Shape measuring device and calibration method of shape measuring device

Abstract

To provide a shape measuring device capable of calibrating the quantity of light, and to provide a calibration method of the shape measuring device.SOLUTION: A shape measuring device 1000 includes: an illumination section; an imaging section; and an image processing section for obtaining a contour shape of a measurement object on the basis of a shadow image of the measurement object generated by imaging the shade of the measurement object formed by illumination light applied from the illumination section by the imaging section while the plate-shaped measurement object is disposed between the illumination section and the imaging section in the case of measurement. The shape measuring device 1000 includes: a dimming filter section 2 disposed between the illumination section and the imaging section in the case of calibration; and a calibration section 33 for calibrating the quantity of light of illumination light applied from the illumination section on the basis of the quantity of received light received from the imaging section via the dimming filter section 2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a shape measuring device that measures the contour shape of a plate-shaped measurement target using illumination light, and a method for calibrating the shape measuring device. [Background technology]

[0002] Conventionally, as disclosed in Patent Document 1, for example, there has been known a shape measuring device that irradiates a parallel light through a measurement object toward an image sensor and measures the shape of the measurement object based on an image of the measurement object projected onto the image sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-145487 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the object to be measured is a long member in the direction of travel of the parallel light, diffraction fringes may occur. When the diffraction fringes occur, the image of the object to be measured and the image of the diffraction fringes are also captured in the image, causing an error in the shape of the measurement result. For this reason, it is considered that the background of the image is made white by saturating the amount of light received by the image sensor. However, this method exceeds the dynamic range of the image sensor, so the amount of light of the parallel light cannot be adjusted to a set value based on the output of the image sensor, and calibration is not possible.

[0005] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a shape measuring device capable of calibrating the amount of light and a method for calibrating a shape measuring device. [Means for solving the problem]

[0006] As a result of various studies, the inventors of the present invention have found that the above object can be achieved by the present invention described below. That is, a shape measuring device according to one aspect of the present invention is a device including an illumination unit, an imaging unit, and an image processing unit that, in the case of measurement, a plate-shaped measurement target is placed between the illumination unit and the imaging unit, and that determines a contour shape of the measurement target based on a shadow image of the measurement target generated by imaging a shadow of the measurement target formed by illumination light irradiated from the illumination unit by the imaging unit, and that, in the case of calibration, includes a neutral density filter unit that is placed between the illumination unit and the imaging unit, and a calibration unit that calibrates the amount of illumination light irradiated from the illumination unit based on the amount of light received by the imaging unit via the neutral density filter unit.

[0007] Such a shape measuring device is equipped with a neutral density filter section that reduces the amount of incident light before outputting it. Therefore, even when calibration is performed by adjusting the amount of illumination light irradiated from the illumination section to a set value that exceeds the dynamic range of the imaging section, the amount of light can be calibrated by attenuating the light using the neutral density filter section so that it is within the dynamic range of the imaging section.

[0008] In another aspect, in the above-mentioned shape measuring device, the calibration unit calibrates the amount of illumination light irradiated from the illumination unit by adjusting the illumination unit so that the amount of light received by the imaging unit becomes a predetermined light amount that has been set in advance.

[0009] This makes it possible to provide a shape measuring device that calibrates the amount of illumination light irradiated from the illumination unit so that the amount of light received by the imaging unit becomes a predetermined light amount that has been set in advance.

[0010] In another aspect, the above-mentioned shape measuring devices further include an alarm unit that issues an alarm to the outside when the current value of the current flowing through the illumination unit after the calibration exceeds a threshold value that is preset based on the maximum rated current value of the illumination unit.

[0011] The amount of illumination light emitted from the illumination unit generally decreases with age. Therefore, the current value of the current flowing through the illumination unit is increased to compensate for the reduced amount of light. Eventually, the current value of the current flowing through the illumination unit exceeds the maximum rated current value of the illumination unit, causing the illumination unit to break down. When the current value exceeds a threshold, the shape measurement device issues an alarm to the outside, allowing the illumination unit to take action, such as replacing the light-emitting element, before the illumination unit breaks down.

[0012] In another aspect, in these above-mentioned shape measurement devices, the neutral density filter section includes a neutral density filter and a moving drive section that moves the neutral density filter between a calibration position and a retracted position, the calibration position being a position where the neutral density filter is disposed between the illumination section and the imaging section, and the retracted position being a position where the neutral density filter is not disposed between the illumination section and the imaging section.

[0013] Such a shape measuring device is equipped with a movement drive unit that moves the light-attenuating filter between a calibration position and a retracted position, so that the light-attenuating filter can be automatically moved between the calibration position and the retracted position for both calibration and measurement.

[0014] A calibration method for a shape measuring device according to another aspect of the present invention is a calibration method for a shape measuring device comprising an illumination unit, an imaging unit, and an image processing unit in which, during measurement, a plate-shaped measurement object is placed between the illumination unit and the imaging unit, and a contour shape of the measurement object is determined based on a shadow image of the measurement object generated by imaging the shadow of the measurement object formed by illumination light irradiated from the illumination unit by the imaging unit, the method comprising, during calibration, a placement step of placing a neutral density filter between the illumination unit and the imaging unit, and a calibration step of calibrating the amount of illumination light irradiated from the illumination unit based on the amount of light received by the imaging unit via the neutral density filter.

[0015] In a calibration method for such a shape measuring device, a neutral density filter that reduces the amount of incident light and emits it is placed between the illumination unit and the imaging unit during calibration. Therefore, even when calibration is performed by adjusting the amount of illumination light irradiated from the illumination unit to a set value that exceeds the dynamic range of the imaging unit, the amount of light can be calibrated by reducing the light using the neutral density filter so that it is within the dynamic range of the imaging unit.

[0016] In another aspect, in the method for calibrating a shape measuring instrument described above, the measurement object is a disk-shaped member, and the contour shape is a contour shape in a thickness direction of the disk-shaped member.

[0017] This provides a method for calibrating a shape measuring instrument that measures the contour shape of a disk-shaped member in the thickness direction.

[0018] In another aspect, in the method for calibrating a shape measuring instrument described above, the measurement object is a disk-shaped member, and the contour shape is a contour shape in a circumferential direction of the disk-shaped member.

[0019] This provides a method for calibrating a shape measuring instrument that measures the contour shape of a disk-shaped member in the circumferential direction.

[0020] In another aspect, in the above-mentioned method for calibrating a shape measuring device, the measurement object is a circular plate-shaped member having a notch formed at a predetermined position in the circumferential direction, and the contour shape is the contour shape of the notch.

[0021] This provides a method for calibrating a shape measuring device that measures the contour shape of a notch. Effect of the Invention

[0022] The shape measuring device and the method for calibrating the shape measuring device according to the present invention are capable of calibrating the amount of light. [Brief description of the drawings]

[0023] [Figure 1]1 is a block diagram showing a configuration of a shape measuring device according to an embodiment. [Diagram 2] 5A and 5B are diagrams for explaining a retracted position of a neutral density filter in the shape measuring instrument. [Diagram 3] 5A and 5B are diagrams for explaining a calibration position of a neutral density filter in the shape measuring instrument. [Figure 4] 4A to 4C are diagrams for explaining a contour shape measured by the shape measuring device as an example. [Diagram 5] 4 is a flowchart showing the operation of the shape measuring device with respect to calibration. [Figure 6] 13A and 13B are diagrams for explaining a shape measuring instrument of a third modified embodiment. [Figure 7] 13A to 13C are diagrams for explaining a measurement target to be measured by the shape measuring instrument of the third modified embodiment. [Figure 8] 11A to 11C are diagrams for explaining a contour shape measured by the shape measuring apparatus of the third modified embodiment, as an example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments. In addition, configurations with the same reference numerals in each drawing indicate that they are the same configurations, and their description will be omitted as appropriate. In this specification, when referring to a general term, a reference numeral without a subscript is used, and when referring to an individual configuration, a reference numeral with a subscript is used.

[0025] The shape measuring device in the embodiment is a device including an illumination unit, an imaging unit, and an image processing unit that, in the case of measurement, a plate-shaped measurement target is placed between the illumination unit and the imaging unit, and the image processing unit obtains a contour shape of the measurement target based on a shadow image of the measurement target generated by imaging the shadow of the measurement target formed by the illumination light irradiated from the illumination unit. In the case of calibration, the shape measuring device includes a neutral density filter unit that is placed between the illumination unit and the imaging unit, and a calibration unit that calibrates the amount of illumination light irradiated from the illumination unit based on the amount of light received by the imaging unit through the neutral density filter unit. Hereinafter, such a shape measuring device and a calibration method for a shape measuring device implemented therein will be described in more detail.

[0026] Fig. 1 is a block diagram showing a configuration of a shape measuring device in an embodiment. Fig. 2 is a diagram for explaining a retracted position of a neutral density filter in the shape measuring device. Fig. 3 is a diagram for explaining a calibration position of a neutral density filter in the shape measuring device. Fig. 4 is a diagram for explaining a contour shape measured by the shape measuring device as an example.

[0027] The shape measuring device 1000 includes, for example, a first contour shape measuring unit 1, a first neutral density filter unit 2, a control processing unit 3, an input unit 4, an output unit 5, an interface unit (IF unit) 6, and a memory unit 7, as shown in Figures 1 to 3.

[0028] The first contour shape measuring unit 1 is an apparatus including an illumination unit, an imaging unit, and an image processing unit that, in the case of measurement, a plate-shaped measurement target WA is disposed between the illumination unit and the imaging unit, and that obtains the contour shape of the measurement target WA based on a shadow image of the measurement target WA generated by imaging the shadow of the measurement target WA formed by the illumination light irradiated from the illumination unit using the imaging unit. More specifically, in this embodiment, the first contour shape measuring unit 1 is an apparatus that measures the contour shape of the measurement target WA based on a shadow image that captures a shadow of the peripheral part generated by applying light to the peripheral part of the measurement target WA from a tangential direction of the outer periphery. The measurement target WA is, for example, a disk-shaped member, and the contour shape is, for example, a contour shape in the thickness direction of the disk-shaped member (outer contour shape viewed from a horizontal direction (side surface) perpendicular to the normal direction of the disk) measured based on a shadow image SWA in the thickness direction as shown in FIG. 4. The measurement object WA is placed on a rotating stage (turntable) not shown, and the first contour shape measuring unit 1 rotates the measurement object WA sequentially at predetermined angular intervals (sampling intervals) using the rotating stage, and measures each contour shape viewed from the side at each measurement location (sampling point) in the circumferential direction. The first contour shape measuring unit 1 includes, for example, a first measurement unit 11 and a first shape calculation unit 12 (32).

[0029] The first measurement unit 11 is connected to the control processing unit 3, and is a device that generates a shadow of the peripheral portion by applying light to the peripheral portion of the measurement target WA from a tangential direction of the outer periphery according to the control of the control processing unit 3, and captures the generated shadow of the peripheral portion. For example, as shown in Figs. 2 and 3, such a first measurement unit 11 includes an illumination unit (first illumination unit) 111, an illumination optical system 112, a light receiving optical system 113, and an imaging unit 114. The first illumination unit 111 is connected to the control processing unit 3, and emits illumination light according to the control of the control processing unit 3, and is configured with a light source such as a white light emitting diode. The illumination optical system 112 collimates the illumination light irradiated (emitted) from the first illumination unit 111 into parallel light, and is configured with, for example, one or more lenses. The light receiving optical system 113 forms an optical image of a shadow of the peripheral portion, which is generated by applying the parallel illumination light to the peripheral portion of the measurement target WA, on an imaging surface (light receiving surface) of the imaging unit 114, and is configured with, for example, one or more lenses. The imaging unit 114 is connected to the control processing unit 3, and converts the optical image of the shadow of the peripheral portion formed on the imaging surface into an electrical signal according to the control of the control processing unit 3, and is configured with, for example, a CCD type area image sensor or a CMOS type area image sensor. The imaging unit 114 outputs data (shadow data) obtained by this imaging to the control processing unit 3. The first illumination unit 111, the illumination optical system 112, the light receiving optical system 113, and the imaging unit 114 are arranged in this order so that their optical axes coincide with each other.

[0030] In this embodiment, the first shape calculation unit 12 (32) is functionally configured in the control processing unit 3 as described later, and performs image processing (first image processing) on ​​the output (the shadow data) of the imaging unit 114 to generate shadow image data that is data representing an image of the shadow (shadow image) of the peripheral portion, and performs image processing (second image processing) on ​​the generated shadow image data to obtain the contour shape of the measurement target WA. The second image processing includes a 21st image processing for extracting edges using an edge filter such as a Sobel filter, a 22nd image processing for removing noise from the edges extracted in the 21st image processing using a preset brightness threshold, and a 23rd image processing for obtaining a curve that fits the edges after noise removal in the 22nd image processing as the shadow contour shape in sub-pixel units.

[0031] In this embodiment, in order to remove the influence of diffraction fringes by making the background of the image white by saturating the amount of light received by the image sensor, the first illumination unit 111 irradiates illumination light with an amount of light of a preset value SV that exceeds the dynamic range DR of the area image sensor in the imaging unit 114. If the dynamic range DR of the area image sensor in the imaging unit 114 is 0≦DR≦DRu, then DRu <SVである。

[0032] The first neutral density filter unit 2 is a device that is disposed between the illumination unit 111 and the imaging unit 114 in the case of calibration, and reduces (diminishes) the amount of incident light before emitting it. More specifically, in this embodiment, the first neutral density filter unit 2 includes a neutral density filter 21 and a movement drive unit 22, as shown in Figs. 2 and 3.

[0033] The neutral density filter (ND filter) 21 is an optical element that reduces (attenuates) the amount of incident light and emits it. Any optical filter can be used for the neutral density filter 21 as long as it can reduce the amount of incident light. For example, the neutral density filter 21 can be an optical filter in which a metal thin film is laminated on a glass substrate, an optical filter in which a light absorbing material is mixed in a glass substrate or a resin substrate, a so-called frosted glass optical filter, or an optical filter in which a dielectric multilayer film is laminated on a glass substrate. The neutral density filter 21 may or may not have a wavelength-dependent light blocking range, and it is sufficient that it can attenuate the wavelength of the illumination light irradiated from the first illumination unit 111. The transmittance RV (0≦RV≦1), which is the ratio of transmitted light to incident light in the neutral density filter 21, is appropriately set so that the amount of light of a set value SV that exceeds the dynamic range DR of the area image sensor in the imaging unit 114 in the case of measurement is reduced to the amount of light within the dynamic range DR of the area image sensor in the case of calibration (0≦SV×RV≦DR).

[0034] The movement drive unit 22 is connected to the control processing unit 3, and is a device that moves the neutral density filter 21 between a calibration position and a retracted position according to the control of the control processing unit 3. The calibration position is a position where the neutral density filter 21 is arranged between the first illumination unit 111 and the imaging unit 114, as shown in FIG. 3, and is a position where the neutral density filter 21 is located in the case of calibration. The retracted position is a position where the neutral density filter is not arranged between the first illumination unit 111 and the imaging unit, as shown in FIG. 2, and is a position where the neutral density filter 21 is located in the case of measurement. That is, the calibration position is a position where the illumination light irradiated from the first illumination unit 111 is received by the imaging unit 114 via the neutral density filter 21, and the retracted position is a position where the illumination light irradiated from the first illumination unit 111 is received by the imaging unit 114 without passing through the neutral density filter 21. In the case of calibration, the measurement target WA may or may not be placed, but the measurement target WA that is not placed is shown by a dashed line in Fig. 3. By overlapping the measurement target WA shown in Fig. 2 with the measurement target WA shown by the dashed line in Fig. 3, the calibration position and the retracted position can be compared, and the difference between these positions can be recognized.

[0035] The moving drive unit 22 may be any device that can move the neutral density filter 21 between the calibration position and the retracted position, and the moving drive unit 22 may be, for example, a hydraulic cylinder or an electric cylinder. In this embodiment, the moving drive unit 22 is an electric cylinder 22, and the neutral density filter 21 is attached to its piston rod 22a. Alternatively, the moving drive unit 22 may be a so-called rack and pinion. The neutral density filter 21 is attached to the rack, and the pinion is driven by a motor. In the above description, the neutral density filter 21 is moved between the calibration position and the retracted position on a straight track, but the neutral density filter 21 may be moved between the calibration position and the retracted position on a curved track. In this case, for example, the retracted position is set to a position rotated 90 degrees clockwise or counterclockwise from the calibration position, and the moving drive unit 22 is configured to include, for example, a reducer and a motor that rotate and move the neutral density filter 21.

[0036] The input unit 4 is connected to the control processing unit 3 and is a device for inputting various commands, such as a command to start measurement, and various data required for operating the shape measuring device 1000, such as the name of a measurement object, to the shape measuring device 1000, and is, for example, a keyboard, a mouse, and a plurality of input switches to which predetermined functions are assigned. The output unit 5 is connected to the control processing unit 3 and is a device for outputting commands, data, contour shapes, etc. input from the input unit 4 under the control of the control processing unit 3, and is, for example, a display device such as a CRT display, LCD (liquid crystal display device), or organic EL display, or a printing device such as a printer.

[0037] The input unit 4 and the output unit 5 may be configured as a touch panel. In the case of configuring this touch panel, the input unit 4 is a position input device that detects and inputs an operation position, for example, a resistive film type or a capacitive type, and the output unit 5 is a display device. In this touch panel, a position input device is provided on the display surface of the display device, and one or more input content candidates that can be input to the display device are displayed. When a user touches a display position that displays the input content that the user wants to input, the position is detected by the position input device, and the display content displayed at the detected position is input to the shape measuring device 1000 as the user's operation input content. In such a touch panel, the user can easily intuitively understand the input operation, and therefore a shape measuring device 1000 that is easy for the user to handle is provided.

[0038] The IF unit 6 is connected to the control processing unit 3 and is a circuit that inputs and outputs data to and from, for example, an external device under the control of the control processing unit 3, such as an interface circuit for RS-232C, which is a serial communication method, an interface circuit using the Bluetooth (registered trademark) standard, and an interface circuit using the USB standard. The IF unit 6 may also be a communication interface circuit that transmits and receives communication signals to and from an external device, such as a data communication card or a communication interface circuit conforming to the IEEE802.11 standard.

[0039] The storage unit 7 is connected to the control processing unit 3 and is a circuit that stores various predetermined programs and various predetermined data according to the control of the control processing unit 3. The various predetermined programs include, for example, a control processing program, and the control processing program includes, for example, a control program, a first shape calculation program, a calibration program, and a movement control program. The control program is a program that controls each of the units 1, 2, 4 to 7 of the shape measuring device 1000 according to the function of each unit. The first shape calculation program is a program that generates the shadow image data by performing the first image processing on the shadow data output from the imaging unit 114, and obtains the contour shape of the measurement target WA by performing the second image processing on the generated shadow image data. The calibration program is a program that calibrates the amount of illumination light irradiated from the first illumination unit 111 based on the amount of light received by the imaging unit 114 via the neutral density filter unit 2. The movement control program is a program for controlling the movement driver 22 of the neutral density filter unit 2 so as to position the neutral density filter 21 at the calibration position during calibration and to position the neutral density filter 21 at the retracted position during measurement.

[0040] The various types of predetermined data include data required for executing each of these programs, such as the name of the measurement object, the set value SV which is the target light amount of the illumination light irradiated from the first illumination unit 111, the light attenuation amount RV of the neutral density filter 21, the adjustment amount Δi for adjusting the current value during calibration, each data and contour shape during information processing, etc. The set value SV and the adjustment amount Δi are appropriately set in advance, for example, from a plurality of samples.

[0041] Such a storage unit 7 includes, for example, a ROM (Read Only Memory) which is a nonvolatile storage element, an EEPROM (Electrically Erasable Programmable Read Only Memory) which is a rewritable nonvolatile storage element, etc. The storage unit 7 also includes a RAM (Random Access Memory) which serves as a so-called working memory of the control processing unit 3 for storing data generated during execution of the predetermined program, etc. The storage unit 7 may also be configured to include a hard disk device with a relatively large storage capacity.

[0042] The control processing unit 3 is a circuit for controlling each of the units 1, 2, 4-7 of the shape measuring device 1000 in accordance with the function of each unit, and for determining the contour shape of the measurement object WA. The control processing unit 3 is configured to include, for example, a CPU (Central Processing Unit) and its peripheral circuits. In the control processing unit 3, a control unit 31, a first shape calculation unit 32 (12), a calibration unit 33, and a movement control unit 34 are functionally configured by executing the control processing program.

[0043] The control unit 31 controls each of the units 1, 2, 4 to 7 of the shape measuring device 1000 in accordance with the function of each unit, and is in charge of controlling the shape measuring device 1000 as a whole.

[0044] As described above, the first shape calculation unit 32(12) generates the shadow image data by performing the first image processing on the shadow data output from the imaging unit 114, and obtains the thickness-wise contour shape of the measurement object WA by performing the second image processing on the generated shadow image data.

[0045] The calibration unit 33 calibrates the amount of illumination light irradiated from the first illumination unit 111 based on the amount of light received by the imaging unit 114 via the neutral density filter 21 of the neutral density filter unit 2.

[0046] The movement control unit 34 controls the movement drive unit 22 of the neutral density filter unit 2 so as to position the neutral density filter 21 at the calibration position during calibration, and to position the neutral density filter 21 at the retracted position during measurement.

[0047] To explain the calibration in more detail, first, the movement control unit 34 controls the movement drive unit 22 to position the neutral density filter 21 at the calibration position. Next, the control unit 31 causes the first illumination unit 111 to emit illumination light by passing a current of a current value adjusted in the previous calibration (a default (initial value) current value in the first calibration) ic through the first illumination unit 111, and receives the emitted illumination light through the neutral density filter 21 at the area image sensor of the imaging unit 114. Within a range (light receiving range) in the area image sensor of the imaging unit 114 for receiving the illumination light through the neutral density filter 21, a plurality of light receiving elements are set in advance for calculating the amount of received light MV. Next, the calibration unit 33 obtains an average value of the outputs of the plurality of light receiving elements as the amount of received light MV, and obtains the true amount of light TV (=MV+RV) of the illumination light emitted from the first illumination unit 111 by adding the amount of light attenuation RV of the neutral density filter 21 to the obtained amount of received light MV. Next, the calibration unit 33 compares the obtained true light quantity TV of the illumination light with the set value SV, and judges, for example, whether or not the true light quantity TV of the illumination light matches the set value SV within a predetermined range (margin) set in advance. If they match, the calibration unit 33 ends the calibration process. On the other hand, if they do not match and the true light quantity TV of the illumination light is smaller than the set value SV, the calibration unit 33 updates the current value ic by adding the adjustment amount Δi to the current value ic (ic←ic+Δi), and if they do not match and the true light quantity TV of the illumination light is larger than the set value SV, the calibration unit 33 updates the current value ic by subtracting the adjustment amount Δi from the current value ic (ic←ic-Δi). With this updated current value ic, the following processes are performed in the same manner as described above: irradiating illumination light from the first illumination unit 111, receiving the illumination light by the area image sensor of the imaging unit 114, calculating the true light intensity TV of the illumination light, comparing the true light intensity TV of the illumination light with the set value SV, and updating the current value ic in accordance with the comparison result; and this is repeated until the comparison results match.Then, when the calibration process is completed, the calibration unit 33 stores the current value i c at that time in the memory unit 7 as the current value adjusted in the current calibration (if no update is performed, the current value i c adjusted in the previous calibration is stored in the memory unit 7 as the current value adjusted in the current calibration, and if an update is performed, the updated current value i c is stored in the memory unit 7 as the current value adjusted in the current calibration). The movement control unit 34 controls the movement drive unit 22 to position the neutral density filter 21 at the retracted position.

[0048] The control processing unit 3, the input unit 4, the output unit 5, the IF unit 6 and the storage unit 7 can be configured, for example, by a desktop or notebook computer.

[0049] Next, the operation of this embodiment will be described with reference to Fig. 5, which is a flow chart showing the operation of the shape measuring device with respect to calibration.

[0050] When the power is turned on, the shape measuring device 1000 having such a configuration initializes each required part and starts its operation. In the control processing unit 3, a control unit 31, a first shape calculation unit 32(12), a calibration unit 33, and a movement control unit 345 are functionally configured by executing the control processing program.

[0051] For example, when a command to start calibration is received at the input unit 4, in FIG. 5, the shape measuring device 1000 controls the movement drive unit 22 by the movement control unit 34 of the control processing unit 3 to move the neutral density filter 21 to the calibration position (S1).

[0052] Next, the shape measuring device 1000 causes the control unit 31 of the control processing unit 3 to irradiate illumination light from the first illumination unit 111 with a current having a current value ic stored in the memory unit 7, and receives this irradiated illumination light by the area image sensor of the imaging unit 114 via the neutral density filter 21 (S2).

[0053] Next, the shape measuring device 1000 determines the amount of received light MV by the calibration unit 33 of the control processing unit 3 to determine the true amount of light TV (=MV+RV) of the illumination light (S3).

[0054] Next, the shape measuring device 1000 causes the calibration unit 33 to compare the determined true light amount TV of the illumination light with the set value SV (S4).

[0055] Next, the shape measuring device 1000 determines whether or not the true light amount TV of the illumination light matches the set value SV within the predetermined range as a result of the comparison by the calibration unit 33 (S5). If the result of the determination indicates that they do not match, the shape measuring device 1000 next executes process S6, whereas if they match, the shape measuring device 1000 next executes process S7.

[0056] In this process S6, the shape measuring device 1000, using the calibration unit 33, updates the current value ic by adding the adjustment amount Δi to the current value ic (ic←ic+Δi) if the true light intensity TV of the illumination light is smaller than the set value SV, and updates the current value ic by subtracting the adjustment amount Δi from the current value ic (ic←ic-Δi) if the true light intensity TV of the illumination light is greater than the set value SV, and then returns the process to process S2.

[0057] In step S7, the shape measuring apparatus 1000 causes the calibration unit 33 to store the current value ic at that time in the memory unit 7 as the current value adjusted by the current calibration.

[0058] Then, the shape measuring device 1000 controls the movement driver 22 by the movement controller 34 of the control processor 3 to move the neutral density filter 21 to the retracted position (S8), and ends this process.

[0059] As described above, the shape measuring device 1000 in the embodiment and the calibration method for a shape measuring device implemented therein are equipped with a neutral density filter unit 2 that reduces the amount of incident light before outputting it. Therefore, even when calibration is performed by adjusting the amount of illumination light irradiated from the first illumination unit 111 to a set value SV that exceeds the dynamic range DR of the imaging unit 114, the amount of light can be calibrated by attenuating the light using the neutral density filter unit 2 so that it is within the dynamic range DR of the imaging unit 114.

[0060] According to this embodiment, a shape measuring device 1000 can be provided that calibrates the amount of illumination light irradiated from the first illumination unit 111 so that the amount of received light MV received by the imaging unit 114 becomes a predetermined light amount, for example, an amount of light that exceeds the dynamic range DR of the area image sensor in the imaging unit 114 and saturates the light receiving element.

[0061] The shape measuring device 1000 is equipped with a movement drive unit 22 that moves the neutral density filter 21 between the calibration position and the retracted position, so that the neutral density filter 21 can be automatically moved between the calibration position and the retracted position when performing calibration and when performing measurement.

[0062] In the above-described embodiment, the neutral density filter 21 is moved between the calibration position and the retracted position by the moving drive unit 22, but a jig (mounting jig) for attaching and detaching the neutral density filter 21 may be provided at the calibration position, and the neutral density filter 21 may be attached to the mounting jig by a user (operator) in the case of calibration, and the neutral density filter 21 may be removed from the mounting jig by the user in the case of measurement (first variant).

[0063] In the above-described embodiment (including the first modified embodiment), the shape measuring device 1000 may further include a notification unit 37 that issues an alarm to the outside when the current value i of the current flowing through the first illumination unit 111 after calibration exceeds a threshold (alarm notification threshold) ith that is preset based on the maximum rated current value imax of the first illumination unit 111 (second modified embodiment). For example, as a program included in the control processing program, a notification program that issues an alarm to the outside when the current value i of the current flowing through the first illumination unit 111 after calibration exceeds an alarm notification threshold ith based on the maximum rated current value imax of the first illumination unit 111 is stored in the storage unit 7, and the control processing program is executed, whereby such a notification unit 37 is functionally configured in the control processing unit 3 as shown by the dashed line in FIG. 1. The alarm notification threshold ith is appropriately set to, for example, 85%, 90%, 95%, or the like of the maximum rated current value imax. When the above-mentioned process S7 is executed, the notification unit 37 judges whether or not the current value ic adjusted in the current calibration exceeds the alarm notification threshold ith, and if the result of this judgment indicates that the current value ic exceeds the alarm notification threshold ith, the notification unit 37 outputs, as the alarm, a message urging replacement of the light source of the first illumination unit 111, such as "We recommend replacing the light source of the illumination light," to the output unit 5. Alternatively, the alarm may be notified by, for example, turning on a warning light or emitting an alarm sound.

[0064] The amount of illumination light emitted from the first illumination unit 111 generally decreases due to aging. Since the amount of light increases as the amount of power supply increases, the current value ic of the current flowing through the first illumination unit 111 is increased at a constant voltage in order to compensate for the reduced amount of light. Therefore, the current value ic of the current flowing through the first illumination unit 111 will eventually exceed the maximum rated current value imax of the first illumination unit 111, causing the first illumination unit 111 to break down. In the shape measurement device 1000 in the second modified embodiment, when the current value ic exceeds an alarm threshold value ith, an alarm is issued to the outside, so that measures can be taken before the first illumination unit 111 breaks down, such as replacing the light-emitting element of the light source.

[0065] In the above-described embodiments (including the first and second modified embodiments), the shape measuring device 1000 may be further configured such that the measurement object is a disk-shaped member and the shape measuring device 1000 measures the circumferential contour shape of the disk-shaped member, or the measurement object is a disk-shaped member having a notch formed at a predetermined position in the circumferential direction and the shape measuring device 1000 measures the contour shape of the notch (third modified embodiment). Either one of these may be further provided in the shape measuring device 1000, but here, a more specific description will be given of a case in which the shape measuring device 1000 is further provided with both of these.

[0066] Fig. 6 is a diagram for explaining a shape measuring device of a third modified embodiment. Note that the first to third neutral density filter units 2, 42, and 52 are omitted from Fig. 6 and are not shown. Fig. 7 is a diagram for explaining a measurement target measured by the shape measuring device of the third modified embodiment. Fig. 8 is a diagram for explaining, as an example, a contour shape measured by the shape measuring device of the third modified embodiment.

[0067] The shape measuring apparatus 1000 in the third modified embodiment further includes a second contour shape measuring section 41, a second neutral density filter section 42, a third contour shape measuring section 51, and a third neutral density filter section 52, as shown by dashed lines in FIG.

[0068] The measurement object WAa here is, for example, a disk-shaped member with a substantially "V"-shaped notch NC formed at a predetermined position in the circumferential direction as shown in Fig. 7. When the measurement object WAa is a semiconductor wafer, the crystal orientation is indicated by the notch NC.

[0069] The second contour shape measuring unit 41 is a device that measures the circumferential contour shape of the measurement object WAa (the outer contour shape viewed from the normal direction of the disk), and includes, for example, a second measurement unit 411 and a second shape calculation unit 412 (35).

[0070] The second measurement unit 411 is connected to the control processing unit 3, and is a device that measures the position of the peripheral edge of the measurement object WAa by irradiating the measurement object WAa with a predetermined illumination light from the thickness direction of the measurement object WAa under the control of the control processing unit 3. The second measurement unit 411 measures each position of the peripheral edge at a plurality of different measurement points along the circumferential direction θ of the measurement object WAa.

[0071] 6, the second measurement unit 411 includes an illumination unit (second illumination unit) 4111 that irradiates the measurement object WAa with illumination light in a linear manner from the thickness direction to the radial direction, a light receiving unit 4112 that receives the illumination light irradiated from the second illumination unit 4111 through the measurement object WAa, and a holder 4113 that holds the second illumination unit 4111 and the light receiving unit 4112 so that they face each other with a predetermined interval, and the second illumination unit 4111, the holder 4113, and the light receiving unit 4112 have an approximately U-shape (a shape obtained by removing the central "-" in an E-shape) in a side view. Therefore, the light receiving unit 412 is disposed so as to face the second illumination unit 4111. The second illumination unit 4111 is configured with, for example, a device that converts light emitted from a light source into parallel light using a collimator lens, converts the parallel light into slit light along the radial direction r through a slit hole of a plate-like member having a rectangular slit hole long in one direction, and irradiates the measurement object WAa with the slit light as the illumination light, and the light receiving unit 4112 is configured with a line sensor or area image sensor wider than the slit hole. In the second measurement unit 411 equipped with such a second illumination unit 4111 and light receiving unit 4112, the measurement object WAa is disposed relative to the second measurement unit 411 so that the radial direction r is along the one direction. Alternatively, for example, the second illumination unit 4111 is a device that irradiates the measurement object WAa with laser light emitted from a light source while scanning it in the radial direction r as the illumination light, and the light receiving unit 4112 is configured with a line sensor or area image sensor wider than the laser light. In the second measurement unit 411 including such a second illumination unit 4111 and light receiving unit 4112, the measurement target WAa is disposed with respect to the measurement unit 1 so that the radial direction r is along the direction of scanning. The holding unit 4113 is, for example, a columnar member extending in one direction, and holds the second illumination unit 4111 and the light receiving unit 4112 at both ends of the columnar member so as to extend in a direction perpendicular to the one direction.

[0072] In this third modified embodiment, the second shape calculation unit 412 (35) is functionally configured in the control processing unit 3, and for each of the plurality of measurement points, the position of the peripheral edge of the measurement object WAa at the measurement point is obtained based on the output of the light receiving unit 4112, and the contour shape in the circumferential direction of the measurement object WAa is obtained based on each position of the peripheral edge of the measurement object WAa obtained at each of the plurality of measurement points. Since the linear illumination light irradiated from the second illumination unit 4111 is blocked by the measurement object WAa, for example, by determining pixels whose luminance is less than a predetermined threshold (peripheral edge position determination threshold) and whose luminance is equal to or greater than the peripheral edge position determination threshold, the position of the pixel where the luminance changes is obtained as the position of the peripheral edge of the measurement object WAa, and the distance L1 from one end of the linear illumination light (the end close to the center of the measurement object WAa) to the peripheral edge of the measurement object WAa is obtained. In principle, the distance L2 from the center of the rotation stage (center of the measurement object WAa) to one end of the linear illumination light is known in advance, so the distance L3 (=L1+L2) from the center of the measurement object WAa to the peripheral edge of the measurement object WAa can be obtained by adding the distance L2 to the distance L1. The contour shape of the measurement object WAa in the circumferential direction can be obtained by obtaining this distance L3 for each of the multiple measurement points.

[0073] The second attenuation filter section 42 is similar to the first attenuation filter section 2, except that it is positioned relative to the second contour shape measurement section 41 so that a calibration position is set between the second illumination section 4111 and the light receiving section 4112, and therefore its description is omitted.

[0074] The calibration unit 33 further calibrates the amount of illumination light irradiated from the second illumination unit 4111 based on the amount of received light received by the light receiving unit 4112 via the second neutral density filter unit 42. The calibration program further includes a program for calibrating the amount of illumination light irradiated from the illumination unit 4111 based on the amount of received light received by the light receiving unit 4112 via the second neutral density filter unit 42.

[0075] The memory unit 7 stores, as a program included in the control processing program, a second shape calculation program for determining, for each of the plurality of measurement points, the position of the peripheral edge of the measurement object WAa at that measurement point based on the output of the light receiving unit 4112, and for determining the circumferential contour shape of the measurement object WAa based on each position of the peripheral edge of the measurement object WAa determined at each of the plurality of measurement points. By executing the control processing program, a second shape calculation unit 35 (412) is functionally configured in the control processing unit 3.

[0076] The third contour shape measuring unit 51 is a device for measuring the contour shape of the notch NC in the measurement object WAa (the contour shape of the notch NC as viewed from the normal direction of the disk), and includes, for example, a third measuring unit 511 and a third shape calculation unit 512 (36). The third measuring unit 511 is similar to the first measuring unit 11, except that it irradiates light onto the peripheral portion of the measurement object WA from the thickness direction of the measurement object. That is, the third measuring unit 511 includes an illumination unit 5111 having an illumination unit and an illumination optical system similar to the first illumination unit 111 and the illumination optical system 112, and a light receiving unit 5112 having a light receiving optical system and an imaging unit similar to the light receiving optical system 113 and the imaging unit 114. The third shape calculation unit 512 (36) is similar to the first shape calculation unit 32 (12), except that it uses the output of the imaging unit of the light receiving unit 5112, and therefore a description thereof will be omitted.

[0077] The third attenuation filter section 52 is similar to the first attenuation filter section 2, except that it is positioned relative to the third contour shape measurement section 51 so that a calibration position is set between the illumination unit 5111 and the light receiving unit 5112, and therefore its description is omitted.

[0078] The calibration unit 33 further calibrates the amount of illumination light irradiated from the illumination unit 5111 based on the amount of received light received by the light receiving unit 5112 via the third neutral density filter unit 52 of the illumination light irradiated from the illumination unit. The calibration program further includes a program for calibrating the amount of illumination light irradiated from the illumination unit 5111 based on the amount of received light received by the light receiving unit 5112 via the third neutral density filter unit 52 of the illumination light irradiated from the illumination unit.

[0079] The storage unit 7 stores a third shape calculation program similar to the first shape calculation program as a program included in the control processing program. By executing the control processing program, a third shape calculation unit 36 ​​(512) is functionally configured in the control processing unit 3.

[0080] In order to express the present invention, the present invention has been described adequately and sufficiently through the embodiments with reference to the drawings in the above description, but it should be recognized that those skilled in the art can easily change and / or improve the above-mentioned embodiments. Therefore, unless the changes or improvements made by those skilled in the art are at a level that departs from the scope of the claims described in the claims, the changes or improvements are interpreted as being included in the scope of the claims. [Explanation of symbols]

[0081] 1000 shape measuring device 1. First contour measuring section 2 First neutral density filter section 3. Control Processing Section 5 Output section 7 Memory section 11 1st measurement section 31 Control Unit 32(12) First shape calculation section 33 Proofreading Department 34 Movement control section 35(412) 2nd shape calculation section 36(512) Third shape calculation section 37 Alarm section 41 Second contour shape measuring section 42 Second neutral density filter section 51 Third contour shape measuring section 52 Third neutral density filter section 411 2nd measurement section 511 Third measurement section

Claims

1. A shape measuring device comprising: an illumination unit; an imaging unit; and an image processing unit that, in the case of measurement, a plate-shaped measurement target is disposed between the illumination unit and the imaging unit, and that obtains a contour shape of the measurement target based on a shadow image of the measurement target generated by imaging a shadow of the measurement target formed by illumination light irradiated from the illumination unit by the imaging unit, A neutral density filter unit disposed between the illumination unit and the imaging unit in the case of calibration; a calibration unit that calibrates the amount of illumination light emitted from the illumination unit based on the amount of received light received by the imaging unit via the neutral density filter unit, Shape measuring device.

2. the calibration unit calibrates the amount of illumination light irradiated from the illumination unit by adjusting the illumination unit so that the amount of light received by the imaging unit becomes a predetermined amount of light that is set in advance. The shape measuring apparatus according to claim 1 .

3. and a notification unit that issues an alarm to an outside when a current value of a current flowing through the illumination unit after the calibration exceeds a threshold value that is set in advance based on a maximum rated current value of the illumination unit. The shape measuring apparatus according to claim 1 .

4. the neutral density filter unit includes a neutral density filter and a movement drive unit that moves the neutral density filter between a calibration position and a retracted position, the calibration position is a position where the neutral density filter is disposed between the illumination unit and the imaging unit, and the retracted position is a position where the neutral density filter is not disposed between the illumination unit and the imaging unit; The shape measuring apparatus according to claim 1 .

5. A method for calibrating a shape measuring device including an illumination unit, an imaging unit, and an image processing unit in which, in the case of measurement, a plate-shaped measurement target is placed between the illumination unit and the imaging unit, and a shadow image of the measurement target formed by illumination light irradiated from the illumination unit is captured by the imaging unit to generate a shadow image of the measurement target, the method comprising the steps of: a step of placing a neutral density filter between the illumination unit and the imaging unit in the case of calibration; and a calibration step of calibrating the amount of illumination light irradiated from the illumination unit based on the amount of received light received by the imaging unit through the neutral density filter. How to calibrate a shape measurement device.

6. the measurement object is a disk-shaped member, The contour shape is a contour shape in a thickness direction of the disk-shaped member. The method for calibrating a shape measuring instrument according to claim 5.

7. the measurement object is a disk-shaped member, The contour shape is a contour shape in a circumferential direction of the disk-shaped member. The method for calibrating a shape measuring instrument according to claim 5.

8. the measurement object is a disk-shaped member having a notch formed at a predetermined position in a circumferential direction, The contour shape is a contour shape of the cutout. The method for calibrating a shape measuring instrument according to claim 5.

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