CN202453113U

CN202453113U - Sensor for measuring temperature and salinity of seawater based on fibre Bragg grating (FBG)

Info

Publication number: CN202453113U
Application number: CN201120543880.9U
Authority: CN
Inventors: 刘贤超; 赵春柳; 陈业慈; 陈永伟; 张聪聪
Original assignee: China Jiliang University
Current assignee: China Jiliang University
Priority date: 2011-12-15
Filing date: 2011-12-15
Publication date: 2012-09-26
Anticipated expiration: 2021-12-15

Abstract

The utility model relates to a sensor for measuring the temperature and salinity of seawater based on a fibre Bragg grating (FBG). According to the sensor, one end of a fibre long-period grating (2) is connected with a broadband light source (1), and the other end of the fibre long-period grating (2) is connected with a first port on one side comprising three ports of a 1*3 branching unit (3); the second and third ports on the side of the 1*3 branching unit (3) are respectively connected with one photodiode (7) in a micro processing system (9) and a matched fibre Bragg grating (6); the other end of the matched fibre Bragg grating (6) is connected with the other photodiode (8) in the micro processing system (9); the ports on the other side of the 1*3 branching unit (3) are connected with a fibre Bragg grating (4) and a uniformly corroded Bragg grating (5) in a cascaded manner; and the output end of the micro processing system (9) is connected with a display nixie tube (10). The utility model has the advantages of small size, corrosion resistance, high sensitivity, capability of remote sensing, low cost and high economic practicability.

Description

A kind of based on the measurement ocean temperature of FBG and the sensor of salinity

Technical field:

The utility model belongs to technical field of optical fiber sensing, relates to a kind of based on the measurement ocean temperature of FBG and the sensor of salinity.

Background technology:

The detection of ocean temperature and salinity detects research thalassography, marine environment, and seasonal climate prediction and sea fishery etc. have crucial Practical significance.Country already is placed on sea farming in 12 planning and focuses the consruction among the object, will already bring huge economic benefit to sea farming to the real-time monitoring of ocean temperature and salinity.

In the classic method; The detection of ocean temperature and salinity adopts the representative water sample of collection to test more; Not only process loaded down with trivial details, waste time and energy, and the sampling liquid temperature (and salinity) possibly in gatherer process, change, cause measuring error; And exist and to monitor in real time ocean temperature and salinity, problems such as measurement data storage difficulty.Fiber-optic grating sensor can solve the problem that above traditional measurement method exists.

Fiber grating is development in recent years one of fiber optic passive device the most rapidly; It has the advantage of general optical fibre refractivity sensor; And adopt the wavelength-modulated mode, need not any indemnifying measure to the joints of optical fibre and coupling mechanism, fibre-optical bending, flashing are fixed etc., the while can also be multiplexing with a plurality of gratings easily; Cascade system realizes the sensing measurement of multiple spot, and this is that other senser elements are incomparable.It is little, anticorrosive that fiber-optic grating sensor also has a volume, do not receive the interference of electromagnetic field, highly sensitive and can remote sensing etc. advantage.Fiber-optic grating sensor technology in the stress measurement of tunnel bridge is comparatively ripe, uses extensivelyr, and technology is backward relatively aspect the temperature salimity measurement, and practical application is very few.

Summary of the invention:

The utility model is loaded down with trivial details to traditional ocean temperature salinity detector measuring process, waste time and energy, and can not monitor ocean temperature and salinity in real time, can not storing data automatically, propose a kind of based on the measurement ocean temperature of FBG and the sensor of salinity.

The technical scheme that the utility model technical solution problem is taked is:

A kind of based on the measurement ocean temperature of FBG and the sensor of salinity, comprise wideband light source, long-period fiber grating, 1*3 shunt, Fiber Bragg Grating FBG, pass through Bragg grating, matched fiber Bragg grating, two photodiodes, microprocessing systems and demonstration charactrons of uniform corrosion.The Bragg grating of Fiber Bragg Grating FBG and process uniform corrosion is measured ocean temperature and salinity respectively as sensing grating.

The wideband light source of power invariability links to each other with an end of long-period fiber grating; The other end of long-period fiber grating links to each other with first port on one side of containing three ports of 1*3 shunt; Second port on this limit of 1*3 shunt directly connects first photodiode in the microprocessing systems; The 3rd port links to each other with the matched fiber Bragg grating; The other end of matched fiber Bragg grating connects second photodiode in the microprocessing systems, and the port of 1*3 shunt another side connects Fiber Bragg Grating FBG and passes through the Bragg grating of uniform corrosion with the mode of cascade, and the other end of microprocessing systems connects and shows charactron.

The beneficial effect that the utility model had is: the wideband light source of the utility model produces power and the linear broadband light of optical wavelength through long-period fiber grating filtering; To cooperate when ocean temperature or the salinity variation; Sensing grating can reflect the different light intensity value information, and reflective light intensity is directly proportional with sensing Bragg grating centre wavelength drift value; Adopt the Bragg grating that corroded through even, the degree of depth to measure salinity, corrosion depth is to fibre core and covering intersection, and it is all very responsive to temperature and salinity, has improved measuring accuracy and sensitivity; Employing is with Bragg grating and the matched fiber Bragg grating of a kind of Fiber Bragg Grating FBG as the measurement temperature; And with sensing with Fiber Bragg Grating FBG, place the seawater same point through the Bragg grating and the matched fiber Bragg grating of uniform corrosion; The matched fiber Bragg grating reflects TEMP grating reflection light fully; Transmitted light only contains the reflected light of salinity sensing grating, realizes that perfect restitution goes out the light intensity that is reflected by the Bragg grating through uniform corrosion; The microprocessing systems that re-uses functions such as having opto-electronic conversion amplification, computing is handled the intensity signal of separating, and meter is calculated ocean temperature and salinity, has avoided use photoswitch, F-P (FBG) demodulator or spectrometer etc., reduces cost greatly.The utility model volume is little, and is anticorrosive, highly sensitive and can remote sensing, and cost is lower, and practicality is high.

Description of drawings:

Be illustrated as the structural drawing of the utility model.

1: wideband light source; 2: long-period fiber grating; The 3:1*3 shunt; 4: Fiber Bragg Grating FBG; 5: through the Bragg grating of uniform corrosion; 6: the matched fiber Bragg grating; 7: photodiode; 8: photodiode; 9: microprocessing systems; 10: show charactron.

Specific embodiments:

Below in conjunction with accompanying drawing the utility model is further described.

As shown in the figure; A kind of based on the measurement ocean temperature of FBG and the sensor of salinity, comprise wideband light source 1, long-

period fiber grating

2,1*3 shunt 3, Fiber Bragg Grating FBG 4, Bragg grating 5, matched fiber Bragg grating 6, photodiode 7, photodiode 8, microprocessing systems 9 and show charactron 10 through uniform corrosion.

Wideband light source 1 links to each other with an end of long-period fiber grating 2; The other end of long-period fiber grating 2 links to each other with first port on one side of containing three ports of 1*3 shunt 3; Second port on 1*3 shunt 3 these limits is connected directly to a photodiode 7 in the microprocessing systems 9; The 3rd port on 1*3 shunt 3 these limits links to each other with matched fiber Bragg grating 6; The other end of matched fiber Bragg grating 6 connects the another photodiode 8 in the microprocessing systems 9; The port of 1*3 shunt 3 another sides connects Fiber Bragg Grating FBG 4 and passes through the Bragg grating 5 of uniform corrosion with the mode of cascade, and the output terminal of microprocessing systems 9 connects and shows charactron 10.

Fiber Bragg Grating FBG 4 and matched fiber Bragg grating 6 are got with a kind of specification, and two photodiodes are got with a kind of specification.Bragg grating 5 centre wavelengths of Fiber Bragg Grating FBG 4 and process uniform corrosion differ 5 to 10nm.Two photodiodes are connected with circuit in microprocessing systems 9.

The utility model is based on following principle:

The light that wideband light source 1 sends goes into to inject the Bragg grating 5 of Fiber Bragg Grating FBG 4 and process uniform corrosion through long-

period fiber grating

2,1*3 shunt 3; Owing to the centre wavelength of Fiber Bragg Grating FBG 4 can change along with ocean temperature; The centre wavelength of the Bragg grating 5 of process uniform corrosion can change and change along with ocean temperature and salinity; And all has the better linearity corresponding relation; When ocean temperature and salinity variation; Fiber Bragg Grating FBG 4 and drift about through the centre wavelength of the Bragg grating 5 of excessive erosion, their reflectance spectrum will be corresponding to the different-wavebands of incident broadband light, because of incident wideband light source 1 through long-period fiber grating 2 filtering; Become the linear broadband light of power and optical wavelength; Then the intensity of reflectance spectrum is along with the proportional variation of the drift value of centre wavelength, when choosing Fiber Bragg Grating FBG with Fiber Bragg Grating FBG 4 specifications of the same race as matched fiber Bragg grating 6, coupling light placed the seawater same point through Bragg grating 6, Fiber Bragg Grating FBG 4 with through the Bragg grating 5 of uniform corrosion; The spectral drift of matched fiber Bragg grating 6 and Fiber Bragg Grating FBG 4 is identical when ocean temperature changes, and matched fiber Bragg grating 6 perfect restitutions go out by Bragg grating 5 spectrum of reflected light through uniform corrosion.So, as long as measure the spectral intensity of transmission overmatching Fiber Bragg Grating FBG 6 and, just can calculate ocean temperature and salinity through the spectral intensity of second port outgoing of 1*3 shunt 3.

The concrete course of work of the utility model is: the light that wideband light source 1 sends obtains power and the linear broadband light of optical wavelength through long-period fiber grating 2 filtering; This broadband light acts on the Bragg grating 5 of Fiber Bragg Grating FBG 4 and process uniform corrosion; When ocean temperature and salinity change; The light of the Bragg grating 5 reflected back different light intensity of Fiber Bragg Grating FBG 4 and process uniform corrosion; Matched fiber Bragg grating 6 demodulates by Bragg grating 5 spectrum of reflected light through uniform corrosion; The spectrum that 9 pairs of microprocessing systems are demodulated by matched fiber Bragg grating 6 and carry out opto-electronic conversion through the spectrum of second port outgoing of 1*3 shunt 3 and amplify, and subtracting makes by the corresponding electric signal of the light intensity signal of 1*3 shunt 3 second port output on one side and the light intensity signal of transmission overmatching Fiber Bragg Grating FBG 6 and subtracts each other; Isolate only corresponding to the corresponding electric signal of Fiber Bragg Grating FBG 4 reflected light; And two path signal carried out A/D conversion, in single-chip microcomputer, carry out computing, with the net result dynamic memory in chip and be input to and show on the charactron 10 and show.

The FBG of the process uniform corrosion in the present embodiment is a SMF-28 single-mode fiber Bragg grating, core diameter 8.3 μ m, and cladding diameter is 125 μ m, numerical aperture is 0.14; FBG grid region length through uniform corrosion is 20mm, and fibre diameter is 10 μ m.

Claims

1. one kind based on the measurement ocean temperature of FBG and the sensor of salinity; It comprises Bragg grating, matched fiber Bragg grating, photodiode, microprocessing systems, the demonstration charactron of wideband light source, long-period fiber grating, 1*3 shunt, Fiber Bragg Grating FBG, process uniform corrosion; It is characterized in that: an end of long-period fiber grating links to each other with wideband light source; The other end of long-period fiber grating links to each other with first port on one side of containing three ports of 1*3 shunt; Second port on this limit of 1*3 shunt connects a photodiode in the microprocessing systems; The 3rd port connects the coupling Bragg grating; The other end of matched fiber Bragg grating connects the another photodiode in the microprocessing systems, and the port of 1*3 shunt another side connects Fiber Bragg Grating FBG and passes through the Bragg grating of uniform corrosion with the mode of cascade, and the other end of microprocessing systems connects and shows charactron.