JPH0345783B2 - - Google Patents
Info
- Publication number
- JPH0345783B2 JPH0345783B2 JP59064215A JP6421584A JPH0345783B2 JP H0345783 B2 JPH0345783 B2 JP H0345783B2 JP 59064215 A JP59064215 A JP 59064215A JP 6421584 A JP6421584 A JP 6421584A JP H0345783 B2 JPH0345783 B2 JP H0345783B2
- Authority
- JP
- Japan
- Prior art keywords
- coating layer
- optical waveguide
- substrate
- refractive index
- oil
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000011247 coating layer Substances 0.000 claims description 22
- 230000003287 optical effect Effects 0.000 claims description 19
- 239000000758 substrate Substances 0.000 claims description 16
- 239000007788 liquid Substances 0.000 claims description 15
- 230000008595 infiltration Effects 0.000 claims 2
- 238000001764 infiltration Methods 0.000 claims 2
- 230000001902 propagating effect Effects 0.000 claims 1
- 239000013307 optical fiber Substances 0.000 description 22
- 230000007423 decrease Effects 0.000 description 6
- 238000005253 cladding Methods 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- 230000000644 propagated effect Effects 0.000 description 4
- 229920002050 silicone resin Polymers 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/43—Refractivity; Phase-affecting properties, e.g. optical path length by measuring critical angle
- G01N21/431—Dip refractometers, e.g. using optical fibres
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Geophysics And Detection Of Objects (AREA)
Description
【発明の詳細な説明】
本発明は、油等の液体を光学的に感知する液体
感知器に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid sensor that optically senses liquid such as oil.
最近、石油備蓄基地や石油化学プラント等で油
漏れ事故が多発しており、この様な事故を早期に
発見する為の法的規制等によつて、信頼度の高い
感知器が必要とされている。 Recently, oil leak accidents have been occurring frequently at oil storage bases, petrochemical plants, etc., and highly reliable detectors are required due to legal regulations to detect such accidents early. There is.
第１図及び第２図は、この様な感知器の１つの
従来例であるポリマクラツド光フアイバを示して
いる。このポリマクラツド光フアイバ１は、石英
から成るコア２と屈折率が石英よりも小さなシリ
コン樹脂等のポリマ（高分子材料）から成るクラ
ツド３とを有している。 1 and 2 illustrate one conventional example of such a sensor, a polymer clad optical fiber. This polymer-clad optical fiber 1 has a core 2 made of quartz and a cladding 3 made of a polymer (polymer material) such as silicone resin having a refractive index smaller than that of quartz.
油漏れが発生していない状態、つまり光フアイ
バ１に油が付着していない状態では、光フアイバ
１の一端からこの光フアイバ１内へ入射した光i1
は、第１図に示す様に、コア２とクラツド３との
界面で全反射を繰り返しながら、低損失で他端ま
で伝播する。 When there is no oil leakage, that is, when no oil is attached to the optical fiber 1, the light i 1 that enters the optical fiber 1 from one end of the optical fiber 1
As shown in FIG. 1, the light propagates to the other end with low loss while repeating total reflection at the interface between the core 2 and the cladding 3.
ところが、屈折率の大きな油が光フアイバ１に
付着してクラツド３内へ浸潤すると、クラツド３
の屈折率が高くなる。この結果、光フアイバ１内
へ入射した光i1の中には、第２図に示す様に、コ
ア２とクラツド３との界面で全反射せずに屈折
し、コア２外へ出て行く光が生じる。 However, when oil with a high refractive index adheres to the optical fiber 1 and infiltrates into the cladding 3, the cladding 3
The refractive index of As a result, some of the light i 1 that has entered the optical fiber 1 is refracted without being totally reflected at the interface between the core 2 and the cladding 3 and exits the core 2, as shown in Figure 2. Light arises.
この為に、光フアイバ１中に全反射しながら伝
播する光の量が、油の浸潤前に比べて減少する。
従つて、光フアイバ１の一端には光源を、また他
端には受光器を夫々配置して、伝播光量の変化を
監視すれば、油漏れを感知することができる。 For this reason, the amount of light that propagates into the optical fiber 1 while being totally reflected is reduced compared to before being infiltrated with oil.
Therefore, by arranging a light source at one end of the optical fiber 1 and a light receiver at the other end and monitoring changes in the amount of propagated light, oil leakage can be detected.
ところで、光フアイバ１の径は非常に小さいの
で、油漏れが発生した場所に光フアイバ１が正確
に位置していなければ、この油漏れを感知するこ
とができない。つまり、光フアイバ１では油漏れ
を言わば線状にしか感知することができない為
に、油漏れを見逃す確率が高くて、信頼度の高い
感知器とは成り得ない。 By the way, since the diameter of the optical fiber 1 is very small, the oil leak cannot be detected unless the optical fiber 1 is precisely positioned at the location where the oil leak occurs. In other words, since the optical fiber 1 can only detect oil leaks linearly, there is a high probability that oil leaks will be missed, and it cannot be a highly reliable sensor.
本発明は、この様な問題点に鑑み、広い範囲に
亘つて液体を感知することができる液体感知器を
提供することを目的としている。 In view of these problems, it is an object of the present invention to provide a liquid sensor that can sense liquid over a wide range.
以下、本発明の一実施例を第３図〜第５図を参
照しながら説明する。 An embodiment of the present invention will be described below with reference to FIGS. 3 to 5.
第３図及び第４図は、本発明の一実施例を示す
夫々斜視図及び縦断面図である。屈折率がn1であ
る透光性の基板１１中には、n1よりも大きな屈折
率n2を有する光導波路１２が形成されている。 3 and 4 are a perspective view and a longitudinal sectional view, respectively, showing an embodiment of the present invention. An optical waveguide 12 having a refractive index n 2 larger than n 1 is formed in a transparent substrate 11 having a refractive index n 1 .
光導波路１２は、その入射端１２Ａと出射端１
２Ｂとの間で２本の分岐路１２Ｃに分岐してい
る。入射端１２Ａと出射端１２Ｂとの近傍の光導
波路１２は基板１１中に完全に埋め込まれている
が、分岐路１２Ｃは基板１１の表面１１Ａに露出
している露出部１２Ｄをその略全長に亘つて有し
ている。 The optical waveguide 12 has an input end 12A and an output end 1.
2B, it branches into two branch paths 12C. The optical waveguide 12 near the input end 12A and the output end 12B is completely embedded in the substrate 11, but the branch path 12C covers almost the entire length of the exposed portion 12D exposed on the surface 11A of the substrate 11. I have it.
露出部１２Ｄとこの露出部１２Ｄに連なつてい
る表面１１Ａとは、共に被覆層１３によつて覆わ
れている。被覆層１３は、n1及びn2の何れよりも
小さな屈折率n3を有し且つ液体の浸潤が可能な材
質、例えばシリコン樹脂から成つている。 The exposed portion 12D and the surface 11A connected to the exposed portion 12D are both covered with a coating layer 13. The covering layer 13 is made of a material that has a refractive index n 3 smaller than either n 1 or n 2 and can be infiltrated with liquid, such as silicone resin.
基板１１、光導波路１２及び被覆層１３の夫々
の屈折率n1，n2，n3は、上述の様にn2＞n1＞n3と
なる様に選定されている。この為に、光導波路１
２中を伝播可能な光は、光導波路１２と基板１１
との界面に於ける臨界角θ1によつて決定される。 The refractive indices n 1 , n 2 , n 3 of the substrate 11, the optical waveguide 12, and the coating layer 13 are selected so that n 2 >n 1 >n 3 as described above. For this purpose, the optical waveguide 1
2, the light that can propagate through the optical waveguide 12 and the substrate 11
It is determined by the critical angle θ 1 at the interface with
もし、屈折率の大きな油等が被覆層１３に付着
してこの被覆層１３内へ浸潤することによつて、
n3がn1よりも大きくなると、夫々の屈折率間の関
係はn2＞n3＞n1となる。従つて、この場合に光導
波路１２中を伝播可能な光は、上述の臨界角θ1で
はなく光導波路１２と被覆層１３との界面に於け
る臨界角θ2によつて決定される。 If oil or the like with a high refractive index adheres to the coating layer 13 and infiltrates into the coating layer 13,
When n 3 becomes larger than n 1 , the relationship between the respective refractive indices becomes n 2 > n 3 > n 1 . Therefore, in this case, the light that can propagate through the optical waveguide 12 is determined by the critical angle θ 2 at the interface between the optical waveguide 12 and the coating layer 13 rather than the critical angle θ 1 described above.
ところが、θ2はθ1よりも大きいので、全反射の
割合が減少して伝播光量も減少し、油漏れを感知
することができる。しかも、被覆層１３は露出部
１２Ｄのみならずこの露出部１２Ｄに連なつてい
る表面１１Ａをも覆つており、露出部１２Ｄ以外
の部分で被覆層１３に付着した油が露出部１２Ｄ
の部分にまで浸潤可能であり、更にまた光導波路
１２が２本の分岐路１２Ｃに分岐しているので、
光導波路１２の径よりもはるかに広い範囲に亘つ
て面状に油漏れを感知することができる。 However, since θ 2 is larger than θ 1 , the total reflection rate decreases and the amount of propagated light also decreases, making it possible to detect oil leakage. Moreover, the coating layer 13 covers not only the exposed portion 12D but also the surface 11A connected to the exposed portion 12D, and the oil adhering to the coating layer 13 in areas other than the exposed portion 12D may be transferred to the exposed portion 12D.
Furthermore, since the optical waveguide 12 is branched into two branch paths 12C,
Oil leakage can be detected in a planar manner over a much wider range than the diameter of the optical waveguide 12.
従つて、この為には、露出部１２Ｄの径の少な
くとも1.5倍以上の巾で、被覆層１３が露出部１
２Ｄを覆つていることが望ましい。 Therefore, for this purpose, the coating layer 13 must be formed on the exposed portion 12D with a width that is at least 1.5 times the diameter of the exposed portion 12D.
It is desirable to cover 2D.
なお、基板１２の材質として石英ガラス或いは
プラスチツクを夫々用いた場合は、光フアイバ等
の製作に利用されている火炎加水分解法、或いは
光重合法等の周知の技術を夫々利用することによ
つて、光導波路１２を形成することができる。こ
の光導波路１２の軸心に垂直な断面に於ける屈折
率分布は、均一であつてもよいし勾配を有してい
てもよい。 In addition, when quartz glass or plastic is used as the material of the substrate 12, it is possible to use well-known techniques such as flame hydrolysis or photopolymerization, which are used in the production of optical fibers, respectively. , the optical waveguide 12 can be formed. The refractive index distribution in a cross section perpendicular to the axis of the optical waveguide 12 may be uniform or may have a slope.
そして、以上の様な構成を有する感知器１４の
光導波路１２の入射端１２Ａと出射端１２Ｂとに
は、夫々入力用及び出力用の光フアイバ１５が接
続されている。 Optical fibers 15 for input and output are connected to the input end 12A and output end 12B of the optical waveguide 12 of the sensor 14 having the above-described configuration, respectively.
具体例 １
基板１１を石英ガラスで構成し、被覆層１３を
シリコン樹脂で構成すると、上記の夫々の屈折率
はn1＝1.456、n2＝1.47、n3＝1.405であり、臨界
角はθ1＝82.1゜、θ2＝72.9゜である。Specific Example 1 When the substrate 11 is made of quartz glass and the coating layer 13 is made of silicone resin, the above respective refractive indices are n 1 = 1.456, n 2 = 1.47, and n 3 = 1.405, and the critical angle is θ. 1 = 82.1°, θ 2 = 72.9°.
そして、1.47の屈折率を有する油が被覆層１３
に浸潤すると、この被覆層１３の屈折率n3が1.46
まで増大して、θ2＝83.3゜となる。この結果、θ2＞
θ1となつて全反射の割合が減少し、伝播光量が減
少して油漏れを感知することができる。 Then, oil having a refractive index of 1.47 is applied to the coating layer 13.
When infiltrated into the coating layer 13, the refractive index n 3 of this coating layer 13 becomes 1.46.
It increases to θ 2 =83.3°. As a result, θ 2 >
θ 1 , the rate of total reflection decreases, the amount of propagated light decreases, and oil leakage can be detected.
この具体例１の様に基板１１を石英ガラスで構
成すれば、光フアイバ１５として伝送損失の少な
いガラス光フアイバを使用しても、この光フアイ
バ１５と基板１１とを融着等によつて容易に接続
することができる。従つて、油漏れ事故が発生し
た場合、油が浸潤して再使用できなくなつた感知
器１４のみを容易に取り替えることができる。 If the substrate 11 is made of quartz glass as in this specific example 1, even if a glass optical fiber with low transmission loss is used as the optical fiber 15, the optical fiber 15 and the substrate 11 can be easily bonded together by fusing or the like. can be connected to. Therefore, in the event of an oil leakage accident, only the sensor 14 that has become infiltrated with oil and cannot be reused can be easily replaced.
具体例 ２
基板１１をプラスチツクで構成し、被覆層１３
をシリコン樹脂で構成すると、上記の夫々の屈折
率はn1＝1.44、n2＝1.48、n3＝1.405であり、臨界
角はθ1＝76.6゜、θ2＝71.7゜である。Specific example 2 The substrate 11 is made of plastic, and the coating layer 13
When made of silicone resin, the respective refractive indexes mentioned above are n 1 =1.44, n 2 =1.48, and n 3 =1.405, and the critical angles are θ 1 =76.6° and θ 2 =71.7°.
そして、1.458の屈折率を有する油が被覆層１
３に浸潤すると、この被覆層１３の屈折率n3が
1.451まで増大して、θ2＝78.6゜となる。この結果、
θ2＞θ1となつて全反射の割合が減少し、伝播光量
が減少して油漏れを感知することができる。 Then, oil with a refractive index of 1.458 is applied to the coating layer 1.
3, the refractive index n 3 of this coating layer 13 becomes
It increases to 1.451 and becomes θ 2 =78.6°. As a result,
When θ 2 >θ 1 , the rate of total reflection decreases, the amount of propagated light decreases, and oil leakage can be detected.
第５図は、感知器１４を適用して実際に油漏れ
を感知する為の装置を示している。まず、油タン
ク２１の油漏れが発生しそうな個所に感知器１４
を配置し、これらの感知器１４を光フアイバ１５
によつて直列若しくは並列に接続しておく。光フ
アイバ１５へは光源２２からの光を入射させ、こ
の光フアイバ１５から射出される光を光検出器２
３で検出する。そして、光検出器２３からの電気
信号を、増巾器２４及び比較器２５を介して警報
器２６へ導く。 FIG. 5 shows a device for actually detecting oil leakage using the sensor 14. First, a sensor 14 is installed at a location in the oil tank 21 where oil leakage is likely to occur.
and connect these sensors 14 with optical fibers 15.
Connect in series or in parallel depending on the Light from a light source 22 is input into the optical fiber 15, and the light emitted from the optical fiber 15 is detected by a photodetector 2.
Detect with 3. Then, the electrical signal from the photodetector 23 is guided to the alarm 26 via the amplifier 24 and the comparator 25.
なお、光フアイバコネクタの接続損失や光フア
イバの伝送損失の測定に利用されている後方散乱
法を併用すれば、単に油漏れを感知するのみでは
なく、油漏れの個所をも知ることができる。 If the backscattering method, which is used to measure the connection loss of optical fiber connectors and the transmission loss of optical fibers, is also used, it is possible to not only detect oil leaks but also to know the location of oil leaks.
以上の説明では油のみの感知について述べた
が、被覆層１３に浸潤してこの被覆層１３の屈折
率を増大させる液体であれば油に限られることな
く感知することができる。 Although the above description deals with sensing only oil, any liquid that infiltrates the coating layer 13 and increases the refractive index of the coating layer 13 can be detected without being limited to oil.
上述の様に、本発明による液体感知器では、光
導波路の露出部以外の基板表面をも被覆層によつ
て覆う様にしているので、露出部以外の部分で液
体が被覆層に浸潤しても、この液体が露出部の部
分にまで浸潤可能であり、広い範囲に亘つて液体
を感知することができる。 As described above, in the liquid sensor according to the present invention, since the surface of the substrate other than the exposed portion of the optical waveguide is also covered with the coating layer, there is no possibility that the liquid will infiltrate into the coating layer in the portion other than the exposed portion. However, this liquid can infiltrate even the exposed parts, and the liquid can be sensed over a wide range.
しかも、光導波路を複数の分岐路に分けて夫々
の分岐路に露出部を設ける様にしているので、更
に広い範囲に亘つて液体を感知することができ
る。 Furthermore, since the optical waveguide is divided into a plurality of branch paths and each branch path is provided with an exposed portion, liquid can be sensed over a wider range.
第１図及び第２図は本発明の一従来例を示す概
略的な側断面図である。第３図及び第４図は本発
明の一実施例を示す夫々概略的な斜視図及び縦断
面図、第５図は第３図及び第４図に示した一実施
例の適用装置を示す概略図である。
なお図面に用いられた符号において、１１…基
板、１１Ａ…表面、１２…光導波路、１２Ａ…入
射端、１２Ｂ…出射端、１２Ｃ…分岐路、１２Ｄ
…露出部、１３…被覆層、１４…感知器である。
1 and 2 are schematic side sectional views showing a conventional example of the present invention. 3 and 4 are schematic perspective views and vertical sectional views, respectively, showing one embodiment of the present invention, and FIG. 5 is a schematic diagram showing an application device of the embodiment shown in FIGS. 3 and 4. It is a diagram. In addition, in the symbols used in the drawings, 11...substrate, 11A...surface, 12...optical waveguide, 12A...incident end, 12B...outgoing end, 12C...branch path, 12D
...Exposed portion, 13...Coating layer, 14...Sensor.
Claims (1)
数の分岐路を有する様に前記基板中に形成されて
いる光導波路と、前記複数の分岐路の夫々が前記
基板の表面に露出する様にこれらの分岐路の夫々
に設けられている露出部と、前記光導波路の屈折
率よりも小さな屈折率を有すると共に液体の浸潤
が可能であり且つ前記露出部よりも広い面積でこ
れらの露出部を覆う様に前記基板の表面に配され
ている被覆層とを夫々具備し、前記液体の浸潤に
よる前記被覆層の屈折率の増大に伴い前記光導波
路中を前記複数の分岐路の夫々を経由して前記入
射端から前記出射端へ伝播する光の量が減少する
ことによつて前記液体を感知する様にした液体感
知器。1. A transparent substrate, an optical waveguide formed in the substrate so as to have a plurality of branch paths extending from an input end to an output end, and each of the plurality of branch paths being exposed on the surface of the substrate. exposed portions provided in each of these branch paths, and having a refractive index smaller than the refractive index of the optical waveguide, allowing infiltration of liquid, and having an area larger than the exposed portion. a coating layer disposed on the surface of the substrate so as to cover a portion of the optical waveguide, and as the refractive index of the coating layer increases due to the liquid infiltration, each of the plurality of branch paths A liquid sensor configured to sense the liquid by reducing the amount of light propagating from the input end to the output end.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59064215A JPS60209144A (en) | 1984-03-31 | 1984-03-31 | Liquid sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59064215A JPS60209144A (en) | 1984-03-31 | 1984-03-31 | Liquid sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60209144A JPS60209144A (en) | 1985-10-21 |
| JPH0345783B2 true JPH0345783B2 (en) | 1991-07-12 |
Family
ID=13251639
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59064215A Granted JPS60209144A (en) | 1984-03-31 | 1984-03-31 | Liquid sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60209144A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5209275A (en) * | 1987-07-09 | 1993-05-11 | Junkosha Co., Ltd. | Liquid dispensing apparatus and method by sensing the type of liquid vapors in the receiver |
-
1984
- 1984-03-31 JP JP59064215A patent/JPS60209144A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60209144A (en) | 1985-10-21 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5903685A (en) | Sensor arrangement | |
| US5253037A (en) | Optimal length for refractive index sensors | |
| JP2008170327A (en) | Refractive index detection device and liquid level detection device | |
| US20220412834A1 (en) | Fiber optics sensor for hydrocabon and chemical detection | |
| WO1991013323A2 (en) | Fiber optic fuel and liquid gauge | |
| JPH0345783B2 (en) | ||
| EP0803745B1 (en) | Fiber optics device | |
| JPH02181707A (en) | Optical fiber for detecting liquid, gas or the like | |
| JP5904578B2 (en) | Optical liquid leak detection apparatus and method | |
| JPS60209143A (en) | Liquid sensor | |
| JPH0260260B2 (en) | ||
| JPH0511780B2 (en) | ||
| JP2513470B2 (en) | Optical fiber sensor for oil leak detection and method of using the same | |
| JPH04148836A (en) | Liquid-leakage detecting apparatus | |
| US5224188A (en) | Eccentric core optical fiber | |
| JPH0260259B2 (en) | ||
| JPS63234115A (en) | Liquid level detector | |
| JPH0446178Y2 (en) | ||
| EP0453233A2 (en) | Eccentric core optical fiber | |
| KR100441344B1 (en) | Submerged optical fiber detection sensor using a side-polished fiber optic coupler | |
| JPS6066137A (en) | liquid refractive index sensor head | |
| JPH0338539B2 (en) | ||
| JPH04258744A (en) | fiber optic gas sensor | |
| JP3349211B2 (en) | Fiber type optical components | |
| JP2511999B2 (en) | Liquid detection optical fiber and liquid detection system using the same |