JP6989911B2 - Spectroscopic elements, measuring methods, and measuring devices - Google Patents

Description

The present invention relates to a spectroscopic element, a measuring method, and a measuring device.

Patent Document 1 describes a conductive periodic structure as a device for measuring the concentration of a solution with high sensitivity by an Attenuated Total Reflection (ATR method) using a terahertz wave, and an interface at which the terahertz wave is totally reflected. Disclosed is an apparatus for measuring the concentration of a substance to be measured and the like by forming a dip showing characteristic absorption in a predetermined frequency band of a terahertz wave.

Further, in Patent Document 2, the water content of the thin film sample is modified by correcting the attenuation of the terahertz wave by using the reflectance coefficient at the interface between the thin film sample provided on the ATR prism and the laminated sample installed above the thin film sample. The method of finding is disclosed.

Further, in Patent Document 3, an arbitrary distance adjusting mechanism is provided for the prism to control the distance between the sample and the reflecting surface to be constant, and the interference phenomenon of light on the reflecting surface side is used. A device capable of improving the measurement accuracy of the terahertz wave is disclosed.

Japanese Unexamined Patent Publication No. 2014-77672 Japanese Unexamined Patent Publication No. 2016-53527 Japanese Unexamined Patent Publication No. 2016-90314

In general, when measuring liquids with terahertz waves, it is difficult to perform transmission measurement due to the strong absorption of terahertz waves, especially for highly polar liquids such as water, and it is necessary to extremely shorten the optical path length of the sample site. be. In addition, since the absorption of terahertz waves changes over a wide range in an aqueous solution, the characteristic spectral structure often does not exist, and it is difficult to confirm the quantitative change.

As a specific method for solving the above problems, the method described in Patent Document 1 can be mentioned, but a conductive structure having a complicated periodic structure is required, and the wavelength of a terahertz wave is about the same. There is a problem that the terahertz wave may cause unexpected diffraction due to its size.

Further, the method described in Patent Document 2 has a problem that the physical constants of some materials need to be known in order to obtain the water content of a specific sample.

Further, in the method described in Patent Document 3, when the surface of the sample is extremely flexible (particularly the liquid surface), the shape of the sample surface changes due to the generation of ripples and the like, and the distance from the sample is not always constant. The case occurs. There is a problem.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a spectroscopic element, a measuring method, and a measuring device capable of measuring spectral information of a measured object with high sensitivity.

In order to achieve the above object, the spectroscopic element according to the first aspect of the present invention includes a first dielectric layer, a second dielectric layer provided on the first dielectric layer, and the first dielectric layer. A third dielectric layer provided on the second dielectric layer is provided, and an electromagnetic wave incident on the first dielectric layer is provided with the first dielectric layer and the second dielectric layer. The first refractive index of the first dielectric layer is larger than the second refractive index of the second dielectric layer so as to be totally reflected at the interface of the second dielectric layer. The third dielectric layer of the third dielectric layer has a higher refractive index than the second dielectric layer so that the evanescent wave is multiple-reflected in the third dielectric layer. The thickness of the layer is smaller than the wavelength of the electromagnetic wave incident on the first dielectric layer.

Further, the spectroscopic element according to the second aspect of the present invention is a prism formed so that the first dielectric layer is incident on the interface at an angle satisfying the condition that the incident electromagnetic wave is totally reflected at the interface. be.

Further, in the spectroscopic element according to the third aspect of the present invention, the second dielectric layer is a quartz plate.

Further, in the spectroscopic element according to the fourth aspect of the present invention, the third dielectric layer is a silicon wafer.
Further, the spectroscopic element according to the fifth aspect of the present invention includes a holding portion for holding the object to be measured by the side wall formed on the third dielectric layer.

Further, in the measuring method according to the sixth aspect of the present invention, the object to be measured is arranged on the third dielectric layer of the spectroscopic element according to any one of the first to fifth aspects, and the first dielectric is provided. An electromagnetic wave is incident on the body layer to generate an evanescent wave at the interface between the first dielectric layer and the second dielectric layer and the interface between the third dielectric layer and the object to be measured. The spectral information of the object to be measured is measured based on the intensity of a specific frequency having a spectral structure characterized by the intensity of the electromagnetic wave emitted from the spectroscopic element, including the wave multiple reflected in the dielectric layer of 3.

Further, in the measuring method according to the seventh aspect of the present invention, the object to be measured is a solution, and the concentration of the solution is measured as the spectral information based on the intensity of the specific frequency.

Further, in the measuring method according to the eighth aspect of the present invention, the electromagnetic wave incident on the spectroscopic element is a terahertz wave.

Further, the measuring device according to the ninth aspect of the present invention is emitted from the spectroscopic element according to any one of the first to fifth aspects, a light source for generating an electromagnetic wave incident on the spectroscopic element, and the spectroscopic element. A measuring unit for measuring spectral information of a measured object on the third dielectric layer based on the intensity of a specific frequency having a spectral structure characterized by the intensity of electromagnetic waves is provided.

As described above, according to the spectroscopic element, the measuring method, and the measuring device of the present invention, it is possible to obtain the effect that the spectroscopic information of the object to be measured can be measured with high sensitivity.

It is a block diagram which shows the structure of a measuring device. It is a block diagram which shows the structure of a spectroscopic element. It is a figure for demonstrating multiple reflection. It is a graph which shows the relationship between the frequency and the intensity of a terahertz wave. It is a graph which shows the relationship between the frequency and the intensity of a terahertz wave. It is a graph which shows the relationship between the frequency and the intensity of a terahertz wave. It is a graph which shows the relationship between the frequency and the intensity of a terahertz wave. It is a graph which shows the relationship between the frequency and the intensity of a terahertz wave. It is a graph which shows the relationship between the water content of a solution, and the intensity of a terahertz wave. It is a graph which shows the relationship between the frequency and the intensity of a terahertz wave. It is a graph which shows the relationship between the concentration of a solution and the intensity of a terahertz wave.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the measuring device according to the present embodiment will be described. FIG. 1 shows the configuration of the measuring device 10 according to the present embodiment. The measuring device 10 is a device that measures the spectral information of the object to be measured by the ATR method using the terahertz wave.

As shown in FIG. 1, the measuring device 10 includes a femtosecond fiber laser 12 as a terahertz wave excitation light source. As the femtosecond fiber laser 12, for example, a femtosecond fiber laser having a center wavelength of 780 nm, a pulse width of 100 fs, an average power of 20 mW, and a repetition frequency of 50 MHz can be used, but is not limited thereto.

The laser light oscillated by the femtosecond fiber laser 12 is divided into a pump light L1 for generating a terahertz wave and a probe light L2 for detecting the terahertz wave by the beam splitter 14.

The pump light L1 is reflected by the mirrors M1 and M2 and incident on the terahertz wave generation photoconducting antenna 16. As the terahertz wave generation photoconducting antenna 16, for example, a gallium arsenide (GaAs) grown at low temperature is used as a substrate.

When a rectangular wave voltage is applied from a power source (not shown) between the gaps of the terahertz wave generation photoconducting antenna 16, it enters free space via a super hemispherical silicon lens (not shown) mounted on the terahertz wave generation photoconducting antenna 16. A terahertz wave (terahertz pulse) is emitted. The square wave voltage may be, for example, ± 10 V, 50 kHz square wave voltage.

The terahertz pulse radiated from the terahertz wave generation photoconducting antenna 16 is collimated by the terahertz lens 18 and incident on the spectroscopic element 20.

As shown in FIG. 2, the spectroscopic element 20 has a prism 22 as a first dielectric layer made of non-doped silicon having a resistivity of 1 kΩcm or more and a second dielectric provided on the prism 22. Silicon ( _Si O 2) made of high resistivity non-doped silicon having a resistivity of 1 kΩcm or more as a quartz ( _Si O ₂ ) plate 24 as a body layer and a third dielectric layer provided on the quartz plate 24. ) A wafer 26 and a solution cell 28 provided on the silicon wafer 26. The solution cell 28 has a holding portion for holding the solution by providing a side wall on the silicon wafer 26. Although it is possible to measure even if the object to be measured is an individual, it is desirable that there is no gap between the object to be measured and the third dielectric layer and they are in close contact with each other for accurate measurement. When the object to be measured is a liquid, it is suitable because it can be easily brought into contact with the third dielectric layer without a gap.

No chemical or physical bond is required between the prism 22 and the quartz plate 24, between the quartz plate 24 and the silicon wafer 26, and between the silicon wafer 26 and the solution cell 28, and they are simply in close contact with each other. You just have to do it. Further, as the solution cell 28, for example, a solution cell made of Teflon (registered trademark) can be used, but the solution cell 28 is not limited thereto.

The prism 22 is incident on the interface 30 at an angle that satisfies the condition that the terahertz wave T incident from the side surface is totally reflected at the interface 30 with the quartz plate 24, that is, the angle of incidence of the terahertz wave T on the interface 30 is larger than the critical angle. It is molded to do so. In the present embodiment, the shape of the prism 22 is a trapezoid as an example, but the prism 22 is limited to a trapezoid as long as it is incident on the interface 30 at an angle satisfying the condition that the incident terahertz wave T is totally reflected at the interface 30. is not it. The frequency of the terahertz wave T incident on the prism 22 is a terahertz pulse including a band of 0.1 to 4 THz as an example in the present embodiment. Further, as the prism 22, for example, a prism made of silicon can be used, but the prism 22 is not limited to this.

Further, the refractive index n1 of the prism 22 is larger than the refractive index n2 of the quartz plate 24 (n1> n2), and the refractive index n3 of the silicon wafer 26 is larger than the refractive index n2 of the quartz plate 24 (n3> n2). ..

As described above, since the refractive index n1 of the prism 22 is larger than the refractive index n2 of the quartz plate 24, as shown in FIG. 3, the terahertz wave T incident on the prism 22 is the interface 30 between the prism 22 and the quartz plate 24. It is totally reflected like the reflected wave R.

When total reflection occurs at the interface 30, an evanescent wave E is generated on the quartz plate 24 side of the interface 30. The evanescent wave E has a characteristic of seeping into a region of about a wavelength on the low refractive index medium side under total reflection conditions. Since the refractive index n2 of the quartz plate 24 is smaller than the refractive index n3 of the silicon wafer 26, the evanescent wave E generated on the quartz plate 24 side is transmitted to the silicon wafer 26 side. The thickness of the quartz plate 24 is smaller than the wavelength of the terahertz wave incident on the prism 22. If the thickness of the quartz plate 24 is smaller than the wavelength of the terahertz wave incident on the prism 22, the evanescent wave E reaches the silicon wafer 26. If the wavelength of the terahertz wave incident on the prism 22 has a certain band (width), the thickness of the quartz plate 24 is smaller than the longest wavelength included in the terahertz wave incident on the prism 22. good.

When the refractive index of the solution S as the object to be measured filled in the solution cell 28 is smaller than the refractive index n3 of the silicon wafer 26, the evanescent wave E is generated on the quartz plate 24 at the interface 32 between the silicon wafer 26 and the solution S. Total internal reflection to the side. Further, since the refractive index n3 of the silicon wafer 26 is larger than the refractive index n2 of the quartz plate 24, total reflection also occurs at the interface 34 between the silicon wafer 26 and the quartz plate 24. As a result, as in the optical path shown in FIG. 3, the total reflection of the evanescent wave E is repeated a plurality of times in the silicon wafer 26, that is, the evanescent wave E is repeatedly reflected in the silicon wafer 26. Since the intensity of the evanescent wave E is small, it is usually difficult to detect changes in the spectral structure, but it is possible to detect changes in the spectral structure with high sensitivity due to interference due to multiple reflections.

The evanescent wave E multiplely reflected in the silicon wafer 26 is radiated (exited) from the prism 22 together with the terahertz wave T totally reflected at the interface 30. Due to the multiple reflection of the evanescent wave E in the silicon wafer 26, the terahertz wave T radiated from the prism 22 interferes, and a dip (interference fringe) is generated in the detected terahertz wave T waveform. The details of the dip will be described later.

As shown in FIG. 1, the terahertz wave T output from the spectroscopic element 20 is collimated by the terahertz lens 40 and incident on the terahertz wave detection photoconducting antenna 42.

On the other hand, the probe light L2 is reflected by the mirror M3 and incident on the delay device 44. The delay device 44 includes a movable mirror Ma that can move in the direction of arrow A in the figure, and has a configuration in which the optical path length can be changed by moving the movable mirror Ma.

The light emitted from the delay device 44 is reflected by the mirrors M4 to M9 and incident on the terahertz wave detection optical conduction antenna 42. As the terahertz wave detection optical conduction antenna 42, for example, a gallium arsenide (GaAs) having a low temperature growth as a substrate is used as in the terahertz wave generation optical conduction antenna 16.

The optical path length was changed by moving the movable mirror Ma of the delay device 44, and the probe light L2 was output from the probe light L2 and the spectroscopic element 20 while shifting the timing at which the probe light L2 reached the terahertz wave detection photoconducting antenna 42. The lock-in amplifier 46 detects the time waveform of the terahertz wave T by changing the temporal overlap with the terahertz wave T.

The personal computer 48 obtains spectral information of the object to be measured based on the time waveform of the terahertz wave T detected by the lock-in amplifier 46.

FIG. 4 shows the relationship between the frequency and the intensity of the terahertz wave measured by the measuring device 10 according to the present embodiment. The solution cell 28 is a solution cell made of Teflon (registered trademark) having a length of 60 mm, a width of 20 mm, and a height of 30 mm (internal dimensions of 40 mm in length, 13 mm in width, and 30 mm in height), and is a solution as a material to be measured. Was methanol (MeOH).

In the example of FIG. 4, when the thickness of the silicon wafer 26 of the spectroscopic element 20 is 300 μm, the thickness of the quartz plate 24 is 50 μm (Si wafer + quartz plate 50 μm), and the thickness of the quartz plate 24 is 100 μm (Si). The measurement result of the wafer + quartz plate 100 μm) is shown.

Further, FIG. 4 shows a measurement result (Si wafer) of the configuration in which the quartz plate 24 is removed from the spectroscopic element 20, that is, a configuration in which only the silicon wafer 26 is provided between the prism 22 and the solution cell 28, and the spectroscopic element. The measurement result (prism only) of the configuration in which the quartz plate 24 and the silicon wafer 26 are removed from 20, that is, the configuration in which the solution cell 28 is provided on the prism 22 is also shown.

As shown in FIG. 4, in the case of "Si wafer + quartz plate 50 μm", it can be seen that a characteristic dip is generated at a frequency around 0.68 THz.

Here, the dip refers to a portion where the intensity of the terahertz wave drops sharply, that is, a portion having a characteristic spectral structure as compared with the intensity of other frequencies. Hereinafter, the specific frequency at which the dip is formed is referred to as a “dip frequency”.

Further, in the example of FIG. 4, when comparing the case where the thickness of the quartz plate 24 is 50 μm and the case where the thickness of the quartz plate 24 is 100 μm, it can be seen that a deeper dip is generated when the thickness of the quartz plate 24 is 50 μm. That is, it was found that the depth of the dip can be adjusted by providing the quartz plate 24 between the silicon wafer 26 and the prism 22 and adjusting the thickness of the quartz plate 24.

Next, FIGS. 5 and 6 show the frequency and intensity of the terahertz wave when the thickness of the quartz plate 24 of the spectroscopic element 20 according to the present embodiment is fixed at 50 μm and the thickness of the silicon wafer 26 is 300 μm, 500 μm, and 750 μm. Shows the relationship between. Note that FIG. 5 shows the measurement results when nothing was put into the solution cell 28 and only air was used. Further, FIG. 6 shows the measurement results when 6 mL of methanol (MeOH) having a purity of 99.9% was added to the solution cell 28.

Table 1 below shows the results of summarizing the dip frequencies for each thickness of the silicon wafer 26 when the inside of the solution cell 28 is only air, based on the measurement results of FIG.

また、下記表２に、図６の測定結果に基づいて、溶液セル２８内に純度９９．９％のメタノールを６ｍＬ入れた場合におけるシリコンウェハ２６の厚み毎のディップ周波数をまとめた結果を示す。

Table 2 below shows the results of summarizing the dip frequencies for each thickness of the silicon wafer 26 when 6 mL of methanol having a purity of 99.9% was put into the solution cell 28 based on the measurement results of FIG.

上記表１、２に示すように、溶液セル２８内が空気のみの場合、メタノールを入れた場合の何れの場合においても、シリコンウェハ２６の厚みが変わると、発生するディップの数やディップ周波数が異なることが判った。

As shown in Tables 1 and 2 above, when the thickness of the silicon wafer 26 changes, the number of dips generated and the dip frequency change regardless of whether the solution cell 28 contains only air or methanol. It turned out to be different.

Therefore, it was found that the dip can be generated in a specific frequency band by adjusting the thickness of the silicon wafer 26.

Next, FIG. 7 shows the relationship between the frequency and the intensity of the terahertz wave measured in a configuration in which the thickness of the quartz plate 24 of the spectroscopic element 20 is 50 μm and the thickness of the silicon wafer 26 is 750 μm.

Further, the measurement result of FIG. 7 is a result of putting a solution in which water and methanol are mixed into the solution cell 28 and measuring by changing the water content. The water content is 0% water (100% methanol), 20% water (80% methanol), 40% water (60% methanol), 60% water (40% methanol), 80% water (20% methanol), and water. It was set to 100% (methanol 0%).

Further, in FIG. 8, as a comparison target of FIG. 7, the frequency of the terahertz wave measured in the configuration in which the quartz plate 24 and the silicon wafer 26 are removed from the spectroscopic element 20, that is, the configuration in which the solution cell 28 is provided on the prism 22 The relationship between and strength is shown for each water content.

As shown in FIG. 7, when the measurement is performed using the spectroscopic element 20 according to the present embodiment, it can be seen that the depth of the dip is significantly changed depending on the water content.

On the other hand, as shown in FIG. 8, in the case of the configuration of only the prism 22 in which the quartz plate 24 and the silicon wafer 26 are omitted, it can be seen that no dip has occurred.

FIG. 9 shows the relationship between the intensity of the 0.49 THz terahertz wave in which the dip occurs in the measurement result of FIG. 7 and the water content (quartz plate 50 μm + silicon wafer 750 μm), and 0.49 THz in the measurement result of FIG. The relationship between the intensity of the terahertz wave and the water content (prism only) was shown.

As shown in FIG. 9, by using the spectroscopic element 20 according to the present embodiment, the difference between the intensity of the terahertz wave when the water content is 0% and the intensity of the terahertz wave when the water content is 100% There are about two digits. On the other hand, in the case of the configuration of only the prism 22, there is almost no difference between the intensity of the terahertz wave when the water content is 0% and the intensity of the terahertz wave when the water content is 100%.

Therefore, by using the spectroscopic element 20 according to the present embodiment, the concentration of the solution can be measured with higher sensitivity than in the case of the configuration of only the prism 22.

Next, in FIG. 10, a 4-Dimethylamino-N'-methyl-4'-stilbazolium tosylate-MeOH solution (hereinafter referred to as DAST-MeOH solution) adjusted to saturation at 23 degrees was placed in the solution cell 28 and subjected to spectroscopy. The relationship between the frequency and the intensity of the terahertz wave measured in the configuration where the thickness of the quartz plate 24 of the element 20 is 50 μm and the thickness of the silicon wafer 26 is 750 μm is shown.

The DAST-MeOH solution is heated to 55 ° C. after mixing 1.89 grams of DAST powder (purity 99.9% or higher) with 100 grams of methanol, specifically methanol for HPLC (high performance liquid chromatography). And completely dissolved. The concentration of the DAST-MeOH solution was measured at an initial concentration of 1.86 wt%, and then methanol was added to the solution cell 28 so as to be 1.59 wt%, 1.40 wt%, and 1.20 wt% with respect to the solution. Was added, and after stirring once with a micropipette, the measurement was started after the fluctuation of the liquid level had subsided.

As shown in FIG. 10, it can be seen that the intensity of the terahertz wave at the dip frequency of 0.49 THz changes with the change in the concentration of the DAST-MeOH solution.

Further, FIG. 11 shows the relationship between the concentration of the DAST-MeOH solution at 0.49 THz and the intensity of the terahertz wave. As shown in FIG. 11, it can be seen that the intensity of the terahertz wave increases as the concentration of the DAST-MeOH solution decreases.

Therefore, the concentration of the solution can be measured with high sensitivity by performing the spectroscopy of the solution using the spectroscopic element 20 according to the present embodiment. That is, the personal computer 48 can obtain the intensity of the terahertz wave at the frequency at which the dip is generated based on the terahertz wave detected by the lock-in amplifier 46, and can obtain the concentration of the solution based on the obtained intensity.

As described above, in the present embodiment, the evanescent wave generated when the terahertz wave is totally reflected at the interface 30 between the prism 22 and the quartz plate 24 is multi-reflected in the silicon wafer 26 to a specific frequency. A dip can be generated, and by measuring the intensity of the terahertz wave at the dip frequency, the spectral information of the object to be measured such as the concentration of the solution in the solution cell 28 can be measured with high sensitivity.

Further, since the method of generating the terahertz wave is not limited, it is possible to measure the change in the concentration of the solution in real time by using the generator that continuously generates the terahertz wave.

In the present embodiment, the case where the concentration of the solution is measured using the terahertz wave has been described, but the object to be measured is not limited to the terahertz wave but also uses electromagnetic waves in other frequency bands, particularly electromagnetic waves in the optical region. Spectral information may be measured.

Further, in the present embodiment, the case where the object to be measured is a solution and the concentration of the solution is measured as spectral information has been described, but the spectral information to be measured is not limited to the concentration of the solution.

Further, in the present embodiment, the case where the first dielectric layer is a prism, the second dielectric layer is a quartz plate, and the third dielectric layer is a silicon wafer has been described, but the present invention is not limited thereto. .. That is, in a material in which the refractive index of the first dielectric layer is larger than the refractive index of the second dielectric layer and the refractive index of the third dielectric layer is larger than the refractive index of the second dielectric layer. It may be configured.

10 Measuring device 12 Femtosecond fiber laser 14 Beam splitter 16 Terahertz wave generation light conduction antenna 18, 40 Terahertz lens 20 Spectral element 22 Prism 24 Quartz plate 26 Silicon wafer 28 Solution cell 30, 32, 34 Interface 42 Terahertz wave detection Photoconducting antenna 44 Delayer 46 Lock-in amplifier 48 Personal computer

Claims (9)

A first dielectric layer, a second dielectric layer provided on the first dielectric layer, and a third dielectric layer provided on the second dielectric layer and in contact with an object to be measured. With layers,
The first bending of the first dielectric layer so that the electromagnetic wave incident on the first dielectric layer is totally reflected at the interface between the first dielectric layer and the second dielectric layer. The second dielectric layer has a higher rate than the second refractive index of the second dielectric layer, and the evanescent wave generated in the second dielectric layer is multiple-reflected in the third dielectric layer. The third dielectric constant of the dielectric layer 3 is larger than the second refractive index, and the thickness of the second dielectric layer is smaller than the wavelength of the electromagnetic wave incident on the first dielectric layer. The thickness of the third dielectric layer is thicker than the thickness of the second dielectric layer .
Spectral element. The spectroscopic element according to claim 1, wherein the first dielectric layer is a prism formed so as to enter the interface at an angle satisfying the condition that the incident electromagnetic wave is totally reflected at the interface. The spectroscopic element according to claim 1 or 2, wherein the second dielectric layer is a quartz plate. The spectroscopic element according to any one of claims 1 to 3, wherein the third dielectric layer is a silicon wafer. The spectroscopic element according to any one of claims 1 to 4, further comprising a holding portion for holding an object to be measured by a side wall formed on the third dielectric layer. An object to be measured is arranged on the third dielectric layer of the spectroscopic element according to any one of claims 1 to 5.
An electromagnetic wave is incident on the first dielectric layer with the incident angle fixed, and the electromagnetic wave is incident on the first dielectric layer.
An evanescent wave is generated at the interface between the first dielectric layer and the second dielectric layer and the interface between the third dielectric layer and the object to be measured.
The spectral information of the object to be measured is measured based on the intensity of a specific frequency having a spectral structure characterized by the intensity of the electromagnetic wave emitted from the spectroscopic element, including the wave multiple reflected in the third dielectric layer. Measurement method. The measuring method according to claim 6, wherein the object to be measured is a solution, and the concentration of the solution is measured as the spectral information based on the intensity of the specific frequency. The measuring method according to claim 6 or 7, wherein the electromagnetic wave incident on the spectroscopic element is a terahertz wave. The spectroscopic element according to any one of claims 1 to 5.
A light source that generates electromagnetic waves and
The electromagnetic wave emitted from the light source is incident on the spectroscopic element with a fixed incident angle, and the intensity of the electromagnetic wave emitted from the spectroscopic element is based on the intensity of a specific frequency having a characteristic spectral structure. A measuring unit that measures the spectral information of the object to be measured on the third dielectric layer,
A measuring device equipped with.

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