JP2003329581A - Optical fiber type multiple wavelength spectrometric apparatus and multiple wavelength spectrometric method using optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly sensitive and accurate optical fiber type multiple wavelength spectrometric apparatus of a simple structure and to provide a spectrometric method. <P>SOLUTION: An optical fiber 20 is provided with both a core and a clad laminated on the periphery of the core and comprises a sensor part SP which enables interaction between part of transmitted light and the outside world. An optical incidence device 15 makes at least two lights of different wavelengths incident onto the optical fiber 20. An optical detector 25 receives light which has been subjected to the interaction with the outside world at a sensor part SP. By the computation of a controller 40, components to be measured are determined on the basis of the difference in light absorbance between an object to be measured present in the outside world and the components to be measured. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-wavelength spectroscopic measurement device and a multi-wavelength spectroscopic measurement method for measuring a measurement target component of a measurement target with high sensitivity and high accuracy using an optical fiber.

[0002]

2. Description of the Related Art Spectroscopic measurement is a measurement for quantifying, for example, the concentration of a component to be measured based on an absorption spectrum obtained by making light energy incident on the component to be measured and absorbing this light energy. It is a technique.
Japanese Patent Publication No. 10-501333 discloses a Raman spectroscopic measurement device and method for performing spectroscopic measurement using a Raman signal, which is one form of scattered light generated by interaction of incident light with a substance of a measurement target component. Has been done.

The spectroscopic measurement is roughly classified into a method of using light of one wavelength (incident light) and a method of multi-wavelength spectroscopic measurement using light of two or more different wavelengths. When measuring the concentration of a known component to be measured using light of one wavelength, the light from the light source is divided into two, and one is
It is made incident on the sample cell containing the component to be measured. The other light is incident as a reference light (reference), for example, on a sample obtained by removing the target measurement target component from the sample cell or a blank cell containing pure water. Using the light of the predetermined peak wavelength corresponding to the target measurement target component, based on the difference between the absorbance by the sample cell and the absorbance by the blank cell,
Quantitatively measure the concentration of the component to be measured.

In the case of multiple wavelengths, light of two or more different wavelengths, for example, is alternately incident on one sample cell containing the component to be measured, and the difference in the absorbance of the sample cell due to the difference in wavelength. Based on the above, the concentration of the component to be measured is quantitatively measured.

On the other hand, in recent years, for example, there has been a proposal to use an optical fiber for a chemical sensor for measuring the concentration of a component to be measured. In an optical fiber type chemical sensor, measurement is performed on the basis of the result of interaction of light with the outside world in a sensor unit that causes light to enter the optical fiber and leaks part of the light to the outside world.

[0006]

In the conventional spectroscopic measurement apparatus in which light is made incident on the sample cell, a sampling operation of preparing the sample cell is required, and the apparatus becomes large in size, and therefore, for example, in a factory or a factory. In situ measurement of leaks and fractures in chemical plant piping is not possible. Although it is possible to use an optical fiber type sensor for in situ measurement, the conventional optical fiber type sensor used light of one wavelength and could not use the reference. Therefore, a stable baseline for measurement cannot be obtained, and the measurement accuracy is low.

For example, in sit using an optical fiber type sensor
In the u measurement, it is sufficient if only the leakage from the pipe can be discriminated. Therefore, for example, a configuration for accurately quantifying the concentration of the measurement target component has not been considered. However, it is expected that the range of application of the optical fiber type sensor will be expanded if the optical fiber type sensor can also perform highly sensitive and highly accurate measurement.

In view of the above circumstances, in the present invention, by applying the multi-wavelength spectroscopic measurement method to the optical fiber type sensor, the optical fiber type multi-wavelength spectroscopic measurement having a simple structure and high sensitivity and high accuracy is applied. The purpose is to provide a device.
It is another object of the present invention to provide a multi-wavelength spectroscopic measurement method using an optical fiber with high sensitivity and high accuracy.

[0009]

A multi-wavelength spectrometer according to the present invention for solving the above-mentioned problems of the prior art and achieving the object of the present invention comprises a core and a clad laminated around the core. And an optical fiber having a sensor unit that enables interaction of a part of transmitted light with the outside world,
Light incidence means for injecting light of at least two different wavelengths into the optical fiber, light receiving means for receiving light that has undergone interaction with the outside world in the sensor section, and a measurement target component of the measurement target existing in the outside world. Is an optical fiber type multi-wavelength spectroscopic measurement device having a calculation means for quantifying the component to be measured based on the difference in light absorbance with respect to.

In the multi-wavelength spectroscopic measurement method of the present invention, light of at least two different wavelengths is made incident on an optical fiber capable of interacting with the outside world, and the light interacted with the outside world is received. A multi-wavelength spectroscopic measurement method using an optical fiber, in which the measurement target component is quantified based on the difference in the light absorbance with respect to the measurement target component of the measurement target existing in the outside world.

In the present invention, the light incident means causes the light used for measurement to enter the core of the optical fiber. The light used for the measurement includes at least two lights having different wavelengths.
The light incident on the optical fiber interacts with the measurement target component of the measurement target existing in the outside in the sensor section of the optical fiber. The light that has interacted with the outside world in the sensor unit is received by the light receiving means. The calculating means calculates and quantifies the concentration of the component to be measured based on the difference in absorbance caused by the interaction of the light having different wavelengths with the component to be measured.

[0012]

DETAILED DESCRIPTION OF THE INVENTION Referring to the accompanying drawings,
An embodiment of the present invention will be described.

First Embodiment FIG. 1 is a schematic configuration diagram of an embodiment of an optical fiber type multi-wavelength spectrometer according to the present invention. The optical fiber type multi-wavelength spectroscopic measurement device 10 shown in FIG. 1 has a light incident device 15 as a light incident device, an optical fiber 20, a photodetector 25 as a light receiving device, and a controller 40.

One end of the optical fiber 20 has a light injector 1
5 and the other end is connected to the photodetector 25. The controller 40 includes the light injector 15 and the light detector 2.
Connected to 5.

The light injector 15 further comprises a light source 6, spectroscopes 7 and 8 and a chopper 9. The light source 6 is for generating light used for measurement, and is composed of, for example, a tungsten lamp and a deuterium lamp.
The tungsten lamp emits light having a wavelength of 350 to 2600 nm and is used as a light source for the visible region. The deuterium lamp emits light having a wavelength of 190 to 400 nm and is used as a light source for ultraviolet light.

The spectroscope disperses the light emitted from the light source 6 with a diffraction grating and rotates it to extract an arbitrary monochromatic light from the slit. In the first embodiment, the light source 6 is provided to each of the two independent spectroscopes 7 and 8.
The light from is made incident and two monochromatic lights are taken out.

The chopper 9 switches the monochromatic lights having different wavelengths, which are extracted and entered by the spectroscopes 7 and 8 at a predetermined interval, and alternately and independently enter the optical fibers 20.

One end of the optical fiber 20 is connected to the chopper 9, and light is alternately incident on the optical fiber 20 from the chopper 9. The length of the optical fiber 20 is appropriately determined according to the usage situation. For example, when quantifying a measurement target component of a measurement target in a laboratory or a laboratory, the length may be several tens of cm. In addition, for example, when measuring a leak from a pipe of a chemical plant, the length can be set to several hundred m.

The optical fiber 20 has a sensor part in the middle thereof.
Have SP. FIG. 2 is a cross-sectional view in the longitudinal direction in the vicinity of the sensor portion SP of the optical fiber 20, for showing an example of the configuration of the sensor portion SP. The optical fiber 20 has a core 21 and a clad 22 laminated around the core 21. Chopper 9
The light from is incident on the core 21. The sensor portion SP shown in FIG. 2 is formed by cutting the clad 22 so that a part of the core 21 is exposed in the optical fiber 20.

As shown in FIG. 2, when a part of the core 21 is directly exposed to the outside to form the sensor portion SP, the evanescent wave generated on the surface of the core 21 of the sensor portion SP can directly act on the outside. . The evanescent wave is
Like the light wave generated in the second medium when the light in the first medium is reflected at the boundary with the second medium, it is exponentially attenuated with the distance from the boundary surface.
cent: gradually disappears) is a light wave that has virtually no energy. The interaction between the evanescent wave and the component to be measured in the outside world can be used for the measurement, and the details will be described later.

It is also possible to adopt another structure as the sensor section SP. 3A to 3C are cross-sectional views in the longitudinal direction in the vicinity of the sensor portion SP of the optical fiber 20, for showing another configuration of the sensor portion SP. In FIG. 3, the optical fiber 20 is cut in the middle, and several millimeters are provided between the one optical fiber portion 20a and the other optical fiber portion 20b.
The sensor portion SP is configured by sandwiching the minute hetero core portion 3 of several cm to several centimeters.

The hetero core 3 is an embodiment of the light transmitting member of the present invention. FIG. 3A shows a hetero core 3 having a core 31 and a clad 32 laminated around the core 31, like the optical fiber 20. In the hetero core 3 shown in FIG. 3A, the diameter bl of the core 31 is sufficiently smaller than the diameter al of the core 21 of the optical fiber 20, for example, al = 50 μm and bl = 3 μm. The length cl of the hetero core 3 is, for example, 5
mm. Optical fiber parts 20a, 20b and hetero
The core portion 3 is coaxially joined so that the cores contact each other at an interface 4 orthogonal to the longitudinal direction. For this joining, a fusion method using a generalized discharge is preferably used.

The light traveling in the core of the optical fiber is substantially totally reflected at the boundary between the core 21 and the clad 22 in the optical fiber portions 20a and 20b, and travels in the core 21 as it is. However, as shown in FIG. 3A, when the diameters of the core 21 of the optical fiber portions 20a and 20b and the core 31 of the hetero core portion 3 are different from each other, a part of the light is transmitted to the hetero core portion at the interface 4. 3 leaks into the clad 32. As a result, the above-mentioned evanescent wave is generated at the boundary between the cladding 32 and the outside world. The light that has been interacted with the outside world by the evanescent wave is incident on the cores 21 of the optical fiber portions 20a and 20b again and transmitted.

According to the structure shown in FIG. 3 (a), since the hetero core 3 is joined by fusion, the cladding 22 needs to be shaved so as not to damage the core 21, as compared with the case of FIG. Inexpensive and easy manufacturing is possible. Further, since not only the thin core but also the clad around the core exist, the thickness of the sensor portion SP can be made the same as the thickness of the optical fiber portions 20a and 20b, so that the strength of the optical fiber 20 is increased.

As shown in FIG. 3B, the hetero core portion 3 may have a structure in which the core diameter bl of the hetero core portion 3 is larger than the core diameter al of the optical fiber portions 20a and 20b. Further, regardless of the inner / outer laminated structure of the core / clad, as shown in FIG. 3C, for example, an optical transmission member 30 having a refractive index similar to that of the clad 22 of the optical fiber 20 is provided.
It is also possible to use it as a light transmitting member instead of the hetero core part 3. The optical fiber 20 and the hetero
As the core portion 3, both a single mode optical fiber and a multi mode optical fiber can be used, and these may be used in combination. Below,
To the optical fiber 20 which is a multi-mode optical fiber, as shown in FIG. 3A, the fusion splicing of the hetero core portion 3 by the single mode optical fiber having the core diameter smaller than the core 21 of the optical fiber 20 is performed. The description will proceed assuming that the sensor section SP is configured.

The sensor portion SP is immersed in, for example, the solution to be measured 12 containing the component to be measured in the measuring container 11. Not limited to this form, for example, when it is desired to detect a leak from the pipe, the sensor unit SP is installed at the desired measurement position of the pipe.

The other end of the optical fiber 20 is connected to a photodetector 25, and the light that has been interacted with the outside in the sensor section SP is incident on the photodetector 25. Photo detector 25
Generally, a photomultiplier tube is used, and 1
Photocurrent is generated at a response speed of μs or less. This photocurrent is amplified and used for signal processing in measurement.

The controller 40 controls the optical fiber type multi-wavelength spectroscopic measurement apparatus 1 such as spectral separation of light of a desired wavelength from the light source 6, selection of light by the chopper 9 and synchronization of detection signals at the photodetector 25. Take control of everything. Further, the controller 40 also functions as an arithmetic unit that quantifies the component to be measured based on the detection result of the photodetector 25.
The density and the like obtained by the calculation are output by a display device, a plotter, or the like (not shown).

Quantification of One Component Next, with reference to the flowchart shown in FIG. 4, a method for quantifying the concentration of one measurement target component using the optical fiber type multi-wavelength spectroscopic measurement device 10 described above. I will describe. It is assumed that the measurement target solution 12 contains a known substance called a substance a as a measurement target component.
The purpose of the measurement is to quantify the concentration of this substance a.

First, as the incident light, two monochromatic lights having wavelengths λ1 and λ2 are alternately incident on the optical fiber 20 by the light injector 15 (step ST1). At this time, for example, one wavelength λ1 is fixed to a wavelength at an isosbestic point which is not affected by the content of the measurement target component as shown in FIG. 5, and the other wavelength λ2 is set to the absorption spectrum of the substance a. Adjust to the peak wavelength. In addition, the intensity of each of the incident lights is measured by a light intensity recognition means such as a detector (not shown).

Each incident light leaks from the core 21 of the optical fiber 20 to the cladding 32 of the hetero core 3 at the interface 4. Due to the leaked light, an evanescent wave is generated at the boundary between the cladding 32 and the outside world as described above. This evanescent wave is absorbed with a strength peculiar to the component to be measured, in this case, the substance a. The evanescent wave attenuated by the amount absorbed by the substance a enters the core 21 again. Therefore, the intensity of light detected by the photodetector 25 is attenuated by the amount absorbed by the substance a. Among the light leaked from the core 21 of the optical fiber 20 to the cladding 32 of the hetero core portion 3, there is also light that does not return to the core 21, but this optical loss is due to the structure of the optical fiber 20 having the sensor portion SP. Is defined by and is almost constant. Therefore, in consideration of the optical loss due to the structure of the optical fiber 20, the controller 4
By comparing the intensity of the detection light detected by the photodetector 25 with 0 and the intensity of the light at the time of being incident on the optical fiber 20 from the chopper 9, the absorbance for the substance a at the respective wavelengths λ1 and λ2 A ^a _λ1 and A ^a _λ2 are obtained (step ST2).

The absorbance A is given by the following formula, assuming that the monochromatic light having the intensity I ₀ is transmitted through the solution to be measured and becomes the intensity I.

[0033]

[Equation 1] I / I ₀ = t (transmittance) -log (I / I ₀ ) ≡-log (t) = A (absorbance)

If the differential absorption ΔA ^a = A ^a _λ2 −A ^a _λ1 is taken, this can be transformed as follows according to Lambert-Beer's law.

[0035]

[Formula 2] ΔA ^a = A ^a _λ2 −A ^a _λ1 = ε ^a ₂ Lc _a −ε ^a ₁ Lc _a = (ε ^a ₂ −ε ^a ₁ ) Lc _a (ε: molar extinction coefficient, L: optical path length, c: Concentration of component to be measured)

Now, ΔA ^a can be detected, and a known substance a
Molar extinction coefficient ε ^a ₁ , of light of wavelengths λ1 and λ2 with respect to
ε ^a ₂ and the optical path length L are also known. These known data can be stored in storage means such as the memory of the controller 40. Using these data by performing the above operation, the controller 40 can calculate and quantify the concentration c _a substance a is a measurement target component (step ST3).

According to the quantification of the component to be measured in this embodiment, two lights having different wavelengths are alternately arranged in the optical fiber 20.
By injecting into, it becomes possible to detect with high accuracy without using reference. Unlike the conventional method of detecting the transmitted light from the sample cell, the sensor part SP of the optical fiber 20 is brought into direct contact with the solution to be measured, and the attenuation of light based on the interaction between the evanescent wave and the component to be measured is detected. With this, it is possible to reduce the influence of drift, light scattering, etc., and perform highly accurate measurement. Further, in this method, one wavelength λ1 of the incident light is fixed to the isosbestic point, and for example, when the solution 12 to be measured is a suspension sample, the influence of turbidity on the absorbances A ^a _λ1 and A ^a _λ2 . Are canceled out, the measurement is performed with higher accuracy. Furthermore, in the present embodiment, the measurement target solution 1 is formed using an optical fiber.
Since the light is directly incident on 2, the structure is simple. By using an optical fiber, the present invention can be applied to real-time in situ measurement at a remote place such as detection of leakage from piping in a factory or a chemical plant. Moreover, since the optical fiber in which the hetero core 3 is joined by fusion is preferably used, the strength of the optical fiber is high,
Suitable for in situ measurements in remote areas.

Quantification of Two Components It is also possible to quantify the concentrations of two components to be measured by using the optical fiber multi-wavelength spectroscopic measurement device 10. Figure 6
Is a flow chart for describing a method for quantifying two components. It is assumed that the measurement target solution 12 contains two types of known measurement target components, a substance a and a substance b. The purpose of the measurement is to quantify the concentrations of substances a and b.

Even in the quantification of two components, the wavelengths λ1 and λ
Two monochromatic lights 2 are alternately incident on the optical fiber 20. For the wavelength λ2, for example, the wavelength at which the absorbance for the substance b is A ^b _λ1 = A ^b _λ2 is selected and fixed (step ST4). The other wavelength λ1 is adjusted to the peak wavelength of the absorption spectrum of substance a.

The light having the wavelengths λ1 and λ2 thus determined is alternately incident on the optical fiber 20 by the light injector 15 while measuring the intensities thereof (step).
ST5). As described above, the incident light leaks into the clad 32 to generate an evanescent wave. Similar to step ST2,
By comparing the intensity of light absorbed by the evanescent wave and attenuated by the intensity of the incident light to the optical fiber 20, the solution to be measured 12 containing the substances a and b at the respective wavelengths λ1 and λ2. Absorbance of light against A
^{a + b} _λ1 and A ^{a + b} _λ2 are obtained (step ST6).

In a mixed solution of substances a and b, A^a _λ1= A^{a + b}
_λ1−A^b _λ1And now A^b _λ1= A^b _λ2Wavelength λ
Since 2 is selected, the difference absorption ΔA^{a + b}= A^{a + b} _λ2−A
^{a + b} _λ1Can be transformed as follows.

[0042]

[Equation 3]

Also in this case, the molar extinction coefficients ε ^a ₁ , ε ^a ₂ ,
And the optical path length L is known, it is possible to quantify the concentration c _a material a by the operation of the controller 40. Similarly, the concentration c _b of the substance b can also be quantified by selecting the wavelength at which the absorbance for the substance a is A ^a _λ1 = A ^a _λ2 (step ST7).

As described above, in this method, the concentrations of the two components to be measured can be quantified at once by simply setting the wavelengths λ1 and λ2 of the two lights once. Further, at that time, the two-component measurement can be performed by the optical fiber type multi-wavelength spectroscopic measurement apparatus 10 having one optical fiber 20 without any change in the configuration of the measurement apparatus.

Derivative Spectrum Method In the spectroscopic measurement, a differential spectrum method is known which enables highly accurate measurement and microanalysis. As shown in FIG. 7, when the absorbance A is first differentiated with respect to the wavelength and recorded with respect to the wavelength λ, a first derivative spectrum is obtained. If Lambert-Beer's law holds true with this derivative, the following equation holds.

[0046]

[Formula 4] dA / dλ = (dε / dλ) Lc

From the above equation, it can be seen that the differential value of the absorbance A is also proportional to the concentration c. Thereby, the measurement target component can be quantified. Further, as shown in FIG. 7, it is possible to clearly obtain the absorption peak and the absorption shoulder in the differential spectrum, and the distinction between the main peak and other peaks becomes clear. Therefore, high-accuracy measurement can be performed without being affected by the absorption of the main component and the scattering of light due to turbidity. Hereinafter, the measurement method based on the differential spectrum method in the present embodiment will be described with reference to the flowchart in FIG.

It is assumed that the solution 12 to be measured contains a known substance called a substance a as a component to be measured.
The purpose of the measurement is to quantify the concentration of one measurement target component called substance a. First, the initial value of the wavelength λi used for measurement is determined. Here, the wavelength λ0 is set as an initial value, and λi = λ0 is set (step ST8). The value of the wavelength λ0 is, for example, λ0 = 350 nm.

Next, the light of wavelength λi (= λ0) is incident on the optical fiber 20 by the light injector 15 (step ST
9). From the absorbance of the evanescent wave at the boundary between the clad 32 and the outside world for the substance a, the absorbance A ^a _λi of the light having the wavelength λi with respect to the measurement target solution 12 containing the substance a can be obtained (step ST10).

When the absorbance for the wavelength λi is obtained, the controller 40 sets λi = λi + Δλ and shifts the wavelength λi by a predetermined wavelength width Δλ (step ST11). The wavelength width Δλ is, for example, about 1 to 3 nm, which is a sufficiently small value for obtaining a differential spectrum. Further, here, the wavelength λi is increased by the wavelength width Δλ.

It is determined whether or not the newly determined wavelength λi is λi> λn with respect to the final value λn of the wavelength used in the measurement. If not, the process returns to step ST9 and steps ST9 to ST11 are repeated, successively sweeping (scanning) the absorbance a ^a _.lambda.i for updated wavelengths .lambda.i. The relationship between the obtained absorbance A ^a _λi and the wavelength λi is stored in the memory of the controller 40, for example. When λi> λn, the controller 40 finishes updating the wavelength λi and proceeds to step ST13 (step ST12). In addition,
Here, the wavelength λn is, for example, λn = 2600 nm.

Each absorbance A for the updated wavelength λi
^A first derivative spectrum is obtained based on ^a _λi (step ST13). Based on the obtained first derivative spectrum,
The controller 40 quantifies the concentration of the substance a (step S
T14).

Sweeping by changing the wavelength of light with a wavelength width Δλ is equivalent to fixing the interval between the wavelengths of two lights to Δλ and then sweeping by changing the wavelengths of these lights. Therefore, also in the present embodiment using two lights having different wavelengths, the component to be measured can be quantified with high accuracy by the differential spectrum method. At that time, it is not necessary to change the configuration of the optical fiber type multi-wavelength spectroscopic measurement device 10 at all, and the measurement can be performed by a simple measurement device.

It is also possible to further obtain a second-order or higher-order differential spectrum. In this case, a circuit or program for calculating the higher-order derivative spectrum by calculation may be added to the controller 40. The use of a higher-order derivative spectrum of the second or higher order enables measurement with higher sensitivity and accuracy.

Second Embodiment In the optical fiber type multi-wavelength spectrometer 10 of the first embodiment, it is possible to measure two or more components to be measured at once by increasing the number of incident lights. Figure 9
FIG. 6 is a schematic configuration diagram showing a second embodiment of the present invention. The optical fiber type multi-wavelength spectroscopic measurement device 100 shown in FIG. 9 has n spectroscopes for taking out the light from the light source 6 into n lights having different wavelengths λ1, λ2, ..., λn. . The chopper 9 switches the n monochromatic lights with different wavelengths, which are extracted and incident by the n spectroscopes, at predetermined intervals and alternately and independently make them enter the optical fiber 20. The other components are the same as in the case of the optical fiber type multi-wavelength spectroscopic measurement device 10 of the first embodiment, and therefore, the same components are designated by the same reference numerals and detailed description thereof will be omitted.

Optical fiber type multi-wavelength spectroscopy of the second embodiment
In the measuring device 100, the wavelengths λ1, λ2, ..., λn
Two or more components to be measured by selecting
It is possible to accurately and separately quantify the concentration of.
For example, when measuring the three components of substances a, b, and c, A
^{b + c} _λ3= A^{b + c} _λ2+ A^{b + c} _λ1Wavelengths λ1, λ2, λ3
By measuring the concentration of substance a by the following formula
can do.

[0057]

[Formula 5] ΔA ^{a + b + c} = A ^{a + b + c} _λ3 −A ^{a + b + c} _λ2 −A ^{a + b + c} _λ1 = (A ^a _λ3 + A ^{b + c} _λ3 ) − (A ^a _λ2 + A ^{b + c} _λ2 )-(A ^a _λ1 + A ^{b + c} _λ1 ) = A ^a _λ3 −A ^a _λ2 −A ^a _λ1 + A ^{b + c} _λ3 −A ^{b + c} _λ2 −A ^{b + c} λ ₁ ＝ A ^a _λ3- A ^a _λ2- A ^a _λ1 = ε ^a ₃ Lc _{a −} ε ^a ₂ Lc _{a −} ε ^a ₁ Lc _a = (ε ^a _{3 −} ε ^a _{2 −} ε ^a ₁ ) Lc _a

The concentrations of the substances b and c can be similarly measured.

Third Embodiment FIG. 10 shows a schematic block diagram of a third embodiment of the optical fiber type multi-wavelength spectroscopic measurement apparatus according to the present invention. The optical fiber type multi-wavelength spectroscopic measurement device 120 shown in FIG. 10 collectively inputs lights of different wavelengths into the optical fiber 20 and disperses the lights of the respective wavelengths which have been interacted with the external world by the spectroscope 90. The point of incidence on the photodetector 25 is different from that of the optical fiber type multi-wavelength spectrometer 10 of the first embodiment.
The other configurations are similar to those of the first embodiment, and thus detailed description thereof will be omitted.

In the third embodiment, the light having the wavelength λ1 and the light having the wavelength λ2 extracted by the spectroscopes 7 and 8 are not incident on the optical fiber 20 alternately by the chopper, but are mixed to form the optical fiber. It is incident on 20.

Even if light is mixed and incident, the light is attenuated at the respective portions of wavelengths λ1 and λ2 by the amount of the absorbance with respect to the component to be measured. Therefore, by using the spectroscope 90 to select the light having the wavelengths λ1 and λ2 from the light emitted from the optical fiber 20, the absorbance of the light having the wavelengths λ1 and λ2 with respect to the measurement target component can be measured. it can. Before mixing and entering the optical fiber 20, the wavelength λ is detected by using a light intensity recognition means such as a detector.
The light intensities of the light of wavelength 1 and the light of wavelength λ2 are measured in advance. By comparing the measured light intensity with the detected light intensity of each wavelength detected by the photodetector 25, the principle described in the case of the first embodiment is applied to calculate the concentration of the measurement target component. -It can be quantified.

According to the third embodiment, since it is not necessary to use a chopper, the structure of the measuring device becomes simpler. Therefore, cost reduction, miniaturization, etc. of the measuring device,
Various merits occur. Although FIG. 10 shows a mode in which light of wavelengths λ1 and λ2 is selected by one spectroscope 90, like the light injector 15, the light emitted from the optical fiber 20 is divided into two. It goes without saying that the light of wavelength λ1 and the light of wavelength λ2 may be extracted respectively by two spectroscopes.

Fourth Embodiment Optical fiber type multi-wavelength spectroscopic measurement device 120 of the third embodiment
Also in the above, it is possible to measure two or more components to be measured at once by increasing the number of incident lights.
FIG. 11 shows a schematic configuration diagram of the fourth embodiment of the optical fiber type multi-wavelength spectrometer according to the present invention. The optical fiber type multi-wavelength spectrometer 150 shown in FIG. 11 has wavelengths λ1, λ2, ..., Which are taken out from the light source 6 by n spectroscopes.
N pieces of light having different wavelengths of λn are mixed and incident on the optical fiber 20. Other configurations and functions are similar to those of the third embodiment, and thus detailed description thereof will be omitted.

Also in the optical fiber type multi-wavelength spectrometer 150 of the fourth embodiment, it is possible to measure two or more components to be measured at once by applying the principle described in the second embodiment. is there. At that time, since it is not necessary to use a chopper, the measuring device can have a simple structure, and the device is small and inexpensive. Also in the fourth embodiment, the light emitted from the optical fiber 20 is divided into n pieces, and the wavelengths λ1,
It goes without saying that n pieces of light having different wavelengths λ2, ..., λn may be extracted and made incident on the photodetector 25.

Modifications For example, protein has a clear peak at a wavelength of 280 nm, and in fructose, since quantitative determination is performed based on the change in the refractive index depending on the concentration, an indicator is not used for the quantitative determination of the concentration. However, in general, an indicator is used for the measurement in order to enhance the selectivity for the component to be measured and to perform the measurement with high accuracy. Also in the first to fourth embodiments described above, by using an indicator in which the absorbance at the peak wavelength changes according to the concentration change of the substance of the target measurement target component, the selectivity is increased, and high-sensitivity and high-precision measurement is performed. Can be done.

The indicator may be dissolved in the solution 12 to be measured and used, but it may be immobilized on the sensor portion SP of the optical fiber 20 for easy handling. 12 and 13 (a) to (c) show diagrams in which the indicator 50 is immobilized on the sensor portion SP of the optical fiber shown in FIGS. 2 and 3 (a) to (c). As the method of immobilizing the indicator, a sol-gel method, a method of chemically bonding a dye of the indicator to the surface of the fiber and fixing the same can be used.

As the indicator 50, it is also possible to use an indicator in which two or more kinds of indicators are mixed and fixed. For example, the indicator Am whose absorbance at the peak wavelength λa changes according to the concentration change of the substance a and the indicator Bm whose absorbance at the peak wavelength λb changes according to the concentration change of the substance b are mixed and immobilized. Then the above substances
Highly selective and highly sensitive and accurate measurements can be performed in the quantification of the two components a and b. It goes without saying that the type of indicator to be mixed can be increased in accordance with the number of measurement target components to be quantified. Further, when a plurality of indicators are immobilized on one optical fiber, they can be provided at the same location or at different locations.

If a pH indicator is used as the indicator and a plurality of pH indicators that react with each pH value are immobilized, an unknown pH of the solution 12 to be measured can be measured. If a metal indicator that reacts with metal ions is used as the indicator, the concentration of the desired metal ion in the measurement object can be quantified. If a plurality of metal indicators are mixed and immobilized, a plurality of metal ions can be quantified at one time. Further, by fixing the indicator, depending on the kind of the indicator, after the sensor is used for the measurement, the sensor unit SP can be washed and dried to be repeatedly used for the measurement. As the indicator corresponding to the component to be measured, for example, those shown in the following table are known.

[0069]

[Table 1] Examples of indicators

5-Br-PAPS is 2- (5-Bromo-2-py
ridylazo) -5- [Nn-propyl-N- (3-sulfopropyl) amino] ph
Enol, disodium salt, dehydrate, 4TF is 4 '-(2,6-Dinitro-4-trifluoromethlphenyl) aminobe
nzo-15-crown-5, SCR is 3,3'-Bis
{[N-methyl-N (carboxymethl)] aminomethyl} -o-cresolsu
lfonphthalein, monosodium salt.

When the indicator is immobilized on the sensor portion SP as in the present modification, the influence of light transmission through the solution to be measured is reduced and the detection time is shortened. Further, since the indicator is present on the side of the measuring device, it is possible to detect and quantify the component to be measured contained not only in liquid but also in gas, such as ammonia detection.

The present invention is not limited to the above embodiments and the contents described in the drawings. For example, in the above embodiment, only one optical fiber 20 is connected to the chopper 9, but it is also possible to connect a plurality of optical fibers. Also for the sensor section SP, the optical fiber 2
It is possible to provide a plurality of 0. Multiple optical fibers 2
When 0 and the sensor unit SP are used, for example, when detecting a leak of a chemical substance from a pipe of a factory or a chemical plant, it is possible to perform integrated measurement in a wide range with a measuring device having a simple structure. Also, OTDR (Optical Time
-A Domain Reflectometer) can be used as both a light incident means and a light receiving means. In this embodiment, the light from the OTDR is split by the spectroscope and is incident on the optical fiber 20 via the chopper 9, and the light that has been interacted with the outside in the sensor unit SP without using the photodetector 25 is used. The backscattered light is received by the OTDR again. When using OTDR, it is not necessary to connect the end of the optical fiber 20 to the photodetector 25,
If the sensor section SP is included, the optical fiber 20 may be left cut at any position. Therefore, the structure of the measuring device is simpler and the handling is simple, and the range of use of the measuring device is widened, for example, it can be carried.

[0073]

As described above, according to the present invention, it is possible to provide an optical fiber type multi-wavelength spectrometer having a simple structure, high sensitivity and high accuracy. According to the present invention, it is possible to provide a multi-wavelength spectroscopic measurement method using an optical fiber, which is highly sensitive and highly accurate.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of an optical fiber type multi-wavelength spectrometer according to the present invention.

FIG. 2 is a longitudinal cross-sectional view showing an embodiment of a sensor unit according to the present invention.

3A to 3C are longitudinal sectional views showing another embodiment of the sensor unit according to the present invention.

FIG. 4 is a flowchart for explaining a method for quantifying one component using the optical fiber type multi-wavelength spectroscopic measurement device shown in FIG. 1.

FIG. 5 is a graph of an absorption spectrum for explaining an isosbestic point.

FIG. 6 is a flowchart for explaining a two-component quantification method using the optical fiber type multi-wavelength spectroscopic measurement device shown in FIG. 1.

FIG. 7 is a graph showing a first derivative spectrum.

FIG. 8 is a flowchart for explaining quantification of one component by a differential spectrum method using the optical fiber type multi-wavelength spectroscopic measurement device shown in FIG. 1.

FIG. 9 is a schematic configuration diagram of a second embodiment of an optical fiber type multi-wavelength spectrometer according to the present invention.

FIG. 10 is a schematic configuration diagram of a third embodiment of an optical fiber type multi-wavelength spectrometer according to the present invention.

FIG. 11 is a schematic configuration diagram of a fourth embodiment of an optical fiber type multi-wavelength spectrometer according to the present invention.

FIG. 12 is a longitudinal cross-sectional view showing an embodiment of a sensor unit having an indicator immobilized thereon.

13 (a) to 13 (c) are longitudinal cross-sectional views showing another embodiment of a sensor unit having an indicator immobilized thereon.

[Explanation of symbols]

10, 100, 120, 150 ... Optical fiber type multi-wavelength spectrometer 3 ... Hetero-core section 6 ... Light source 7, 8, 90, N ... Spectrometer 9 ... Chopper 15 ... Light injector 20 ... Optical fiber 21, 31 ... Cores 22, 32 ... Clad 25 ... Photodetector 40 ... Controller 50 ... Indicator SP ... Sensor section

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G01N 21/35 G01N 21/35 Z (72) Inventor Toshio Kobayashi 1-236, Tikicho, Hachioji, Tokyo Soka F-term in the Faculty of Engineering (reference) 2G059 AA01 BB04 EE01 EE02 EE12 FF07 FF12 GG03 GG10 HH01 HH02 HH03 JJ05 JJ17 JJ24 KK01 MM01 MM04 2G086 DD05

Claims (8)

[Claims] 1. An optical fiber having a core and a clad laminated around the core, the optical fiber having a sensor section that enables interaction of part of transmitted light with the outside world, and at least two different wavelengths. A light incident means for injecting light into the optical fiber, a light receiving means for receiving light that has interacted with the outside world in the sensor section, and a difference in absorbance of light with respect to a measurement target component of the measurement target existing in the outside world. An optical fiber type multi-wavelength spectroscopic measurement device having a calculation means for quantifying the component to be measured based on the above. 2. One of the different wavelengths of the light emitted by the light incident means is a wavelength at an isosbestic point not affected by the content of the component to be measured, and the remaining wavelengths are at the isosbestic point. 2. The optical fiber type multi-wavelength spectroscopic measurement device according to claim 1, wherein the wavelength is different from the wavelength. 3. The light incident means causes light of a predetermined wavelength width within a predetermined wavelength range to be incident on the optical fiber, and the computing means obtains a first derivative spectrum of light absorbance with respect to the wavelength. The optical fiber multi-wavelength spectroscopic measurement device according to claim 1, wherein the measurement target component is quantified. 4. The sensor section is formed by fusion-bonding a light transmitting member having a refractive index equal to the refractive index of the core of the optical fiber or the refractive index of the cladding of the optical fiber in the middle of the optical fiber. The optical fiber type multi-wavelength spectrometer according to any one of claims 1 to 3. 5. An indicator which is immobilized on the surface of the sensor portion and which selectively reacts with the component to be measured and causes the light incident on the light incident means to change the absorbance according to the component to be measured. Item 5. The optical fiber multi-wavelength spectroscopic measurement device according to any one of items 1 to 4. 6. Measurement of an object to be measured existing in the outside world by injecting light of at least two different wavelengths into an optical fiber capable of interacting with the outside world and receiving the light which has been interacted with the outside world. A multi-wavelength spectroscopic measurement method using an optical fiber for quantifying the measurement target component based on the difference in light absorbance with respect to the target component. 7. One of the lights from the light incident means having a wavelength at an isosbestic point which is not affected by the content of the component to be measured.
7. The multi-wavelength spectroscopic measurement method using an optical fiber according to claim 6, wherein one wavelength is fixed and the wavelength of the remaining light is different from the wavelength of the isosbestic point to measure the absorbance. 8. A quantitative analysis of a component to be measured by injecting light into the optical fiber for each predetermined wavelength width within a predetermined wavelength range and obtaining a first derivative spectrum of the light absorbance with respect to the wavelength. A multi-wavelength spectroscopic measurement method using the optical fiber described in.