JPS6334421B2 - - Google Patents
Info
- Publication number
- JPS6334421B2 JPS6334421B2 JP57125508A JP12550882A JPS6334421B2 JP S6334421 B2 JPS6334421 B2 JP S6334421B2 JP 57125508 A JP57125508 A JP 57125508A JP 12550882 A JP12550882 A JP 12550882A JP S6334421 B2 JPS6334421 B2 JP S6334421B2
- Authority
- JP
- Japan
- Prior art keywords
- refractive index
- light
- optical fiber
- measured
- reflection
- 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
Links
- 239000013307 optical fiber Substances 0.000 claims description 29
- 230000003287 optical effect Effects 0.000 claims description 14
- 230000000644 propagated effect Effects 0.000 claims description 3
- 238000000691 measurement method Methods 0.000 claims description 2
- 238000001514 detection method Methods 0.000 description 9
- 238000010586 diagram Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 230000007423 decrease Effects 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- 238000010276 construction Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 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)
Description
【発明の詳細な説明】
この発明は光フアイバを用いて被測定物の屈折
率を測定する屈折率測定方法に関するものであ
る。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refractive index measuring method for measuring the refractive index of an object to be measured using an optical fiber.
従来においては、屈折率を測定するには、最小
偏角法、アツベの屈折計、液浸法、各種干渉計な
どを用いて行なわれていた。しかし、これらの方
法は何れも構成が大がかりであり、狭い場所（局
所）の屈折率測定が困難であり、試作作りも困難
である等の欠点があつた。 Conventionally, the refractive index has been measured using the minimum deviation angle method, Atsube's refractometer, immersion method, various interferometers, and the like. However, all of these methods have drawbacks such as large-scale construction, difficulty in measuring the refractive index in a narrow place (local area), and difficulty in making a prototype.
この発明は光フアイバを用い、光フアイバと被
測定物体との境界から反射する光信号と入射光と
の比を測定することを特徴とし、その目的は簡便
で局所的な場所の屈折率測定を可能とする屈折率
測定方法を実現するにある。 This invention is characterized by using an optical fiber to measure the ratio of the optical signal reflected from the boundary between the optical fiber and the object to be measured and the incident light, and its purpose is to easily and locally measure the refractive index. The objective is to realize a refractive index measurement method that makes it possible.
実施例
第１図はこの発明の実施例を示し、この例では
それぞれ波長λ1〜λnの光を出力する例えばレー
ザの光源１1〜１ｎが設けられる。このｎ個の光
源１1〜１ｎから光パルスを光フアイバ２の一端
に光方向性結合器３を介して入射することができ
るようにされる。光フアイバ２の他端は例えば液
体の被測定物４と接触される。この光フアイバ２
の他端で反射した反射光は光方向性結合器３を介
して検出部５に入射される。Embodiment FIG. 1 shows an embodiment of the present invention, in which light sources 1 1 to 1n, such as lasers, which output light having wavelengths λ 1 to λn, respectively, are provided. Light pulses from these n light sources 1 1 to 1 n can be input to one end of the optical fiber 2 via the optical directional coupler 3 . The other end of the optical fiber 2 is brought into contact with, for example, a liquid object 4 to be measured. This optical fiber 2
The reflected light reflected at the other end enters the detection section 5 via the optical directional coupler 3.
この構成において光パルスが光フアイバ２に入
射されると、光フアイバ２を伝搬した光パルスは
光フアイバ２及び被測定物４の境界で反射され、
この反射光は光フアイバ２を逆方向に伝搬して検
出部５に入射する。検出部５は光を電気信号に変
換する受光素子及びオシロスコープなどで構成さ
れる。検出部５に入射される光の検出出力は第２
図に示すように反射光パルスが被測定物４に入射
した時点に電気的パルス６が得られる。なお光フ
アイバ２内で光源側から被測定物４側へ伝搬する
光パルスはレイレイ散乱により、その一部は検出
部５に入射され、そのレイレイ散乱の検出光は第
２図に線７で示すように時間の経過と共に減少す
る。 In this configuration, when a light pulse is incident on the optical fiber 2, the light pulse propagated through the optical fiber 2 is reflected at the boundary between the optical fiber 2 and the object to be measured 4,
This reflected light propagates in the opposite direction through the optical fiber 2 and enters the detection section 5 . The detection unit 5 includes a light receiving element that converts light into an electrical signal, an oscilloscope, and the like. The detection output of the light incident on the detection unit 5 is the second
As shown in the figure, an electrical pulse 6 is obtained when the reflected light pulse is incident on the object to be measured 4. Note that the light pulse propagating from the light source side to the measured object 4 side within the optical fiber 2 is caused by Ray-Ray scattering, and a part of it is incident on the detection unit 5, and the detected light of the Ray-Ray scattering is shown by line 7 in FIG. decreases over time.
反射パルス６の光反射量Ｒは、
Ｒ＝−10log10（PR／Pi）（dB） (1)
である。こゝでPiは入射光パワー、PRは反射光
パワーである。この反射量Ｒと屈折率は次式で関
係づけられる。 The amount of light reflection R of the reflected pulse 6 is R=-10log 10 (P R /Pi) (dB) (1). Here, Pi is the incident light power and P R is the reflected light power. The amount of reflection R and the refractive index are related by the following equation.
Ｒ＝−10log10〔（ｎ−nf）2／（ｎ＋nf）2〕（dB）(2)
こゝでｎは被測定物４の屈折率、nfは光フアイ
バ２のコア部の屈折率である。R=-10log 10 [(n-n f ) 2 / (n+nf) 2 ] (dB) (2) Here, n is the refractive index of the object to be measured 4, and nf is the refractive index of the core part of the optical fiber 2. be.
第３図に0.8μｍの波長の光を光フアイバ２に入
射した時の各種屈折率ｎの被測定物４からの反射
量Ｒの測定例を示す。実線は式(2)による反射量Ｒ
を示し、光フアイバ２は石英系のものを使用し
た。図中の黒丸は式(1)で測定した反射量Ｒであ
る。これから反射量Ｒを測定することにより、被
測定物４の屈折率ｎを求めることができる。しか
し、第３図からわかるように、同一の反射量Ｒに
対して２つの屈折率ｎが対応する。例えばＲ＝−
35dBのとき、ｎ＝1.415とｎ＝1.52となりこれら
の何れかの判別がつかない。 FIG. 3 shows an example of measuring the amount of reflection R from the object to be measured 4 having various refractive indexes n when light with a wavelength of 0.8 μm is incident on the optical fiber 2. The solid line is the reflection amount R according to equation (2)
The optical fiber 2 was made of quartz. The black circle in the figure is the amount of reflection R measured using equation (1). By measuring the amount of reflection R from this, the refractive index n of the object to be measured 4 can be determined. However, as can be seen from FIG. 3, two refractive indices n correspond to the same amount of reflection R. For example, R=-
At 35 dB, n=1.415 and n=1.52, and it is difficult to distinguish between these two.
この判別をつけるため、異なる波長をもつ複数
個の光源をもちいる。説明のため以下それぞれ波
長λ1とλ2の光を出す２個の光源１1，１2を用い
る。光フアイバ２のコア部の屈折率は一般に波長
によつて変化する。例えば石英系の光フアイバで
は第４図に示すように波長が長くなると屈折率が
小さくなる。２個の波長の光を使用して屈折率ｎ
を測定する例を第５図を参照して説明する。第５
図において実線は波長λ1の反射量Ｒ−屈折率ｎ特
性を、点線は波長λ2の反射量Ｒ−屈折率ｎ特性で
ある。例えば波長λ1の光の反射量がR1のとき、
屈折率はn1またはn2となつた時に、同一の被測定
物に対し他の波長λ2の光で測定し、反射量がR2
ならば屈折率はn1であり、反射量がR3ならば屈
折率はn2と判定できる。より多くの波長の光を用
いることで判別の正確さ及び精度の向上が期待で
きる。 To make this distinction, multiple light sources with different wavelengths are used. For the purpose of explanation, two light sources 1 1 and 1 2 that emit light with wavelengths λ 1 and λ 2 respectively will be used below. The refractive index of the core portion of the optical fiber 2 generally changes depending on the wavelength. For example, in the case of a quartz-based optical fiber, as shown in FIG. 4, the refractive index decreases as the wavelength increases. Using light of two wavelengths, the refractive index n
An example of measuring will be explained with reference to FIG. Fifth
In the figure, the solid line represents the reflection amount R vs. refractive index n characteristic for the wavelength λ 1 , and the dotted line represents the reflection amount R vs. refractive index n characteristic for the wavelength λ 2 . For example, when the amount of reflection of light with wavelength λ 1 is R 1 ,
When the refractive index is n 1 or n 2 , the same measured object is measured with light of another wavelength λ 2 , and the amount of reflection is R 2
Then, the refractive index can be determined to be n 1 , and if the amount of reflection is R 3 , the refractive index can be determined to be n 2 . By using light of more wavelengths, it can be expected that the accuracy and precision of discrimination will be improved.
第６図にこの発明の他の一実施例を示す。光源
１1〜１ｎからの各波長λ1〜λnの光は光合波器８
に同時に入射され、これら合波された光は光方向
性結合器３を介して光フアイバ２に入射される。
光フアイバ２を伝搬したこれら波長λ1〜λnの光
は光フアイバ２の被測定物４との接触端で反射さ
れ、その反射光は光源側に光フアイバ２を伝搬
し、光方向性結合器３にて光源よりの入射光と分
離されて光分波器９に到達し、各波長λ1〜λnの
成分に分離されて検出部５1〜５ｎに供給される。
このようにして各波長λ1〜λnの反射量R1〜Rnを
測定し、これらより、被測定物４の屈折率を求め
る。なお光源１1〜１ｎより光フアイバ２への入
射は光パルスでも連続光でもよい、光パルスの場
合は光方向性結合器３の構成が簡単なものとする
ことができる。 FIG. 6 shows another embodiment of the invention. The light of each wavelength λ 1 to λn from the light sources 1 1 to 1n is sent to an optical multiplexer 8
The multiplexed lights are input to the optical fiber 2 via the optical directional coupler 3.
The light with wavelengths λ 1 to λn propagated through the optical fiber 2 is reflected at the contact end of the optical fiber 2 with the object to be measured 4, and the reflected light propagates through the optical fiber 2 to the light source side and is connected to the optical directional coupler. 3, the light is separated from the incident light from the light source and reaches the optical demultiplexer 9, where it is separated into components of wavelengths λ 1 to λn and supplied to the detection units 5 1 to 5n.
In this way, the reflection amounts R 1 to Rn of each wavelength λ 1 to λn are measured, and the refractive index of the object to be measured 4 is determined from these. Incidentally, the light input from the light sources 1 1 to 1 n to the optical fiber 2 may be a light pulse or a continuous light. In the case of a light pulse, the structure of the optical directional coupler 3 can be made simple.
以上説明したように、この発明によれば光フア
イバを用い、光フアイバと被測定物体との境界か
らの反射光を測定することにより屈折率を測定す
るものであるから、簡便で局所的な場所での屈折
率測定も可能である。また、被測定物体の屈折率
の温度特性なども容易に測定することができる。 As explained above, according to the present invention, the refractive index is measured by using an optical fiber and measuring the reflected light from the boundary between the optical fiber and the object to be measured. It is also possible to measure the refractive index at Furthermore, the temperature characteristics of the refractive index of the object to be measured can be easily measured.
第１図はこの発明による屈折率測定方法の一例
を示すブロツク図、第２図は検出部で検出された
出力−時間特性を示す図、第３図は反射量−屈折
率特性の測定例を示す図、第４図は石英系光フア
イバの屈折率波長特性を示す図、第５図は複数波
長による屈折率の判定を説明するための反射量−
屈折率特性図、第６図はこの発明による屈折率測
定方法の他の例を示すブロツク図である。
１1〜１ｎ：光源、２：光フアイバ、３：光方
向性結合器、４：被測定物、５，５1〜５ｎ：反
射光検出部、８：光合波器、９：光分波器。
Figure 1 is a block diagram showing an example of the refractive index measuring method according to the present invention, Figure 2 is a diagram showing the output-time characteristic detected by the detection section, and Figure 3 is an example of measuring the reflection amount-refractive index characteristic. Figure 4 is a diagram showing the refractive index wavelength characteristics of a silica-based optical fiber, and Figure 5 is a diagram showing the amount of reflection to explain the determination of refractive index using multiple wavelengths.
The refractive index characteristic diagram, FIG. 6, is a block diagram showing another example of the refractive index measuring method according to the present invention. 1 1 to 1n: light source, 2: optical fiber, 3: optical directional coupler, 4: object to be measured, 5, 5 1 to 5n: reflected light detection unit, 8: optical multiplexer, 9: optical demultiplexer .
Claims (1)
バの一端に入射し、その光フアイバの他端を被測
定物と接触させ、その光フアイバと被測定物との
接触端面で反射されて光フアイバを伝ぱんして来
た反射光のレベルを検出し、上記各波長における
反射量−屈折率特性曲線を参照して上記複数の光
信号に対する各反射光のレベルから上記被測定物
の屈折率を決定する屈折率測定方法。1. A plurality of optical signals with different wavelengths are input into one end of an optical fiber, the other end of the optical fiber is brought into contact with an object to be measured, and the optical signals are reflected from the contact end surface between the optical fiber and the object to be measured, and the optical fiber is Detect the level of the reflected light that has propagated, and determine the refractive index of the object to be measured from the level of each reflected light for the plurality of optical signals by referring to the reflection amount-refractive index characteristic curve at each of the wavelengths. refractive index measurement method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12550882A JPS5915841A (en) | 1982-07-19 | 1982-07-19 | Refractive index measuring apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12550882A JPS5915841A (en) | 1982-07-19 | 1982-07-19 | Refractive index measuring apparatus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5915841A JPS5915841A (en) | 1984-01-26 |
| JPS6334421B2 true JPS6334421B2 (en) | 1988-07-11 |
Family
ID=14911858
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12550882A Granted JPS5915841A (en) | 1982-07-19 | 1982-07-19 | Refractive index measuring apparatus |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5915841A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04336064A (en) * | 1991-05-10 | 1992-11-24 | Paramount Bed Co Ltd | Patient transferring bed |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2524128B2 (en) * | 1986-09-16 | 1996-08-14 | スタンレー電気株式会社 | Curve prism type liquid refractometer |
| JPH07119633B2 (en) * | 1986-11-07 | 1995-12-20 | 株式会社竹中工務店 | Drainage |
| JPH01257245A (en) * | 1987-09-22 | 1989-10-13 | Nkk Corp | Measuring apparatus for mixing ratio of fuel for internal combustion engine |
| JP2008089565A (en) * | 2006-09-06 | 2008-04-17 | Toyohashi Univ Of Technology | Optical fiber plant sensing device and its method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS53116188A (en) * | 1977-03-19 | 1978-10-11 | Touhoku Rikoo Kk | Refractive index measuring device |
| JPS5489680A (en) * | 1977-12-26 | 1979-07-16 | Matsushita Electric Ind Co Ltd | Optical measuring method and optical measuring apparatus |
| JPS5690244A (en) * | 1979-12-25 | 1981-07-22 | Nippon Sheet Glass Co Ltd | Refraction index meter for liquid |
-
1982
- 1982-07-19 JP JP12550882A patent/JPS5915841A/en active Granted
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS53116188A (en) * | 1977-03-19 | 1978-10-11 | Touhoku Rikoo Kk | Refractive index measuring device |
| JPS5489680A (en) * | 1977-12-26 | 1979-07-16 | Matsushita Electric Ind Co Ltd | Optical measuring method and optical measuring apparatus |
| JPS5690244A (en) * | 1979-12-25 | 1981-07-22 | Nippon Sheet Glass Co Ltd | Refraction index meter for liquid |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04336064A (en) * | 1991-05-10 | 1992-11-24 | Paramount Bed Co Ltd | Patient transferring bed |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5915841A (en) | 1984-01-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| ATE27489T1 (en) | FIBER OPTIC MEASUREMENT DEVICE. | |
| CA1290589C (en) | Sensing strain and temperature | |
| JPH0364812B2 (en) | ||
| US6618536B1 (en) | Integrated optical waveguide system | |
| CA1267790A (en) | Fiber optic doppler anemometer | |
| JPH02116716A (en) | Fiber optical sensor | |
| KR930016767A (en) | Measurement method of fiber optical force by birefringence of stress-induced single mode photoelectric tube | |
| EP1265062B1 (en) | Chromatic-dispersion measuring apparatus and method for optical fibres | |
| EP0260894A1 (en) | Optical fibre measuring system | |
| JPH1164119A (en) | Optical fiber thermal distorsion sensor and thermal distorsion measuring device | |
| JPS6334421B2 (en) | ||
| JP2001201407A (en) | Wavelength measuring device | |
| JPH03107702A (en) | Photosensor having multimode interference | |
| JPH0549057B2 (en) | ||
| JPH0354292B2 (en) | ||
| JP2657018B2 (en) | Optical Connector Return Loss Measurement System | |
| JP3063138B2 (en) | Waveguide type wavelength measuring device | |
| GB2207236A (en) | Sensing temperature or pressure distribution | |
| JPS6330739A (en) | Method for measuring back scattering of optical fiber | |
| JPS59226832A (en) | Optical ic sensor | |
| JPS62159027A (en) | Detecting device for degree of deterioration of oil | |
| GB2150687A (en) | Fibre optic sensor | |
| JPS6066137A (en) | Liquid refractive index sensor head | |
| JPH0510833A (en) | Fiber for temperature sensor | |
| SU1027562A1 (en) | Method of measuring transitional attenuation between two channels of optical fibrebranching |