Observation method and observation device

Abstract

In the present observation method, measurement values ​​of a measurement object at a plurality of different positions in a plane intersecting with a depth direction are acquired from an optical coherence tomography apparatus (S100). In the present observation method, the measurement values ​​of the same depth position at each of the plurality of positions are averaged (S104). In the present observation method, an integral value is calculated for the average value at each of the plurality of depth positions in the depth direction (S105). In the present observation method, a contraction parameter of the measurement object is calculated based on the integral value (S106).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Japanese Patent Application No. 2018-175163 filed in the Japan Patent Office on September 19, 2018, the disclosure of which is hereby incorporated by reference in its entirety. Technical Field

[0003] The present disclosure relates to an observation method and an observation device. Background Art

[0004] Ceramics are excellent in various physical properties such as hardness, heat resistance, corrosion resistance, and electrical insulation, etc. Therefore, ceramic structures manufactured to achieve functions required in specific applications are being used for various purposes.

[0005] The ceramic structure is made by performing steps such as a mixing step, a molding step, a drying step, and a firing step on the raw materials (see Patent Document 1). The ceramic structure being manufactured shrinks during the steps such as the drying step and the firing step. The shrunk structure is ground to meet the required size. The shrunk structure is hard, and grinding takes time. Therefore, the size of the structure before shrinkage in the molding step (hereinafter, referred to as a "molded body") is determined so that the structure is as close as possible to the required size after shrinkage.

[0006] The shrinkage during the manufacturing process varies depending on factors such as the properties of the molded body. Therefore, even with the same mixing, the size of the molded body to be determined varies with each batch of mixed raw materials. In the molding step of the prior art, an intermediate molded body is molded by a rubber press or the like, the shrinkage rate is estimated by inspecting the intermediate molded body, the size of the molded body is determined based on the shrinkage rate, and the intermediate molded body is cut to a size that matches the size of the molded body. Inspection of the intermediate molded body takes a relatively long time. Therefore, a portion of the intermediate molded body made of the same batch of mixed raw materials is extracted to inspect the portion of the intermediate molded body, and the shrinkage rate estimated based on the inspection is used as the shrinkage rate of the molded body of the same batch to adjust the cutting conditions such as the cutting amount.

[0007] Citation List

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Publication No. 2017-170869 Summary of the invention

[0010] The observation method according to the first aspect comprises:

[0011] acquiring, from the optical coherence tomography imager, measurement values ​​of the measurement object at a plurality of different positions in a plane intersecting the depth direction;

[0012] calculating an average by averaging the measurements at the same depth position at each of the plurality of positions;

[0013] calculating an integrated value by integrating the average value at each of the depth positions in the depth direction; and

[0014] A contraction parameter of the measurement object is calculated based on the integrated value.

[0015] In addition, the observation method according to the second aspect includes:

[0016] acquiring, from the optical coherence tomography imager, measurement values ​​of the measurement object at a plurality of different positions in a plane intersecting the depth direction;

[0017] calculating an integrated value by integrating the measured value at each of the plurality of positions in the depth direction;

[0018] calculating an average value by averaging the integrated values ​​calculated for each of the plurality of positions; and

[0019] A contraction parameter of the measurement object is calculated based on the average value.

[0020] In addition, the observation device according to the third aspect includes:

[0021] A controller that acquires measurement values ​​of a measurement object at different multiple positions in a plane intersecting a depth direction from an optical coherence tomography imager, calculates an average value by averaging the measurement values ​​at the same depth position at each of the multiple positions, calculates an integrated value by integrating the average value at each of the depth positions, and calculates a contraction parameter of the measurement object based on the integrated value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In the attached picture:

[0023] Figure 1 is a functional block diagram showing a schematic configuration of an observation system including an observation apparatus of the first embodiment;

[0024] Figure 2 It shows Figure 1 A diagram showing the relationship between the measured value calculated by the controller of the optical coherence tomography apparatus and the depth direction;

[0025] Figure 3 It is used to illustrate Figure 1A diagram of measurements calculated at multiple locations by an optical coherence tomography instrument in FIG.

[0026] Figure 4 It is used to illustrate Figure 1 A diagram showing how a controller of an observation device in FIG. 1 aligns a depth position as a peak value of a measurement value with a reference position;

[0027] Figure 5 It is used to illustrate Figure 1 A diagram showing how a controller of an observation device in FIG. 1 averages measurement values ​​detected at a plurality of positions for the same depth position;

[0028] Figure 6 It is used to illustrate Figure 1 A diagram showing how a controller of an observation device in FIG. 1 calculates an integrated value based on an average value of measurement values ​​at the same depth position;

[0029] Figure 7 is a graph for explaining a calibration curve showing a corresponding relationship between an integral value of a measured value and a green embryo density;

[0030] Figure 8 It is used to explain that in the first embodiment, Figure 1 A flowchart of a contraction parameter output process performed by a controller of an observation device in; and

[0031] Fig. 9 : is a flowchart for explaining the contraction parameter output process executed by the controller of the observation apparatus in the second embodiment. DETAILED DESCRIPTION

[0032] Hereinafter, an embodiment of an observation device to which the present disclosure is applied will be described with reference to the drawings.

[0033] like Figure 1 As shown in FIG. 1 , an observation system 11 including an observation device 10 according to a first embodiment of the present disclosure is configured to include an optical coherence tomography imager 12 and the observation device 10. The observation system 11 observes, for example, a molded body as a measurement object obj, which is an intermediate of a ceramic structure. Note that in Figure 1 In FIG. 1 , the solid lines with arrows connecting the functional blocks show the travel of the light beam. Figure 1 In FIG. 1 , the dotted lines connecting the functional blocks show the flow of control signals or communication information. The communication indicated by the dotted lines may be wired communication or wireless communication.

[0034] The optical coherence tomography imager 12 captures an image from the surface of the measurement object obj to a maximum depth of about 10 mm by optical coherence tomography (OCT). In the first embodiment, the optical coherence tomography imager 12 is a wavelength sweeping OCT device, but it may also be another type of OCT device. The optical coherence tomography imager 12 includes a light source 13, a beam splitter 14, a reference mirror 15, a scanner 16, a detector 17, and a controller 18.

[0035] For example, the light source 13 emits light in a frequency band detectable by the detector 17, such as light in a near-infrared band. The light source 13 may be a wavelength swept type light source, and may repeatedly emit light of a wavelength that varies within a predetermined range along the time axis. Note that in a configuration in which the optical coherence tomography imager 12 is an OCT device of a type other than the wavelength swept type, the light source 13 may be a light source corresponding to the type. For example, the light source 13 includes a collimating lens, and emits collimated light having a narrower diameter.

[0036] A beam splitter 14 is provided in the emission direction of the light source 13. For example, the beam splitter 14 is a half mirror. The beam splitter 14 separates the light emitted from the light source 13 and causes the light to travel in two directions. In addition, the beam splitter 14 causes coherent light obtained by mixing the reference light incident from the reference mirror 15 with the signal light incident from the measurement object obj to travel toward the detector 17.

[0037] The reference mirror 15 is provided in one of the traveling directions of the light separated by the beam splitter 14. The reference mirror 15 is arranged so that the mirror plane is perpendicular to the traveling direction, and reflects the incident light toward the beam splitter 14 as reference light.

[0038] The scanner 16 scans the measuring object obj by using the light that travels in a direction different from the reference mirror 15 among the light separated by the beam splitter 14 as the irradiation light. The scanner 16 can scan by any of various methods. For example, the scanner 16 can scan by reflecting the irradiation light while changing the reflection direction using a reflection member such as a galvanometer mirror. In addition, the scanner 16 can also scan by changing the irradiation position of the irradiation light on the surface of the measuring object obj using a movable stage.

[0039] Note that in the optical coherence tomography imager 12, the measuring object obj is set so that the irradiation light irradiates the measuring object obj at an incident angle equal to or greater than 0°. The irradiation light irradiating each position of the measuring object obj by the scanner 16 advances from the surface in the depth direction while being attenuated due to absorption, and is reflected and scattered at each depth position. The reflected and scattered signal light is incident on the beam splitter 14.

[0040] The detector 17 receives the coherent light traveling from the beam splitter 14. The detector 17 outputs a measurement signal having an intensity corresponding to the amount of the received light.

[0041] The controller 18 includes one or more processors and a memory. The processor may include a general-purpose processor that performs a specific function by loading a specific program, and a dedicated processor dedicated to a specific process. The dedicated processor may include an application-specific integrated circuit (ASIC). The processor may also include a programmable logic device (PLD). The PLD may include a field programmable gate array (FPGA). The controller 18 may also be a system on chip (SoC) or a packaged system (SiP) in which one or more processors cooperate.

[0042] The controller 18 calculates the following by performing inverse Fourier transform on the measurement signal obtained from the detector 17: Figure 2 The controller 18 uses the reflected light intensity in the depth direction at any irradiation position EP of the irradiation light EL as a measured value. The controller 18 identifies the irradiation position EP in the plane intersecting with the depth direction, which overlaps with the irradiation direction of the irradiation light EL, by acquiring the position information from the scanner 16. The controller 18 outputs the irradiation position EP and the reflected light intensity in the depth direction to the observation device 10 in association with each other.

[0043] The observation device 10 includes a controller 19 and a storage device 20 .

[0044] The controller 19 includes one or more processors and memory. The processor may include a general-purpose processor that performs a specific function by loading a specific program, and a dedicated processor dedicated to a specific process. The dedicated processor may include an application-specific integrated circuit (ASIC). The processor may also include a programmable logic device (PLD). The PLD may include an FPGA. The controller 19 may also be a SoC or SiP in which one or more processors are used.

[0045] like Figure 3 As shown in , the controller 19 acquires the measurement values ​​of the measurement object obj at a plurality of different positions in a plane intersecting the depth direction, or in other words, at a plurality of irradiation positions EP from the optical coherence tomography imager 12. Note that in the first embodiment, as described above, the measurement value of the measurement object obj is the reflected light intensity along the depth direction. The controller 19 may cause the storage device 20 to store the acquired measurement value along the depth direction at each of the plurality of positions.

[0046] The controller 19 may detect the position in the depth direction where a peak appears in the measurement value of the measurement object obj at each of the plurality of positions as the peak position. Figure 4As shown in , the controller 19 may align a reference position in the depth direction of a measurement value of the measuring object obj at each of a plurality of positions (eg, from a first irradiation position to a fifth irradiation position) with the detected peak position.

[0047] like Figure 5 As shown in , the controller 19 calculates the average value by averaging the measured values ​​at the same depth position at each of the multiple positions. In the configuration in which the reference position in the depth direction is aligned with the detected peak position as described above, the controller 19 can average the measured values ​​at the same depth position with reference to the peak position at each of the multiple positions.

[0048] like Figure 6 As shown in , the controller 19 integrates the average measurement value in the depth direction to calculate the integrated value. Note that when calculating the integrated value, the controller 19 may integrate the measurement value within the range included in the predetermined depth position. The predetermined depth position may be a depth position in a coordinate system with a reference point in the optical coherence tomography imager 12 as the origin, or a depth position based on a peak position in the depth direction.

[0049] Based on the integral value, the controller 19 calculates the shrinkage parameter of the measurement object obj. Note that the shrinkage parameter is an arbitrary variable representing the internal state of the molded part as the measurement object obj, and the shrinkage parameter affects the degree of shrinkage of the measurement object obj when it is dried and fired. The shrinkage parameter is a parameter such as the green density or porosity of the molded part. The integral value is related to the shrinkage parameter such as the green density and may vary depending on the density of the molded part. Therefore, the controller 19 may use a calibration curve (such as the integral value) of the shrinkage parameter relative to the integral value. Figure 7 The contraction parameters were calculated by conversion from the integrated values ​​using the calibration curve shown in .

[0050] The controller 19 reports the calculated shrinkage parameters to the ceramic structure manufacturing device. Based on the reported shrinkage parameters, the manufacturing device determines the cutting conditions for the measurement object obj for which the shrinkage parameters have been calculated. The manufacturing device cuts the measurement object obj under the determined cutting conditions, and manufactures the ceramic structure by undergoing a drying step and a firing step. Note that the controller 19 may also calculate the cutting conditions based on the shrinkage parameters. In a configuration in which the controller 19 calculates the cutting conditions, the controller 19 controls the manufacturing device to cut the measurement object obj according to the calculated cutting conditions.

[0051] The storage device 20 includes any type of storage device such as a random access memory (RAM) and a read only memory (ROM), for example. The storage device 20 stores various programs for causing the controller 19 to function, and various information used by the controller 19.

[0052] For example, the storage device 20 stores the reflected light intensity in the depth direction at each of the plurality of positions for each measurement object obj. In addition, for example, the storage device 20 stores a calibration curve of the contraction parameter with respect to the integral value. In addition, for example, the storage device 20 stores the contraction parameter calculated for each measurement object obj.

[0053] Next, we will use Figure 8 The shrinkage parameter output process performed by the controller 19 in the first embodiment is described with reference to the flowchart in FIG. When the optical coherence tomography imager 12 starts measuring the measurement value of any measurement object obj, the shrinkage parameter output process starts together. Note that, for example, the controller 19 can recognize the start of measurement by the optical coherence tomography imager 12 by a synchronization signal obtained from the optical coherence tomography imager 12.

[0054] In step S100, the controller 19 acquires the measurement value of the measuring object obj at any irradiation position EP, or in other words, the reflected light intensity in the depth direction. After the acquisition, the process proceeds to step S101.

[0055] In step S101, the controller 19 detects the position in the depth direction where the peak appears in the measurement value acquired in step S100 as the peak position. After the peak position is detected, the process proceeds to step S102.

[0056] In step S102, the controller 19 determines whether measurement values ​​have been acquired at all positions where the measurement object obj is to be measured. Note that the controller 19 may determine whether measurement values ​​have been acquired at all positions based on a synchronization signal acquired from the optical coherence tomography imager 12, notification information indicating completion, or the like. In the case where measurement values ​​have not been acquired at all positions, the process returns to step S100. In the case where measurement values ​​have been acquired at all positions, the process proceeds to step S103.

[0057] In step S103, the controller 19 aligns the reference position in the depth direction of the measurement value at each of the plurality of positions with the peak position detected in step S101. After the reference positioning, the process proceeds to step S104.

[0058] In step S104, the controller 19 averages the measured values ​​at each of the plurality of positions aligned with the reference position in step S103 for the same depth position, respectively, to calculate an average value. After the average value is calculated, the process proceeds to step S105.

[0059] In step S105, the controller 19 integrates the measured values ​​averaged in step S104 within a predetermined depth position to calculate an integrated value. After the integrated value is calculated, the process proceeds to step S106.

[0060] In step S106, the controller 19 calculates a contraction parameter based on the integrated value calculated in step S105. After the contraction parameter is calculated, the process proceeds to step S107.

[0061] In step S107, the controller 19 outputs the shrinkage parameter calculated in step S106 to the manufacturing device. After the shrinkage parameter is output, the shrinkage parameter output process ends.

[0062] In the observation device 10 according to the first embodiment having the above-described configuration, the measurement values ​​of the measurement object obj measured at a plurality of positions by the optical coherence tomography imager 12 are used. Therefore, since the observation device 10 uses the measurement results from the optical coherence tomography imager 12 capable of rapid and non-invasive imaging, the observation device 10 can rapidly observe each measurement object obj that is finally processed into a finished product.

[0063] Furthermore, the observation device 10 according to the first embodiment averages the measured values ​​at each of the plurality of positions. Therefore, the observation device 10 can calculate the contraction parameter for inferring the contraction of the entire measurement object obj while reducing the variation of the measured values ​​caused by the plurality of positions.

[0064] In addition, the observation device 10 according to the first embodiment averages the measured values ​​at the same depth position. As the light travels farther in the depth direction of the measurement object obj, the irradiation light from the optical coherence tomography imager 12 is greatly attenuated. Therefore, even if the internal state of the measurement object obj is uniform in the depth direction, the measured values ​​at different depths are generally different values. In view of this phenomenon, the observation device 10 having the above configuration averages the measured values ​​at the same depth position having approximately the same attenuation degree, so the influence of the variation caused by attenuation can be eliminated from the average value.

[0065] Furthermore, the observation device 10 according to the first embodiment integrates the average values ​​of the plurality of depth positions in the depth direction and calculates the shrinkage parameter of the entire measurement object obj based on the integrated value. Therefore, the observation device 10 can detect the parameters that affect the shrinkage in the steps such as the drying step and the firing step.

[0066] In addition, the observation device 10 according to the first embodiment performs averaging on the measured values ​​at the same depth position with reference to the peak position. In the optical coherence tomography imager 12, the surface of the measured object is tilted relative to the traveling direction of the irradiation light (or in other words, the depth direction) to reduce the strong back reflection detected from the surface of the measured object. As described above, as the irradiation light EL irradiating the measured object obj travels in the depth direction from the surface, the irradiation light EL is greatly attenuated, and therefore, as the depth position from the surface becomes longer, the intensity of the measured value also decreases. In response to this phenomenon, the observation device 10 having the above-mentioned configuration averages the measured values ​​at the same depth position with reference to the peak position estimated as the surface position, and therefore, even with the configuration in which the measured object obj is tilted relative to the depth direction, the influence of the change caused by attenuation can be removed from the average value.

[0067] In addition, the observation device 10 according to the first embodiment integrates the measured values ​​within a range of a predetermined depth position. Using the resolution capability of the optical coherence tomography, the surface of the measurement object obj can be detected with one or two pixels (or in other words, at one or two depth positions, respectively). The measured value obtained by detecting the surface of the measurement object obj with one pixel is greatly different in intensity from the measured value detected with two pixels. Therefore, the average value of the measured values ​​at the depth position corresponding to the surface where the intensity is particularly strong has a relatively low reliability as a measured value. On the other hand, the observation device 10 having the above-mentioned configuration can integrate the average value of the measured values ​​within a range other than the depth position corresponding to the surface, and therefore, the estimation accuracy of the contraction of the measurement object obj based on the contraction parameter can be improved.

[0068] Furthermore, in the observation apparatus 10 according to the first embodiment, the integrated value is converted into a contraction parameter by using a calibration curve. Therefore, the observation apparatus 10 can reduce the processing load on the controller 19.

[0069] Next, an observation device according to a second embodiment of the present disclosure will be described. In the second embodiment, the order of the processing performed by the controller of the observation device is different from that of the first embodiment. Hereinafter, the second embodiment will be described focusing on the differences from the first embodiment. Note that components having the same configuration as the first embodiment are represented by the same reference numerals.

[0070] like Figure 1 As shown in , the observation device 10 according to the second embodiment includes a controller 19 and a storage device 20 as in the first embodiment. Note that in the second embodiment, the configuration and function of the optical coherence tomography imager 12 are the same as those of the optical coherence tomography imager 12 according to the first embodiment.

[0071] In the second embodiment, as in the first embodiment, the controller 19 of the observation device 10 acquires the measurement values ​​of the measuring object obj at the plurality of irradiation positions EP. In the second embodiment, as in the first embodiment, the controller 19 may detect the position in the depth direction at which a peak appears in the measurement value of the measuring object obj at each of the plurality of positions as the peak position. Moreover, in the second embodiment, as in the first embodiment, the controller 19 may also align the reference position in the depth direction of the measurement value of the measuring object obj at each of the plurality of positions with the detected peak position.

[0072] In the second embodiment, unlike the first embodiment, the controller 19 integrates the measured values ​​at each of the plurality of positions in the depth direction before averaging to calculate an integrated value for each of the plurality of positions. Note that in the second embodiment, as in the first embodiment, the controller 19 may integrate the measured values ​​included in the range of the predetermined depth position when calculating the integrated value. The predetermined depth position in the second embodiment may be the same as that in the first embodiment.

[0073] In the second embodiment, unlike the first embodiment, the controller 19 averages the integrated values ​​calculated for each of the plurality of positions to calculate an average value. In the second embodiment, unlike the first embodiment, the controller 19 calculates the shrinkage parameter of the measuring object obj based on the calculated average value. In the second embodiment, as in the first embodiment, the controller 19 may report the calculated shrinkage parameter to the manufacturing device, or calculate the cutting condition based on the calculated shrinkage parameter to control the manufacturing device.

[0074] Next, we will use Fig. 9 The shrinkage parameter output process executed by the controller 19 in the second embodiment is described with reference to the flowchart in FIG. In the second embodiment, as in the first embodiment, when the optical coherence tomography apparatus 12 starts measuring the measurement value of any measurement object obj, the shrinkage parameter output process starts together.

[0075] In steps S200 to S203, the controller 19 performs the same operations as those in steps S100 to S103 of the contraction parameter output process of the first embodiment. In step S204, the controller 19 integrates the measured values ​​at each of the plurality of positions aligned with the reference position in step S203 within the range of the predetermined depth position to calculate an integrated value. After the integrated value is calculated, the process proceeds to step S205.

[0076] In step S205, the controller 19 averages the integrated values ​​calculated for each of the plurality of positions in step S204 to calculate an average value. After the average value is calculated, the process proceeds to step S206.

[0077] In step S206, the controller 19 calculates a contraction parameter based on the average value calculated in step S205. After the contraction parameter is calculated, the process proceeds to step S207.

[0078] In step S207, the controller 19 outputs the shrinkage parameter calculated in step S206 to the manufacturing device. After the shrinkage parameter is output, the shrinkage parameter output process ends.

[0079] In the observation device 10 according to the second embodiment having the above configuration, as in the first embodiment, the measurement values ​​of the measurement object obj measured at a plurality of positions by the optical coherence tomography imager 12 are used. Therefore, the observation device 10 can quickly observe each measurement object obj that is finally processed into a finished product.

[0080] Furthermore, the observation device 10 according to the second embodiment integrates the measured values ​​at each of the plurality of positions in the depth direction, and finally calculates the shrinkage parameter of the entire measurement object obj based on the integrated value. Therefore, the observation device 10 according to the second embodiment can detect the parameters that affect the shrinkage in steps such as the drying step and the firing step.

[0081] Furthermore, the observation device 10 according to the second embodiment averages the integrated values ​​at each of the plurality of positions. Therefore, the observation device 10 according to the second embodiment can calculate the contraction parameter for inferring the contraction of the entire measurement object obj while reducing the variation of the integrated values ​​caused by the plurality of positions.

[0082] The present disclosure has been described based on the drawings and examples, but it should be noted that those skilled in the art can easily make various modifications and changes based on the present disclosure. Therefore, it should be noted that these modifications and changes are included in the scope of the present disclosure.

[0083] Although the foregoing discloses a system described as including various modules and / or units that perform specific functions, it should be noted that these modules and units are schematically shown to briefly describe their functions, and do not necessarily indicate specific hardware and / or software. In this sense, it is sufficient for these modules, units and other structural elements to be implemented as hardware and / or software that basically performs the specific functions described herein. The various functions of different structural elements can be combined or separated into hardware and / or software in any way, and each of the various functions of different structural elements can be used alone or in some combination with each other. In addition, devices such as keyboards, displays, touch screens and pointer devices are included, but the input / output, I / O devices or user interfaces that are not limited to the above devices can be directly or connected to the system through an intermediate I / O controller. In this way, various aspects of the content disclosed herein can be implemented in many different modes, and these modes are all included in the scope of the content disclosed herein.

[0084] Reference numerals list

[0085] 10 Observation device

[0086] 11 Observation System

[0087] 12 Optical Coherence Tomography

[0088] 13 Light Source

[0089] 14 Beam splitter

[0090] 15 Reference mirror

[0091] 16 Scanner

[0092] 17 Detector

[0093] 18 Controller

[0094] 19 Controller

[0095] 20 Storage Device

[0096] EL irradiation light

[0097] EP irradiation location

[0098] Obj The measurement object.

Claims

1. An observation method comprising: acquiring, from an optical coherence tomography device, measurement values ​​of a measurement object at different multiple positions in a plane intersecting with a depth direction, the measurement object being a ceramic molded body; calculating an average by averaging the measurements at the same depth position at each of the plurality of positions; calculating an integrated value by integrating the average value at each of the depth positions in the depth direction; as well as A green density of the molded body of the measurement object is calculated based on the integrated value.

2. The observation method according to claim 1, further comprising: At each of the plurality of positions, a peak position of the measurement value in the depth direction is detected, wherein: Calculating the average value includes averaging the measured values ​​at the same depth position with reference to the peak position at each of the plurality of positions.

3. The observation method according to claim 1 or 2, wherein: Calculating the integrated value includes integrating the measured value within a range of predetermined depth positions.

4. The observation method according to claim 1 or 2, wherein: A calibration curve is used to convert the integrated value into the green density of the shaped body.

5. An observation method comprising: acquiring, from an optical coherence tomography device, measurement values ​​of a measurement object at different multiple positions in a plane intersecting with a depth direction, the measurement object being a ceramic molded body; calculating an integrated value by integrating the measured value at each of the plurality of positions in the depth direction; calculating an average value by averaging the integrated values ​​calculated for each of the plurality of positions; as well as The green density of the molded body of the measurement object is calculated based on the average value.

6. An observation device comprising: A controller that acquires measurement values ​​of a measurement object at different multiple positions in a plane intersecting a depth direction from an optical coherence tomography imager, the measurement object being a ceramic molded body, calculates an average value by averaging the measurement values ​​at the same depth position at each of the multiple positions, calculates an integrated value by integrating the average value at each of the depth positions, and calculates a green density of the molded body of the measurement object based on the integrated value.

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