JPH01134230A - Liquid sensor head - Google Patents
Liquid sensor headInfo
- Publication number
- JPH01134230A JPH01134230A JP29176487A JP29176487A JPH01134230A JP H01134230 A JPH01134230 A JP H01134230A JP 29176487 A JP29176487 A JP 29176487A JP 29176487 A JP29176487 A JP 29176487A JP H01134230 A JPH01134230 A JP H01134230A
- Authority
- JP
- Japan
- Prior art keywords
- liquid
- tip
- light
- sensor head
- liquid sensor
- 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.)
- Pending
Links
- 239000007788 liquid Substances 0.000 title claims abstract description 42
- 239000013307 optical fiber Substances 0.000 claims abstract description 24
- 239000011248 coating agent Substances 0.000 claims description 6
- 238000000576 coating method Methods 0.000 claims description 6
- 238000005259 measurement Methods 0.000 abstract description 5
- 239000000835 fiber Substances 0.000 abstract description 4
- 239000005304 optical glass Substances 0.000 abstract description 2
- 230000000644 propagated effect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 8
- 239000011521 glass Substances 0.000 description 7
- 230000007423 decrease Effects 0.000 description 6
- 230000003287 optical effect Effects 0.000 description 4
- 230000005484 gravity Effects 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、液体の比重、密度、溶液濃度等を測定する液
体センサに係わり、特に光ファイバを使用した液体セン
サに関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid sensor that measures the specific gravity, density, solution concentration, etc. of a liquid, and particularly relates to a liquid sensor using an optical fiber.
一般に、液体の比重、密度、溶液濃度等を測定する場合
、試料中に浮秤針を浮かせて比重や密度を測定したり屈
折計に試料を滴下して屈折率を測定することがおこなわ
れていた。また、光ファイバとプリズムとを組み合わせ
た液体センサも提案されていた。第４図は、従来の光フ
ァイバを使用した液体センサの一例を示すものである。Generally, when measuring the specific gravity, density, solution concentration, etc. of a liquid, the specific gravity and density are measured by floating a floating balance needle in the sample, or the refractive index is measured by dropping the sample into a refractometer. Ta. A liquid sensor that combines an optical fiber and a prism has also been proposed. FIG. 4 shows an example of a liquid sensor using a conventional optical fiber.
ここで液体センサはガラスプリズム１と、光源２からの
光ヲ光ファイバ３でレンズ４（セルフォックレンズ）へ
導きガラスプリズム１に入射させる光学系と、ガラスプ
リズム１からの光をレンズ５および光ファイバ６を介し
て受光する光検出器７等から成り、ガラスプリズム１を
測定すべき液体面に配置し光源２からの反射光レベルの
低下率を光検出器７で検出することにより測定していた
。Here, the liquid sensor includes a glass prism 1, an optical system that guides light from a light source 2 through an optical fiber 3 to a lens 4 (Selfoc lens) and enters the glass prism 1, and a lens 5 and an optical system that guides the light from the glass prism 1 to a lens 5 and the optical system. It consists of a photodetector 7 etc. that receives light through a fiber 6, and the glass prism 1 is placed on the surface of the liquid to be measured, and the photodetector 7 measures the rate of decrease in the level of reflected light from the light source 2. Ta.
ところで、上述した従来の液体センサにあっては、プリ
ズム内に於いて全反射している疑似平行光がプリズムの
全反射面が計測すべき液体に浸されることにより全反射
しなくなり反射光レベルが低下するという理論を利用し
て液体の屈折率を間接的に計測している。しかし、液体
の屈折率変化に対し、反射光レベルの低下率は屈折率が
大きくなるに従い低下するため測定感度が低下するとい
う欠点があった。By the way, in the conventional liquid sensor mentioned above, the pseudo-parallel light that is totally reflected inside the prism is no longer totally reflected because the total reflection surface of the prism is immersed in the liquid to be measured, and the reflected light level is reduced. The refractive index of a liquid is indirectly measured using the theory that the refractive index decreases. However, with respect to changes in the refractive index of the liquid, the rate of decrease in the level of reflected light decreases as the refractive index increases, resulting in a disadvantage in that measurement sensitivity decreases.
本発明は上述した欠点に鑑みなされたもので、プリズム
内に於いて全反射している擬似平行光がプリズムの全反
射面が計測すべき液体に浸されることにより全反射しな
くなり反射光レベルが低下するという理論を利用しつつ
小型で高性能の液体センサを提供することを目的とする
。The present invention was made in view of the above-mentioned drawbacks, and the pseudo-parallel light that is totally reflected inside the prism is no longer totally reflected when the total reflection surface of the prism is immersed in the liquid to be measured, and the reflected light level is The purpose of this invention is to provide a small, high-performance liquid sensor by utilizing the theory that the amount of water decreases.
本発明に係わる液体センサヘッドは、プリズムの代わり
に光ファイバの直径の数倍程度の太さを有したガラス性
のロッド部内に人力光ファイバから出射した光線を伝搬
させる。光線は、ロッド部が空気中に在る場合は、内面
で全反射するが、浸液時にふいては、液体の屈折率が次
第に大きくなるに従って高次モードの光線からロッド部
の外部へ漏れ出す。また、ロッド部に緩やかな曲がりが
設けられることにより最低次のモードでも測定に関与す
ることが可能となっている。The liquid sensor head according to the present invention propagates a light beam emitted from a human-powered optical fiber into a glass rod portion having a thickness several times the diameter of the optical fiber instead of a prism. When the rod is in the air, the light is totally reflected on the inner surface, but when it is wiped when immersed in liquid, as the refractive index of the liquid gradually increases, higher-order modes of light leak out to the outside of the rod. . Further, by providing a gentle bend in the rod portion, it is possible to participate in measurement even in the lowest order mode.
以下、添付図面に従って本発明の液体センサヘッドの一
実施例について説明する。An embodiment of the liquid sensor head of the present invention will be described below with reference to the accompanying drawings.
第１図は、本発明の一実施例を示す構成図である。同図
において、液体センサヘッド１０は略平行に配置された
光ファイバ１１．１２とこの光ファイバの先端に取り付
けられた軸方向に緩やかに湾曲したロッド部１３とから
構成されている。FIG. 1 is a configuration diagram showing an embodiment of the present invention. In the figure, a liquid sensor head 10 is composed of optical fibers 11 and 12 arranged substantially parallel to each other and a rod section 13 that is gently curved in the axial direction and attached to the tip of the optical fiber.
ここで、ロッド部１３は、光学ガラスから成り先端に全
反射被膜１４が被着されており、ロッド部１３の先端が
空気中存在するときは、内部を伝搬して来た光は全反射
する。ロッド部１３の端部は、光ファイバ１１．１２が
光学的に接続されており、光ファイバ１１．１２のコア
部を含む断面積を有している。また、光ファイバ１１は
、図示しない光線に接続されており、この光線からの光
を伝搬させる。一方、光ファイバには、全反射被膜１４
からの反射光を受光し、図外の光検出器へ搬送する。Here, the rod portion 13 is made of optical glass and has a total reflection coating 14 applied to its tip, and when the tip of the rod portion 13 is in the air, the light propagating inside is totally reflected. . The end of the rod portion 13 is optically connected to an optical fiber 11.12 and has a cross-sectional area that includes the core portion of the optical fiber 11.12. Further, the optical fiber 11 is connected to a light beam (not shown), and propagates light from this light beam. On the other hand, the optical fiber has a total reflection coating 14.
The reflected light is received and conveyed to a photodetector (not shown).
次に、以上のように構成された液体センサヘッド１０の
使用方法について説明する。まず、液体センサヘッド１
０の先端を測定すべき液体に浸す。Next, a method of using the liquid sensor head 10 configured as above will be explained. First, liquid sensor head 1
Dip the tip of the 0 into the liquid to be measured.
すると、今まで、空気中にあった場合は、全反射被膜１
４で全反射していた光ファイバ１１からの光は、被測定
液体の屈折率の増加に応じて変化する。Then, if it was in the air until now, the total reflection coating 1
The light from the optical fiber 11 that has been totally reflected by the optical fiber 11 changes in accordance with the increase in the refractive index of the liquid to be measured.
このように、本発明の液体センサヘッドは、出射および
受光用光ファイバ１１１２と一体的に構成されているの
で著しく小型化を図ることができるとともに操作性が向
上する。As described above, since the liquid sensor head of the present invention is integrally constructed with the optical fiber 1112 for emitting and receiving light, it is possible to significantly reduce the size and improve operability.
さらに、ロッド部１３は、緩やかに湾曲しているので、
浸液時においても最低次のモードでも測定に関与できる
。Furthermore, since the rod portion 13 is gently curved,
Even when immersed in liquid, it can participate in measurements even in the lowest order mode.
第２図は、ステップ・インデックス形多モードファイバ
の伝搬モードとモードパワーとの関係を示すパワースペ
クトル図である。ここに挙げる関係は、通常のモード励
振で容易に実現することができる。同図から明らかな如
く、高次モード程、光の電力は小さい。FIG. 2 is a power spectrum diagram showing the relationship between propagation mode and mode power of a step-index multimode fiber. The relationships listed here can be easily realized by normal mode excitation. As is clear from the figure, the higher the mode, the smaller the optical power.
第３図は、液体の屈折率とガラス−液体境界面での反射
損失との関係を示す特性図である。同図から明らかな如
く、高次モードであれば、液体の屈折率が小さい部分で
あっても現象の把握が可能である。しかし、すぐに変化
率は、飽和してしまう。一方、低次モードについては、
逆に、容易に変化率が飽和しない代わりに、比較的屈折
率が大きくないと現象の把握ができない。また、本実施
例においては、ロッド部を緩やかに湾°曲させたので、
低次モードであっても、必ずロッド側面で全反射し、光
のパワーを有効に利用することができる。FIG. 3 is a characteristic diagram showing the relationship between the refractive index of the liquid and the reflection loss at the glass-liquid interface. As is clear from the figure, if it is a higher order mode, it is possible to understand the phenomenon even in a portion where the refractive index of the liquid is small. However, the rate of change soon becomes saturated. On the other hand, for lower-order modes,
Conversely, the phenomenon cannot be understood unless the rate of change is easily saturated and the refractive index is relatively large. In addition, in this example, since the rod portion is gently curved,
Even low-order modes are always totally reflected on the side of the rod, making it possible to effectively utilize the power of the light.
なお、本発明は、以上の実施例に限定されることなく本
発明の技術思想に基づいて、種々の変形が可能である。Note that the present invention is not limited to the above-described embodiments, and various modifications can be made based on the technical idea of the present invention.
以上説明したように、本発明の液体センサヘッドによれ
ば、プリズムの代わりにガラス製ロッドと出射光ファイ
バと受光光ファイバとを一体的に構成したので、装置の
小型、軽量化を達成することができる。また、ロッド部
が緩やかに湾曲しているので測定対象の液体の屈折率が
広い範囲に亘って変化しても精度が低下することなく測
定が可能である。特に低次モード光の有効利用を図るこ
とができる。As explained above, according to the liquid sensor head of the present invention, the glass rod, the emitting optical fiber, and the receiving optical fiber are integrally configured instead of the prism, so that the device can be made smaller and lighter. Can be done. Furthermore, since the rod portion is gently curved, measurement can be performed without deterioration of accuracy even if the refractive index of the liquid to be measured changes over a wide range. In particular, it is possible to effectively utilize low-order mode light.
第１図は本発明の液体センサヘッドの一実施例を示す構
成図、第２図はステップインデックス型多モードファイ
バの伝搬モードのパワースペクトルを示す図、第３図は
液体の屈折率とガラス−液体境界面での反射損の関係を
示す図、第４図は従来の光ファイバを使用した液体セン
サの一例を示す構成図である。
１０・・・・・・液体センサヘッド、
１１．１２・・・・・・光ファイバ、
１３・・・・・・ロッド部、
１４・・・・・・全反射被膜。
出願人 日本電気株式会社
代理人 弁理士 山内 梅雄
第１図
胆
第２（２）
モード書′！FIG. 1 is a configuration diagram showing an embodiment of the liquid sensor head of the present invention, FIG. 2 is a diagram showing the power spectrum of the propagation mode of a step index multimode fiber, and FIG. 3 is a diagram showing the refractive index of the liquid and the glass FIG. 4, which is a diagram showing the relationship between reflection loss at a liquid boundary surface, is a configuration diagram showing an example of a liquid sensor using a conventional optical fiber. 10... Liquid sensor head, 11.12... Optical fiber, 13... Rod portion, 14... Total reflection coating. Applicant NEC Co., Ltd. Agent Patent Attorney Umeo Yamauchi Figure 1 Part 2 (2) Mode book'!
Claims (1)
この光ファイバの先端に取り付けられた軸方向に緩やか
な曲がりを有したロッド部とから成り、前記ロッド部は
、前記光ファイバのコアを含む断面積を有すると共に先
端に軸とほぼ直角に全反射被膜が付加された反射面を有
し、後端の反射被膜が付加されていない端部が光学的に
接続されてなることを特徴とする液体センサヘッド。at least two optical fibers arranged substantially parallel;
The rod part is attached to the tip of the optical fiber and has a gentle bend in the axial direction. 1. A liquid sensor head comprising a reflective surface coated with a coating, and a rear end to which a reflective coating is not coated and optically connected to the rear end.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29176487A JPH01134230A (en) | 1987-11-20 | 1987-11-20 | Liquid sensor head |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29176487A JPH01134230A (en) | 1987-11-20 | 1987-11-20 | Liquid sensor head |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH01134230A true JPH01134230A (en) | 1989-05-26 |
Family
ID=17773116
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP29176487A Pending JPH01134230A (en) | 1987-11-20 | 1987-11-20 | Liquid sensor head |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01134230A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001051068A (en) * | 1999-08-17 | 2001-02-23 | Hightech Research Kk | Freezing detection sensor and its sensor element |
| CN108825484A (en) * | 2018-06-15 | 2018-11-16 | 天津中德应用技术大学 | The compressor oil position monitoring system and its method of total reflection principle based on light |
-
1987
- 1987-11-20 JP JP29176487A patent/JPH01134230A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001051068A (en) * | 1999-08-17 | 2001-02-23 | Hightech Research Kk | Freezing detection sensor and its sensor element |
| CN108825484A (en) * | 2018-06-15 | 2018-11-16 | 天津中德应用技术大学 | The compressor oil position monitoring system and its method of total reflection principle based on light |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JPH1068843A (en) | High reflection attenuation type light receiving device | |
| KR101109093B1 (en) | Optical fiber sensor and measuring device using the same | |
| CA1332205C (en) | Fibre optic sensors for the continuous measurement of liquid level and other parameters | |
| JPH04230821A (en) | Detector for detecting leakage of liquid from optical fiber | |
| KR940003737B1 (en) | Fibre optic liquid level gauge | |
| CN105352491A (en) | Y-waveguide structure for fiber-optic gyroscope light path extension | |
| JPH01134230A (en) | Liquid sensor head | |
| JP3176582U (en) | Light guide cell | |
| JP2650998B2 (en) | Optical fiber for detecting liquid, gas, etc. | |
| KR20100072671A (en) | Liquid level measuring sensor made of optical fibers | |
| KR970705017A (en) | Method and apparatus for determining the refractive index of different media | |
| US4688883A (en) | Integrated optics stress transducer | |
| JPH0219730A (en) | Optical fiber temperature sensor | |
| KR20010109797A (en) | Tap coupler | |
| JPS6217173B2 (en) | ||
| JP2794829B2 (en) | Optical fiber refractometer | |
| RU2750691C1 (en) | Optical fiber device with side input-output of radiation | |
| SU939935A2 (en) | Device for measuring displacements | |
| JPH01248040A (en) | Liquid concentration sensor | |
| JPS6221948Y2 (en) | ||
| RU2249838C2 (en) | Method of making device for eliminating reversed ray in fiber-optic gyroscope | |
| SU922539A1 (en) | Device for measuring temperature | |
| RU2021130405A (en) | FIBER-OPTICAL METHOD FOR DETERMINING REFRACTIVE COEFFICIENT OF TRANSPARENT SUBSTANCE AND FIBER-OPTICAL REFRACTOMETRIC MEASURING CONVERTER IMPLEMENTING IT | |
| Apriyanto | Study, analysis and experimental validation of fiber refractometers based on single-mode, multimode and photonic crystal fibers for refractive index measurements with application for the detection of methane | |
| JP2001074607A (en) | Method for measuring transmission loss of optical fiber and apparatus for executing it |