reference to FIG.

  The confocal microscope apparatus 100 includes a confocal microscope main body 20, a control device 30 that controls the confocal microscope main body 20, a computer 40 connected to the control device 30, a display device 50 connected to the computer 40, and an instruction input. Device 60.

  The confocal microscope main body 20 includes a beam splitter 2, a two-dimensional deflector 3, a projection lens 4, a Z scanner 5, an objective lens 7, and an objective lens on the illumination optical path where the laser light emitted from the laser 1 reaches the object 14. A stage 8 on which the test object 14 is arranged is provided.

  The laser 1 is a light source that emits laser light as parallel light. The amount of laser light emitted from the laser 1 is controlled based on an input from the control device 30. Specifically, for example, the amount of light emitted from the laser 1 changes as the drive current of the laser 1 is changed by the control device 30.

  The beam splitter 2 is, for example, a polarization beam splitter or a half mirror. The beam splitter 2 transmits the laser light from the laser 1 and reflects the reflected light from the test object 14.

The two-dimensional deflector 3 is a device that deflects the laser light from the laser 1 in a desired direction, and is a scanner that scans the object 14 in a two-dimensional direction perpendicular to the optical axis 15 of the objective lens 7 with the laser light. is there. The two-dimensional deflector 3 is, for example, a galvanometer mirror, a resonant scanner, an acoustooptic device, or the like disposed at or near a position optically conjugate with the pupil of the objective lens 7. The two-dimensional deflector 3 is configured to deflect laser light independently in the X direction and the Y direction, respectively. The two-dimensional deflector 3 changes the deflection angle θ _{x in} the X direction and the deflection angle θ _y in the Y direction of the laser light based on the deflection timing instruction from the control device 30. In FIG. 2, a plurality of light beams deflection angle theta _x is different is shown.

  The projection lens 4 is a lens that projects the pupil of the objective lens 7 onto the two-dimensional deflector 3 or the vicinity thereof. The projection lens 4 is arranged such that the focal position on the object side of the projection lens 4 is located in the vicinity of the rear focal position 16 of the objective lens 7. The projection lens 4 enlarges the diameter of the laser light, which is parallel light emitted from the laser 1, and makes it incident on the objective lens 7.

  The Z scanner 5 is a device that changes the relative distance between the objective lens 7 and the stage 8. The Z scanner 5 is a direction along the optical axis 15 of the objective lens 7 (hereinafter, optical axis direction, Z direction, or height). This is a scanner that scans in the axial direction. The Z scanner 5 is configured to move in the Z direction. The Z scanner 5 is provided with a displacement meter 6 that measures the amount of displacement caused by the movement of the Z scanner 5 in the Z direction, that is, the amount of change in the relative distance between the objective lens 7 and the stage 8. The displacement meter 6 is, for example, an optical linear encoder. Further, a capacitance type displacement meter and other displacement meters may be used. The displacement amount measured by the displacement meter 6 is output to the control device 30.

  The objective lens 7 is attached to the Z scanner 5 and moves in the Z direction when the Z scanner 5 moves in the Z direction. The test object 14 is arranged near the front focal position of the objective lens 7 on the stage 8. The stage 8 is a movable stage that moves in the X direction and the Y direction orthogonal to the optical axis 15 of the objective lens 7. The stage 8 may be an electric stage or a manual stage.

  The confocal microscope main body 20 further includes an objective lens 7, a Z scanner 5, a projection lens 4, a two-dimensional deflector 3, a beam splitter on the detection optical path where the laser light reflected from the test object 14 reaches the AD converter 13. 2, an imaging lens 9, a confocal stop 10, and a photodetector 11.

  The imaging lens 9, the confocal stop 10, and the photodetector 11 are provided on a reflected light path along which the laser light reflected by the beam splitter 2 travels. The confocal stop 10 is arranged so that a pinhole provided in the confocal stop 10 is located at the focal position of the imaging lens 9. The photodetector 11 disposed at the rear stage of the confocal stop 10 is, for example, a photomultiplier (PMT), an avalanche photodiode (APD), or the like.

  The confocal microscope main body 20 further includes an amplifier 12 that amplifies the analog signal output from the photodetector 11 and an AD converter 13 that converts the analog signal amplified by the amplifier 12 into a digital signal.

  The amplification factor in the amplifier 12 is determined by an input from the control device 30. Specifically, for example, it is determined by the voltage applied to the amplifier 12. Here, an example is shown in which the amplification factor of the analog signal output from the photodetector 11 is changed by an amplifier 12 separate from the photodetector 11. However, the amplification factor of the analog signal may be changed by changing the amplification factor in the photodetector 11, that is, the amplification factor of the analog signal output from the photodetector 11. For example, the control device 30 may change the amplification factor by changing the voltage applied to the photomultiplier or the avalanche photodiode that is the photodetector 11. The AD converter 13 converts the analog signal amplified by the amplifier 12 into, for example, a 12-bit or 16-bit digital signal and outputs the digital signal to the control device 30.

  The confocal microscope main body 20 having the above-described configuration scans the test object 14 under the control of the control device 30, and a signal and a displacement meter according to the amount of reflected light from the test object 14 detected by the photodetector 11. The displacement amount measured in 6 is output to the control device 30.

  The control device 30 generates image data of a confocal image based on a signal from the confocal microscope body 20 and outputs the image data to the computer 40. Further, the displacement amount measured by the displacement meter 6 is also output to the computer 40. Further, the control device 30 controls the confocal microscope main body 20 in accordance with an instruction input to the computer 40 by the microscope operator using the instruction input device 60. For example, the control device 30 controls the two-dimensional deflector 3 and the Z scanner 5 for scanning the test object 14.

  The computer 40 includes an image input unit 41, a storage unit 42, an arithmetic processing unit 43, and an interface unit 44. The image input unit 41 receives input of confocal image data from the control device 30. The storage unit 42 is, for example, a hard disk device or a semiconductor memory. The storage unit 42 stores image data such as confocal images and omnifocal images, and other data. The arithmetic processing unit 43 is, for example, a central processing unit (CPU) or the like, and performs various calculations by executing a program stored in the storage unit 42. For example, the measurement and analysis of the three-dimensional shape (surface height) of the test object 14 is performed based on the image data of the confocal image input from the control device 30 and the amount of displacement in the Z direction. More specifically, the height data of the test object 14 is generated, the generated height data is corrected according to the reference plane, and the corrected new height data is generated, whereby the test object 14 is generated. Measure the three-dimensional shape. Various analyzes are performed based on the corrected height data. The interface unit 44 exchanges necessary data between the computer 40 and other devices.

  The display device 50 is a device that displays a confocal image, an omnifocal image, a three-dimensional image, a reference plane candidate, and the like of the test object 14. The display device 50 is, for example, a liquid crystal display, an organic EL (Electro-Luminescence) display, a CRT (Cathode Ray Tub) display, or the like. The instruction input device 60 is a device for an operator to input an instruction to the computer 40, and is, for example, a keyboard or a mouse. The display device 50 and the instruction input device 60 may be configured integrally with the computer 40 or may be a part of the computer 40.

  As described above, in the confocal microscope apparatus 100, the confocal microscope main body 20 and the control apparatus 30 are image acquisition apparatuses that acquire a confocal image of the test object 14 that is a measurement object. The computer 40 is a height data processing device that generates and corrects height data.

  Next, a method for acquiring a confocal image in the confocal microscope apparatus 100 and generating image data of the confocal image will be described. Laser light emitted from the laser 1 passes through the beam splitter 2 and enters the projection lens 4 via the two-dimensional deflector 3. The laser beam, which is parallel light incident on the projection lens 4, has its beam diameter enlarged by the projection lens 4 and enters the objective lens 7. Thereafter, the laser light is condensed in a spot shape on the front focal plane of the objective lens 7 by the refractive power of the objective lens 7, and is irradiated on the test object 14 disposed in the vicinity of the front focal position of the objective lens 7. .

The condensing position of the laser beam on the front focal plane is determined by the direction in which the laser beam is deflected by the two-dimensional deflector 3. Thus, by controlling the deflection angle theta _x and deflection angle theta _y of the laser beam in two-dimensional deflector 3, the condensing position of the laser light changes in the X direction and the Y direction on the focal plane. In the confocal microscope apparatus 100, for example, the control device 30 controls the two-dimensional deflector 3 so that raster scanning is performed. Thereby, the test object 14 is scanned two-dimensionally.

  The laser beam reflected from the test object 14 enters the two-dimensional deflector 3 through the objective lens 7 and the projection lens 4. The laser beam deflected toward the beam splitter 2 by the two-dimensional deflector 3 is reflected by the beam splitter 2 and enters the confocal stop 10 via the imaging lens 9. Only the laser beam that has passed through the pinhole provided in the confocal stop 10 is detected by the photodetector 11.

  The photodetector 11 outputs an analog signal corresponding to the detected amount of laser light to the amplifier 12. The AD converter 13 converts the analog signal amplified by the amplifier 12 into a digital signal and outputs the digital signal to the control device 30. The digital signal input from the AD converter 13 to the control device 30 represents a luminance value corresponding to the current laser beam condensing position.

  In the confocal microscope apparatus 100, the control device 30 controls the two-dimensional deflector 3 to acquire a luminance value for each condensing position changed, and the acquired luminance value is two-dimensionally mapped, so that a confocal image is obtained. Is acquired. In other words, the control device 30 sets the luminance value acquired for each condensing position to the pixel value of the pixel corresponding to the condensing position, thereby generating confocal image data. The confocal image data generated by the control device 30 is output to the image input unit 41 of the computer 40 and then displayed on the display device 50.

  Next, a height data generation method and an omnifocal image acquisition method in the confocal microscope apparatus 100 will be described with reference to FIGS. 3 and 4. FIG. 3 is a diagram illustrating image data of a plurality of confocal images acquired by the confocal microscope apparatus 100. FIG. 4 is a diagram illustrating a luminance change curve generated by the confocal microscope apparatus 100.

The control device 30 performs Z scanning for changing the relative distance between the objective lens 7 and the stage 8 by the Z scanner 5 and acquires a confocal image at each Z position. As a result, a plurality of confocal images acquired at different Z positions are acquired, and image data of the plurality of confocal images is stored in the storage unit 42 of the computer 40. FIG. 3 illustrates image data of k confocal images stored in the storage unit 42. Each confocal image is assigned an image number from 1 to k (k is a natural number). Luminance value of each pixel of the confocal image of the image number n is represented by luminance values I _n (x, y). Here, x and y indicate the position in the X direction (X position) and the position in the Y direction (Y position) of the target pixel.

  When the relative distance is changed, the amount of light reflected from the point on the test object 14 detected by the photodetector 11 (that is, the luminance) changes. The locus of this luminance change has a generally determined shape depending on the numerical aperture of the objective lens 7, the wavelength of the laser light, and the size of the aperture (pinhole) of the confocal stop 10. Hereinafter, this locus of luminance change is referred to as a luminance change curve. The arithmetic processing unit 43 estimates a luminance change curve for each XY position based on the image data of a plurality of confocal images acquired at different Z positions.

  A case where a luminance change curve at a certain position (x0, y0) is estimated will be described with reference to FIG. First, the luminance value of the pixel at the position (x0, y0) is acquired from each of the acquired k confocal images. The luminance values are plotted on an I-Z space where the vertical axis indicates the luminance value (I) and the horizontal axis indicates the Z position (Z). Black circles shown in FIG. 4 indicate plotted points. Note that the Z positions of these points are determined by the amount of displacement received from the displacement meter 6 when acquiring the confocal image. After that, tens of points are extracted from the plotted points indicating the highest luminance value and several points in the vicinity thereof. Further, the approximate curve AC is calculated using the extracted point data (luminance value and Z position), and the calculated approximate curve AC is estimated as the luminance change curve. In calculating the approximate curve, a quadratic polynomial, a higher order polynomial, a Gaussian curve, or the like is used as the curve to be approximated. As an approximation method used, the least square method is typical.

  The arithmetic processing unit 43 further estimates a peak luminance value having the maximum luminance value from the estimated luminance change curve and a Z position (hereinafter referred to as a peak Z position) from which the peak luminance value is obtained. This process is also performed for each XY position, as in the luminance change curve estimation process. As a result, a peak Z position distribution Zp (x, y) indicating a set of peak Z positions at all XY positions, and a peak luminance value distribution Ip (x, y) indicating a set of peak luminance values at all XY positions. ) Is calculated.

  In the confocal microscope apparatus 100, the luminance value is maximized when the surface of the test object 14 is at the condensing position of the laser beam (in other words, the position of the surface of the test object 14 is the in-focus position). Accordingly, the peak Z position distribution Zp (x, y) is height data indicating the height distribution (that is, the surface shape) of the surface of the test object 14. The computer 40 can generate the height data of the test object 14 by the above-described method for calculating the peak Z position distribution Zp (x, y).

  The peak luminance value distribution Ip (x, y) calculated together with the peak Z position distribution Zp (x, y) is a set of luminance values at the peak Z position that is the in-focus position. Accordingly, the peak luminance value distribution Ip (x, y) is image data itself of an omnifocal image focused on all positions on the surface of the test object 14. For this reason, the computer 40 can acquire the omnifocal image and generate image data of the omnifocal image by the above-described method of calculating the peak luminance value distribution Ip (x, y).

  Next, a method for correcting the height data by appropriately determining the reference plane without excessively burdening the operator will be described. FIG. 5 is a functional block diagram of the height data correction device 70. As shown in FIG. 5, the height data correction device 70, which is a computer 40, includes height data generation means 71, plane extraction means 72, plane selection means 73, inclination correction means 74, and display control means 75. I have. These means are realized by the arithmetic processing unit 43 of the computer 40 executing a predetermined program.

  The height data generation means 71 generates height data and omnifocal image data of the test object 14 from the image data of a plurality of confocal images acquired by the image acquisition device. The plane extraction unit 72 extracts one or more planes constituting the surface of the test object 14 based on the height data of the test object 14 generated by the height data generation unit 71. The plane selection unit 73 selects a reference plane from one plane extracted by the plane extraction unit 72 according to an input designating the reference plane from the input device 60. The inclination correction unit 74 corrects the height data generated by the height data generation unit 71 according to the reference plane selected by the plane selection unit 73. The display control means 75 causes the display device 50 to display one or more planes extracted by the plane extraction means 72 as reference plane candidates.

  FIG. 6 is a flowchart of height data correction processing performed by the height data correction device 70. FIG. 7 is a flowchart of the plane extraction process performed by the height data correction device 70. When the height data correction process shown in FIG. 6 is started by the height data correction device 70, the plane extraction unit 72 generates one or more planes based on the height data generated by the height data generation unit 71. Plane extraction processing is performed (step S10).

  In the plane extraction process, as shown in FIG. 7, first, the plane extraction means 72 identifies abnormal data in the height data (step S11) and excludes it from the processing target of the height histogram creation process described later. The method for identifying abnormal data is not particularly limited, and any algorithm can be adopted.

  Next, the plane extraction means 72 creates a height histogram from the height data from which abnormal data has been excluded (step S12). FIG. 9 is an example of a height histogram generated from the height data of the test object 14 represented by the omnifocal image shown in FIG. When the height histogram is created, the plane extracting means 72 extracts one or more planes as reference plane candidates based on the height histogram (step S13). For example, the plane extraction unit 72 calculates a plane from the height data by calculating a plane corresponding to each peak (peak) appearing in the height histogram using a large number of data included in each peak by the least square method. Extract. When the height histogram shown in FIG. 9 is used, four peaks (peaks A1 to A4) are specified, and corresponding four planes (plane B1 to plane B4) are extracted.

  When one or more planes are extracted by the plane extraction process, the display control means 75 causes the display device 50 to display the extracted planes as reference plane candidates (step S20). FIG. 10 shows an example in which the four planes B1 to B4 extracted using the height histogram shown in FIG. 9 are separately displayed as reference plane candidates. In FIGS. 10A to 10D, the extracted planes are shaded so that they can be recognized as candidates for the reference plane (that is, candidate planes).

  The method for displaying the extracted plane is not particularly limited. For example, all candidate surfaces may be displayed in a single image so that they can be identified by changing the color for each candidate surface. FIG. 10 shows an example in which all the positions on the omnifocal image are included in any plane, but the extracted plane may not cover all the positions in the image. Moreover, although the example which displays a candidate surface in a two-dimensional image was shown in FIG. 10, you may display a candidate surface in a three-dimensional image. For example, as shown in FIG. 11, candidate planes C1 to C4 may be displayed in the three-dimensional image of the test object 14.

  When the operator designates the reference plane from the candidate plane displayed on the display device 50 using the input device 60, the plane selection unit 73 selects the reference plane from the candidate plane according to the input designating the reference plane from the input device 60. Select (step S30).

  When the reference plane is selected, the inclination correction unit 74 executes an inclination correction process for correcting the height data so that the height axis direction matches the normal direction of the selected reference plane (step S40). ). Specifically, the inclination correction unit 74 is generated by the height data generation unit 71 so that the normal direction of the reference plane faces the height axis direction (that is, the z direction) in the corrected height data. Correct height data. The height axis direction is a direction serving as a reference for the height represented by the height data, is the z direction of the confocal microscope apparatus 100, and is the optical axis direction of the objective lens 7. Therefore, in other words, the inclination correcting means 74 is when the height axis direction and the normal direction of the reference plane do not coincide as shown in FIG. 12A (that is, the reference plane is not parallel to the xy plane). As shown in FIG. 12B, the height data is corrected so that the direction of the height axis coincides with the normal direction of the reference plane (that is, the reference plane is parallel to the xy plane). As a result, the inclination of the reference plane (more specifically, the inclination of the reference plane with respect to the xy plane) is corrected. The generated height data after correction may be stored in the storage unit 42 and displayed on the display device 50 by the display control means 75. The inclination of the reference plane and the normal direction of the reference plane are calculated using height data at as many points as possible in the selected reference plane.

  According to the height data correction process described above, the operator can specify the reference plane from among the reference plane candidates displayed on the display device 50 after the height data is generated, and the inclination with respect to the reference plane can be increased. Corrected height data can be obtained. Therefore, the inclination correction process can be performed by determining the reference plane without imposing a burden on the operator. Further, the reference plane is selected from candidate planes extracted by processing using the height histogram. Further, the inclination of the selected reference plane is calculated by the computer 40 from the height data at many points. For this reason, it is possible to suppress variation in the reference plane or the inclination of the reference plane as compared with the conventional method, and the reference plane can be determined appropriately. Accordingly, it is possible to avoid such a situation that the result is different every time the analysis is performed.

  FIG. 13 is a flowchart of another plane extraction process performed by the height data correction device 70. Although FIG. 7 shows an example in which height data is extracted from one or more planes using a height histogram, the method of extracting planes is not limited to using a height histogram, and any method is adopted. Can do. For example, the plane may be extracted by the method shown in FIG.

  First, the plane extraction means 72 identifies abnormal data in the height data (step S11). This process is the same as step S11 in FIG. Thereafter, the plane extraction means 72 may extract one or more planes using a sample consensus method (step S14). Regarding the sample consensus method, for example, Non-Patent Document 1 (Martin A. Fischler and Robert C. Bolles (June 1981). "Random Sample Consensus: A Paradigm for Model Fitting with Applications to Image Analysis and Automated Cartography". Comm. Of the ACM 24).

  Even if the plane extraction process shown in FIG. 13 is performed instead of the plane extraction process shown in FIG. 7, the reference plane for the inclination correction process can be appropriately determined without imposing an excessive burden on the operator.

[Second Embodiment]
FIG. 14 is a functional block diagram of the height data correction device 80 according to the present embodiment. Note that the configuration of the surface shape measuring apparatus according to the present embodiment is the same as the configuration of the confocal microscope apparatus 100 according to the first embodiment. The height data correction device 80 which is the computer 40 shown in FIG. 14 is provided with a plane selection unit 83 instead of the plane selection unit 73 and a display control unit 85 instead of the display control unit 75 in FIG. This is different from the height data correction device 70 shown. Other points are the same as those of the height data correction device 70.

  The plane selection unit 83 is different from the plane selection unit 73 in that the plane selection unit 83 does not select the reference plane according to the input from the operator but automatically selects the reference plane according to a predetermined reference based on the height data. The display control unit 85 is different from the plane selection unit 83 in that the reference plane candidate is not displayed on the display device 50. The means constituting the height data correction device 80 is realized by the arithmetic processing unit 43 of the computer 40 executing a predetermined program.

  FIG. 15 is a flowchart of height data correction processing performed by the height data correction device 80. FIG. 16 is a flowchart of the plane selection process performed by the height data correction device 80.

  When the height data correction process shown in FIG. 15 is started by the height data correction device 80, the plane extraction unit 72 generates one or more planes based on the height data generated by the height data generation unit 71. Plane extraction processing is performed (step S110). This plane extraction process is the same as the plane extraction process in step S10 of FIG. For example, a plane is extracted using a height histogram or a sample consensus method.

  When one or more planes (candidate planes) are extracted by the plane extraction process, the plane selection unit 83 selects a reference plane from the candidate planes based on the height data generated by the height data generation unit 71. A plane selection process is executed (step S120).

  In the plane selection process, as shown in FIG. 16, the plane selection unit 83 first calculates the area of the plane for each plane extracted by the plane extraction unit 72 (step S121). And based on the area of the candidate surface extracted by the plane extraction means 72, it selects as a reference plane (step S122). Here, for example, a plane having the largest area may be selected.

  When the reference plane is selected, the inclination correction unit 74 executes an inclination correction process for correcting the height data so that the height axis direction matches the normal direction of the selected reference plane (step S130). . This inclination correction process is the same as the inclination correction process in step S40 of FIG.

  Even in the height data correction process described above, as in the height data correction process of the first embodiment, the reference plane for the inclination correction process is appropriately determined without imposing an excessive burden on the operator. Can do. In the present embodiment, since the height data correction device 80 automatically determines the reference plane, it is possible to further reduce the burden on the operator and to further suppress the variation in results. .

  FIG. 17 is a flowchart of another plane selection process performed by the height data correction device 80. FIG. 16 shows an example in which the reference plane is selected using the area of the plane calculated from the height data. However, the method of selecting the reference plane is not limited to using the area, and any method can be adopted. . For example, the reference plane may be selected by the method shown in FIG.

  First, the plane selection unit 83 calculates the average height of each plane extracted by the plane extraction unit 72 (step S123). And based on the average height of the candidate surface extracted by the plane extraction means 72, it selects as a reference | standard plane (step S124). Here, according to the setting selected beforehand, the plane with the highest average height may be selected, for example, and the lowest plane may be selected. Instead of the average height, for example, the plane may be selected based on another height such as a median height.

  Even if the plane selection process shown in FIG. 17 is performed instead of the plane selection process shown in FIG. 16, the reference plane for the inclination correction process can be appropriately determined without imposing an excessive burden on the operator.

  The embodiments described above are specific examples for facilitating understanding of the invention, and the present invention is not limited to the embodiments described above. The height data processing device, the surface shape measuring device, the height data correcting method, and the program of the present invention can be variously modified and changed within the scope described in the claims. For example, although FIG. 2 illustrates a confocal microscope apparatus as an example of the surface shape measuring apparatus, the surface shape measuring apparatus may be an apparatus using a fringe projection method, for example.

DESCRIPTION OF SYMBOLS 1 ... Laser, 2 ... Beam splitter, 3 ... Two-dimensional deflector, 4 ... Projection lens, 5 ... Z scanner, 6 ... Displacement meter, 7 ... Objective lens, DESCRIPTION OF SYMBOLS 8 ... Stage, 9 ... Imaging lens, 10 ... Confocal stop, 11 ... Optical detector, 12 ... Amplifier, 13 ... AD converter, 14 ... Test 15 ... optical axis, 16 ... back focal position, 20 ... confocal microscope body, 30 ... control device, 40 ... computer, 41 ... image input unit, 42. ..Storage unit 43... Arithmetic processing unit 44... Interface unit 50... Display device 60 .. input device 70... 80 height data correction device 71. Height data generation means, 72 ... plane extraction means, 73, 83 ... plane selection means, 74 ... inclination correction means, 5,85 ... display control means, 100 ... confocal microscope

Claims (11)

Plane extraction means for extracting one or more planes constituting the surface of the measurement object based on height data of the measurement object;
Inclination correction means for correcting the height data so that a height axis direction matches a normal direction of a reference plane selected from the one or more planes extracted by the plane extraction means; A height data processing apparatus comprising: The height data processing apparatus according to claim 1, further comprising:
A height data processing apparatus comprising plane selection means for selecting the reference plane based on the area of the one or more planes extracted by the plane extraction means. The height data processing apparatus according to claim 1, further comprising:
A height data processing apparatus comprising plane selection means for selecting the reference plane based on the height of the one or more planes extracted by the plane extraction means. The height data processing apparatus according to claim 1, further comprising:
A height data processing apparatus comprising plane selection means for selecting the reference plane from the one or more planes extracted by the plane extraction means in accordance with an input designating the reference plane. In the height data processing device according to any one of claims 1 to 4,
The height data processing device, wherein the plane extraction means extracts the one or more planes based on a height histogram generated from the height data. In the height data processing device according to any one of claims 1 to 4,
The height data processing apparatus, wherein the plane extraction means extracts the one or more planes using a sample consensus method. An image acquisition device for acquiring a plurality of images of the measurement object;
A height data processing device according to any one of claims 1 to 6,
The height data processing device further includes height data generation means for generating height data of the measurement object from the plurality of images of the measurement object acquired by the image acquisition device,
The surface shape measuring apparatus, wherein the inclination correcting unit corrects the height data generated by the height data generating unit. In the surface shape measuring apparatus according to claim 7,
The surface shape measurement device, wherein the image acquisition device acquires a confocal image of the measurement object. In the surface shape measuring apparatus according to claim 7 or 8,
The height data processing device further includes a display control unit that causes the display device to display the one or more planes extracted by the plane extraction unit as candidates for the reference plane. . Based on the height data of the measurement object, one or more planes constituting the surface of the measurement object are extracted,
A height data correction method, wherein the height data is corrected so that a height axis direction and a normal direction of a reference plane selected from the one or more planes coincide with each other. A computer of a surface shape measuring device for measuring the surface shape of a measurement object,
Means for extracting one or more planes constituting the surface of the measurement object based on the height data of the measurement object;
Means for correcting the height data such that a height axis direction matches a normal direction of a reference plane selected from the one or more planes;
A program characterized by functioning as