TWI407082B - Fiber optic sensing system - Google Patents
Fiber optic sensing system Download PDFInfo
- Publication number
- TWI407082B TWI407082B TW99118056A TW99118056A TWI407082B TW I407082 B TWI407082 B TW I407082B TW 99118056 A TW99118056 A TW 99118056A TW 99118056 A TW99118056 A TW 99118056A TW I407082 B TWI407082 B TW I407082B
- Authority
- TW
- Taiwan
- Prior art keywords
- optical
- wavelength
- sensing
- fiber
- filter
- Prior art date
Links
Landscapes
- Optical Transform (AREA)
- Measuring Temperature Or Quantity Of Heat (AREA)
Abstract
Description
本發明係關於一種光纖感測技術，尤指一種利用光學共振腔信號調制技術將一光纖光柵波長的位移量直接轉換為光強度信號。同時因光調置信號可在光共振腔中連續放大，因此可以獲得良好的信號/雜訊比。The invention relates to a fiber sensing technology, in particular to an optical resonant cavity signal modulation technique for directly converting a displacement of a fiber grating wavelength into a light intensity signal. At the same time, since the light modulation signal can be continuously amplified in the optical cavity, a good signal/noise ratio can be obtained.
傳統利用光柵元件進行感測的系統主要包含有一寬頻光源、一作為感測頭之光纖光柵元件與一光譜儀(Optical spectrum analizer)。當寬頻光源由光柵元件反射後，因為受到溫度或應力使光纖光柵的週期變化，造成光柵反射波長位移，故利用光譜儀可測得光柵反射波長的位移。此種量測方法的精度較高，但其缺點在於系統複雜、光譜儀成本昂貴，難以廣泛普及運用，在實際作業時光譜儀掃描讀取皆需要一時間，所以無法達到光纖光柵波長變化的即時量測。Conventional systems that utilize grating elements for sensing primarily include a broadband source, a fiber grating component as a sensing head, and an optical spectrum analizer. When the broadband source is reflected by the grating element, the grating reflects the wavelength shift due to the temperature or stress, which causes the grating to reflect the wavelength shift. Therefore, the displacement of the grating reflection wavelength can be measured by the spectrometer. The accuracy of the measurement method is high, but the disadvantage is that the system is complicated, the spectrometer is expensive, and it is difficult to widely use it. In the actual operation, the spectrometer scans and reads all takes a time, so the instantaneous measurement of the wavelength change of the fiber grating cannot be achieved. .
鑑於傳統光纖光柵必須以專業之光譜儀方能判讀出反射信號之波長位移，光譜儀設備成本昂貴而不利廣泛運用，且難以達到對反射信號波長變化的即時量測，故本發明之主要目的係提供一種光纖感測系統，以利用光振腔特性直接將光纖光柵反射信號的波長位移差異轉換成光調置信號，藉此達到待測物理量的變化程度。In view of the fact that the conventional fiber grating must be able to read the wavelength shift of the reflected signal by a professional spectrometer, the spectrometer equipment is expensive and unsuitable for widespread use, and it is difficult to achieve an instantaneous measurement of the wavelength change of the reflected signal, so the main object of the present invention is to provide a The optical fiber sensing system directly converts the wavelength shift difference of the fiber grating reflection signal into a light modulation signal by utilizing the characteristics of the optical vibration cavity, thereby achieving the degree of change of the physical quantity to be measured.
為達成前述目的，本發明光纖光柵感測系統係包含有：一激發光源，係可產生增益居量反置之雷射光源；一波長多工器，係耦合激發光源及感測光源；一光增益介質，係連接該波長多工器，激發光源使光增益介質達到光居量反置而產生光增益效果；一參考波長濾波器，具有一特定頻寬的波長濾波器，提供一參考信號波長，其波長可藉電壓或電流調整；至少一感測光纖光柵，其反射波長範圍在參考波長濾波器的可調波長範圍之內，係感測一物理量之變化而造成本身反射波長的位移，該參考波長濾波器受激發之光增益介質與感測光纖光柵形成一光共振腔；一第一光耦合器，連接光共振腔及感測光纖光柵；一第二光耦合器，連接該光共振腔及一光偵測器；一第三光耦合器，連接光共振腔及該參考波長濾波器、；一信號處理電腦主機，係連接該光偵測器，接收該光偵測器轉換出之電流或電壓信號，並運算成為代表該感測光纖光柵實際測量之物理量。In order to achieve the foregoing objective, the fiber grating sensing system of the present invention comprises: an excitation light source, which is a laser light source capable of generating a gain reversal; a wavelength multiplexer coupled to the excitation light source and the sensing light source; The gain medium is connected to the wavelength multiplexer, and the excitation light source causes the optical gain medium to reach the optical quantity inverse to generate an optical gain effect; a reference wavelength filter has a wavelength filter of a specific bandwidth to provide a reference signal wavelength The wavelength can be adjusted by voltage or current; at least one of the sensing fiber gratings has a reflection wavelength range within a tunable wavelength range of the reference wavelength filter, and senses a change in a physical quantity to cause a displacement of the reflected wavelength itself. The reference wavelength filter is excited by the optical gain medium and the sensing fiber grating forms an optical cavity; a first optical coupler connecting the optical cavity and the sensing fiber grating; and a second optical coupler connecting the optical cavity And a photodetector; a third optocoupler connecting the optical resonant cavity and the reference wavelength filter; and a signal processing computer host connected to the photodetector, The received photodetector converts a signal of current or voltage, and calculates a representative of a physical quantity sensing the actual measurement of the fiber grating measured.
前述參考波長濾波器可利用一光纖光柵或其他形式之濾波元件構成；該感測光纖光柵的數目可為複數個並搭配一光多工切換裝置於各感測光柵之間加以切換以達到多點量測目的。The reference wavelength filter may be constructed by using a fiber grating or other types of filtering components; the number of the sensing fiber gratings may be plural and matched with an optical multiplexing switching device to switch between the sensing gratings to achieve multiple points. Measurement purposes.
利用前述架構，參考波長濾波器受激發之光增益介質與感測光柵形成一光學共振腔，該參考波長濾波器可利用電壓控制而提供一參考信號的調整，當感測光纖光柵用於指定地點測量如溫度、壓力之物理量時，參考波長濾波器及感測光纖光柵兩者之濾波波長會產生位移差異，該波長之差異量可提供該光學放大共振腔之光增益放大調制，該光調制信號經由光偵測器將光調制信號轉成電流或壓信號，該信號處理電腦主機進行光柵感測解調運算，即能快速獲得該感測光纖光柵所實際測量之物理量。With the foregoing architecture, the optical gain medium excited by the reference wavelength filter and the sensing grating form an optical resonant cavity, and the reference wavelength filter can provide a reference signal adjustment by voltage control when the sensing fiber grating is used for the designated location. When measuring physical quantities such as temperature and pressure, the filter wavelengths of both the reference wavelength filter and the sensing fiber grating may produce a displacement difference, and the difference amount of the wavelength may provide optical gain amplification modulation of the optical amplification cavity, the light modulation signal The optical modulation signal is converted into a current or voltage signal by a photodetector, and the signal processing computer host performs raster sensing demodulation operation, that is, the physical quantity actually measured by the sensing fiber grating can be quickly obtained.
請參考第一圖所示，為本發明之系統架構圖，包含有：一激發光源(2)，係可產生增益居量反置之雷射光源，光源波長為980nm；一波長多工器(WDM)(4)，連接該激發光源(2)與感測雷射光源；一光增益介質(6)，例如摻鉺光纖或其他光增益介質，係連接該波長多工器(4)，來自激發光源(2)的雷射通過光增益介質(6)在光共振腔內產生感測光柵光調置作用，其波長範圍約為1515nm~1575nm之間；一參考波長濾波器(wave length filter)(20)，具有一特定頻寬的濾波性能，本實施例以一可調式之波長濾波器(Turnable wave length filter)為例說明其波長範圍可介在1540nm~1580nm之間，該參考波長濾波器(20)可透過電壓信號的調整，藉由壓電效應可改變該參考波長濾波器(20)之濾波波長；至少一感測光纖光柵(sensing fiber Bragg grating)(30)，其反射波長在參考波長濾波器(20)可調範圍之內，該感測光纖光柵(30)係感測一物理量之變化而造成本身反射波長的位移，包括溫度、形變、應力，及其所應用之感測物理量，在本實施例中係以多個感測光纖光柵(30)配合一光多工切換裝置(40)進行多點的信號量測，該光多工切換裝置(40)可任意或依序切換或固定選擇其中一感測光纖光柵(30)作為長時間測量或動態信號掃描資料來源；一第一光耦合器(11)，連接該光增益介質(6)，本實施範例為一摻鉺光纖及透過該光多工切換裝置(11)並連接該感測光纖光柵(30)，該第一光耦合器(11)其耦合比依系統需要調整，而本範例為10/90；一第二光耦合器(12)，其功能為將部份光共振腔內之調置光強度輸出至一光偵測器(14)，光偵測器(14)將光信號轉換成電流或電壓信號後輸出至一信號處理電腦主機(50)作光柵感測信號調置，該第二光耦合器(12)其耦合比可依系統需求而訂，本實施範例為10/90；一第三光耦合器(13)，連接該參考波長濾波器(20)、波長多工器(4)及第二光耦合器(12)，其作用為提供光共振腔之參考波長，該第三光耦合器(13)其耦合比可依系統需求而訂，本實施範例為10/90。Please refer to the first figure, which is a system architecture diagram of the present invention, comprising: an excitation light source (2), which is a laser source capable of generating a gain-reducing inverse, the wavelength of the light source is 980 nm; a wavelength multiplexer ( WDM) (4), connecting the excitation light source (2) and the sensing laser light source; an optical gain medium (6), such as an erbium-doped fiber or other optical gain medium, is connected to the wavelength multiplexer (4) from The laser of the excitation light source (2) generates a sensing grating light modulation effect in the optical cavity through the optical gain medium (6), and the wavelength range thereof is between 1515 nm and 1575 nm; a reference wavelength filter (wave length filter) (20), having a specific bandwidth filter performance, this embodiment uses a tunable wave length filter as an example to illustrate that the wavelength range can be between 1540 nm and 1580 nm, the reference wavelength filter ( 20) modulating the voltage signal, the filter wavelength of the reference wavelength filter (20) can be changed by a piezoelectric effect; at least one sensing fiber Bragg grating (30) whose reflection wavelength is at a reference wavelength Within the adjustable range of the filter (20), the sensing fiber grating (3 0) sensing a change in a physical quantity to cause a displacement of a self-reflecting wavelength, including temperature, deformation, stress, and a sensing physical quantity to which it is applied. In this embodiment, a plurality of sensing fiber gratings (30) are used. An optical multiplexing switching device (40) performs multi-point signal measurement, and the optical multiplexing switching device (40) can switch or fixed one of the sensing fiber gratings (30) as long-term measurement or dynamics arbitrarily or sequentially. a source of signal scanning data; a first optical coupler (11) connected to the optical gain medium (6), which is an erbium doped fiber and transmitted through the optical multiplexing switching device (11) and connected to the sensing fiber grating (30), the first optical coupler (11) has a coupling ratio adjusted according to the system, and the example is 10/90; a second optical coupler (12) functions as a part of the optical cavity The light intensity output is adjusted to a photodetector (14), and the photodetector (14) converts the optical signal into a current or voltage signal and outputs the signal to a signal processing computer host (50) for raster sensing signal adjustment. The coupling ratio of the second optical coupler (12) can be set according to system requirements, and the embodiment is 10/90; a three-optical coupler (13) connected to the reference wavelength filter (20), the wavelength multiplexer (4) and the second optical coupler (12) for providing a reference wavelength of the optical resonant cavity, the third optical coupling The coupling ratio of the device (13) can be set according to the system requirements, and the embodiment is 10/90.
基於上述的光柵感測信號解調系統硬體架構，本發明中的參考波長濾波器(20)可利用電壓的調整而提供一參考波長信號，該感測光纖光柵(30)則是作為一待測元件，用以感應如溫度或壓力之物理量，使得參考波長濾波器(20)、 光增益介質(6)及感測光纖光柵(30)之間形成一環型光共振腔，當前述感測光纖光柵(30)因為溫度或壓力差導致反射波長發生位移，會造成光學共振腔之光放大強度調置。Based on the hardware architecture of the grating sensing signal demodulation system described above, the reference wavelength filter (20) of the present invention can provide a reference wavelength signal by adjusting the voltage, and the sensing fiber grating (30) is treated as a Measuring component for sensing a physical quantity such as temperature or pressure, such that the reference wavelength filter (20), A ring-shaped optical cavity is formed between the optical gain medium (6) and the sensing fiber grating (30). When the sensing fiber grating (30) is displaced due to temperature or pressure difference, the optical cavity is caused to be displaced. Magnification intensity adjustment.
因感測光柵所產生之光強度信號調置在光學放大共振腔裡面重覆獲得光增益放大，如此一來有助於遠距離光纖感測的信號偵測，放大後的信號部份經由該第二光耦合器(12)輸出至一光偵測器(14)，該光偵測器(14)可以將此光調置信號直接轉成電流或電壓信號，該信號經信號處理電腦主機(50)運算，轉換成代表該感測光纖光柵(30)實際的溫度或壓力應變之資料。The light intensity signal generated by the sensing grating is placed in the optical amplifying cavity to repeatedly obtain the optical gain amplification, thereby facilitating signal detection of the long-distance fiber sensing, and the amplified signal portion is passed through the first The two optocoupler (12) outputs to a photodetector (14), and the photodetector (14) can directly convert the optical modulation signal into a current or voltage signal, and the signal is processed by a computer processing host (50) The operation is converted to data representative of the actual temperature or pressure strain of the sensing fiber grating (30).
本發明利用一個環狀光學放大共振腔，藉由其中一個光纖光柵(30)感測外界環境變化產生波長的位移，造成環狀光學放大共振腔的光調置，以將光柵的反射信號再放大，藉一光偵測器(14)將感測光柵波長位移量直接轉成電流或電壓信號，如此提高其信號雜訊比，並可達到瞬時環境變化的監測。The invention utilizes a ring-shaped optical amplifying resonant cavity, wherein one of the fiber gratings (30) senses the displacement of the wavelength caused by the change of the external environment, thereby causing the optical modulation of the annular optical amplifying resonant cavity to re-amplify the reflected signal of the grating The light detector (14) directly converts the wavelength shift of the sensing grating into a current or voltage signal, thereby increasing the signal noise ratio and monitoring the instantaneous environmental change.
本發明可以廣泛應用於公共建築物，如橋樑、大樓、堤防、隧道、鐵路、儲油槽、輸油管等設施的安全監測，也可以應用於其它與民生有關之環境監控，如地震、火災、土石流等天然災害的警報，甚至一般家庭的防盜及水電安全警報系統，可應用層面之涵蓋範圍廣大，因為不需要使用昂貴的光譜分析儀，可以降低光纖感測系統的成本，且可以提高光纖光柵信號感測解調時間，達到高頻率的振動或變化量測。The invention can be widely applied to safety monitoring of public buildings, such as bridges, buildings, dikes, tunnels, railways, oil storage tanks, oil pipelines, etc., and can also be applied to other environmental monitoring related to people's livelihood, such as earthquakes, fires, earth and rock flows, etc. Natural disaster warnings, even general household anti-theft and hydro-electric security alarm systems, can be applied at a wide range of applications, because the use of expensive spectrum analyzers is not required, the cost of the fiber-optic sensing system can be reduced, and the fiber-optic grating signal can be improved. Demodulation time is measured to achieve high frequency vibration or change measurement.
(2)．．．激發光源(2). . . Excitation source
(4)．．．波長多工器(4). . . Wavelength multiplexer
(6)．．．光增益介質(6). . . Optical gain medium
(11)．．．第一光耦合器(11). . . First optocoupler
(12)．．．第二光耦合器(12). . . Second optocoupler
(13)．．．第三光耦合器(13). . . Third optical coupler
(14)．．．光偵測器(14). . . Light detector
(20)．．．參考波長濾波器(20). . . Reference wavelength filter
(30)．．．感測光纖光柵(30). . . Sense fiber grating
(40)．．．光多工切換裝置(40). . . Optical multiplexing switching device
(50)．．．信號處理電腦主機(50). . . Signal processing computer host
第一圖：本發明之系統架構圖。First Figure: System architecture diagram of the present invention.
(2)．．．激發光源(2). . . Excitation source
(4)．．．波長多工器(4). . . Wavelength multiplexer
(6)．．．光增益介質(6). . . Optical gain medium
(11)．．．第一光耦合器(11). . . First optocoupler
(12)．．．第二光耦合器(12). . . Second optocoupler
(13)．．．第三光耦合器(13). . . Third optical coupler
(14)．．．光偵測器(14). . . Light detector
(20)．．．參考波長濾波器(20). . . Reference wavelength filter
(30)．．．感測光纖光柵(30). . . Sense fiber grating
(40)．．．光多工切換裝置(40). . . Optical multiplexing switching device
(50)．．．信號處理電腦主機(50). . . Signal processing computer host
Claims (7)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| TW99118056A TWI407082B (en) | 2010-06-04 | 2010-06-04 | Fiber optic sensing system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| TW99118056A TWI407082B (en) | 2010-06-04 | 2010-06-04 | Fiber optic sensing system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| TW201144773A TW201144773A (en) | 2011-12-16 |
| TWI407082B true TWI407082B (en) | 2013-09-01 |
Family
ID=46765715
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| TW99118056A TWI407082B (en) | 2010-06-04 | 2010-06-04 | Fiber optic sensing system |
Country Status (1)
| Country | Link |
|---|---|
| TW (1) | TWI407082B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103620350B (en) * | 2012-06-19 | 2016-03-30 | 株式会社利倍库斯 | Determinator |
| CN104198085B (en) * | 2014-09-16 | 2017-02-08 | 深圳先进技术研究院 | Method for processing data of temperature demodulation for fiber-optic temperature sensor |
| CN107121217A (en) * | 2017-04-27 | 2017-09-01 | 北京石油化工学院 | Soil moisture detection means, system and heating system in earth source heat pump |
-
2010
- 2010-06-04 TW TW99118056A patent/TWI407082B/en active
Non-Patent Citations (1)
| Title |
|---|
| Jharna Mandal, Suchandan Pal, Tong Sun, Kenneth T. V. Grattan, Andreas T. Augousti, and Scott A. Wade, Bragg Grating-Based Fiber-Optic Laser Probe for Temperature Sensing, IEEE Photonics Technology Letters January 2004, vol. 16, No. 1, p.p.218~220. * |
Also Published As
| Publication number | Publication date |
|---|---|
| TW201144773A (en) | 2011-12-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Lu et al. | Distributed optical fiber sensing: Review and perspective | |
| US9146095B2 (en) | FBG vibration detection system, apparatus and vibration detection method using the system | |
| US8553211B2 (en) | Stimulated Brillouin system with multiple FBG's | |
| WO2001009565A1 (en) | System for sensing strain in optical fiber structure | |
| CN101387527B (en) | Optical fiber grating sensing demodulator and use thereof | |
| TWI407082B (en) | Fiber optic sensing system | |
| Gaudron et al. | LPG-based optical fibre sensor for acoustic wave detection | |
| CN110967107A (en) | Interference type fiber Bragg grating acoustic emission signal sensing system | |
| CN105783996B (en) | It is a kind of to measure sound wave and the fibre optical sensor of pressure simultaneously | |
| CN104019760A (en) | Sensitivity enhancement demodulation method and device of fiber optical Bragg grating strain sensor | |
| Wild et al. | Distributed sensing, communications, and power in optical Fibre Smart Sensor networks for structural health monitoring | |
| CN211576347U (en) | Interference type fiber Bragg grating acoustic emission signal sensing system | |
| JP4485236B2 (en) | FBG temperature or strain measurement device using ASE light source and Raman amplification | |
| Wild et al. | Distributed optical fibre smart sensors for structural health monitoring: A smart transducer interface module | |
| JPWO2011033649A1 (en) | Distributed fiber optic sensor device with multiple sensing areas | |
| Mao et al. | Fast interrogation of dynamic fiber Bragg grating using neighborhood average algorithm | |
| da Silveira et al. | Interferometric optical fiber inclinometer with dynamic FBG based interrogation | |
| Comanici et al. | Measurement of dynamic strain using a fiber Bragg grating-based laser sensor system | |
| Tan et al. | Simultaneous measurement of temperature, hydrostatic pressure and acoustic signal using a single distributed Bragg reflector fiber laser | |
| Hong et al. | Strain monitoring of a smart bridge using a fiber Bragg grating sensor system with a wavelength-swept fiber laser | |
| Mao et al. | Dynamic sensors based on fiber-ring laser using a semiconductor optical amplifier | |
| Xiao et al. | Polarimetric Fiber Laser Sensor with Enhanced Sensitivity by Utilizing a Hi-Bi EDF | |
| Semenova et al. | Fabry-Perot liquid crystal tunable filter for interrogation of multiple fibre Bragg grating sensors | |
| Benson et al. | Fibre Optic Sensor Systems without Using Spectral Analysis | |
| Jaharudin et al. | Optical Strain Detection with Transmitted Light of Fiber Bragg Grating |