JP2019070590A - Optical characteristic measuring device - Google Patents

Abstract

To provide an optical characteristic measuring device for irradiating a liquid sample with light and thereby detecting light having passed through the inside of the liquid sample, in which the distance that the light passes through the inside of the liquid sample is kept constant.SOLUTION: Provided is an optical characteristic measuring device characterized by comprising: a sample cell 21; a stationary wave former 40 for forming, inward by a prescribed distance from the liquid surface of a liquid sample 20 contained in the sample cell 21, an acoustic stationary wave in the liquid sample where the closest knot to the liquid surface is located and perpendicular to the liquid surface; a cylindrical member 23 composed of a material having prescribed acoustic impedance, to the inside of which the liquid sample flows in, and which is arranged so that its upper end is located above the liquid surface and its lower end is located downward of the knot; a light source 30 for irradiating the liquid surface inside the cylindrical member 23 with measurement light; and a detector 50 for detecting the light emitted from the liquid surface.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical characteristic measurement apparatus that measures the optical characteristics of a sample based on transmitted light when the sample is irradiated with light.

  One of the methods for identifying the type of sample and the components contained in the sample is a method using optical characteristics such as refractive index, absorbance, transmittance, and spectral characteristics (spectrum). In these methods, the optical characteristics are measured by detecting the wavelength and intensity of the transmitted light when the light from the light source is irradiated onto the sample (Patent Documents 1 and 2).

  The light passing through the sample is absorbed by or scattered by the components contained in the sample, so the intensity of the light transmitted through the sample depends on the distance (optical path length) which has passed through the inside of the sample. Therefore, in order to make the intensity of the transmitted light correspond only to the concentration of the component in the sample, it is necessary to make the optical path length of the transmitted light constant.

  When measuring a liquid sample, the liquid sample is enclosed or circulated in a sample cell formed of a material transparent to light from a light source. The sample cell comprises, for example, a rectangular cylindrical container having a liquid sample storage space therein. Since the size of the containing space is constant, when light from the light source is made to enter from one of the opposing side walls of the sample cell and emitted from the other side, the distance the emitted light passes through the containing space, that is, the optical path length Can be fixed.

  When the liquid sample to be measured is of biological origin (for example, blood) or an organic compound, light in the mid-infrared region is often used to measure the optical characteristics. The light in the mid-infrared region has a very high absorptivity by water, and when the optical path length exceeds 100 μm, almost all the light is absorbed by the water contained in those liquid samples. Therefore, when light in the mid-infrared region is irradiated to those liquid samples to measure their optical characteristics, a sample cell in which the storage space is made smaller is used. However, when the storage space is small, air bubbles that have entered into the storage space when entering the liquid sample are difficult to escape. In addition, when the viscosity of the liquid sample is high, it is difficult to fill the storage space. Furthermore, there is also a problem that it is difficult to clean the sample cell if the storage space is small.

  On the other hand, there is a built-up type sample cell constituted by holding a ring-like spacer between two plate-like window members and fastening them together with a holder. In this sample cell, with the spacer placed on one window material, a liquid sample is slightly overfilled inside the spacer, another window material is placed on the spacer, and they are fastened together by the holder. . With such a built-in sample cell, any liquid sample can be easily filled in the space surrounded by the two window members and the spacer and without containing air bubbles. . Moreover, since the window material and the spacer can be separated by removing the holder, the sample cell can be easily cleaned.

JP, 2008-309706, A JP, 2008-309707, A

  In the assembled sample cell, the light from the light source is irradiated so that the light passes from one side to the other side of the two window materials. Therefore, the distance between the two window materials is the optical path length. However, there is a problem that the distance between the two window members changes slightly depending on the degree of tightening of the holder.

  The problem to be solved by the present invention is that, in an optical characteristic measurement apparatus that detects light that has passed through the inside of a liquid sample by irradiating the liquid sample with light, the distance that the light passes through the inside of the liquid sample is constant. It is to

  The inventor of the present invention invented the following optical property measuring apparatus capable of solving the above-mentioned problems, and applied for a patent earlier (hereinafter, this optical property measuring apparatus is referred to as "apparatus of the prior application").

That is, the device of the prior application is
A light source for irradiating the surface of the sample with light;
A standing wave former for forming an acoustic standing wave in the sample perpendicular to the surface, wherein a node closest to the surface is located inside by a predetermined distance from the surface;
And a detector disposed on the same side as the light source with respect to the light incident surface for detecting light emitted from the surface of the sample.

The device of the prior application can be used for both the measurement of solid samples and the measurement of liquid samples.
The device of the prior application utilizes the phenomenon that when an acoustic standing wave is formed in a sample, high density and low density (i.e., "coarse") occur in the sample.
The above-mentioned “acoustic standing wave perpendicular to the light incidence, in which a node is located at a predetermined distance from the surface of the sample, is a standing wave in which antinodes and nodes are arranged in order along a direction perpendicular to the surface of the sample. Say.

The operation of this apparatus will be described by way of example where the apparatus is used to measure a liquid sample.
In the device of the prior application, the acoustic wave perpendicular to the liquid surface has a node located inside the liquid sample contained in the sample cell by the standing wave former from the surface (liquid surface) by a predetermined distance. Form a standing wave. As a result, in the liquid sample, the components in the liquid sample aggregate in the vicinity of the node and the density in the vicinity of the node increases, and the refractive index of that portion (hereinafter, the node portion) becomes the other portion including the belly portion It will be higher than that. Since the acoustic standing wave is a node (first node from the liquid surface) located closest to the liquid surface at a predetermined distance from the liquid surface, the first acoustic wave is the first in the liquid sample. A difference in refractive index occurs between the node portion and the portion sandwiched by the first node portion and the liquid surface, and an apparent reflective surface is formed by this difference in refractive index. As described above, when light from a light source is irradiated to the liquid surface in a state in which an acoustic standing wave is formed inside the liquid sample, part of the light is reflected by the liquid surface, and part of the light from the liquid surface After entering the inside of the sample, the light is reflected by the above-described apparent reflection surface, emitted from the liquid surface, and detected by the detector. That is, the light emitted from the liquid surface includes the reflected light on the liquid surface and the reflected light from the apparent reflecting surface inside the liquid sample. The reflected light from the apparent reflecting surface is light which has passed (reciprocated) the inside of the liquid sample by a distance twice the predetermined distance, and reflects the optical characteristics of the sample.

  As described above, in the device of the prior application, an acoustic standing wave in which a node is positioned at a predetermined distance from the liquid surface is formed, and an apparent reflecting surface is formed at a predetermined position inside the liquid sample. Therefore, after being emitted from the light source, the light enters the inside of the liquid sample, is reflected by the apparent reflection surface, and the light emitted from the liquid surface passes through the inside of the liquid sample, that is, the optical path length is constant. Can be Thus, the optical path length of the light passing through the inside of the liquid sample can be made constant by using the apparatus of the prior application.

  When measuring a liquid sample using the apparatus of the prior application, by increasing the amplitude of the acoustic standing wave formed inside the liquid sample, the difference in the density between the inside of the liquid sample is increased to increase the nodes. The measurement sensitivity can be improved by increasing the refractive index difference of the antinode portion and the reflection efficiency of light by the apparent reflection surface. However, as the amplitude of the acoustic standing wave formed inside the liquid sample is increased, the convection generated inside the liquid sample gradually increases and the liquid surface sways (waves), and the liquid surface The direction in which the irradiated light is reflected by the liquid surface and the direction of the light emitted from the liquid surface to the outside after entering the liquid sample from the liquid surface fluctuate, and these lights are detected stably. Becomes difficult. In such a case, it is effective to set the optical property measuring apparatus as follows.

That is, the optical characteristic measuring apparatus according to the present invention is
a) Sample cell,
b) An acoustic standing wave perpendicular to the liquid level is placed inside the liquid sample, with a node closest to the liquid level located inside a predetermined distance from the liquid level of the liquid sample contained in the sample cell Standing wave former to form,
c) A cylindrical body made of a material having a predetermined acoustic impedance, in which the liquid sample flows, the upper end is located above the liquid surface, and the lower end is located below the node When,
d) a light source for irradiating the liquid level inside the cylindrical body with measurement light;
e) A detector for detecting light emitted from the liquid surface.

  The material having the predetermined acoustic impedance refers to a material having an acoustic impedance different from the acoustic impedance of the liquid sample to be measured.

  In the optical characteristic measuring apparatus according to the present invention, a hollow cylindrical body made of a material having a predetermined (different from the liquid sample to be measured) acoustic impedance is disposed inside the sample cell. In this optical characteristic measuring apparatus as well as the apparatus of the previous application, the measuring light for measuring the sample from the light source is irradiated on the surface of the liquid sample contained in the sample cell, and the predetermined wave is given from the liquid surface by the standing wave former. An acoustic standing wave perpendicular to the liquid surface is formed, with a node closest to the liquid surface located inside by a distance of. In the device of the prior application, the sound wave provided by the standing wave former spreads over the entire liquid sample contained in the sample cell. This sound wave basically propagates in the vertical direction, but its directivity is not perfect, and also propagates slightly in the horizontal direction. Therefore, when the amplitude of the sound wave given to the liquid sample is increased, the convection generated inside the liquid sample is gradually increased and the liquid level is shaken. In the optical characteristic measuring apparatus according to the present invention, a cylindrical body made of a material having an acoustic impedance different from that of the liquid sample to be measured is provided inside the sample cell, with the upper end above the liquid level and the lower end in the liquid level. In order to locate the lower position than the nearest node, in the inside of the cylindrical body, the horizontal propagation of the sound wave, which causes the generation of convection in the liquid sample, is suppressed. Therefore, even if the amplitude of the acoustic standing wave formed inside the liquid sample is increased, no fluctuation occurs in the liquid level inside the cylindrical body, and the light emitted from the liquid level is detected stably by the detector. Therefore, the measurement sensitivity can be made higher than that of the device of the prior application.

  In the optical property measuring apparatus and method for detecting light passing through the liquid sample by irradiating the liquid sample with light by using the optical property measuring apparatus according to the present invention, the light passes through the liquid sample The distance can be made constant. In addition, the measurement sensitivity can be made higher than the optical characteristic measurement device of the prior application.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of one Example of the optical characteristic measuring apparatus based on this invention. The figure which shows the state in which the acoustic standing wave is formed inside the liquid sample accommodated in the sample cell in the optical characteristic measuring apparatus of a present Example. The figure which shows the state in which the acoustic standing wave is not formed in the inside of the sample accommodated in the sample cell in the optical characteristic measuring apparatus of a present Example. The figure which shows the state in which the standing wave is formed inside the control sample accommodated in the sample cell in the optical characteristic measuring apparatus of a present Example. The figure which shows the mode of the liquid level before excitation in the optical characteristic measuring apparatus of a prior application, the liquid level under excitation, and a virtual reflective surface. The figure explaining the simulation result of the propagation of the sound pressure wave front radiated | emitted to z-axis direction from the circular vibration surface of diameter 20 mm located in xy plane. FIG. 17 is another diagram illustrating simulation results of propagation of a sound pressure wave front emitted in the z-axis direction from a 20 mm-diameter circular vibration surface located in the xy plane. FIG. 6 is a view showing the state of a liquid surface and a virtual reflection surface during vibration when an aluminum tube is used in Experiment 1. FIG. 16 is another view showing the state of the liquid surface and the virtual reflection surface during vibration when a vinyl tube is used in Experiment 1. The result using the cylindrical body and each cylindrical body which were used in Experiment 2. FIG. Sample cell used as an example in Experiment 3. Sample cell used as a comparative example in Experiment 3. FIG. 8 is a configuration diagram of an optical measurement device used in Experiment 3. 18 is a spectrum obtained by using the sample cell of Example in Example 3. 16 is a spectrum obtained by using the sample cell of the comparative example in Example 3. The schematic block diagram of the optical characteristic measuring apparatus of a modification.

  One embodiment of an optical characteristic measuring apparatus according to the present invention will be described below with reference to the drawings.

  FIG. 1 shows a schematic configuration of the optical identification measuring apparatus of the present embodiment. The optical characteristic measurement apparatus includes a sample cell 21 in which a liquid sample 20 to be measured (hereinafter simply referred to as “sample 20”) is accommodated, and in which a hollow cylindrical body 23 is disposed; Of the light source 30 for emitting light to the surface (liquid surface) of the sample, the standing wave forming unit 40, and the detector 50 for detecting light emitted from the surface (liquid surface) of the sample 20 on which the light from the light source 30 is incident. An analog-to-digital converter (A / D converter) 60 for converting a detection signal from the detector 50 into digital data, and a data processor for performing predetermined data processing on detection data obtained by analog-to-digital conversion It has 70 and.

  The sample cell 21 is configured of a rectangular cylindrical container 22 having an opening at the top and bottom, and a window material 24 for closing the opening at the bottom. Although the upper portion of the sample cell 21 is opened in the present embodiment, a translucent window material may be disposed on the upper portion.

  The standing wave forming unit 40 is composed of an ultrasonic transducer 41 and a drive unit 42 for driving the ultrasonic transducer 41. The ultrasonic transducer 41 is mounted on the bottom surface of the sample cell 21, and the cylindrical body 23 is mounted on the upper portion thereof. The upper end of the cylindrical body 23 is exposed above the liquid level. Here, the arrangement in which the cylindrical body 23 is in contact with the upper surface (the ultrasonic wave generation surface) of the ultrasonic transducer 41 is shown, but these may be separated.

  The drive unit 42 includes a frequency adjustment unit 422 that adjusts the frequency of the AC power output from the AC power supply 421, and an amplitude adjustment unit 423 that adjusts the amplitude of the ultrasonic wave generated by the ultrasonic transducer 41. The drive unit 42 is connected to an operation unit 424 operated by the user, and the drive unit 42 turns on / off the operation of the ultrasonic transducer 41 based on an input signal from the operation unit 424, or generates an alternating current. The frequency of the power is adjusted, or the amplitude of the ultrasonic wave generated by the ultrasonic transducer 41 is adjusted. Therefore, the operation unit 424 and the drive unit 42 correspond to the switch in the present invention. The frequency adjustment unit 422 and the amplitude adjustment unit 423 correspond to the wavelength changer and the sound wave vibration change unit in the present invention.

  The light from the light source 30 is reflected by the half mirror 83 and then irradiated to the surface of the sample 20. The light emitted from the surface of the sample 20 is transmitted through the half mirror 83 and then enters the detector 50. As the detector 50, a photodetector such as a photomultiplier tube, a photodiode, a CCD, a pyroelectric detector, or a spectrophotometer can be used. Although the half mirror 83 is used in the embodiment shown in FIG. 1, the light from the light source 30 is directly incident on the surface of the sample 20 and the light emitted from the surface of the sample 20 is directly incident on the detector 50. The sample 20, the light source 30, and the detector 50 may be disposed. In that case, the half mirror 83 can be omitted.

  The data processing unit 70 includes a data collection unit 71 that collects detection data subjected to analog-to-digital conversion, a data analysis unit 72 that analyzes the collected detection data, and a database 73 used in analysis by the data analysis unit 72. And an absorbance calculation unit 74 for calculating an absorbance (or transmittance), which is an optical characteristic of the sample, using the detection data, and creating an absorption spectrum. The absorbance calculator 74 corresponds to the optical characteristic calculator in the present invention.

  The function of the data processing unit 70 can also be realized using dedicated hardware, but by using a general purpose personal computer as a hardware resource and executing dedicated processing software installed in the personal computer It is common to realize. The data processing unit 70 includes an input unit 81 connected to a personal computer for performing various input operations and a pointing device (mouse or the like), and a monitor 82 for displaying measurement results and the like.

  When the ultrasonic transducer 41 is operated in the optical characteristic measuring apparatus shown in FIG. 1, as shown in FIG. 2, the acoustic constant perpendicular to the surface (ultrasonic wave generation surface) of the ultrasonic transducer 41 is formed inside the sample 20. A standing wave Sw is formed. In FIG. 2, the cylindrical body 23 is omitted to easily show the acoustic standing wave Sw. In the sample 20 shown in FIG. 1, since the surface (sound wave generation surface) of the ultrasonic transducer 41 and the surface (liquid surface) on which the light from the light source 30 is incident are parallel, the acoustic standing wave Sw is also liquid surface It will be vertical. In addition, by appropriately adjusting the frequency of the AC power supplied to the ultrasonic transducer 41 and the amplitude of the ultrasonic wave generated by the ultrasonic transducer 41, only a predetermined distance from the surface on which the light from the light source 30 is incident The acoustic standing wave Sw can be formed such that the nodes are located at

  In FIG. 2, it is shown that the acoustic standing wave Sw having free ends on both the ultrasonic transducer side and the liquid surface side is formed in the sample 20. Whether the end on the liquid surface side of the acoustic standing wave Sw is the free end or the fixed end depends on the magnitude of the acoustic impedance of the material in contact with the liquid surface. In the example of FIG. 2, the sample 20 is in contact with air at the liquid level, and the acoustic impedance of air is smaller than that of the sample 20, and thus the free end is obtained. Since the end of the acoustic standing wave Sw on the liquid surface side is a free end, assuming that the wavelength of the acoustic standing wave Sw is λ, the distance from the liquid surface to the node closest to the liquid surface (first node) Is λ / 4.

  Next, with reference to FIGS. 2 to 4, the principle of measurement of optical characteristics using the optical characteristic measurement apparatus of the present embodiment will be described. The cylindrical body 23 is omitted in FIGS. 3 and 4 as in FIG. 2.

  FIG. 2 shows a state in which the acoustic standing wave Sw is formed inside the sample 20 by the standing wave forming portion (the ultrasonic transducer 41), and FIG. 3 shows an acoustic standing wave formed inside the sample 20 FIG. 4 shows a state where the acoustic standing wave Sw is formed inside the control sample 20A. In either state, when the light (irradiated light) from the light source 30 is irradiated to the sample 20 or the control sample 20A, a part of the irradiated light is reflected by the surface (liquid surface) of the sample 20 or the control sample 20A. (Hereafter, this is referred to as surface reflection light), a part of which enters the inside of the sample 20 or the control sample 20A.

  When an acoustic standing wave Sw is formed inside the sample 20, the density of nodes and nodes in the sample 20 near the nodes due to the nodes and antinodes of the acoustic standing wave Sw becomes higher than the density in the other regions. That is, periodical density occurs inside the sample 20. Since the refractive index of the substance and the density of the substance are in a proportional relationship, the refractive index is larger than the refractive index of the other regions at the node position where the density increases. As a result, a difference in refractive index occurs between the position of the node of the acoustic standing wave Sw and the other region, and an apparent reflecting surface (hereinafter referred to as a "virtual reflecting surface") is formed at the position of the node. Ru. For this reason, a part of the irradiation light which has entered the inside of the sample 20 from the surface of the sample 20 is reflected by the virtual reflection surface and then emitted from the surface of the sample 20, and a part of the irradiation light is a virtual reflection surface Pass through. In the following description, the light reflected by the virtual reflection surface is referred to as internally reflected light. From the above, when the light from the light source 30 is irradiated to the sample 20 in a state where the acoustic standing wave Sw is formed in the sample 20, the light emitted from the surface of the sample 20 is surface reflected light and internal reflection. It becomes light.

  One or more virtual reflecting surfaces are formed inside the sample 20 depending on the length of the sample 20 and the length of the wavelength of the acoustic standing wave Sw in the traveling direction of the irradiation light. When a plurality of virtual reflecting surfaces are formed inside the sample 20, part of the irradiation light that has entered the sample 20 and has passed through the first virtual reflecting surface from the surface (liquid surface) side of the sample 20 is It is reflected by the second virtual reflection surface, and the rest passes through the second virtual reflection surface. The same applies to the third and subsequent virtual reflecting surfaces. However, compared to the amount of light reflected by the first virtual reflection surface, the amount of light reflected by the second and subsequent virtual reflection surfaces is very small, so here, only the light reflected by the first virtual reflection surface To consider.

  The internally reflected light passes through the inside of the sample 20 by a distance twice the distance from the surface (liquid surface) of the sample 20 to the virtual reflection surface, and then exits from the liquid surface to the outside. The internally reflected light is the light after the light entering the inside of the sample 20 is affected by absorption, scattering, etc. by the sample 20, and reflects the optical characteristics of the sample 20, so it was explained in the background art. It corresponds to "transmitted light". The virtual reflection surface is formed at the position of the first node from the surface of the sample 20 among the nodes of the acoustic standing wave Sw formed in the sample 20. The position of the node of the acoustic standing wave Sw is determined by the wavelength of the acoustic standing wave Sw, and the wavelength of the acoustic standing wave Sw is determined by the frequency or period of ultrasonic vibration of the ultrasonic transducer 41. Therefore, by adjusting the frequency or period of the ultrasonic vibration of the ultrasonic transducer 41 to an appropriate value, the position of the virtual reflection surface, that is, the optical path length of the internally reflected light can be adjusted. For example, when the sample 20 is an organism-derived substance or organic compound such as blood, and light in the mid-infrared region is emitted from the light source 30, it is preferable to adjust the optical path length of internally reflected light to 100 μm or less. .

  On the other hand, in the state where the acoustic standing wave is not formed in the sample 20, the virtual reflection surface is not formed in the sample 20 (see FIG. 3). For this reason, the irradiation light which has entered the inside of the sample 20 from the surface of the sample 20 passes through the sample 20 as it is and is absorbed by the sample 20 or a window material attached to the opposite side of the surface of the sample 20 The light is emitted from the sample cell 24 to the outside of the sample cell 21 or is reflected by the window material 24 and absorbed by the sample 20. From the above, when the light from the light source 30 is irradiated to the sample 20 in a state where no acoustic standing wave is formed in the sample 20, the light emitted from the surface of the sample 20 is substantially only surface reflected light. Become.

  Therefore, when the light from the light source 30 is irradiated to the sample 20 in each of the state in which the acoustic standing wave Sw is formed inside the sample 20 and the state in which the acoustic standing wave is not formed, the detector 50 The intensity of internally reflected light, that is, the optical characteristic (absorbance) of the sample 20 can be determined from the result detected by

Assuming that the light quantity of the wavelength λ of light (irradiated light) irradiated from the light source 30 to the sample 20 is I ₀ (λ) and the reflectance of the wavelength λ from the surface of the sample 20 is α (λ) The amount of reflected light for each wavelength is α (λ) × I ₀ (λ). Here, the reflectance α (λ) is determined by the refractive index of the atmosphere and the refractive index of the sample 20.

The light quantity incident on the inside of the sample 20 is a value obtained by subtracting the light quantity of the surface reflected light from the light quantity of the irradiation light, and the internal incident light quantity of the wavelength λ is expressed as (1−α (λ)) × I ₀ (λ) be able to. Therefore, assuming that the light amount of the internally reflected light of wavelength λ is I (λ), the absorbance A (λ) of wavelength λ can be calculated by the following equation.
A (λ) = − log ₁₀ [I (λ) / ((1−α (λ)) × I ₀ (λ))]

  If the refractive index of the sample 20 is known, the reflectance α (λ) can be theoretically obtained from the Fresnel reflection law in consideration of the dispersion n (λ) which is the difference in refractive index for each wavelength. Further, even if the reflectance α (λ) can not be determined because the refractive index of the sample 20 is unknown, it can be determined experimentally. The point is that the light is emitted from the surface of the sample 20 when the light from the light source 30 is irradiated to the sample 20 in the state where the acoustic standing wave Sw is formed and not formed in the inside of the sample 20, respectively. The spectral absorbance of the sample 20 can be determined from the detection result of the light.

  When the relative optical properties of the sample 20 are to be determined, or when the optical properties of one or more components included in the sample 20 (biological tissue fluid, blood, etc.) are to be determined, the acoustic standing wave Sw is It is preferable to use the detection result of the detector 50 in each of the formed state and the state in which the acoustic standing wave Sw is formed inside the control sample 20A. As the control sample 20A, a standard product of the sample 20 or a sample obtained by removing one or more specific components from the sample 20 (eg, pure water) can be used.

  Specifically, as shown in FIG. 4, while the control sample 20A is accommodated in the sample cell 21, the acoustic standing wave Sw is formed inside the control sample 20A. Then, in this state, the light from the light source 30 is irradiated to the control sample 20A. As a result, surface reflected light and internally reflected light are emitted from the surface of the control sample 20A.

Assuming that the light quantity for each wavelength of the irradiation light is I ₀ (λ), the light quantity for each wavelength of the surface reflected light emitted from the surface of the control sample 20A is substantially the same as the light quantity of the surface reflected light of the sample 20. It can be considered that λ) × I ₀ (λ). On the other hand, the light quantity I _b (λ) for each wavelength of the internally reflected light reflects the optical characteristics of the control sample 20A.

  Therefore, from the detection results of the detector 50 in each of the state in which the acoustic standing wave Sw is formed inside the sample 20 and the state in which the acoustic standing wave Sw is formed inside the control sample 20A, The relative optical properties of or the optical properties of the components contained in the sample 20 can be determined.

  According to this measurement principle, if the amplitude of the acoustic standing wave formed inside the sample 20 is increased, the difference in density between the inside of the sample 20 is increased, and the difference in refractive index between the node portion and the antinode portion is increased. As a result, the reflection efficiency of light by the virtual reflection surface can be improved, and the intensity of surface reflected light can be increased to enhance the measurement sensitivity.

  Therefore, when the voltage applied to the ultrasonic transducer 41 in the apparatus of the prior application is increased and the amplitude of the acoustic standing wave formed inside the sample 20 is increased, the liquid level of the sample 20 is shaken, The inside of the sample 20 was observed using OCT (optical coherence tomography) functioning as a light source and a detector. The state of the liquid surface before excitation by ultrasonic vibration is shown in FIG. 5 (a), and the state of the liquid surface and virtual reflecting surface during excitation when a voltage of 10 V is applied to the ultrasonic vibrator 41 is shown in FIG. 5 (b) Shown in. While a flat liquid surface is observed in FIG. 5 (a), it can be seen that both the liquid surface and the virtual reflection surface are shaking in FIG. 5 (b). When the liquid surface and the virtual reflection surface shake in this way, the traveling directions of the surface reflection light and the internal reflection light both change, which makes it difficult to stably detect the light.

  In order to confirm the internal state of the sample 20 in more detail, when the sample 20 in which fine particles are dispersed in colored water is similarly observed using an optical coherence tomography (OCT), convection in the sample 20 is observed. It has been confirmed that it has occurred. That is, when the sound pressure wave front propagates not only in the vertical direction but also in the horizontal direction, convection is generated inside the sample 20, and it is considered that the liquid level and the virtual reflection surface are shaken.

  Based on the above results, in order to enhance the directivity in the vertical direction of the propagation of the sound wave front, the hollow cylindrical body 23 is disposed inside the sample cell 21 in the optical characteristic measuring apparatus of the present embodiment. This is a configuration derived from the simulation results shown in FIGS. 6 and 7. This simulation is a simulation of the propagation of a sound pressure wave front emitted in the z-axis direction from a circular vibration surface with a diameter of 20 mm located in the xy plane. The upper part of FIG. 6 is obtained by cutting out the phase distribution of the radiation sound pressure wave front in the yz plane (width 20 mm in the y-axis direction and length 100 mm in the z-axis direction). It cut out by length 10 mm of z axial direction. In the upper part of FIG. 7, the sound pressure distribution is cut out in the yz plane (width 20 mm in the y-axis direction, length 100 mm in the z-axis direction). In the lower part, the xz plane (width 20 mm in the x-axis direction, z-axis direction) Cut out with a length of 100 mm). By cutting out the sound pressure wave front in the vicinity of the central axis (z axis) from these simulation results, the directivity in the vertical direction of the propagation of the sound pressure wave front can be enhanced.

[Experiment 1]
In order to confirm the effect of the cylindrical body 23, a cylinder whose material is different in the upper part of the central position of the ultrasonic wave generation surface of the ultrasonic transducer 41 placed on the bottom surface of the sample cell 21 containing the sample 20 (pure water) The rods 23 (each having an inner diameter of 5 mm) were disposed, and the liquid surface and the virtual reflection surface were observed by OCT (optical coherence tomography). The materials of the cylindrical body 23 used are metal (aluminum, copper, brass) and soft materials (vinyl, rubber, silicone). American gum is a type of natural rubber. FIG. 8 shows a state in which the cylindrical body 23 made of aluminum is used, and FIG. 9 shows a state in which the cylindrical body 23 made of vinyl is used.

  As shown to Fig.8 (a), when the voltage of 10 V was applied using the cylindrical body 23 which consists of aluminum, it has confirmed that a liquid level and a virtual reflective surface were stabilized. However, when the voltage to be applied was increased to 15 V, shaking occurred again on the liquid surface and the virtual reflection surface in the liquid (FIG. 8 (b)). Similar results were obtained for other metals (copper, brass).

  On the other hand, as shown in FIGS. 9 (a) and 9 (b), in the case of using the cylindrical body 23 made of vinyl, the liquid level and the virtual reflection surface shake even when any voltage of 10 V and 15 V is applied. Did not occur. Similar results were obtained for the cylindrical body 23 made of silicon resin. However, when the cylindrical body 23 made of amebaceous rubber was used, the effect of the cylindrical body 23 was not confirmed.

The above experimental results can be interpreted based on the difference in acoustic impedance between the sample 20 (water in the above experiment) and the material constituting the cylindrical body 23. Metal (aluminum, copper, brass) both are hard material, even the several tens of times as compared with the acoustic impedance samples 20 acoustic impedance ^{(1.46 × 10 6 N · s} / m 3) of the (in the above experiment water) Large (for example, the acoustic impedance of copper is 44.6 × 10 ⁶ N · s / m ³ ). Therefore, although the sound wave propagating in the horizontal direction by the cylindrical body 23 is absorbed to some extent when the voltage applied to the ultrasonic transducer 41 is small, a part of the sound wave propagated in the horizontal direction when the applied voltage increases. It is considered that the reflection is caused and the shaking occurs on the liquid surface and the virtual reflection surface in the liquid.

On the other hand, the acoustic impedance of vinyl which is a soft material is 3.23 × 10 ⁶ N · s / m ³ , and the acoustic impedance of silicone is 1.28 × 10 ⁶ N · s / m ^3. The difference in acoustic impedance with (water) is small. Therefore, it is considered that the sound wave propagating in the horizontal direction is absorbed, and no vibration occurs on the liquid surface and the virtual reflection surface even if the applied voltage is increased to 15V. Also, although amegum is a soft material, it has a sound impedance of 1.46 × 10 ⁶ N · s / m ³ , that is, approximately the same as that of the sample 20 (water), so a cylinder that absorbs acoustic waves propagating in the horizontal direction It is considered that it did not function as the solid body 23.

[Experiment 2]
Next, an experiment was also conducted to verify the effect of the case where the tubular body 23 has a double tube structure. In this experiment, acrylic covers (inner diameter 6 mm, outer diameter 15 mm, outside the silicon tube (inner diameter 4 mm, outer diameter 6 mm, length 20 mm) and vinyl tubes (inner diameter 4 mm, outer diameter 6 mm, length 20 mm) The same experiment as described above was performed using a tubular body 23 having a double tube structure attached with a length of 20 mm. In addition, for comparison, silicon tube, vinyl tube, and copper tube (The shape of silicon tube and vinyl tube is the same as above. Copper tube has an inner diameter of 4 mm, an outer diameter of 5 mm, a length of 20 mm. There is no cover) The experiment used as was also conducted. In addition, since the type of the used ultrasonic transducer is different from the above-mentioned Experiment 1, the magnitude of the applied voltage is different from the above-described experiment.

The experimental results are shown in FIG.
First, when a voltage of 4 V was applied to the ultrasonic transducer, the effect of stabilizing the liquid level was confirmed for all of the cylindrical bodies 23 other than the copper tube. Therefore, when the voltage to be applied was increased to 15 V, the liquid level was observed for the silicon tube and the vinyl tube, while the liquid level was observed for the configuration using the cylindrical body 23 with the cover attached to each. It was not done. This is because when only a tube made of a soft material such as a silicon tube or a vinyl tube is used, if the intensity of the ultrasonic wave is increased, the straight cylinder shape is bent or the like, and the directivity of the sound pressure wave front propagation is reduced in the vertical direction. On the other hand, it is thought that the directivity in the vertical direction of the propagation of the sound pressure wave front can be maintained even when an ultrasonic wave of high strength is applied, by using an auxiliary member for maintaining the straight cylinder shape of the tubes. . In this experiment, the cylindrical body 23 has a double tube structure, but the shape of the auxiliary member (the acrylic cover in the above experiment) does not have to be cylindrical, and it spirals around the outer peripheral surface of the silicon tube etc. The same effect can be expected by using a spring-shaped member, a support member attached in the longitudinal direction of the outer periphery of the tube, or the like.

[Experiment 3]
Another experiment was also conducted to verify the effect of using the cylindrical body 23 of the present embodiment. In this experiment, as an optical characteristic measuring apparatus according to the present embodiment, a double-pipe structure cylinder in which an acrylic cover is disposed outside a rubber tube in a cubic acrylic sample cell 21 having 25 mm on each side. A rod-like body 23 (outer diameter 15 mm, inner diameter 7 mm, height 20 mm) was disposed (Example). In addition, as a comparative example, a portion container made of polypropylene having a diameter of 32 mm and a height of 15 mm was used as a sample cell 121 (without a cylindrical body) (comparative example). The sample cell 21 of the embodiment is shown in FIG. 11, and the sample cell 121 of the comparative example is shown in FIG. The same ultrasonic transducer 41 (141) was placed on the bottom of each of the sample cell 21 of the example and the sample cell 121 of the comparative example. In this experiment, colored water is accommodated in the sample cell 21 of the embodiment and the sample cell 121 of the comparative example, and light having a central wavelength of 565 nm is irradiated at an incident angle of 53 degrees to the liquid surface, and the reflected light intensity Was measured. The overall configuration of the device is shown in FIG. In addition, since the type of the ultrasonic transducer used differs from the above-mentioned experiment 1 and 2, the magnitude | size of an applied voltage differs from the said experiment.

  For each of the example and the comparative example, while changing the magnitude of the voltage applied to the ultrasonic transducer 41 (141), the reflected light from the liquid surface was measured to obtain a spectrum in the wavelength range of 400 to 800 nm. . FIG. 14 shows the result of the embodiment, and FIG. 15 shows the result of the comparative example.

  In the sample cell 21 of the example, the intensity of the entire spectrum increases with the applied voltage until the voltage applied to the ultrasonic transducer 41 reaches 3.5 V, and the spectrum intensity decreases when the voltage reaches 4.0 V. From this result, in the sample cell 21 of the embodiment, the maximum applicable voltage (the maximum value of the voltage that can be measured without causing fluctuation in the liquid surface and the virtual reflection surface) is a value between 3.5 and 4.0 V I understand. On the other hand, in the sample cell 121 of the comparative example, the intensity of the entire spectrum increases with the applied voltage as in the example until the applied voltage reaches 1.8 V, but the spectrum intensity decreases at 2.0 V did. That is, it is understood that the maximum applicable voltage of the sample cell 121 of the comparative example is a value between 1.8 and 2.0V. And while the maximum intensity (arbitrary unit) of the spectrum of the example is 57 (when a voltage of 3.5 V is applied), the maximum intensity of the spectrum of the comparative example (arbitrary unit common to the example) is 41 (1.8 V) (When applying a voltage of Also from these experimental results, it is understood that by disposing the cylindrical body inside the sample cell 21, the maximum applicable voltage becomes higher than that of the device of the prior application, and the measurement sensitivity is improved.

  The above-described embodiment is an example, and can be appropriately modified in accordance with the spirit of the present invention. In the above embodiment, a cylindrical body having a length reaching the liquid level from immediately above the ultrasonic vibration surface of the ultrasonic transducer 41 was used. However, as described above, it is considered that the amount of light reflected by the second and subsequent virtual reflection surfaces is extremely small compared to the amount of light reflected by the first virtual reflection surface (the virtual reflection surface closest to the liquid surface) In this case, the lower end of the cylindrical body 23 may be located at least below the first virtual reflection surface, and the length does not necessarily reach the ultrasonic vibration surface (or just above it). Good.

  Moreover, the optical characteristic measuring apparatus of the following structures can be comprised as a modification. The optical characteristic measuring apparatus 90 is composed of a main body 90a and a lid 90b. As shown in FIG. 16A, the main body 90a has the ultrasonic transducer 41 fixed to the central portion of the bottom surface of the sample cell 21. The lid 90 b is, as shown in FIG. 16 (b), a small light source 92 such as an LED light source disposed on one side of the upper portion inside the lid body 91, and a small detection disposed on the other side. Tube 93, a reflecting member 94 disposed between them, a reflecting surface whose inclined surface is a mirror surface, and a tubular member made of silicone, vinyl or the like integrated with a member extended from the inner side surface of the lid body 91 It has 95. In addition, although appropriate wiring is connected to the ultrasonic transducer 41, the light source 92, the detector 93 and the like in actuality, illustration of these is omitted in FIG.

  When using this optical characteristic measuring apparatus 90, the liquid sample 20 to be analyzed is accommodated in the sample cell 21 of the main body 90a, and then the lid 90b is attached to the main body 90a. Then, the light source 92 emits light of a predetermined wavelength. The light emitted from the light source 92 is reflected by the reflecting member 94 and is incident on the liquid surface inside the cylindrical body 23. The light reflected by the liquid surface (surface reflection light) and the light reflected by the virtual reflection surface formed inside the liquid sample 20 (internal reflection light) are reflected by the reflection member 94 and enter the detector 93. The detector 93 generates a signal corresponding to the intensity of the incident light and outputs the signal to a signal processing unit (not shown).

  In the optical characteristic measuring apparatus 90 of the modified example, the optical characteristic of the liquid sample 20 can be easily measured simply by introducing the liquid sample 20 into the main body 90 a and mounting the lid 90 b to operate each part. When the sample cell of several cm (25 mm in Experiment 3) in size is used as the sample cell 21 of the main body 90a like the sample cell used in Experiment 3 described above, the entire optical characteristic measuring apparatus 90 is several cm It can be configured small. Such an optical characteristic measuring apparatus 90 can be suitably used, for example, for the purpose of measuring an ingredient contained in urine or the like for an individual's own health management. In that case, a storage unit is provided in the signal processing unit, and measurement data (for example, spectrum data) of the control sample 20A is stored in advance in the storage unit, so that the liquid sample 20 to be measured and the control sample 20A simultaneously with the measurement completion. The difference of the data of the above can be determined, and the identification and the quantification of the components contained in the liquid sample 20 can be performed. Such a signal processing unit can be embodied by executing a predetermined program (application) on a portable terminal such as a smartphone, for example. As a result, the user can easily perform his / her own health management only by using the small-sized optical characteristic measuring apparatus 90 and the portable terminal in which a predetermined program (application) is stored.

10: Optical property measuring apparatus 20: Liquid sample (sample)
20A: control sample 21, 121: sample cell 23: cylindrical body 30: light source 41, 141: ultrasonic transducer 42: drive unit 421: AC power supply 422: frequency adjustment unit 423: amplitude adjustment unit 424: operation unit 50: Detector 70: Data processing unit 71: Data collection unit 72: Data analysis unit 73: Database 74: Absorbance calculation unit 81: Input unit 82: Monitor 83: Half mirror 90: Optical characteristic measurement device 90a: Main unit 90b: Lid 91: Lid body 92: Light source 93: Detector 94: Reflecting member 95: Tubular body

Claims (10)

a) Sample cell,
b) An acoustic standing wave perpendicular to the liquid level is placed inside the liquid sample, with a node closest to the liquid level located inside a predetermined distance from the liquid level of the liquid sample contained in the sample cell Standing wave former to form,
c) A cylindrical body made of a material having a predetermined acoustic impedance, in which the liquid sample flows, the upper end is located above the liquid surface, and the lower end is located below the node When,
d) a light source for irradiating the liquid level inside the cylindrical body with measurement light;
e) A detector for detecting the light emitted from the liquid surface, and an optical characteristic measuring device. In the optical characteristic measuring apparatus according to claim 1,
An auxiliary member for maintaining the shape of the cylindrical body is attached to the outer periphery of the cylindrical body. In the optical characteristic measurement device according to claim 1 or 2, further,
f) An optical characteristic calculator for obtaining an optical characteristic of the liquid sample based on a detection result of the detector when light from the light source is irradiated to the liquid sample,
The optical characteristic calculator determines an optical characteristic of the liquid sample based on a detection result of the detector when an acoustic standing wave is formed inside the liquid sample by the standing wave former. Optical characteristic measurement device to be characterized. In the optical characteristic measurement device according to claim 3, further,
g) in a first state in which the acoustic standing wave is formed inside the liquid sample by the acoustic standing wave former and in a second state in which the acoustic standing wave is not formed inside the liquid sample Equipped with a switch to switch
Determining an optical characteristic of the liquid sample from the detection result of the detector when the optical characteristic calculator is in the first state and the detection result of the detector when the optical property calculator is in the second state Optical characteristic measurement device to be characterized. In the optical characteristic measurement device according to claim 3, further,
h) A control result of the detector when the control sample is irradiated with light from the light source in a state where the acoustic standing wave is formed inside the control sample by the standing wave former. A storage unit for storing sample detection results;
The detection result of the detector when the optical characteristic calculator irradiates the surface of the liquid sample with light in a state where an acoustic standing wave is formed inside the liquid sample by the standing wave former; An optical characteristic measuring apparatus, wherein optical characteristics of the liquid sample are obtained from the control sample detection result. In the optical characteristic measuring apparatus according to any one of claims 1 to 5, further,
i) An optical characteristic measuring apparatus comprising: a wavelength changer configured to change the wavelength of the acoustic standing wave formed by the standing wave former. The optical characteristic measurement device according to any one of claims 1 to 6.
An optical characteristic measuring apparatus characterized in that the standing wave forming device includes a sound wave vibrator and a sound wave vibration changing unit which changes the frequency and / or the amplitude of the sound wave vibration emitted by the sound wave vibrator. In the optical characteristic measuring apparatus according to claim 5,
The optical property measuring device characterized in that the liquid sample is a composite sample consisting of a known substance and an unknown substance, and the control sample is the known substance. The optical characteristic measuring apparatus according to any one of claims 1 to 8.
The light source is a multi-wavelength light source that emits light in a predetermined wavelength range,
The optical characteristic measuring apparatus according to claim 1, wherein the detector is a spectrophotometer that measures the intensity of light for each wavelength. The optical characteristic measuring apparatus according to any one of claims 1 to 9.
The optical characteristic measuring apparatus characterized in that the detector is an optical coherence tomography.