JPS61217744A - Optical fiber moisture sensor and moisture measuring apparatus - Google Patents
Optical fiber moisture sensor and moisture measuring apparatusInfo
- Publication number
- JPS61217744A JPS61217744A JP5931785A JP5931785A JPS61217744A JP S61217744 A JPS61217744 A JP S61217744A JP 5931785 A JP5931785 A JP 5931785A JP 5931785 A JP5931785 A JP 5931785A JP S61217744 A JPS61217744 A JP S61217744A
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- Prior art keywords
- optical fiber
- moisture
- light
- humidity
- core
- Prior art date
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- 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
- G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
- G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
- G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour
- G01N21/81—Indicating humidity
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Plasma & Fusion (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth 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)
Abstract
Description
【発明の詳細な説明】
（技術分野）
本発明は光ファイバー湿度センサ及びその湿度センサを
用いた湿度測定装置に関する。DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an optical fiber humidity sensor and a humidity measuring device using the humidity sensor.
（従来技術）
湿度を、誘電体の容量変化として検出する静電容量型や
、電極間に設けた吸湿性物質の抵抗変化として検出する
抵抗変化型等の電子式湿度センサは従来より多用されて
いるが、これらの湿度センサは誘電体や吸湿性物質等を
用いる間接測定であるため、材料自身の湿度に対する履
歴について配慮する必要があり、このような配慮が不十
分な材料を用いた場合には忠実な再現性が得られずその
出力特性が不安定となる問題を有していた。(Prior art) Electronic humidity sensors such as a capacitance type that detects humidity as a change in capacitance of a dielectric material and a variable resistance type that detects humidity as a change in resistance of a hygroscopic material provided between electrodes have been widely used. However, since these humidity sensors use dielectric materials, hygroscopic substances, etc. for indirect measurement, consideration must be given to the humidity history of the material itself, and when using materials with insufficient consideration, had the problem that faithful reproducibility could not be obtained and the output characteristics became unstable.
他方、光ファイバーに湿度変化に対応して伸縮する湿度
変形部材を設け、湿度変化に基づく湿度変形部材の伸縮
に対応して光ファイバーを変形させ、その光伝送特性の
変化から湿度を検出するようにしたものは実開昭５９−
８７５６号公報に開示されており、またプラスチックフ
ァイバーに赤外光を投射し、プラスチックファイバーの
吸湿性と吸湿した水分による赤外光の吸収特性とを利用
して赤外光の減衰量から湿度を検出するようにしたもの
も特開昭５８−１９０７４２号公報に開示されているが
、前者は間接測定法に属するものであるため、電子式湿
度センナと同様に湿度吸収部材の出力特性の再現性が不
十分であり、また後者は、吸湿された水分が赤外光の特
定波長を吸収する特性を有し、かつその吸光度量は微弱
であるため、高価な高感度増幅器を用いることが必要と
なって製造コストの低下をはかることが困難であるとい
った問題を有している。On the other hand, an optical fiber is provided with a humidity deforming member that expands and contracts in response to humidity changes, the optical fiber is deformed in response to the expansion and contraction of the humidity deformable member based on humidity changes, and humidity is detected from changes in the optical transmission characteristics. The thing is from 1984.
It is disclosed in Japanese Patent Application No. 8756, and humidity can be determined from the amount of attenuation of the infrared light by projecting infrared light onto a plastic fiber and utilizing the hygroscopicity of the plastic fiber and the absorption characteristics of the infrared light due to the absorbed moisture. A method for detecting humidity is also disclosed in JP-A No. 58-190742, but since the former belongs to the indirect measurement method, the reproducibility of the output characteristics of the humidity absorbing member is low, similar to the electronic humidity sensor. In the latter case, absorbed moisture has the property of absorbing a specific wavelength of infrared light, and the amount of absorbance is weak, so it is necessary to use an expensive high-sensitivity amplifier. This poses a problem in that it is difficult to reduce manufacturing costs.
（目的）
本発明は上記した従来技術の有する問題を解消するため
に、光ファイバーの表面に蒸着された吸湿被膜に吸着し
た水分からの反射光を検出して湿度変化を検出する安定
した出力特性を持つ光ファイバー湿度センサを提供する
ことを目的とするものであり、また他の目的は、第１の
光ファイバー湿度センサを基準用測定用として用い、光
ファイバーの装架の際の曲がりによる測定誤差を除いた
ダブルビーム型の湿度測定装置を提供することにある。(Purpose) In order to solve the problems of the prior art described above, the present invention provides stable output characteristics for detecting changes in humidity by detecting reflected light from moisture adsorbed on a moisture-absorbing film deposited on the surface of an optical fiber. Another object of the present invention is to provide a first optical fiber humidity sensor that uses the first optical fiber humidity sensor for reference measurement, and eliminates measurement errors due to bending when installing the optical fiber. An object of the present invention is to provide a double beam type humidity measuring device.
（目的達成のための手段）
すなわち１本発明はかかる目的を達成するために、光フ
ァイバーの表面に多孔質吸湿層を形成してなる線材をコ
イル状に巻回して湿度検出部とした光ファイバー湿度セ
ンサと、このように構成した２つの湿度センサを基準セ
ル及び測定セルに配設するとともに、各湿度センサの一
端をビームスプリッタを介して共通の発光部に、他端を
出力差検出手段に接続させた湿度測定装置にある。(Means for Achieving the Object) In other words, 1. In order to achieve the above object, the present invention provides an optical fiber humidity sensor in which a humidity detecting portion is formed by winding a wire material formed by forming a porous moisture absorbing layer on the surface of an optical fiber into a coil shape. The two humidity sensors configured in this way are arranged in the reference cell and the measurement cell, and one end of each humidity sensor is connected to a common light emitting section via a beam splitter, and the other end is connected to the output difference detection means. It is located in the humidity measuring device.
（実施例）
そこで以下に本発明の詳細を図示した実施例に基づいて
説明する。(Example) The details of the present invention will be described below based on illustrated examples.
第２図は本発明の一実施例をなす光ファイバー湿度セン
ナの断面を示すもので、１はメタクリル樹脂からなるコ
アで、その表面にはポリテトラフルオロエチレン、フッ
化エチレンプロピレンコポリマー等の耐温性に富んだフ
ッ素樹脂からなるクラッド層が被覆され、さらにその上
には、クラッド層２の外周に被着した図示しない被膜を
剥離したあと、スパッタリング又はイオンブレーティン
グ等の蒸着方法により、グラファイト等よりなる１００
Ａ程度の厚みを持った多孔質の吸湿層３が蒸着されてい
る。Fig. 2 shows a cross section of an optical fiber humidity sensor that is an embodiment of the present invention. 1 is a core made of methacrylic resin, and its surface is coated with a temperature-resistant material such as polytetrafluoroethylene or fluorinated ethylene propylene copolymer. A cladding layer made of a fluorine-rich resin is coated, and after peeling off a coating (not shown) attached to the outer periphery of the cladding layer 2, a layer of graphite, etc. Naru 100
A porous moisture absorption layer 3 having a thickness of approximately A is deposited.
このように構成された光ファイバーを第１図に示すよう
に、コイル状に数回巻いて湿度センサを構成し、これを
湿度検出をすべき雰囲気中に配置する。As shown in FIG. 1, the optical fiber thus constructed is wound into a coil several times to form a humidity sensor, and this is placed in an atmosphere in which humidity is to be detected.
次に、第３図に示した原理に基づいて上記湿度センナの
検出作用について説明する。Next, the detection operation of the humidity sensor will be explained based on the principle shown in FIG.
本発明に係る光ファイバー湿度センサの検出原理は必ず
しも十分解明されてはいないが、光ファイバーを図示す
るように曲げ、コアｌの入射側ｌａから可視光もしくは
赤外光を入射すると、その一部Ａは矢印にて示すように
コアｌ内において反射を繰返しながら出射側１ｂより出
射するが、残りの−６Ｂは、矢印で示すようにコアｌ内
を透過してクラッド層２からさらに吸湿被膜３に入射し
、ここでその−・部Ｂは減衰して消滅する。ところでこ
の吸湿液ＩＩＩ ３に水分４が吸着すると、コアＩＡ％
ｃ、ｍ：Ｍ１４＄Ｍ−ｍｔｔ＋ａｎｔｔｓｚ＋を憂ツ籠
ｎｎ＋、ｓｎｕ咄−−ｚれた水分４により反射し、再び
コア１内に入射して出射側ｉｂから出射する。したがっ
て、出射側ｌｂに配置された受光器の受光出力の増減か
ら湿度変化を検出することができる。Although the detection principle of the optical fiber humidity sensor according to the present invention is not fully elucidated, when the optical fiber is bent as shown in the figure and visible light or infrared light is incident from the incident side la of the core l, a part of the optical fiber A is As shown by the arrow, it is emitted from the output side 1b while repeating reflection within the core l, but the remaining -6B is transmitted through the core l as shown by the arrow and further enters the hygroscopic coating 3 from the cladding layer 2. However, at this point, the - part B attenuates and disappears. By the way, when moisture 4 is adsorbed to this hygroscopic liquid III 3, the core IA%
c, m: M14$M-mtt+anttsz+ is reflected by the water 4 that has been absorbed by the basket nn+, snu--z, enters the core 1 again, and exits from the exit side ib. Therefore, a change in humidity can be detected from an increase or decrease in the light reception output of the light receiver disposed on the emission side lb.
なお、吸湿被膜３は、多孔質の層状構成をなしているか
ら、水分の吸着効果が大となり、このため反射光量を大
ならしめることができる。In addition, since the moisture-absorbing film 3 has a porous layered structure, the effect of adsorbing moisture is large, and therefore the amount of reflected light can be increased.
第４図は、実験の結果得られた受光出力対相対湿度特性
曲線を示したもので、イオンブレーティング法によりク
ラッドｅ２の表面にグラファイトを１００Ａ程度の厚み
に蒸着して多孔質の吸湿被膜を形成し、このようにして
形成した光ファイバーを直径６ｃｍ程度のコイル状に４
，５回巻いて湿度センナとなした上、相対湿度を２０％
から１００％に近い値まで増加させてその特性実験を行
なったところ、受光器により受光された光量は図中Ｏ印
線に見られるように ３．１７５４ｗから３．４７５ｐ
ｗまで増加した０次いで、相対湿度を１００％に近い値
から２０％程度まで減少させたとこ六 彎を六台、＋ｖ
−播ｔ±Ｍ山Δ印の情で云Ｌトように３．４７５ｕＬｗ
から３．１５５７ｚＷに減少した。Figure 4 shows the light receiving output vs. relative humidity characteristic curve obtained as a result of the experiment. Graphite was deposited to a thickness of about 100A on the surface of the cladding e2 using the ion blating method to form a porous moisture-absorbing film. The optical fiber thus formed is coiled into a coil with a diameter of about 6 cm.
, Wrap it 5 times to create a humidity sensor, and set the relative humidity to 20%.
When we conducted a characteristic experiment by increasing the amount of light from 3.1754w to a value close to 100%, the amount of light received by the receiver was 3.1754w to 3.475p, as shown by the O-marked line in the figure.
Then, the relative humidity was decreased from a value close to 100% to about 20%.
- 3.475uLw as it says due to the t±M mountain Δ mark
It decreased from 3.1557zW to 3.1557zW.
第５図は上記した光ファイバー湿度センサを用いた本発
明の基本的なシングルビーム型湿度測定装置を示したも
のであり、同図において符号２０は可視光を出力する光
源、２１と２３は光ファイバーの往路と復路であり、２
４は測定セル、２２は光ファイバー湿度センナ、２５は
受光器、２６は非線形出力を線形出力に変換する線形変
換器、２７は指示器を示している。FIG. 5 shows a basic single beam type humidity measuring device of the present invention using the above-described optical fiber humidity sensor. In the figure, reference numeral 20 is a light source that outputs visible light, and 21 and 23 are optical fibers. It is an outbound trip and a return trip, and 2
4 is a measurement cell, 22 is an optical fiber humidity sensor, 25 is a light receiver, 26 is a linear converter for converting nonlinear output into linear output, and 27 is an indicator.
このように構成された装置において、光源２０から出力
された可視光は光ファイ、バー２１を介して湿度センサ
２２に送光される。そして測定セル２４内の湿度に対応
した光量は光ファイバー２３を介して受光器２５に送光
され、さらにここからの非線形出力は線形変換器２６に
より線形出力に変換された上、指示器２７に入力して湿
度として表示される。In the device configured in this manner, visible light output from the light source 20 is sent to the humidity sensor 22 via the optical fiber and bar 21. The amount of light corresponding to the humidity inside the measurement cell 24 is sent to the light receiver 25 via the optical fiber 23, and the nonlinear output from here is converted into a linear output by the linear converter 26, and then input to the indicator 27. and displayed as humidity.
ところでこの湿度測定装置によると、光ファイバー２１
．２３の装架の仕方によっては曲がりが生じ、これによ
り光伝送特性が変化して測定誤差の生じる虞れがあるた
め、光ファイバーを直線状に装架するよう慎重に作業す
ることが必要となる。By the way, according to this humidity measuring device, the optical fiber 21
．． Depending on how the optical fibers 23 are installed, bends may occur, which may change the optical transmission characteristics and cause measurement errors, so it is necessary to work carefully to install the optical fibers in a straight line.
第６図ｔ＊光ファイバーに多少の曲がりがあっても正確
に湿度が測定できるようさらに改良を加えたもので、３
０は可視光を出力する光源、３１は光ファイバー、３２
は入射された可視光を基準光と測定光とに２分し、基準
光を光ファイバー３３に測定光を反射鏡３４に送光する
ビームスプリッタ、３５Ａは基準ガスとして乾燥ガスが
導入された基準セル、３５Ｂはファン３６により測定対
象となる大気が導入、排出される測定セルで、基準セル
３５Ａと測定セル３５Ｂとには基準用の光ファイバー湿
度センサ３７と測定用の光ファイバー湿度センサ３８と
が配置されている。Figure 6 t* This is a device that has been further improved so that humidity can be measured accurately even if the optical fiber is slightly bent.
0 is a light source that outputs visible light, 31 is an optical fiber, 32
35A is a beam splitter that splits the incident visible light into a reference light and a measurement light, and sends the reference light to an optical fiber 33 and measurement light to a reflecting mirror 34; 35A is a reference cell into which dry gas is introduced as a reference gas; , 35B are measurement cells into which the air to be measured is introduced and exhausted by a fan 36, and a reference optical fiber humidity sensor 37 and a measurement optical fiber humidity sensor 38 are arranged in the reference cell 35A and the measurement cell 35B. ing.
４０．４１は基準光と測定光が送光される光ファイバー
で、これらの光ファイバー４０．４１は光ファイバーペ
ア線４２により固定保持されている。４３．４４は基準
光と測定光とを電気量に変換する受光器であり、４５は
受光器４３．４４の出力信号の差を検出する差動増幅器
、４６は指示器を示している。Reference numerals 40 and 41 denote optical fibers through which the reference light and measurement light are transmitted, and these optical fibers 40 and 41 are fixedly held by optical fiber pairs 42. Reference numerals 43 and 44 designate light receivers that convert the reference light and measurement light into electrical quantities, 45 a differential amplifier that detects the difference between the output signals of the light receivers 43 and 44, and 46 an indicator.
この実施例においては、光源３０から出力された可視光
は光ファイバー３１を介してビームスプリッタ３２に入
射しここで基準光と測定光に２分される。そして、２分
された一方の基準光は、光ファイバー３３を介して基準
セル３５Ａの光ファイバー湿度センサ３７に送光され、
そこから一定光最の光として出力して受光器４３に送ら
れる。In this embodiment, visible light output from a light source 30 enters a beam splitter 32 via an optical fiber 31, where it is split into two parts: a reference light and a measurement light. Then, one of the two divided reference lights is sent to the optical fiber humidity sensor 37 of the reference cell 35A via the optical fiber 33,
From there, it is output as constant light and sent to the light receiver 43.
他方測定光は、反射ｔ１ｔ３４で反射されて測定セル３
５Ｂの光ファイバー湿度センナ３８内に入射し、大気の
湿度に対応した光量となって受光器４４に送光される。On the other hand, the measurement light is reflected by reflection t1t34 and passes through the measurement cell 3.
The light enters the optical fiber humidity sensor 38 of 5B, and is transmitted to the light receiver 44 in an amount corresponding to the humidity of the atmosphere.
そして、受光器４３．４４に入力した基準光と測定光は
ここで光電変換された上洛出力信号は差動増幅器４５に
入力し、その差の出力が指示器４６に入力して湿度を指
示する。The reference light and measurement light input to the light receivers 43 and 44 are photoelectrically converted here, and the output signal is input to the differential amplifier 45, and the output of the difference is input to the indicator 46 to indicate the humidity. .
したがって、この装置では光ファイバー４０．４１が多
少の曲りを持って装架されたとしても。Therefore, in this device, even if the optical fibers 40, 41 are installed with some bends.
差動増幅器４５により光量差を検出するものであるため
、光伝送特性の変動は相殺される。Since the difference in light amount is detected by the differential amplifier 45, fluctuations in optical transmission characteristics are canceled out.
（効果）
以上説明したように本発明によれば、光ファイバーの表
面に多孔質吸湿層を設けた線材を用い、これをコイル状
に巻回して湿度センサとなしたので、材料自体の湿度に
対する履歴やその物理的な伸縮、変形吸湿量等に影響さ
れることなく、吸湿層に吸着した水分の量に応じて変化
する反射光量から湿度を正確かつ安定的に検出すること
ができる。しかも高利得増幅器を必要としないため、装
置を安価に構成することができ、また湿度検出用の電極
を必要としないため、腐食性ガスの発生する雰囲気にお
いて使用することが可能で、その上電磁的影響を受けず
、防爆性に優れた光ファイバー湿度センサとして構成す
ることができる。さらに、これらの湿度センサを基準セ
ルと測定セルにそれぞれ配置し、各湿度センサが検出し
た光量の差によって湿度を測定するように構成したので
、線材に多少の曲がりがあっても光の伝送特性の変動か
ら派生する測定誤差を除いて、その装荷作業をきわめて
容易にすることができる。(Effects) As explained above, according to the present invention, a wire rod with a porous moisture absorption layer provided on the surface of an optical fiber is used and is wound into a coil shape to form a humidity sensor. Humidity can be accurately and stably detected from the amount of reflected light that changes depending on the amount of moisture adsorbed in the moisture absorption layer, without being affected by its physical expansion/contraction, deformation, moisture absorption, etc. Moreover, since it does not require a high gain amplifier, the device can be constructed at low cost, and since it does not require an electrode for humidity detection, it can be used in an atmosphere where corrosive gases are generated. It can be configured as an optical fiber humidity sensor that is not affected by the environment and has excellent explosion-proof properties. Furthermore, these humidity sensors are placed in the reference cell and the measurement cell, respectively, and the humidity is measured based on the difference in the amount of light detected by each humidity sensor, so even if the wire has some bends, the light transmission characteristics will not change. The loading operation can be made extremely easy by eliminating measurement errors derived from variations in .
第１図は本発明の一実施例を示す湿度センサの斜視図、
第２図は温度センサ用線材の断面図、第３図は光ファイ
バー湿度センサの検出原理を示す説明図、第４図は光フ
ァイバー湿度センサの特性を示す図、第５．６図はいず
れも本発明の実施例をなすシングルビーム型の湿度測定
装置の構成図である。
ｌ・・・・コア ２・・・・クラッド暦３
・・・・多孔質層 ３０・・・・光源３１．３
３．４０．４１・・・・光ファイバー３２・・・・ビー
ムスプリッタ
３４・・・・反射＠ ３５Ａ・・・・基準セ
ル３５Ｂ・・・・測定セル
２２．３７．３８・・・・光ファイバー湿度センサ４３
．４４・・・・受光器 ４５・・・・差動増幅器４６
・・・・指示器
出願人 オリエント時計株式会社
代理人 弁理士 西 川 慶 治
第１図 第２図
第３図FIG. 1 is a perspective view of a humidity sensor showing an embodiment of the present invention;
Figure 2 is a cross-sectional view of a wire for a temperature sensor, Figure 3 is an explanatory diagram showing the detection principle of an optical fiber humidity sensor, Figure 4 is a diagram showing the characteristics of an optical fiber humidity sensor, and Figures 5 and 6 are all in accordance with the present invention. FIG. 1 is a configuration diagram of a single beam type humidity measuring device according to an embodiment of the present invention. l... Core 2... Clad calendar 3
... Porous layer 30 ... Light source 31.3
3.40.41...Optical fiber 32...Beam splitter 34...Reflection @ 35A...Reference cell 35B...Measurement cell 22.37.38...Optical fiber humidity sensor 43
．． 44... Light receiver 45... Differential amplifier 46
...Indicator applicant: Orient Watch Co., Ltd. Agent: Patent attorney Keiji Nishikawa Figure 1 Figure 2 Figure 3
Claims (2)
線材をコイル状に巻回して湿度検出部となしたことを特
徴とする光ファイバー湿度センサ。1. An optical fiber humidity sensor characterized in that a humidity detecting section is formed by winding a wire material formed by forming a porous moisture absorbing layer on the surface of an optical fiber into a coil shape.
をコイル状に巻回して検出部となした２つの湿度センサ
を基準セル及び測定セルに配設するとともに、上記各湿
度センサの一端をビームスプリッタを介して共通の発光
部に、他端を出力差検出手段に接続したことを特徴とす
る湿度測定装置。2. Two humidity sensors, each of which is a detection section made by winding a wire whose surface is coated with a porous moisture absorption layer on the surface of an optical fiber, are arranged in a reference cell and a measurement cell, and one end of each humidity sensor is connected to a beam splitter. 1. A humidity measuring device, characterized in that the other end is connected to a common light emitting section through a common light emitting section, and the other end is connected to an output difference detection means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5931785A JPS61217744A (en) | 1985-03-23 | 1985-03-23 | Optical fiber moisture sensor and moisture measuring apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5931785A JPS61217744A (en) | 1985-03-23 | 1985-03-23 | Optical fiber moisture sensor and moisture measuring apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS61217744A true JPS61217744A (en) | 1986-09-27 |
Family
ID=13109860
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5931785A Pending JPS61217744A (en) | 1985-03-23 | 1985-03-23 | Optical fiber moisture sensor and moisture measuring apparatus |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61217744A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1995020151A3 (en) * | 1994-01-21 | 1995-08-17 | Fiberchem Inc | Reducing the effects of water vapor and liquid water on optical waveguide sensors (ows) and optical waveguide chemical sensors (owcs) |
| US6965708B2 (en) | 2002-10-04 | 2005-11-15 | Luna Innovations, Inc. | Devices, systems, and methods for sensing moisture |
| JP2017015521A (en) * | 2015-06-30 | 2017-01-19 | ファナック株式会社 | Rotary encoder with function to acquire moisture absorption amount of absorbent |
| US20220268685A1 (en) * | 2019-07-26 | 2022-08-25 | 3M Innovative Properties Company | Porous Fluid Sensor |
-
1985
- 1985-03-23 JP JP5931785A patent/JPS61217744A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1995020151A3 (en) * | 1994-01-21 | 1995-08-17 | Fiberchem Inc | Reducing the effects of water vapor and liquid water on optical waveguide sensors (ows) and optical waveguide chemical sensors (owcs) |
| US6965708B2 (en) | 2002-10-04 | 2005-11-15 | Luna Innovations, Inc. | Devices, systems, and methods for sensing moisture |
| JP2017015521A (en) * | 2015-06-30 | 2017-01-19 | ファナック株式会社 | Rotary encoder with function to acquire moisture absorption amount of absorbent |
| US10317258B2 (en) | 2015-06-30 | 2019-06-11 | Fanuc Corporation | Rotary encoder having function to obtain moisture absorbing amount of desiccant |
| US20220268685A1 (en) * | 2019-07-26 | 2022-08-25 | 3M Innovative Properties Company | Porous Fluid Sensor |
| US11768145B2 (en) * | 2019-07-26 | 2023-09-26 | 3M Innovative Properties Company | Porous fluid sensor |
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