JP2017146275A - Method and device for measuring sample made of inorganic material with heating history - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new method and a new device for measuring such characteristics as a heating history of a sample made of an inorganic material, including a ceramic or glass, easily and rapidly.SOLUTION: A sample 12 made of an inorganic material with a heating history is irradiated with a terahertz wave as a 0.1 THz-10 THz electromagnetic wave, and the terahertz wave having passed through the sample 12 is detected. Further, it is possible to obtain unknown information, including the burning temperature of a ceramic and the compositions of glass, based on the detected terahertz wave as characteristics of the sample 12, without breaking the sample.SELECTED DRAWING: Figure 2

Description

  The present invention provides a novel measuring method and measuring apparatus capable of obtaining characteristics such as firing temperature and glass composition of a sample having a heating history made of an inorganic material (hereinafter referred to as ceramics) such as ceramics, porcelain, fine ceramics, and glass. It is about.

  As is well known, products such as ceramics are baked in the firing process when they are manufactured. Here, in order to obtain the desired characteristics, it is necessary to correctly control the firing temperature during firing.

  By the way, in general, ceramics and the like process a plurality of molded bodies in one firing kiln, so it may be insufficient to manage the firing kiln temperature alone. That is, depending on the position and orientation of the molded body in the kiln during firing, the firing temperature of the molded body is partially different, and the fired body may be unevenly burned, which may result in product defects.

  Therefore, there may be a need for a measurement method or a measurement device for nondestructively confirming whether or not the fired body has been fired at a correct temperature for reasons of product management.

  Here, as a non-destructive measuring apparatus for products, for example, the measurement of internal density by X-ray CT described in Japanese Patent Application Laid-Open No. 2003-262512 (Patent Document 1) can be applied. It is also conceivable to apply the measurement by the X-ray diffraction method described in Document 2).

  However, in the former method of measuring internal density by X-ray CT described in Patent Document 1, since measurement before firing is necessary, it is difficult to apply to post-inspection only for products after firing, Not practical.

  In addition, the measurement method based on the X-ray diffraction method described in Patent Document 2 requires a large-scale X-ray apparatus, and in addition to processing by calculation and its reading (diffraction angle and intensity based on Bragg conditions). Spectrum analysis, etc.) are also difficult, and it is difficult to measure easily and quickly.

JP 2003-262512 A JP 2013-136503 A

  Here, the present invention has been made in the background as described above, and the problem to be solved is the characteristics such as the temperature history of a sample made of an inorganic material having a heating history such as ceramic or glass. It is an object of the present invention to provide a novel measurement method and measurement apparatus that can measure the above easily and quickly.

  In order to solve such a problem, the present inventor first tried to measure the temperature history of the sample using X-rays. The result is as shown in FIG. 11, and even when the measurement results of a plurality of types of samples (ceramics) having different firing temperatures at the time of firing are compared, almost no difference can be found, and an effective result is obtained. I couldn't. Note that FIG. 11 shows a comparison of the measurement results using a fired body obtained by firing a molded body of a rectangular semi-porcelain base (thickness 2 mm, no glaze) at 600 to 1200 ° C. An X-ray transmission photographed image is shown, and a photograph taken by a general visible light camera is shown as a visual state on the lower side in the figure.

  Hereinafter, embodiments of the present invention will be described. In addition, the component employ | adopted in each aspect as described below is employable by arbitrary combinations as much as possible.

  A first aspect of the present invention includes a terahertz wave irradiation step of irradiating a sample made of an inorganic material having a heating history with a terahertz wave that is an electromagnetic wave of 0.1 to 10 THz, and the terahertz that is transmitted or reflected by the sample. A terahertz wave detecting step for detecting waves, and a method for measuring a sample made of an inorganic material having a heating history, wherein the characteristics of the sample are obtained based on the terahertz wave detected in the terahertz wave detecting step .

  According to the measurement method according to this aspect, the characteristics of the sample are obtained by irradiating the sample with a terahertz wave and detecting the terahertz wave transmitted or reflected by the sample. Such a complicated calculation and a large-scale apparatus are not required, and the characteristics of the sample can be measured easily and quickly.

  In addition, the sample measured by the method of the present invention is an inorganic material having a heating history, and a sample made of an organic material such as wood or paper is excluded. Not included. For example, in addition to fired bodies such as ceramics, porcelain, and fine ceramics having a heating history during firing, glass having a heating history during molding is included in the sample made of an inorganic material targeted by the present invention.

  Examples of the characteristics of the sample required by the method of the present invention include, but are not limited to, the firing temperature of a fired body such as ceramics, porcelain, and fine ceramics, and the glass composition.

  According to a second aspect of the present invention, in the measurement method according to the first aspect, the plurality of samples are differentiated based on the terahertz waves detected in the terahertz wave detection step as characteristics of the plurality of samples. Is what you want.

  According to the measuring method according to the present aspect, it is possible to obtain differences in temperature histories of a plurality of samples as characteristics, or to distinguish a plurality of samples from the obtained information.

  According to a third aspect of the present invention, in the measurement method according to the first or second aspect, when obtaining the characteristics of the sample, the reference sample is obtained using the reference data acquired in the terahertz wave detection step. The reference data is compared with the acquired data acquired in the terahertz wave detection step for the sample.

  According to the measurement method according to this aspect, by using the reference data obtained from one or more reference samples, it is possible to determine the difference in characteristics from the acquired data obtained from one or more samples. . In addition, depending on the conditions of the reference data and the acquired data, it is possible to grasp the degree and tendency of the difference in characteristics of the sample with respect to the reference sample.

  According to a fourth aspect of the present invention, in the measurement method according to any one of the first to third aspects, the sample is one of earthenware, porcelain, and fine ceramics, and is detected in the terahertz wave detection step. Based on the terahertz wave, the firing temperature of the sample is obtained as a characteristic.

  According to the measurement method according to this embodiment, since the firing temperature of the sample obtained through the firing step can be obtained as a characteristic, whether or not the firing temperature at the time of firing has reached a predetermined temperature for the fired sample. Can be easily determined, and the efficiency of product management can be improved. It is also possible to examine the presence or absence of uneven baking by obtaining the firing temperature at a plurality of locations for the same sample.

  According to a fifth aspect of the present invention, in the measurement method according to any one of the first to fourth aspects, the sample is glass, and the sample is based on the terahertz wave detected in the terahertz wave detection step. Is determined as a characteristic.

  According to the measuring method according to this aspect, when the sample is made of glass, the composition of the glass as a characteristic can be determined by the difference between a plurality of samples or the specification using a reference sample. Further, by referring to the measurement result of the reference sample as necessary, for example, it is possible to confirm whether the sample (glass) contains impurities or to estimate impurities.

  According to a sixth aspect of the present invention, there is provided a sample measuring device made of an inorganic material having a heating history, the terahertz wave irradiating means for irradiating the sample with a terahertz wave that is an electromagnetic wave of 0.1 to 10 THz, and the sample Terahertz wave detecting means for detecting the terahertz wave transmitted or reflected from the terahertz wave, and measurement data output means for outputting measurement data corresponding to the sample based on the terahertz wave detected by the terahertz wave detector It is characterized by this.

  According to the measuring apparatus having the structure according to the present aspect, for example, the measuring method according to any one of the first to fifth aspects can be performed, and the effect can be enjoyed.

  According to the measurement method and the measurement apparatus according to the present invention, it is possible to easily and quickly obtain characteristics such as firing temperature and composition in a sample made of an inorganic material having a heating history, such as ceramics and glass, nondestructively. .

Explanatory drawing which shows the measuring apparatus as one Embodiment of this invention. 2 is a graph showing a transmission spectrum of a terahertz wave in Example 1. FIG. 6 is a graph showing a transmission spectrum of a terahertz wave in Example 2. 6 is a graph showing a transmission spectrum of a terahertz wave in Example 3. 10 is a graph showing a transmission spectrum of a terahertz wave in Example 4. 6 is a graph showing a transmission spectrum of a terahertz wave in Example 5. 10 is a graph showing a transmission spectrum of a terahertz wave in Example 6. 10 is a graph showing a transmission spectrum of a terahertz wave in Example 7. FIG. 10 is an explanatory diagram showing a transmission imaging image of a terahertz wave in Example 8. 10 is a graph showing a transmission spectrum of terahertz waves in Example 9. It is a measurement result as a reference, the upper side is an X-ray transmission image, and the lower side is a photograph taken with a visible light camera.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, FIG. 1 schematically shows a sample measuring device (hereinafter simply referred to as a measuring device) 10 made of an inorganic material having a heating history, as one embodiment of the present invention. In the measuring apparatus 10, a terahertz wave that is irradiated on the sample 12 and transmitted or reflected by the sample 12 is detected. In FIG. 1, the terahertz wave irradiated to and transmitted through the sample 12 is indicated by a thick line, and the terahertz wave reflected by the sample 12 is indicated by a broken line.

  More specifically, the measurement apparatus 10 includes a measurement unit 14 that irradiates and detects a terahertz wave, and an analysis unit 16 that analyzes information on the detected terahertz wave. Are electrically connected to each other.

  The measurement unit 14 includes a terahertz wave generator 18 as a terahertz wave irradiation unit that generates a terahertz wave having a frequency of 0.1 to 10 THz and irradiates the terahertz wave in a specific direction. The measurement unit 14 includes a terahertz wave detector 20 that receives and detects the terahertz wave irradiated by the terahertz wave generator 18.

  Further, the measurement unit 14 is provided with a stage 22, and the sample 12 can be placed on the stage 22. The stage 22 is disposed on the irradiation line of the terahertz wave from the terahertz wave generator 18 and on the opposing line between the terahertz wave generator 18 and the terahertz wave detector 20. The stage 22 is formed of a member that is sufficiently transmissive to the terahertz wave, and the terahertz wave that has passed through the sample 12 is not reflected or absorbed by the stage 22.

  Accordingly, the terahertz wave irradiated from the terahertz wave generator 18 passes through the sample 12 and is detected by the terahertz wave detector 20.

  In addition, when detecting the terahertz wave reflected by the sample 12, the terahertz wave is reflected on the reflection line of the terahertz wave irradiated from the terahertz wave generator 18 by the sample 12, as shown by a broken line in FIG. The detector 20 will be installed.

  Further, a mechanism for generating and irradiating terahertz waves by the terahertz wave generator 18, a mechanism for detecting terahertz waves by the terahertz wave detector 20, and a terahertz wave from the terahertz wave generator 18 through the sample 12 to the terahertz wave detector 20. The route is not limited. For example, any of the conventionally known mechanisms described in JP 2008-268164 A, JP 2007-17419 A, and the like can be employed. Specifically, a THz wave pulse generated by irradiating a photoconductive antenna with a femtosecond laser pulse (pulse width: 50 fs) can be used as the light source.

  Furthermore, only one sample 12 may be placed on the stage 22, but for example, a plurality of samples 12 may be arranged on the stage 22 in the X-axis direction or the Y-axis direction. The XY plane is a direction orthogonal to the paper surface shown in FIG. Then, the terahertz waves generated from the terahertz wave generator 18 are sequentially applied to the sample 12 aligned on the stage 22, and the terahertz waves transmitted or reflected by the sample 12 are sequentially applied to the terahertz wave detector 20. May be detected. At that time, for example, the terahertz wave generator 18 and detector 20 and the stage 22 may be moved relative to each other in parallel with the XY plane, or the path from the terahertz wave generator 18 to the terahertz wave detector 20 is adjusted and changed. You may do it. Alternatively, by using a plurality of terahertz wave detectors 18, it is possible to simultaneously detect the terahertz waves transmitted through the respective samples 12.

  On the other hand, the analysis unit 16 that analyzes the terahertz wave detected by the terahertz wave detector 20 includes a computer 24. For example, in the case of a computer 24 having a general electronic arithmetic device, the wave intensity level as information detected by the terahertz wave detector 18 is converted into an electric intensity level and input to the computer 24 to obtain information on the electric signal. The target analysis process can be executed by performing the calculation process. For example, the transmission characteristic of the terahertz wave in the sample 12 is obtained by an arithmetic process that obtains a transmission level for each frequency using Fourier transform or the like, and obtains an integral value of the transmission energy of the terahertz wave in a specific frequency region as necessary. A measurement result reflecting the reflection characteristics can be obtained.

  The measurement results corresponding to the sample 12 thus obtained are stored in a storage device such as a RAM, a magnetic disk, or an optical disk of the computer 24, and are externally displayed in an appropriate form such as a graph or a table on the monitor 26. Is displayed in a recognizable manner, and is printed as necessary. That is, in this embodiment, the measurement data output means for outputting the measurement data detected by the terahertz wave detector 20 and analyzed by the computer 24 includes the monitor 26 of the computer 24.

  Here, the sample 12 is made of an inorganic material having a heating history. That is, as the sample 12 according to the present invention, a sample made of an organic material such as wood or paper is excluded, and a metal is not included in the target sample because of its high conductivity. For example, in addition to a fired body such as ceramics, porcelain, and fine ceramics having a heating history during firing, glass having a heating history during molding is used as the ceramic sample 12 that is an inorganic material targeted by the present invention.

  By analyzing the terahertz wave transmitted through or reflected by the terahertz wave detector 20 and detected by the terahertz wave detector 20 with the computer 24, measurement data corresponding to the sample 12 is obtained as characteristics of the sample 12. The characteristics of the sample 12 are not particularly limited. For example, when the sample 12 is a fired body such as ceramics, porcelain, or fine ceramics, the firing temperature is set, and the sample 12 is made of glass. In some cases, the composition thereof may be mentioned.

  Specific measurement results of the sample 12 using the measuring apparatus 10 having the above-described structure are shown as examples below.

  In the following examples, “TAS-7400TS” manufactured by Advantest Co., Ltd. was adopted as a basic device including the terahertz wave generator 18 and the terahertz wave detector 20 constituting the measurement unit 14. Terahertz time-domain spectroscopy (Terahertz Time-Domain Spectroscopy: THz-TDS) was employed to measure the transmission spectrum and transmission imaging of terahertz waves.

  Moreover, in Examples 1-4, while showing the detection result to 0.1-2.0 THz, in Examples 5-7, the detection result to 0.1-1.5 THz is shown. Further, in the results of the examples, the transmittance is (the intensity of the detected terahertz wave) / (the intensity of the irradiated terahertz wave), and is expressed in decibels (dB) or arbitrary units (au). .

[Example 1]
The semi-porcelain base powder was kneaded with distilled water to form a 20 × 20 × 3 mm plate using a gypsum mold as a dough. The molded body was dried and then fired at temperatures different from each other within a range of 600 to 1200 ° C. to obtain a plurality of fired bodies. The obtained fired body was cut into a size of 10 × 10 × 2 mm to obtain a plurality of types of samples having different firing temperatures. And about each sample, the measurement using the above-mentioned measuring apparatus was performed, and the transmission spectrum of the terahertz wave was measured by the terahertz time domain spectroscopy (THz-TDS). The result is shown in FIG.

  As shown in FIG. 2, it was confirmed that the transmission spectrum of the terahertz wave changed according to the firing temperature in the measurement result of each sample.

  Therefore, for example, by obtaining a transmission spectrum as a measurement result for any one sample, the firing temperature of the sample can be known from the graph shown in FIG. Further, it is possible to discriminate between different samples by comparing transmission spectra measured for different samples. Alternatively, if each sample shown in FIG. 2 is used as a reference sample and the transmission spectrum information of FIG. 2 is prepared, the transmission spectrum obtained for another sample is evaluated using the transmission spectrum information of the reference sample. It is also possible to specify the firing temperature of the other sample.

  Therefore, for example, in the case of controlling the firing temperature at 1200 to 1250 ° C. in the production process of semi-porcelain, the actual firing for each product is obtained by obtaining the firing temperature information by obtaining the transmission spectrum of the product by nondestructive inspection. It is possible to know the temperature, and based on such information, it is possible to perform quality judgment and quality control of the product.

[Example 2]
A plurality of types of samples were obtained in the same process as in Example 1 using the low-temperature fired ceramic substrate described in Japanese Patent No. 5083971. FIG. 3 shows the results of measuring the transmission spectrum of the terahertz wave for these multiple types of samples in the same manner as in Example 1.

  As shown in FIG. 3, even in a low-temperature fired porcelain, since the transmission spectrum of terahertz waves changes according to the firing temperature, the sample can be evaluated nondestructively as in Example 1. It is considered possible.

[Example 3]
Using a heat-resistant ceramic body, a plurality of types of samples were obtained in the same process as in Example 1. FIG. 4 shows the results of measuring the transmission spectrum of the terahertz wave for these multiple types of samples in the same manner as in Example 1.

  As shown in FIG. 4, even in a heat-resistant pottery, the transmission spectrum of terahertz waves changes according to the firing temperature. Is considered possible.

[Example 4]
Using yttria-stabilized zirconia, which is a kind of fine ceramics (also called new ceramics), a plurality of types of samples were obtained in the same process as in Example 1. In the present example, the firing temperature of the molded body was set differently within a range of 1100 to 1500 ° C., and the obtained fired body was cut into a size of 10 × 10 × 1 mm to obtain a sample. FIG. 5 shows the results of measuring the transmission spectrum of the terahertz wave for these multiple types of samples in the same manner as in Example 1.

  As shown in FIG. 5, even with fine ceramics made of yttria-stabilized zirconia, the transmission spectrum of the terahertz wave changes depending on the firing temperature. It can be considered nondestructive.

[Example 5]
A plurality of types of samples having different thicknesses in the range of 2.00 to 9.76 mm were obtained through the same steps as in Example 1 using the same semi-porcelain substrate as in Example 1 above. FIG. 6 shows the results of measuring the transmission spectrum of the terahertz wave for these multiple types of samples in the same manner as in Example 1.

  As shown in FIG. 6, it was confirmed that the transmission spectrum of the terahertz wave changes when the thickness dimension of the sample changes. It is considered that the transmittance of the terahertz wave decreases as the thickness dimension of the sample increases. Therefore, when measuring the characteristics according to the present invention, when the thickness dimension of the sample is greatly different, more accurate evaluation can be realized by considering the difference in thickness dimension. Further, the difference in the thickness dimension of the product can be determined by the measuring method according to the present invention, and therefore, it can be used for, for example, quality evaluation or quality evaluation based on the thickness dimension of the product.

[Example 6]
Using the same semi-ceramic body as in Example 1, a plurality of molded bodies were obtained in the same manner as in Example 1, and then glaze was applied only to one side of some of the molded bodies. And by baking these some molded object at 1200 degreeC, the baking body with a glaze and the baking body without a glaze were baked on the same conditions, and the some sample was obtained. In addition, the lime transparent candy was used as the glaze. Moreover, when measuring the transmission spectrum of the terahertz wave in the sample coated with glaze, terahertz waves were irradiated from the side where the glaze was applied and the side where the glaze was not applied, and the results were compared.

  The result of measuring the transmission spectrum of the terahertz wave for the sample thus obtained in the same manner as in Example 1 is shown in FIG. In addition, in the sample with a glaze, the result measured about the case where the irradiation surface of a terahertz wave is made into the glaze application surface side and the case where it is made into the ground surface side where no glaze is applied is shown in FIG.

  As shown in FIG. 7, the influence on the measurement result by the presence or absence of glaze was hardly recognized. Therefore, it can be said that the measurement method and the measurement apparatus according to the present invention can be similarly applied to measurement of various samples regardless of the presence or absence of glaze.

[Example 7]
As in Example 6 above, the glaze layer was applied to one side of a 3 mm thick substrate by applying a glaze to one side of a molded body using a semi-porcelain substrate, so that no glaze layer was applied to one side of the 3 mm thick substrate (no glaze application) ) To 1.76 mm, a plurality of types of samples provided in a plurality of types were obtained. FIG. 8 shows the result of measuring the transmission spectrum of the terahertz wave for each of these samples in the same manner as in Example 6.

  As shown in FIG. 8, it was confirmed that the transmission spectrum of the terahertz wave is different when the thickness of the glaze is different. Since the transmittance of terahertz waves tends to decrease as the thickness of the glaze increases, when measuring the characteristics according to the present invention, if the thickness of the glaze layer varies greatly, the difference in the thickness of the glaze layer is also taken into account. Thus, a more accurate evaluation can be realized. Further, the difference in the thickness dimension of the glaze layer can be determined by the measuring method according to the present invention, and therefore, it can be used for, for example, evaluation of quality or quality by the thickness dimension of the glaze layer in the product. it can.

[Example 8]
Using a semi-porcelain substrate, a low-temperature fired ceramic substrate, and a heat-resistant ceramic substrate, a molded body made of a plate-like body having the same dimensions is prepared and fired at various firing temperatures of 600 to 1200 ° C. A sample having a rectangular plate shape of 2 mm was obtained. Then, transmission imaging images of terahertz waves were taken for each of these samples. In photographing, a terahertz wave of 0.7 to 1.0 THz was used.

  The transmission imaging image in the semi-porcelain substrate thus obtained is shown in the middle part of FIG. 9 (a), the transmission imaging image in the low-temperature fired ceramic body is shown in the middle part of FIG. 9 (b), and further the transmission in the heat-resistant ceramic substrate. An imaging image is shown in the middle part of FIG. 9 (a) to 9 (c) is an index indicating the transmittance of the terahertz wave by color coding, which is difficult to understand in black and white for the patent application drawing, but the transmittance becomes high ( While the color gradually becomes lighter as it approaches 100 on the left side of the figure, it is displayed as a darker color as the transmittance decreases (approaching 0 on the right side of the figure). Moreover, the camera photograph which shows the visual external appearance of each sample is shown in the lowest stage of Fig.9 (a)-(c).

  As shown in FIGS. 9A to 9C, it can be seen that the color of the transmission imaging image is darker and the transmittance of the terahertz wave is lower toward the right side where the baking temperature is higher. Then, it can be understood that the difference in the firing temperature as the characteristic in each sample that cannot be determined by the visual appearance photograph shown in each lower stage can be determined by using the terahertz wave. In particular, also in each of the samples on the left side of FIGS. 9A to 9C, since the color of the central portion is thinner than that of the outer peripheral portion in the transmission imaging image, the central portion is compared with the outer peripheral portion. It can be seen that the firing temperature is low and not sufficiently fired. As described above, by measuring the transmittance of terahertz waves at a plurality of points in the same sample, it is possible to determine the unevenness of baking.

[Example 9]
Each glass of silica glass, borosilicate glass, and soda lime glass was heated and melted to prepare glass plates each having a thickness of 2 mm, and a plurality of types of samples having different materials were used. Then, in the same manner as in Example 1, the terahertz wave was irradiated and the terahertz wave transmitted through each sample was detected, and the transmittance was calculated. The result is shown in FIG. In addition, although the terahertz wave was changed in the range of 0-5.0 THz, the result of 0.1-1.5 THz is shown in FIG.

  As shown in FIG. 10, it was confirmed that when the glass composition is different, the graph of the transmittance of the terahertz wave is also different. Therefore, in the same manner as in Example 1 for ceramics, by measuring a sample made of glass with an unknown composition by the method of the present invention using terahertz waves, the difference in composition with another glass can be determined, If necessary, the glass composition of the sample can also be estimated by referring to reference data consisting of known glass measurement results. Also, for example, by using reference data of various high-purity glass materials, constructing simultaneous equations with the transmittance of terahertz waves and the composition ratio of the glass, and finding the solution, the composition of the unknown glass used as the sample Can also be requested. Alternatively, by managing the transmittance of the terahertz wave in the sample, it is possible to detect unintentional impurity contamination without destruction, and it can also be used for quality control of products.

  The basic embodiment and some examples of the present invention have been described above. However, the present invention is not limited to these specific descriptions, and various modifications are made based on the knowledge of those skilled in the art. The present invention can be implemented in a form to which changes, corrections, improvements and the like are added.

  That is, the measuring method and measuring apparatus according to the present invention are not limited to ceramics, porcelain, fine ceramics, and glass, but for example, ceramics including earthenware and ceramics, and ceramics in a broad sense including bricks and grindstones. Applicable.

10: Measuring apparatus for sample made of inorganic material having heating history, 12: Sample, 18 terahertz wave generator (terahertz wave irradiation means), 20: Terahertz wave detector (terahertz wave detecting means), 26: Monitor (measurement data) Output means)

Claims (6)

A terahertz wave irradiation step of irradiating a terahertz wave that is an electromagnetic wave of 0.1 to 10 THz to a sample made of an inorganic material having a heating history;
A terahertz wave detecting step of detecting the terahertz wave transmitted or reflected by the sample;
A method for measuring a sample made of an inorganic material having a heating history, wherein the characteristics of the sample are obtained based on the terahertz wave detected in the terahertz wave detection step.   The method for measuring a sample made of an inorganic material having a heating history according to claim 1, wherein the difference between the plurality of samples is obtained based on the terahertz waves detected in the terahertz wave detection step as characteristics of the plurality of samples. .   The reference data acquired in the terahertz wave detecting step for the reference sample is compared with the acquired data acquired in the terahertz wave detecting step for the sample when determining the characteristics of the sample. Or the measuring method of the sample which consists of an inorganic material which has a heating history of 2.   The sample is any one of ceramics, porcelain, and fine ceramics, and the firing temperature of the sample is obtained as a characteristic based on the terahertz wave detected in the terahertz wave detection step. A method for measuring a sample made of an inorganic material having the described heating history.   From the inorganic material having a heating history according to any one of claims 1 to 3, wherein the sample is glass, and the composition of the sample is obtained as a characteristic based on the terahertz wave detected in the terahertz wave detection step. A method for measuring a sample. An apparatus for measuring a sample made of an inorganic material having a heating history,
Terahertz wave irradiation means for irradiating the sample with terahertz waves which are electromagnetic waves of 0.1 to 10 THz;
Terahertz wave detecting means for detecting the terahertz wave transmitted or reflected by the sample;
An apparatus for measuring a sample made of an inorganic material having a heating history, comprising: measurement data output means for outputting measurement data corresponding to the sample based on the terahertz wave detected by the terahertz wave detector .