JP3079347B2 - Contact type optical fiber sensor and flow measuring method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact type optical fiber sensor and a flow measuring method and apparatus. More specifically, a contact type optical fiber sensor which can be configured extremely small and does not require a highly sensitive detector and has a high specific sensitivity, and a flow rate measuring flow rate or flow rate or flow path distance using the contact type optical fiber sensor. The present invention relates to a measuring method and an apparatus.

[0002]

2. Description of the Related Art FIG. 10 is a block diagram showing an example of a conventional contact type optical fiber sensor. This contact type optical fiber sensor 900 is configured such that an optical fiber 91 composed of a core 91a and a clad 91b is bent and a stainless steel holding tube 9 is bent.
6, a light source 901 for inputting light to the optical fiber cable 903 on the light source side including the optical fiber 91, and a light emitted from the optical fiber cable 904 on the detector side including the optical fiber 91. Light source 9 to be detected
06 is provided. The optical fiber 91
Is bent at the contact portion 90 in contact with the sample liquid G.
a.

As shown in FIG. 11, the tip of a contact portion 90a is polished until a core 91a is exposed, and a flat polished surface 90a is formed.
b. Light X1 propagating from the light source 901 side
Is divided into light X2 leaking from the flat polished surface 90b and light X3 propagating to the detector side. The flat polished surface 90
Since the degree of the light X2 leaking from b depends on the refractive index of the test liquid G, the refractive index of the test liquid G can be known by measuring the intensity of the light X3 with the detector 906. Further, when the contact portion 90a comes into contact with air, the light X2 hardly leaks from the flat polished surface 90b. Therefore, if the intensity of the light X3 is measured by the detector 906, the test liquid G can be measured.
Of the liquid level is higher or lower than the contact portion 90a.

[0004]

In the above-mentioned conventional contact type optical fiber sensor 900, the optical fiber 91 is bent into a U-shape. However, there is a problem that even if a relatively bendable plastic fiber is used, the bending radius is limited to about 1 mm, and the size of the contact portion 90a cannot be made smaller than about 2 mm. In addition, light leakage (flat polished surface 9)
0b) is large, the light X3 reaching the detector 906 is weak, and there is a problem that the detector 906 with high sensitivity is required.
Further, since the light X3 reaching the detector 906 is weak, there is a problem that the amount of change of the light X3 with respect to the change of the refractive index of the sample liquid G is small (specific sensitivity is small). SUMMARY OF THE INVENTION It is an object of the present invention to provide a contact type optical fiber sensor which can be made extremely small, does not require a highly sensitive detector, and has a high specific sensitivity.

[0005]

According to a first aspect of the present invention, there is provided a contact type light measuring device for measuring a degree of light propagating through an optical fiber leaking from a contact portion with an object according to a refractive index of the object. In the fiber sensor, a light source side optical fiber for guiding light from the light source side to the contact portion, and a detector side optical fiber for guiding light from the contact portion to the detector side, one end of the light source side optical fiber and the One end of the optical fiber on the detector side is melted and integrated at the contact portion, and the tapered shape is formed .
The optical fiber on the light source side is the polarization maintaining optical fiber on the light source side.
And the single-mode optical fiber on the contact part side
Provided is a contact-type optical fiber sensor characterized in that it is manufactured .

According to a second aspect, the present invention relates to a contact-type optical fiber sensor for measuring the degree of leakage of light propagating through an optical fiber from a contact portion with an object in accordance with the refractive index of the object. A light source side optical fiber for guiding light from the contact portion to the contact portion, a detector side optical fiber for guiding light from the contact portion to the detector side, and sandwiched between the light source side optical fiber and the detector side optical fiber. comprising at least one dummy optical fiber, and one end of the one end and the dummy optical fiber of the detector-side optical fiber and one end of the light source side optical fiber melted integrated at the contact portion, and the tapered shape, the Optical fiber on the light source side preserves the polarization plane on the light source side
The optical fiber and the single-mode optical fiber
Provided is a contact-type optical fiber sensor having a fused structure .

[0007]

[0008]

According to a third aspect of the present invention, in the contact-type optical fiber sensor having the above-described structure, each of the optical fibers is inserted into a glass capillary, and the glass capillary is inserted into a stainless steel tube. Provided is a contact-type optical fiber sensor, wherein an optical connector is provided at the other end of the detector-side optical fiber.

According to a fourth aspect, the present invention provides a method for contacting a contact portion of a first contact-type optical fiber sensor upstream of a flow of a liquid, and contacting a contact portion of a second contact-type optical fiber sensor with a flow of a liquid. and the portion where the refractive index of the liquid changes is the first contact.
From the contact portion of the tactile optical fiber sensor, a second contact type optical fiber
The relationship between the output of the first contact-type optical fiber sensor and the output of the second contact-type optical fiber sensor when reaching the contact portion of the iva sensor is determined, and based on the relationship, the flow rate or flow rate or the relationship between both contact portions is determined. Provided is a method for measuring a flow, characterized by measuring a flow path distance.

In a fifth aspect , the present invention provides a first contact-type optical fiber sensor having a contact portion contacting upstream of a liquid flow and a second contact type optical fiber sensor having a contact portion contacting downstream of a liquid flow. Contact type optical fiber sensor and liquid refractive index changing part
The second portion is moved from the contact portion of the first contact type optical fiber sensor to the second portion.
The flow velocity or the flow rate or the flow between the contact portions based on the relationship between the output of the first contact type optical fiber sensor and the output of the second contact type optical fiber sensor when reaching the contact portion of the contact type optical fiber sensor. A flow measuring device, comprising: an arithmetic processing means for measuring a road distance.

[0012]

In the contact type optical fiber sensor according to the first aspect, instead of bending one optical fiber, two optical fibers of a light source side optical fiber and a detector side optical fiber are arranged and one end of each other is melted. It was unified, and its tip was extended in a tapered shape, and this portion was used as a contact portion. For this reason, the size of the contact portion can be made extremely small (it is possible to make the diameter twice or less the diameter of the optical fiber). Further, since the leaked portion is small, the light reaching the detector is strong, and a high-sensitivity detector is not required. Furthermore, since the light reaching the detector is strong, the amount of change in the light with respect to the change in the refractive index of the subject is large (the specific sensitivity is large), so that even a small change in the refractive index can be detected. Furthermore, a light source side optical fiber
The polarization-maintaining optical fiber on the light source side and the
A structure fused with a multimode optical fiber was used. Polarization plane
In storage optical fiber, boron is contained in the cladding near the core.
Due to the doping, boron expands into the core when heated.
Scattering, lowering the refractive index of the core. That is, the contact part
Also, if the polarization maintaining optical fiber is
Performance deteriorates when heated for However, contact
Because a single mode optical fiber was used for the contact part,
Such deterioration in performance can be prevented.

In the contact type optical fiber sensor according to the second aspect, one optical fiber is not bent, but is bent.
Three or more optical fibers of a light source side optical fiber, a detector side optical fiber, and at least one dummy optical fiber are arranged side by side (however, one end of the dummy optical fiber is closer than one end of the light source side optical fiber and the detector side optical fiber). It is preferable to have a slightly retracted positional relationship), and one end of each was melted and integrated, and the tip was extended in a tapered shape, and this portion was used as a contact portion. For this reason, the size of the contact portion can be extremely reduced (it becomes possible to reduce the diameter of the optical fiber to several or less). In addition, since the light leaking portion is small and the optical path from the light source side optical fiber to the detector side optical fiber is moderately bent, the light reaching the detector is strong, and a highly sensitive detector is not required. A detector will be enough. Furthermore, since the light reaching the detector is strong, the amount of change in the light with respect to the change in the refractive index of the subject is large (the specific sensitivity is large), so that even a small change in the refractive index can be detected. In addition, light source side optical fiber
The polarization maintaining fiber on the source side and the single mode
A structure in which a fused optical fiber was used. Polarization-maintaining light
In a fiber, boron is doped in the cladding near the core
When heated, boron diffuses into the core,
It lowers the refractive index of the core. That is, the contact part is also polarized
When the surface preserving optical fiber is used, the contact part is fused and integrated.
, The performance deteriorates. However, in the contact area
Used a single-mode optical fiber.
Performance deterioration can be prevented.

[0014]

[0015]

In the contact-type optical fiber sensor according to the third aspect , the optical fiber is inserted into a glass capillary, the glass capillary is inserted into a stainless steel tube, and the other ends of the light source side optical fiber and the detector side optical fiber. The optical connector was provided with an optical connector. For this reason, mechanical strength and chemical stability are improved, and insertion into a living body becomes possible. In addition, handling becomes easy.

In the flow measuring method according to the fourth aspect and the flow measuring device according to the fifth aspect , the contact portion of the first contact type optical fiber sensor is brought into contact with the upstream of the flow, and the second contact type optical fiber sensor is contacted. The contact portion of the fiber sensor is contacted downstream of the flow, and the relationship between the output of the first contact type optical fiber sensor and the output of the second contact type optical fiber sensor is determined. Then, the flow velocity or the flow rate or the flow path distance between both contact portions is measured based on the relationship. That is, the delay time τ can be determined from the relationship between the two outputs.
Is known, the flow velocity V can be measured by V = L / τ. Furthermore, if the flow path cross section S is also known, Q = S ·
The flow rate Q can be measured by L / τ. On the other hand, if the flow velocity V or the flow rate Q is known, by any of the above equations,
The flow path distance L can be measured.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the embodiments shown in the drawings. It should be noted that the present invention is not limited by this. FIG. 1 is a configuration diagram of a contact type optical fiber sensor 100 according to a first embodiment of the present invention. The contact type optical fiber sensor 100 includes a light source 1 including a semiconductor laser or a light emitting diode, a light source side optical connector 2, and a light source side optical fiber 1.
Light source side optical fiber cable 3 including
And a detector-side optical fiber cable 4 including a detector-side optical fiber 13, a detector-side optical connector 5, and a detector 6 composed of a phototransistor or a photodiode. The sensor section 10 has a contact section 10a at the tip and a glass capillary 15;
And a stainless steel tube 16.

As shown in FIG. 2, another optical fiber 11 on the light source side is fused to the tip of the optical fiber 12 on the light source side. The light source side optical fiber 12 is a silica-based polarization maintaining optical fiber, for example, a PANDA type (Polariz).
ation Maintaining and Reducing Fiber). The mode field diameter is, for example, 10 μm,
The outer diameter is, for example, 125 μm. 12a is a core,
12b is a clad. The light source side optical fiber 11
Is a silica-based single mode optical fiber. The mode field diameter is, for example, 10 μm, and the outer diameter is, for example, 125 μm. 11a is a core and 11b is a clad. The detector-side optical fiber 13 is a silica-based single mode optical fiber. The mode field diameter is, for example, 10 μm, and the outer diameter is, for example, 125 μm.
m. 13a is a core, and 13b is a clad. The dummy optical fiber 14 is a silica-based single mode optical fiber. Its outer diameter is, for example, 125 μm.

As shown in FIGS. 2 and 3, the sensor section 10 has a light source-side optical fiber 11 and a detector-side optical fiber 13 arranged at one end thereof and a dummy optical fiber 14 therebetween. In the state where one end of the dummy optical fiber 14 is drawn in from one end of each of the light source side optical fiber 11 and the detector side optical fiber 13, each end is heated, melted and integrated, and formed into a spherical and tapered tip. Each of the optical fibers 1 is extended to form a contact portion 10a.
1, 12 and 13 are inserted into a glass capillary 15 and the glass capillary 15 is inserted into a stainless steel tube 16. The diameter of the light leaking part of the contact part 10a is, for example, 100 μm. As shown in FIG. 3C, an adhesive 17 is filled between each of the optical fibers 12, 13, and 14 and the glass capillary 15. The glass capillary 15 and the stainless steel tube 16 are also integrated by bonding.

As shown in FIG. 4, light X1 from light source 1
From the core 11a of the light source side optical fiber 11 to the contact portion 10
a, and is reflected and refracted by the contact portion 10a,
X2 that leaks to the core 1 of the detector-side optical fiber 13
It is split into light X3 entering 3a. Since the degree of the light X2 that leaks depends on the refractive index of the sample liquid G, the refractive index of the sample liquid G can be known by measuring the intensity of the light X3 with the detector 6. When the contact portion 10a comes into contact with air, the light X2 hardly leaks. Therefore, if the intensity of the light X3 is measured by the detector 6, it is determined whether the liquid level of the subject liquid G is higher or lower than the contact portion 10a. You can know.

According to the above-mentioned contact type optical fiber sensor 100, the following effects can be obtained. The size of the contact portion 10a can be made extremely small. As a result, for example, blood flowing through a blood vessel can be measured. Since the optical fibers 11, 12, and 13 are not bent at a small curvature, the optical loss does not increase when the optical fibers are bent at a small curvature. Further, since the dummy optical fiber 14 is interposed, the optical path from the light source side optical fiber 11 to the detector side optical fiber 13 is gradually bent, so that an increase in optical loss does not occur. As a result, the intensity of the light X3 is increased, and it is possible to sufficiently detect the light X3 with the detector 6 which is a popular product. Since the light reaching the detector 6 is strong, the amount of change in the light X3 with respect to the change in the refractive index of the subject liquid G is large, and even a slight change in the refractive index can be detected. Since the light source side optical fiber 12 is composed of the polarization maintaining optical fiber, the polarization direction does not fluctuate, the degree of light leakage from the contact portion 10a becomes stable, and a stable detection result is obtained. Since the single-mode optical fiber 11 is used for the contact portion 10a, deterioration in performance due to heating can be prevented. Optical fibers 11, 12, and 13 are connected to a glass capillary 15
And insert the glass capillary 15 into the stainless steel tube 1
6, and the optical connectors 2 and 3 are provided at the other ends of the light source side optical fiber 12 and the detector side optical fiber 13, respectively, so that the mechanical strength and chemical stability are improved and handling is improved. It will be easier.

(Experimental Example 1) Output 1 mW as the light source 1
The light X3 was measured using the laser light source described above and water, ethyl alcohol, and an aqueous solution of sodium chloride as the test liquid G. Next, the type of the test liquid G, the refractive index, and the output (nW) are shown. Water 1.3330, 5.8 1 wt% saline solution (close to living body), 1.3348, 5.2 2 wt% saline solution, 1.3366, 4.5 3 wt% saline solution, 3383, 4.0 FIG. 5 shows a graph obtained by curve fitting the above measurement results. It shows a linear characteristic, indicating that even a slight change in the refractive index can be detected.

FIG. 6 shows a flow measuring apparatus 200 according to a second embodiment of the present invention.
FIG. Light source 21 and optical coupler 22
The light source-side optical cable 23A, the sensor unit 10A, the detector-side optical cable 24A, and the detector 26A constitute a first contact-type optical fiber sensor, and contact the upstream of the flow of the subject liquid G. 10Aa. The light source 21, the optical coupler 22, the light source side optical cable 23B, the sensor unit 10B, the detector side optical cable 24B, and the detector 26B constitute a second contact type optical fiber sensor. It has a contact portion 10Ba that contacts the downstream of the flow of the sample liquid G. The sensor unit 1
Reference numerals 0A and 10B have the same configuration as the sensor unit 10 in the contact type optical fiber sensor 100 of the first embodiment.

The arithmetic processor 27 is provided with the detectors 26A, 2
6B are read, the refractive index of the sample liquid G is obtained from the output values and a given calibration curve, and the refractive index is output to the printer 28. If the relationship between the refractive index and the concentration of the sample liquid G is given, the concentration of the sample liquid G is output to the printer 28. In addition, the arithmetic processing unit 27
The outputs of the detectors 26A and 26B are read, and a cross-correlation calculation of both outputs is performed to calculate a delay time τ. When the distance L between the contact portions 10Aa and 10Ba and the flow path cross section S are given, the flow velocity V and the flow rate Q are calculated by V = L / τ Q = S · V, and the flow velocity V and the flow rate Print Q on printer 28. On the other hand, when the flow velocity V is given, the distance L between the contact portions 10Aa and 10Ba is calculated by L = V · τ,
The distance L is output to the printer 28. In FIG. 6, the test liquid G is a mixture of the solutions S1 and S2 having different concentrations. The solution S1 flows constantly from the tank W to the pipe P, while the solution S2 is unsteadily injected into the pipe P from the syringe J, thereby changing the refractive index of the subject liquid G (rise / fall, peak). Waveform) and the detector 26
The correlation between the outputs of A and 26B becomes clear. If the change in the refractive index of the sample liquid G (rising / falling, peak waveform) is relatively clear, the delay time τ is calculated from the difference between the rising / falling times of both outputs instead of the cross-correlation calculation. Can be obtained (rising / falling method). Further, the delay time τ can be obtained from the difference between the peak times of both outputs (peak method). Further, the delay time τ can be obtained from the difference between the centroid times of the peak waveforms of both outputs (centroid method).

According to the flow measuring device 200 described above, the refractive index of the flow and the flow velocity V, the flow rate Q, or the flow path distance L can be suitably measured using the contact type optical fiber sensor.

(Experimental example 2) Water (refractive index: 1.3330) is supplied from the tank W to the pipe P at a constant flow rate without inserting the syringe J into the pipe P, and the outputs Ia and Ib of the detectors 26A and 26B are observed. did. Further, from the tank W, saline solutions having different concentrations (1 wt% / refractive index 1.3348-3 wt% /
Refractive index 1.3383) was passed through the pipe P at a constant flow rate, and the outputs Ia and Ib of the detectors 26A and 26B were observed. FIG.
Shows a graph of the observation results. Both outputs Ia and Ib show linear characteristics, and it can be seen that even a slight change in the refractive index can be detected.

(Experimental Example 3) The contact portions 10Aa and 10Ba were inserted into the pipe P at an interval L = 500 mm. Pipe P
Used a silicon tube having an inner diameter of 1.5 mm. In addition, a 1 wt% saline solution S1 (refractive index 1.33) is placed in the tank W.
48), and the saline S1 was flowed through the pipe P at 3.3 ml / min. On the other hand, insert the syringe J into the pipe P,
2 wt% at a flow rate of 0.1 ml / min from upstream of the contact part 10Aa
% Saline S2 was injected for only 10 seconds, and the detectors 26A,
Outputs Ia and Ib of 26B were observed. FIG. 8 shows the output I
3 shows graphs of waveforms a and Ib. In the processor 27, the flow rate and the error were obtained by the falling method, the peak method, and the center of gravity method. The flow rate Q1 by the falling method was 4.8 ml / min, and the error was + 45%. Flow Q2 = 5.9 by peak method
ml / min, error = + 79%. The flow rate Q3 by the centroid method was 3.5 ml / min, and the error was + 6.1%. From this result, it is understood that the flow rate can be obtained with a small error by the centroid method.

(Experimental Example 4) The contact portions 10Aa and 10Ba were inserted into the pipe P at an interval L = 500 mm. Pipe P
Used a silicon tube having an inner diameter of 1.5 mm. In addition, a 1 wt% saline solution S1 (refractive index 1.33) is placed in the tank W.
48), and the saline S1 was flowed through the pipe P at a constant flow rate. On the other hand, a syringe J is inserted into the pipe P, and a 2 wt% saline solution S2 at a flow rate q is injected from the upstream of the contact portion 10Aa for a time T, and the outputs Ia, I of the detectors 26A, 26B are injected.
b was observed. Further, the flow rate Q of the subject liquid G was actually measured with a measuring cylinder. In the arithmetic processor 27, the flow rate Q1 and the error were obtained by the falling method. In addition, the flow rate Q
2 and the error were determined. Further, the flow rate Q3 and the error were obtained by the centroid method. FIG. 9 shows a table of the observation results. In this experimental example, the best result was obtained when the injection amount q was small and the injection time T was short, and the centroid method was used.

(Experimental Example 5) The contact portions 10Aa and 10Ba were inserted into the pipe P at an interval L = 500 mm. Pipe P
Used a silicon tube having an inner diameter of 1.5 mm. In addition, a 1 wt% saline solution S1 (refractive index 1.33) is placed in the tank W.
48), and the saline S1 was flowed through the pipe P at 3.3 ml / min. On the other hand, the position where the syringe J is inserted into the pipe P is set to 100 mm, 500 m upstream of the contact portion 10Aa.
m and 1000 mm, and 2 wt% saline S2 was injected at a flow rate of 0.1 ml / min for 5 seconds and 10 seconds, and the outputs Ia and Ib of the detectors 26A and 26B were observed. As a result, it was found that when the injection time was 5 seconds, it did not depend on the injection position. On the other hand, when the injection time was 10 seconds, it was found that the error increased as the injection position became shorter.

[0031]

According to the contact type optical fiber sensor of the present invention, the size of the contact portion can be extremely reduced. As a result, for example, blood flowing through a blood vessel can be measured. In addition, since the optical fiber is not bent at a small curvature, the optical loss does not increase, and it is possible to sufficiently detect the optical fiber even with a widely used detector. In addition, since the light reaching the detector is strong, the amount of change in the output of the detector with respect to the change in the refractive index of the subject becomes large, and even a slight change in the refractive index can be detected. Further, according to the flow measuring method and apparatus of the present invention, it is possible to suitably measure the refractive index of the flow and the flow velocity or the flow rate or the flow path distance using the contact type optical fiber sensor.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a contact type optical fiber sensor according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a sensor section of the contact type optical fiber sensor of FIG.

3A is a sectional view taken along line AA of FIG. 2, FIG. 3B is a sectional view taken along line BB of FIG. 2, and FIG. 3C is a sectional view taken along line CC of FIG.

FIG. 4 is an explanatory view of a contact portion of the contact type optical fiber sensor of FIG. 1;

FIG. 5 is a graph showing measurement results of Experimental Example 1.

FIG. 6 is a configuration diagram of a flow measuring device according to a second embodiment of the present invention.

FIG. 7 is a graph showing measurement results of Experimental Example 2.

FIG. 8 is a graph showing measurement results of Experimental Example 3.

FIG. 9 is a table of measurement results of Experimental Example 4.

FIG. 10 is a configuration diagram showing an example of a conventional contact optical fiber sensor.

FIG. 11 is an explanatory diagram of a contact portion of the contact type optical fiber sensor of FIG. 9;

[Explanation of symbols]

 1, 21 light source 2 light source side optical connector 3, 23A, 23B light source side optical cable 4, 24A, 24B detector side optical cable 5 detector side optical connector 6, 26A, 26B detector 10, 10A, 10B sensor unit 10a, 10Aa, 10Ba Contact part 11,12 Light source side optical fiber 11a, 12a Core 11b, 12b clad 13 Detector side optical fiber 13a Core 13b clad 14 Dummy optical fiber 15 Glass capillary 16 Stainless steel tube 17 Adhesive 22 Optical coupler 27 Arithmetic processor 100 Contact Type optical fiber sensor 200 Flow measuring device

Continuation of the front page (56) References JP-A-57-39317 (JP, A) JP-A-58-215561 (JP, A) JP-A-1-248040 (JP, A) JP-A-57-74617 (JP) , A) Fully open 1986-123936 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01D 21/00 G01F 1/00 G01F 1/708 G01N 21/41 G01P 5/20

Claims (5)

(57) [Claims] 1. A contact-type optical fiber sensor for measuring the degree of light leaking from a contact portion with an object according to a refractive index of the object, wherein the light propagating through the optical fiber is guided from the light source side to the contact portion. Light source side optical fiber,
A detector-side optical fiber that guides light from the contact portion to the detector side, and one end of the light source-side optical fiber and one end of the detector-side optical fiber are melted and integrated at the contact portion to form a tapered shape. The light source side optical fiber is
Polarization-maintaining optical fiber and single-mode light on the contact side
A contact type optical fiber sensor having a structure in which a fiber is fused . 2. A contact-type optical fiber sensor for measuring the degree of leakage of light propagating through an optical fiber from a contact portion with a subject according to the refractive index of the subject, wherein the light is guided from the light source side to the contact portion. Light source side optical fiber,
A detector-side optical fiber for guiding light from the contact portion to a detector side, and at least one dummy optical fiber sandwiched between the light-source-side optical fiber and the detector-side optical fiber; One end of the side optical fiber, one end of the detector-side optical fiber, and one end of the dummy optical fiber are melted and integrated at the contact portion, and are tapered ,
The optical fiber on the light source side is different from the polarization-maintaining optical fiber on the light source side.
Structure fused to single-mode optical fiber on contact side
Contact optical fiber sensor, characterized in that the at. 3. The contact type according to claim 1 or 2.
In the optical fiber sensor, each of the optical fibers is made of glass.
Insert the glass capillary into a capillary
Light source side optical fiber and the detector
A contact type optical fiber sensor, wherein an optical connector is provided at each of the other ends of the side optical fibers . 4. A contact portion of a first contact type optical fiber sensor.
Is contacted upstream of the liquid flow, and a second contact type optical fiber
The contact part of the sensor contacts the liquid flow downstream,
The changing part of the bending ratio is the contact of the first contact type optical fiber sensor.
From the part to the contact part of the second contact type optical fiber sensor
Output from the first contact type optical fiber sensor and the second contact type.
Find the relationship between the outputs of the tactile optical fiber sensor and find the relationship.
Flow rate or flow rate or flow path distance between both contact parts based on
Flow Re methods of measurements and measuring a. 5. A method according to claim 1, further comprising a contact portion contacting upstream of the liquid flow.
One contact-type optical fiber sensor and one downstream of the liquid flow
Contact type optical fiber sensor having a contact portion for contacting the optical fiber
And the portion where the refractive index of the liquid changes is the first contact type optical fiber.
The contact of the second contact type optical fiber sensor from the contact portion of the sensor
Output from the first contact-type optical fiber sensor when reaching the contact part
Based on the relationship between the force and the output of the second contact-type optical fiber sensor.
The flow rate or flow rate or the flow path distance between the two contacts.
Characterized by comprising arithmetic processing means for determining
Measuring device.