JPH0718792B2 - Optical salt particle deposition amount detection sensor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sensor for detecting the amount of salt particles attached by an optical method.

[Prior Art] Conventionally, there are the following techniques for detecting the amount of salt.

The first is analysis by resistance measurement, in which the resistance of a NaCl-containing solution is measured and the amount of salt is obtained from a conversion table. The second is optical analysis such as X-ray diffraction, in which a solid sample containing NaCl is irradiated with X-rays, and the diffraction line intensity from the surface on which the single component crystal is present is measured and quantitatively measured. To detect. The third is by a refractometer method, in which the content of each component in a mixed solution of NaCl and KCl is evaluated by a refractometer to quantitatively measure it.

[Problems to be Solved by the Invention] However, the above-mentioned conventional techniques have the following problems.

(1) It is necessary to prepare various types of measuring equipment.

(2) A change in salt content with time cannot be detected.

(3) Real-time detection is not possible.

(4) Measurement requires skill and takes time.

(5) It is difficult to measure in a bad environment such as a high voltage or a high magnetic field, or a dangerous environment.

(6) The measuring system becomes bulky and expensive.

(7) The refractive index method can be measured only in a solution whose refractive index changes depending on the concentration of the contained solution.

The object of the present invention is to solve the above-mentioned problems of the prior art,
An object of the present invention is to provide a sensor that detects the amount of salt particles that is excellent in wearability and responsiveness.

[Means for Solving the Problems] In the optical salt particle deposition amount detection sensor of the present invention, a groove is linearly formed on a quartz substrate, and an adhesive layer having a refractive index lower than that of quartz is interposed along the groove. The quartz optical waveguide is embedded and integrated with its surface exposed, and the transmitted light that enters from one end of the optical waveguide and exits from the other end is received by the light receiver, and the quartz exposed from the change in transmitted light intensity is exposed. The amount of salt particles adhering to the surface of the optical waveguide is calculated. In this case, it is preferable to polish the surface of the optical waveguide that is embedded and exposed on the quartz substrate to form a flat plate shape.

As another form, the outer periphery of the optical waveguide is exposed by coating only a resin having the same refractive index as that of the optical waveguide, and the transmitted light intensity change when salt particles adhere to the exposed resin surface. It is also possible to adopt a configuration in which the amount of salt particles is obtained.

[Operation] Since the exposed surface of the quartz optical waveguide (clad) is covered with air and the other part is covered with a low-refractive-index resin, if no salt particles adhere to the exposed surface, The propagating light reaches the other end of the optical waveguide with almost no loss. However, when salt particles adhere to the exposed surface of the optical waveguide, most of the propagating light is radiated outside, and most of the reflected light at the core-clad interface becomes Fresnel reflection, resulting in the emission end. Detected as radiation loss. When the amount of salt particles attached increases, the number of radiation modes of propagating light also increases, which allows the amount of salt particles attached to be detected if the change in transmitted light intensity is monitored.

If the surface of the optical waveguide exposed and embedded on the quartz substrate is polished into a flat plate shape, the adhesion state of salt particles attached to the substrate does not change before and after the waveguide is embedded.
The accuracy of detecting the amount of deposited salt particles is significantly improved.

In the case where the outer periphery of the optical waveguide is exposed by coating only the resin with the same refractive index as the optical waveguide, if salt particles adhere to the exposed resin surface, the propagating light leaks to the outside and radiation loss occurs. Becomes Since the radiation loss increases as the amount of salt particles attached increases, the amount of salt particles attached can be quantitatively detected from the change in transmitted light intensity. Further, since the optical waveguide is protected by the resin, its mechanical strength is increased, and the long-term stability of the sensor part is significantly improved.

[Examples] The present invention will be described below with reference to the illustrated examples.

FIG. 1 is a sectional view of the sensor unit 6 of the salt particle deposition amount detection sensor shown in FIG.

The sensor unit 6 shown in FIG. 1 includes a quartz optical waveguide 1, a quartz substrate 2,
And resin 3. This is because a groove having an arcuate cross section is formed linearly in the plane direction of the quartz substrate 2 on a flat plate-shaped quartz substrate 2, and a quartz optical waveguide 1 having a groove diameter smaller than the groove diameter is formed in the groove. This is a structure in which the embedded surface is exposed through the resin 3 having a value. Embedded optical waveguide 1
Has its surface polished to the same height as the quartz substrate 2 and has a flat plate shape as a whole.

By thus forming a flat plate shape, the distribution state of the amount of salt particles attached to the substrate 2 does not change before and after the waveguide 1 is embedded, and the accuracy of detecting the amount of salt particles attached is significantly improved. . Further, since the substrate 2 used is small, the range of application is greatly expanded.

In the method of manufacturing the sensor unit 6, first, a groove for embedding a part of the quartz optical waveguide 1 is formed on the quartz substrate 2, the quartz optical waveguide 1 is placed there, and a resin is provided between the substrate 2 and the waveguide 1. Inject 3 and glue. Quartz optical waveguide 1 after bonding
Alternatively, both the quartz substrate 2 and the quartz optical waveguide 1 are mechanically polished so that their cross sections are aligned with the substrate surface and the optical waveguide surface.

Next, the salinity detection principle of the above sensor will be described.

When light is incident from one end of the optical waveguide (core) 1, the exposed surface portion of the periphery (clad) of the optical waveguide 1 is air and the other portion is covered with the low refractive resin 3.
The propagating light is totally reflected at the interface between the core and the clad, and reaches the other end of the optical waveguide 1 with almost no loss.

However, when salt particles adhere to the exposed surface of the optical waveguide 1, most of the propagating light is radiated to the outside at that portion, and most of the reflected light at the core-clad interface becomes Fresnel reflection, resulting in the emission end. Is detected as radiation loss. As the amount of salt particles attached increases, the number of radiation modes of propagating light also increases, which allows the amount of salt particles attached to be detected if the change in transmitted light intensity is monitored.

FIG. 2 shows a sensor for detecting the amount of deposited salt particles, which is configured by using the sensor 6 having the above configuration.

Light emitted from the light source 4 is branched by the branch path 5, and a part thereof is
As a reference light, it is guided by the optical fiber 9 to the first light receiver 7,
The output signal is guided to one input terminal of the calculator 8.
The other part is guided to the sensor section 6 by the optical fiber 9 and, after undergoing a loss change due to the effect of adhering salt particles, is guided to the second light receiver 11 as measurement light, the output signal of which is output from the calculator 8. It is introduced to the other input terminal.

The transmitted light intensity obtained from the first light receiver 7 is the same as the sensor unit 6
The transmitted light intensity obtained from the second light receivers 7 and 11 is almost constant regardless of the above, but the degree of light loss received by passing through the sensor unit 6, that is, the presence or absence of salt particles adhering and the salt particles It corresponds to the adhesion amount. Therefore, it is possible to know the presence or absence of salt particle adhesion and the amount of salt particle adhesion from the difference between them and the degree thereof.

Therefore, the calculator 8 divides the transmitted light intensity signal obtained from the second light receiver 11 by the transmitted light intensity signal obtained from the first light receiver 7, and presets the calculation result. Calculate the actual amount of attached salt particles by adding it to the calculated formula.

As described above, by using the quartz optical waveguide 1 and the quartz substrate 2 for the sensor unit 6, it is possible to perform detection under the environment of high voltage and high magnetic field. From this viewpoint, the material of the optical waveguide 1 and the substrate 2 may be any non-metal, and the optical waveguide 1 may be an optical fiber. Further, a simple device such as a light source, a sensor unit, a light receiver, a calculator, and a branching device is sufficient for detecting the amount of salt particles attached, and the sensor can be inexpensively and easily configured.

Although the sensor unit 6 is formed in a flat plate shape in the above-described embodiment, when the sensor unit 6 is installed in an uneven place, a shape, a substrate, and an optical waveguide suitable for the installation place can be used. Further, by increasing the number of the optical waveguides 1 and arranging them in parallel in a plane, for example, a wider area can be used as the sensor region.

Next, the embodiment shown in FIGS. 3 and 4 will be described.

As shown in FIG. 3, the sensor section 26 of this embodiment has a structure in which the optical waveguide 21 having a circular cross section is covered and exposed only by the resin 22 having the same refractive index as the optical waveguide 21. With this configuration, the light propagating through the portion of the optical waveguide 21 is completely transmitted through the portion of the resin 22, and is repeatedly reflected at the interface between the resin 22 and the outside air.
For this reason, when the salt particles adhere to the surface of the resin 22, light leaks and an optical loss change occurs.

The resin 22 that covers the outer periphery of the optical waveguide 21 increases the mechanical strength of the optical waveguide 21 and significantly improves the long-term stability of the sensor unit 26. The resin 22 needs to have the same refractive index as the optical waveguide 21 (n = 1.458 for a quartz rod), and for example, an acrylate silicone resin is used.

The thickness of the coating resin 22 is limited for the following reasons. In the case of this embodiment, the thickness of the resin 22 (thickness at the interface between the optical waveguide and the resin) is about 200 μm or less when using a quartz rod having a diameter of 1 mmφ. The reason is that the thickness of the resin 22 is 2
When the thickness is more than 00 μm, the propagation light is lost due to the interface reflection between the resin 22 and the optical waveguide 21, the resin 22 and the air, and the absorption in the resin 22, which makes it difficult to detect the amount of salt particles. Because there are things.

The structure of the salt particle deposition amount detection sensor using the sensor 26 is as shown in FIG. 4, which is essentially the same as that of FIG.

The light emitted from the light source 4 passes through the optical fiber 9 and is branched by the optical branching path 5. One of the light beams is directly transmitted to the optical receiver 7 by the optical fiber 9 and is supplied to the calculator 8 as a reference signal of the light source light intensity due to temperature fluctuation. Is entered. The other light branched by the light branching path 5 is transmitted to the sensor section 5 by the optical fiber 9, where it is subjected to a change in light intensity due to the amount of salt particles attached to the light receiver 11
Is transmitted by the optical fiber 9 to the arithmetic unit 8 and is input to the arithmetic unit 8 as a sensor section signal.

If sodium chloride (clad) particles having a refractive index of 1.54 adhere to the resin surface of the sensor unit 26 (core; refractive index 1.458), the propagating light leaks to the outside at the interface, resulting in radiation loss. Since the radiation loss increases as the sodium chloride particles adhere to the core, the amount of salt particles adhering to the core can be quantitatively detected by monitoring the change in transmitted light intensity.

By dividing the signals of the light receiver 7 and the light receiver 11 in the calculator 8, it is possible to eliminate the influence of the fluctuation of the output light of the light source 4 due to the temperature.

The shape of the sensor portions 16 and 26 is preferably a shape corresponding to the shape of the detection place where the sensor portions 16 and 26 should be arranged. this is,
This is because the distribution state of the salt particles adhering to the sensor portion differs due to the difference in the shape of the sensor portion, and this may cause a detection error. Further, depending on the shape of the counterpart member on which the sensor unit is to be mounted, the ease of mounting the sensor unit should be considered.

FIG. 5 shows an example in which the surface of the resin 22 is processed to be flat so that the state of adhering salt particles is the same as the detection location (flat surface) when the detection location is flat. In this way, if the same planar shape as that of the detection location is adopted, the state in which the salt particles adhere will be the same, and the device of the sensor section will be easy.

[Advantages of the Invention] Since the present invention is configured as described above, it has the following advantages.

Since the configuration is such that the quartz optical waveguide is embedded on the quartz substrate in a state where the surface is exposed, the detection unit is compact and measurement in a wide range is possible. Since the sensor unit is made of an insulator, it is possible to perform measurement under a high electric field and a high magnetic field, for example, to detect salt particle adhesion to an insulator of a transmission line facility.
Further, it is possible to detect in real time and to detect the change with time of the amount of salt particles.

If the surface of the optical waveguide embedded on the quartz substrate is polished into a flat plate shape, the salt particles will adhere evenly, so the measurement error due to the difference in the salt particle adhesion status will be minimized, and the accuracy of detection of the amount of salt particle adhesion will be greatly improved. Improve to.

In the case of a structure in which only the resin having the same refractive index as the quartz optical waveguide is coated and exposed on the outer periphery of the quartz optical waveguide, the quartz optical waveguide is protected by the resin, and its mechanical strength increases,
The long-term stability of the sensor part is greatly improved. Since the shape of the resin coating the optical waveguide can be easily changed, the resin section can be used as a sensor unit according to the shape of the object to be measured, and the ease of mounting is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a sensor unit in an embodiment of the present invention, FIG. 2 is a configuration diagram of the entire optical salt particle deposition amount detection sensor using the sensor unit of FIG. 1, and FIG. 4 is a cross-sectional view of the sensor section in the embodiment of FIG. 4, FIG. 4 is a configuration diagram of a salt particle adhesion amount detection sensor using the sensor section of FIG. 3, and FIG. 5 is a diagram showing a modification of FIG. In the figure, 1 is a quartz optical waveguide, 2 is a quartz substrate, 3 is resin, 4
Is a light source, 5 is a light branching device, 6 is a sensor unit, 7 is a light receiver, 8
Is an arithmetic unit, 9 is an optical fiber, 10 is a connecting cable, 11 is a light receiver, 21 is an optical waveguide, 22 is resin, and 26 is a sensor section.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 61-186836 (JP, A) JP 62-28641 (JP, A) JP 59-206746 (JP, A) JP 62- 235546 (JP, A) Japanese Patent Publication Sho 50-17147 (JP, B1)

Claims (3)

[Claims] 1. A quartz substrate is linearly formed with a groove, and a quartz optical waveguide is embedded and integrated along the groove with an adhesive layer having a lower refractive index than quartz, with its surface exposed.
Light which is characterized in that a transmitted light which is incident from one end of the optical waveguide and emitted from the other end is received by a light receiver, and the amount of salt particles adhering to the exposed surface of the quartz optical waveguide is obtained from the change of the transmitted light intensity. Sensor for detecting the amount of attached salt particles. 2. An optical salt particle deposition amount detection sensor according to claim 1, wherein the surface of the optical waveguide which is embedded and exposed on the quartz substrate is polished into a flat plate shape. 3. The change in transmitted light intensity when salt particles adhere to the exposed resin surface by coating only the resin having the same refractive index as that of the optical waveguide on the outer periphery of the optical waveguide to expose the resin. An optical salt particle deposition amount detection sensor, characterized in that the amount of salt particles is obtained.