KR101894183B1 - The optical waveguide sensor and the concentration measurement system with it - Google Patents

Abstract

Provided are an optical waveguide sensor, and a concentration measurement system using the same, wherein the sensor has high sensitivity while being simply manufactured. According to an embodiment of the present invention, provided is an optical waveguide sensor, which comprises: an optical waveguide obtaining a first light from one side connected to a light source to transfer a second light to the other side; an inner cover formed in the outside with respect to the optical waveguide; and a measurement unit allowing a portion of the inner cover to be removed so as to enable a portion of the optical waveguide to be exposed to the outside. Moreover, the optical waveguide comes in contact with a measurement material, of which concentration is to be measured through the measurement unit.

Description

[0001] The present invention relates to an optical waveguide sensor and a concentration measurement system using the same,

The present invention relates to an optical waveguide sensor and a concentration measuring system using the same, and more particularly, to a sensor capable of detecting a concentration of a specific substance using an optical waveguide and a concentration measuring system using the same.

Generally, a sensor using an optical waveguide typified by an optical fiber uses various variables such as intensity of light passing through the optical waveguide, refractive index and length of the optical waveguide, mode, and polarization state, Pressure and so on. Optical waveguide sensors are capable of ultra-high-precision broadband measurement, are not affected by electromagnetic waves, and are easy to measure remotely. In addition, there is an advantage that there is almost no restriction on the use environment because the measurement part does not use electricity and has excellent corrosion resistance of the silica material.

On the other hand, a general chemical sensor or biosensor for concentration measurement includes an electrode for taking advantage of the electrical property of the measurement substance. In this case, there is a problem in the use environment because electric power must be received from the electrode, and a conductor such as a wire is required to transmit the electric signal measured by the measuring part to an external measuring device.

KR 10-1226264 B1

In order to solve the problems of the prior art as described above, an embodiment of the present invention provides an optical waveguide sensor capable of real-time field diagnosis, being simple and compact, .

According to an aspect of the present invention, an optical waveguide sensor is provided. The optical waveguide sensor includes: an optical waveguide for acquiring a first light from one side connected to a light source and transmitting the second light to the other side; An inner layer formed outside the optical waveguide; And a measurement part formed by removing a part of the inner surface of the optical waveguide so that a part of the optical waveguide is exposed to the outside, wherein the optical waveguide is in contact with a measurement material to be measured through the measurement part.

The optical waveguide may be provided so that the other side is connected to an optical output measuring device for measuring the output of the second light.

The light source may be a helium-neon laser.

The concentration of the measurement substance may be measured using the intensity of the first light and the second light expressed by the following equation.

: 내피의 굴절률, n_{(liquid cladding)} : 측정 물질의 굴절률, L : 측정부의 길이, α : 측정 물질 농도 C에 따른 손실 함수(α=α₀+α₁C+α₂C²), C≤0.1%)(Wherein, T: the light output ratio, P _in: a first intensity of the light, P _out: a second intensity of the light, T _0: if the concentration is zero, the light output ratio, loss (dB): the optical loss due to the numerical aperture differences, NA _B : numerical aperture of the measurement part, NA _C : numerical aperture of the optical waveguide sensor outside the measurement part, n _core : refractive index of the optical waveguide,

: Refractive index of the endothelium, n _{(liquid cladding)} : refractive index of the substance to be measured, L: length of the measurement part, α: loss function (α = α ₀ + α ₁ C + α ₂ C ² ) 0.1%)

Wherein the measurement material is a glycerol aqueous solution, and when the intensity of the first light is 3200 mW, the concentration of the measurement substance may be expressed by the following equation.

(Where C: sample concentration)

According to an aspect of the present invention, a concentration measurement system using an optical waveguide sensor is provided. The concentration measuring system using the optical waveguide sensor includes: a light source for generating a first light having a predetermined intensity; An optical waveguide sensor that receives the first light from the light source and converts the first light into a second light using a measurement material; And a detection device which receives the second light from the optical waveguide sensor and detects the concentration of the measurement substance.

The light source may be a helium-neon laser.

The sensor comprising: an optical waveguide that receives the first light from one side connected to the light source and transmits the second light to the detection device; An inner layer formed outside the optical waveguide; And a measurement unit that is formed to be in contact with the measurement material so that a part of the optical waveguide is partially exposed and exposed to the outside.

The concentration of the measurement substance may be measured using the intensity of the first light and the second light expressed by the following equation.

: 내피의 굴절률, n_{(liquid cladding)} : 측정 물질의 굴절률, L : 측정부의 길이, α : 측정 물질 농도 C에 따른 손실 함수(α=α₀+α₁C+α₂C²), C≤0.1%)(Wherein, T: the light output ratio, P _in: a first intensity of the light, P _out: a second intensity of the light, T _0: if the concentration is zero, the light output ratio, loss (dB): the optical loss due to the numerical aperture differences, NA _B : numerical aperture of the measurement part, NA _C : numerical aperture of the optical waveguide sensor outside the measurement part, n _core : refractive index of the optical waveguide,

: Refractive index of the endothelium, n _{(liquid cladding)} : refractive index of the substance to be measured, L: length of the measurement part, α: loss function (α = α ₀ + α ₁ C + α ₂ C ² ) 0.1%)

Wherein the measurement material is a glycerol aqueous solution, and when the intensity of the first light is 3200 mW, the concentration of the measurement substance may be expressed by the following equation.

(Where C: sample concentration)

The optical waveguide sensor according to an embodiment of the present invention and the concentration measurement system using the optical waveguide sensor have the effect of measuring the concentration of a measurement substance in real time.

In addition, the optical waveguide sensor and the concentration measuring system using the optical waveguide sensor according to an embodiment of the present invention can be manufactured in a small size and can measure the concentration of a measurement substance with high sensitivity.

In addition, the optical waveguide sensor and the concentration measuring system using the optical waveguide sensor according to the embodiment of the present invention do not use an electrode for measuring the concentration of a measurement substance, have.

In addition, the optical waveguide sensor according to an embodiment of the present invention and the concentration measuring system using the optical waveguide sensor according to the present invention have the effect of reducing the restriction of the use environment by utilizing a change in the aberration inside the optical waveguide due to the contact of the measurement material.

1 is a view illustrating an optical waveguide sensor according to an embodiment of the present invention.
2 is a view illustrating a measurement unit of an optical waveguide sensor according to an embodiment of the present invention.
3 is a diagram illustrating a concentration measurement system using an optical waveguide sensor according to an embodiment of the present invention.
4 is a view schematically showing an optical waveguide sensor according to an embodiment of the present invention.
5 is a graph illustrating simulation results for comparing optical output ratios according to lengths of measurement units of an optical waveguide sensor according to an embodiment of the present invention.
FIG. 6 is a graph illustrating a simulation result of measuring an optical output when a length of a measurement part of an optical waveguide sensor according to an embodiment of the present invention is 5 cm.
FIG. 7 is a graph comparing a simulation result and a theory of an optical waveguide sensor according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

FIG. 1 is a view illustrating an optical waveguide sensor according to an embodiment of the present invention, and FIG. 2 is a view illustrating a measurement unit of an optical waveguide sensor according to an embodiment of the present invention.

Referring to FIG. 1, an optical waveguide sensor 100 according to an embodiment of the present invention includes an optical waveguide 110, an inner skin 120, and a skin 130. At this time, the optical waveguide sensor 100 includes an inner skin 120 on the outer side of the optical waveguide 110, and an outer skin 130 for protecting the optical waveguide 110 and the inner skin 120, As shown in FIG. The refractive index of the optical waveguide 110 may be greater than the refractive index of the endothelium 120. The optical waveguide 110 may be formed of silica, have.

Referring to FIG. 2, the optical waveguide sensor 100 according to the embodiment of the present invention includes a measurement unit 150. The measuring unit 150 measures the concentration of the substance to be measured contained in the sample by contacting the sample. For this, the measuring unit 150 is formed by exposing a part of the optical fiber 110 by removing the outer cover 130 and the inner skin 120 of the optical waveguide sensor 100.

In other words, the measuring unit 150 is a portion where the optical waveguide 110 is exposed to the outside, and the optical waveguide 110 is brought into contact with the sample so that the sample can serve as the endocardial 120, have. At this time, the measurement unit 150 may be formed to have a length of preferably 5 cm, but the present invention is not limited thereto and may be formed to have a predetermined length.

1 and 2 show that a portion of the end portion 120 of the optical waveguide sensor 100 according to the present invention in which the end portion 120 does not exist is present at both ends of the measuring portion 150. However, And the connection relationship of the outer shell, the inner shell and the optical waveguide of the waveguide sensor can be easily explained. A preferred example of the present invention is that the inner shell is exclusively exposed to the outside.

Meanwhile, FIG. 3 shows a concentration measurement system using an optical waveguide sensor according to an embodiment of the present invention.

3, a concentration measuring system 200 using an optical waveguide sensor according to an embodiment of the present invention includes a light source 210, a fiber coupler 230, an optical waveguide sensor 100, a collimator 250, And a meter 270.

The light source 210 generates the first light and transmits the first light to the fiber coupler 230. At this time, the output of the first light generated by the light source 210 may be adjustable according to the setting of the user, and may be a visible light line. This is because the amount of light absorbed by the aqueous solution hardly exists in the visible light region. Accordingly, the light source 210 may be a device for generating and emitting visible light such as a laser diode or an LED. In one embodiment of the present invention, the light source 210 may be a helium-neon laser (He-Ne laser).

The fiber coupler 230 is used when there is more than one input or output in the optical waveguide system. The fiber coupler 230 receives the first light generated by the light source 210 and separates and transmits the same amount of light to another optical waveguide (not shown) other than the optical waveguide sensor 100, May be provided to directly compare the differences. In the density measuring system 200 using the optical waveguide sensor according to the embodiment of the present invention, the fiber coupler 230 may be omitted according to the setting of the user.

The optical waveguide sensor 100 receives the first light from the fiber coupler 230 or the light source 210 and converts the first light into the second light using a sample contacted to the measuring unit 150. The optical waveguide sensor 100 receives the first light through one end and contacts the sample through the measurement unit 150. Therefore, the first light passing through the optical waveguide sensor 100 is reduced in transmission efficiency due to the difference between the refractive indexes of the inner film 120 and the sample. The intensity of the first light is changed into the second light having the changed intensity, .

The collimator 250 converts the traveling direction of the second light into a certain direction. The second light passes through the inside of the optical waveguide sensor 100 using the reflection at the interface between the optical waveguide 110 and the inner film 120 or the sample. Accordingly, the second light transmitted to the other end of the optical waveguide sensor 100 has various traveling directions. In order to prevent the loss of the second light, the collimator 250 receives the second light, Respectively.

The measuring instrument 270 receives the second light and measures the intensity thereof. The measurer 270 receives the converted second light through the collimator 250 so as to proceed in a predetermined direction, and measures the intensity of the obtained second light. Also, the measuring device 270 may compare the intensity of the first light with the intensity of the second light using the intensity of the first light set and outputted by the light source 210, and the result of the comparison may be expressed as Equation 1 have.

(Where T: transmitted light output ratio, P _in : intensity of first light, P _out : intensity of second light)

At this time, the intensity of the second light changes according to the concentration of the substance contained in the sample. This is because if the concentration of the substance contained in the sample changes, the refractive index of the sample also changes.

FIG. 4 is a schematic view of an optical waveguide sensor according to an embodiment of the present invention. Referring to FIG. 4, the optical waveguide sensor according to an embodiment of the present invention may be divided into an A-region where the first light flows, a B-region where the measurement portion exists, and a C-region where the second light flows. In this case, the numerical aperture in each zone can be expressed by the following equation (2), and the numerical aperture (NA) is a numerical value showing the light condensing ability of light.

(Where NA is the numerical aperture, n ₁ is the refractive index of the optical fiber, and n ₂ is the refractive index of the inner film)

Using the equation 2, A section and the C section of Figure 4 is the n ₂ value and the other n ₂ value of has the same number of openings, measuring denied because the B zone endothelial that has been replaced by a sample A zone and C zone I have.

On the other hand, in the case of a general optical waveguide, the refractive index of the optical waveguide is formed to be about 1.46 to 1.47 so that the index of refraction of the optical waveguide is made 0.2 to 1% lower than the refractive index of the optical waveguide to induce total reflection of light passing through the inside of the optical waveguide , And the inner film has a refractive index of 1.44 to 1.46.

Therefore, ₂ n A value of the area C and the area is formed to be larger than the refractive index of the zone B n ₂ value of the air. In the optical waveguide sensor 100 according to the embodiment of the present invention, the overall intensity is not reduced in the course of transmitting the first light to the measuring unit 150, but the numerical aperture A part of the light is lost in the process of forming the second light and transmitting it to the C zone. Such light loss can be determined by the numerical aperture ratio expressed by the following equation (3).

(Where NA _B : numerical aperture of zone B, NA _C : numerical aperture of zone C)

In this case, when a sample having a certain concentration is bonded to the region B, the value of n ₂ is larger than that of the air, so that light loss may be reduced in the process of transmitting light from the region B to the region C.

On the other hand, the optical loss due to the difference in numerical aperture can be expressed by the following equation (4).

(Where P _{in is} the intensity of the first light, P _{out is} the intensity of the second light)

Accordingly, by integrating the equations (1) to (4), the transmitted light output ratio T can be modified by the following equation (5).

(Α = α ₀ + α ₁ C + α ₂ C ² ) in accordance with the sample concentration C, T ₀ is the light output ratio when the density is 0, L is the length of the measuring section,

In other words, the optical waveguide sensor 100 according to the embodiment of the present invention generates the difference in aberration due to the liquid inner film replaced with the sample in the region B, Changing optical waveguide capable of measuring a concentration of a liquid substance to be detected by measuring a changed light intensity by generating optical loss in light passing through the sensor 100. [

Meanwhile, a simulation result for proving Equation (5) according to an embodiment of the present invention is shown in FIG. 5 is a graph illustrating a simulation result for comparing optical output ratios according to lengths of measurement units of an optical waveguide sensor according to an embodiment of the present invention. The simulation according to an embodiment of the present invention was performed by dividing the length of the measuring part into (A) 5 cm and (B) 1 cm, and the glycerol aqueous solution in which the well- And the size of the first light generated from the light source was kept constant at 3200 mW. The results for each experiment are shown in Table 1 below.

density(%) Output power (mW)
density(%) Output power (mW) (A) (B) (A) (B) 0 2924.89 2480.00 0.1 3097.36 2560.00 0.001 2935.72 2516.67 0.3 3098.64 2566.67 0.003 2939.28 2500.00 0.5 3092.70 2550.00 0.005 2949.16 2510.00 One 3053.29 2550.00 0.007 2950.45 2506.67 3 3060.67 2546.67 0.009 2966.71 2516.67 5 3043.90 2536.67 0.01 2985.76 2506.67 7 3029.81 2523.33 0.02 2999.24 2506.67 10 3022.34 2513.33 0.03 3012.24 2506.67 15 3008.05 2506.67 0.04 3007.42 2536.67 20 3011.62 2493.33 0.05 3014.28 2526.67 25 3007.77 2483.33 30 2990.52 2483.33

The graphs for the data shown in Table 1 are shown in FIGS. 5A and 5B, respectively. As shown in Table 1 and the graph, when the length of the measuring unit 150 is 5 cm (A), the length of the measuring unit 150 is 1 cm ( B). In both experiments, the intensity of the second light increased until the glycerol concentration reached 0.3%, and the intensity of the second light decreased by more than 0.3%.

6 is a graph illustrating a simulation result of measuring the optical output when the length of the measurement unit of the optical waveguide sensor according to the embodiment of the present invention is 5 cm. In the case where the measuring unit 150 of the optical waveguide sensor according to the embodiment of the present invention is 5 cm, the intensity of the first light is fixed to 3200 mW, and the intensity of the second light according to the concentration of glycerol is measured. Are displayed.

density(%) Output power (mW) density(%) Output power (mW) 0 2383.39 0.05 2942.19 0.001 2458.50 0.1 2950.81 0.002 2490.65 0.3 2922.44 0.003 2557.25 0.5 2851.17 0.004 2572.34 0.7 2778.97 0.005 2589.91 0.9 2733.67 0.006 2587.91 One 2688.98 0.007 2600.34 3 2656.39 0.008 2625.68 5 2610.47 0.009 2650.72 10 2590.57 0.01 2749.88 15 2582.67 0.02 2771.71 20 2581.90 0.03 2820.03 25 2590.57 0.04 2845.36 33 2562.89

Referring to the graphs of Table 2 and FIG. 6, a simulation result according to an embodiment of the present invention shows that the output intensity of the second light increases as the concentration of glycerol aqueous solution is less than 0.1% , And when it exceeds 0.1%, it decreases gradually, and when it exceeds 5%, the decrease in output decreases remarkably.

Accordingly, in the present invention, when the glycerol concentration is 0.1% or less, the sample is brought into contact with the measuring unit 150, the first light is emitted to measure the intensity of the second light, and the intensity of the two lights is compared to determine the concentration of glycerol And the inverse calculation results are shown in Table 3 below.

T = (2 light / 1 light) density(%) T = (2 light / 1 light) density(%) 0.7448 0 0.9194 0.05 0.7683 0.001 0.9221 0.1 0.7783 0.002 0.9133 0.3 0.7991 0.003 0.8910 0.5 0.8039 0.004 0.8684 0.7 0.8093 0.005 0.8543 0.9 0.8088 0.006 0.8403 One 0.8126 0.007 0.8301 3 0.8205 0.008 0.8158 5 0.8284 0.009 0.8096 10 0.8593 0.01 0.8071 15 0.8662 0.02 0.8068 20 0.8813 0.03 0.8096 25 0.8892 0.04 0.8009 30

FIG. 7 shows a graph comparing the experimental results of Table 3 with the T values of Equation 5. FIG. Referring to FIG. 7, the T value of Equation (5) is represented by a solid line when the first light size is 3200 mW, and the experimental result of Table 3 is represented by a dot.

Both results show similar shapes and values up to a maximum concentration of 2%, but the ratio of the first light to the second light represented by the light transmittance (T) has two concentrations, and the graph shows that the concentration of glycerol is 0.1% It is preferable to limit the glycerol concentration to 0.1% in order to increase the accuracy of the sensor.

Therefore, in the optical waveguide sensor and the concentration measuring system using the optical waveguide sensor according to an embodiment of the present invention, when the concentration of glycerol is limited to 0.1% or less and the intensity of the first light is kept constant at 3200 mW, The concentration of glycerol in the sample can be measured using the following equation (6).

Equation 6

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100: optical waveguide sensor 110: optical waveguide
120: inner skin 130: outer skin
150:
200: Concentration measurement system using optical waveguide sensor
210: light source 230: fiber coupler
250: collimator 270: measuring instrument

Claims (10)

An optical waveguide for acquiring a first light from one side connected to a light source formed by a helium-neon laser and transmitting the second light to the other side connected to an optical output measuring device for measuring an output of the second light;
An inner layer formed outside the optical waveguide; And
And a measurement part formed by removing a part of the inner skin so that a part of the optical waveguide is exposed to the outside,
Wherein the optical waveguide is in contact with a measurement substance to be measured through the measurement unit,
Wherein the concentration of the measurement substance is measured using the intensity of the first light and the second light expressed by the following equation.

(Wherein, T: the light output ratio, P _in: a first intensity of the light, P _out: a second intensity of the light, T _0: if the concentration is zero, the light output ratio, loss (dB): the optical loss due to the numerical aperture differences, NA _B : numerical aperture of the measurement part, NA _C : numerical aperture of the optical waveguide sensor outside the measurement part, n _core : refractive index of the optical waveguide,

: Refractive index of the endothelium, n _{(liquid cladding)} : refractive index of the substance to be measured, L: length of the measurement part, α: loss function (α = α ₀ + α ₁ C + α ₂ C ² ) 0.1%) delete delete delete The method according to claim 1,
Wherein the measurement material is a glycerol aqueous solution and the concentration of the measurement substance is expressed by the following equation when the intensity of the first light is 3200 mW.

(Where C: sample concentration) A light source formed of a helium-neon laser generating a first light of a predetermined intensity;
An optical waveguide sensor that receives the first light from the light source and converts the first light into a second light using a measurement material; And
And a detection device which receives the second light from the optical waveguide sensor and detects the concentration of the measurement substance,
The optical waveguide sensor includes:
An optical waveguide that receives the first light from one side connected to the light source and transmits the second light to the detection device;
An inner layer formed outside the optical waveguide; And
Further comprising: a measurement unit that is formed to be in contact with the measurement material so that a part of the optical waveguide is exposed to the outside,
Wherein the concentration of the measurement substance is measured using the intensity of the first light and the second light expressed by the following equation.

(Wherein, T: the light output ratio, P _in: a first intensity of the light, P _out: a second intensity of the light, T _0: if the concentration is zero, the light output ratio, loss (dB): the optical loss due to the numerical aperture differences, NA _B : numerical aperture of the measurement part, NA _C : numerical aperture of the optical waveguide sensor outside the measurement part, n _core : refractive index of the optical waveguide,

: Refractive index of the endothelium, n _{(liquid cladding)} : refractive index of the substance to be measured, L: length of the measurement part, α: loss function (α = α ₀ + α ₁ C + α ₂ C ² ) 0.1%) delete delete delete The method according to claim 6,
Wherein the measurement material is a glycerol aqueous solution and the concentration of the measurement substance is expressed by the following equation when the intensity of the first light is 3200 mW.

(Where C: sample concentration)

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