Summary of the invention
The object of the invention is exactly the above-mentioned defective that will overcome prior art; A kind of fibre-optical probe and the combined type liquid fiber densimeter that adopts this fibre-optical probe are provided, and its error is little, and reliability is high; Do not receive the influence of electromagnetic field, big electric current and high temperature; Probe size is little, and easy mounting and maintenance can realize Distance Test.
For reaching above-mentioned purpose; Fibre-optical probe provided by the invention comprises measuring staff; The front end of said measuring staff is equipped with Fibre Optical Sensor, is equipped with and leads fibre bundle, fiber distribution box, has single-core fiber bundle, detector and the light source of protective sleeve in the inner chamber of said measuring staff, and said Fibre Optical Sensor comprises input optical fibre, output optical fibre and 45 prism; Said 45 prism is positioned at the outside of said measuring staff, inserts in the fluid to be measured 20; Said input optical fibre links to each other with said light source; Said output optical fibre links to each other with said detector through the single-core fiber bundle of saidly leading fibre bundle, fiber distribution box, having a protective sleeve successively; Said input optical fibre imports light into said 45 prism, and the refract light that said output optical fibre is accepted from said 45 prism is measured electric signal through said detector output; Said Fibre Optical Sensor is 2; Comprise concentration sensor and temperature sensor; Said detector comprises concentration detector and hygrosensor, and said light source comprises LASER Light Source and led light source, and said LASER Light Source is used for said concentration sensor; Said led light source is used for said temperature sensor, and the output optical fibre of said hygrosensor receives end face and is provided with the ASGA semiconductor material layer.
Fibre-optical probe of the present invention; Wherein said LASER Light Source is connected with the first bright detecting device through optical fiber; Said led light source is connected with the second bright detecting device through another optical fiber, the bright detection signal separately of output respectively of the said first bright detecting device and the second bright detecting device.
Fibre-optical probe of the present invention, wherein said LASER Light Source adopts semiconductor laser, and its wavelength is 650 wavelength nm, and said Laser Power Devices are provided with the luminous energy control circuit, and the wavelength of said led light source is 910nm.
Fibre-optical probe of the present invention, wherein said detector adopts silicon photocell.
Fibre-optical probe of the present invention; Wherein in said concentration sensor; Said 45 prism replaces with circular arc optical fiber, and said circular arc optical fiber is positioned at the outside of said measuring staff, inserts in the fluid to be measured; Input optical fibre imports light into said circular arc optical fiber, and the reflected light that output optical fibre is accepted from said circular arc optical fiber is measured electric signal through said concentration detector output.
Fibre-optical probe of the present invention; Wherein in said concentration sensor; Said 45 prism replaces with bare fibre, and said bare fibre is positioned at the outside of said measuring staff, inserts in the fluid to be measured; Input optical fibre imports light into said bare fibre, and the light that output optical fibre is accepted from said bare fibre is measured electric signal through said concentration detector output.
For reaching above-mentioned purpose; The combined type liquid fiber densimeter of the said fibre-optical probe of employing provided by the invention; Also comprise the test macro that links to each other with this fibre-optical probe; Said test macro comprises first amplifier that links to each other with said concentration detector and second amplifier that links to each other with said hygrosensor, first bright detecting device that links to each other with said LASER Light Source and the second bright detecting device that links to each other with said led light source; And a dsp processor, the output signal of said first amplifier, second amplifier, the first bright detecting device and the second bright detecting device is connected to said dsp processor respectively, and said dsp processor is connected with display and output port.
Combined type liquid fiber densimeter provided by the invention, wherein said first amplifier is connected with first sensitivity controller and first zero regulator, and said second amplifier is connected with second sensitivity controller and second zero adjuster.
Fibre-optical probe of the present invention with the advantage of the combined type liquid fiber densimeter that adopts this fibre-optical probe is: because optical fiber is to be processed by glass or plastics, thereby be not afraid of the corrosion of liquid or gas.Probe size is little; And because optical fiber is flexible, very little to the flow resistance of fluid to be measured or gas, and Optical Fiber Transmission does not receive the influence of electromagnetic field, big electric current and high temperature; Therefore safety and good reliability, error is little, installation and maintenance is easy, distribution mustn't special consideration.Because separate with main frame the test side, the test side is directly inserted sample and just can be measured, and does not need special reconstitute device, can directly include the technological process production line in, has realized remote measurement in real time.Therefore, in the process for making that with liquid is main various industries, need not select special place,,, run into the outdoor of wind and rain and need and to use in the pipeline of explosion-proof technological process like high temperature, high humidity in the abominable place of test environment.
Embodiment
The principle of work of fibre optic concentration sensor is following:
A branch of light incides second kind of medium (refractive index n 2) from a kind of medium (refractive index n 1), and according to the Snell law, incident angle θ 1 and refraction angle θ 2 satisfy following relational expression
n1Sinθ1=n2Sinθ2----------(1)
The reflection coefficient parallel with vertical with the plane of incidence is by Fresnel formulate formula (1)
rp=-tg(θ1-θ2)/tg(θ1+θ2)------------(2)
rs=-Sin(θ1-θ2)/Sin(θ1+θ2)-----------(3)
The reflection of light rate does
R=(rp2+rs2)1/2---------(4)
Reflection of light intensity does
IR=rp2Iop+rs2Ios------------(5)
Io=Iop+Ios is an incident intensity, and on behalf of the plane of polarization and the plane of incidence, footnote p s parallel and vertical component respectively.
For selected optical fiber, its n1 is that definite value, θ 1 also are definite value, when it touches the liquid of different refractivity, by formula (1) formula n2=n1Sin θ 1/ θ 2, for the θ 2 decision what n2 of formula (2) (3).Therefore n2 gets different values, has directly determined the value of IR.Mini optical fibre refractive index concentration sensor utilizes this principle and designs.
Specify the embodiment of a kind of fibre-optical probe of the present invention and the combined type liquid fiber densimeter that adopts this fibre-optical probe below in conjunction with accompanying drawing.
With reference to Fig. 1, fibre-optical probe provided by the invention is equipped with Fibre Optical Sensor 1 at the front end of measuring staff, and single-core fiber bundle 4, detector and the light source of leading fibre bundle 2, fiber distribution box 3, having protective sleeve are installed in the inner chamber of measuring staff.In conjunction with reference to Fig. 2 or Fig. 6, Fibre Optical Sensor 1 comprises input optical fibre 31, output optical fibre 33 and 45 prism 32, and 45 prism 32 is positioned at the outside of measuring staff, and Fibre Optical Sensor length is no more than 50mm, inserts and gathers concentration and temperature signal in the fluid to be measured 20.Input optical fibre 31 links to each other with light source, and output optical fibre 33 links to each other with detector through the single-core fiber bundle 4 of leading fibre bundle 2, fiber distribution box 3, having a protective sleeve successively.
Input optical fibre 31 imports light into 45 prism 32, and the refract light that output optical fibre 33 is accepted by 45 prism 32 is measured electric signal through detector output.The length of measuring staff signal hop is decided according to user's needs, and design length is 2 meters, generally is no more than 4 meters.
Because the production scene of chemical combination liquid exists temperature and concentration state variation simultaneously; So; In the embodiment of fibre-optical probe provided by the invention, utilize big core diameter silica fibre to constitute the compound sensor of concentration and temperature, two optical fiber are formed concentration sensor; Two optical fiber are formed temperature sensor, are installed in the same probe.So Fibre Optical Sensor 1 is 2, comprises concentration sensor and temperature sensor, adopt like Fig. 2 and structure shown in Figure 6 respectively.
Detector comprises concentration detector 5 and hygrosensor 6, and light source comprises LASER Light Source 7 and led light source 8.LASER Light Source 7 is used for concentration sensor, adopts semiconductor laser, and its wavelength is 650 wavelength nm.Led light source 8 is used for temperature sensor, and wavelength is 910nm.Detector adopts silicon photocell.The output of fiber distribution box 3 is divided into three beams single-core fiber bundle 4; All has the protective casing protection; A branch of single-core fiber bundle 4 links to each other with LASER Light Source 7, and other two bundle single-core fiber bundles 4 are used for linking to each other with 6 two detectors of concentration detector 5 and hygrosensor, and two detectors convert light signal to electric signal.
In the embodiment of fibre-optical probe provided by the invention, utilize the 45 prism to change the direction of propagation of light, when prism was present in the air (the refractive index n 0=1 of air), light produced total reflection.When prism was present in the different liquid, because its refractive index is different, light will produce refraction, the proportional relation of concentration of its refract light brightness size and liquid refractive index and liquid, thus realize the concentration of liquid is measured fast, accurately.With reference to Fig. 6, the output optical fibre 33 of hygrosensor 6 receives end face and is provided with ASGA semiconductor material layer 34.ASGA semiconductor material layer 34 is the material responsive to temperature variation.
In another embodiment of fibre-optical probe provided by the invention, with reference to Fig. 3, the 45 prism of concentration sensor replaces with circular arc optical fiber 12, and circular arc optical fiber 12 is positioned at the outside of measuring staff, inserts in the fluid to be measured 20.Circular arc optical fiber 12 pats two whole bare fibres by the end and abuts against together, through special process end face is processed into a smooth arc surface.Input optical fibre 11 imports light into circular arc optical fiber 12, during light process circular arc optical fiber 12, is divided into reflected light and refract light by its inherent characteristic.Refract light gets into testing liquid 20, and output optical fibre 13 is accepted reflected light from circular arc optical fiber 12 and measured electric signal through 5 outputs of concentration detector.
In the another embodiment of fibre-optical probe provided by the invention, with reference to Fig. 4,450 angle prisms of concentration sensor replace with bare fibre 22, and bare fibre 22 is positioned at the outside of measuring staff, insert in the fluid to be measured 20.Input optical fibre 21 imports light into bare fibre 22; Because will leak by emergence pattern in the time of in the bare fibre 22 immersion solution 20, just optical fiber and fluid to be measured 20 produce coupling mutually, light characteristic is different because of the light quantity of the different outside scattering of refractive index of liquid; Also be that the light loss vector is different; Because the optical index of fluid to be measured 20 is higher than air, optical fiber light leakage rate different in liquid and air, the light of transmission will die down; This variable quantity is relevant with the concentration value of liquid, and the light that output optical fibre 23 is accepted from bare fibre 22 is measured electric signal through 5 outputs of concentration detector.
The embodiment of the combined type liquid fiber densimeter of this fibre-optical probe of employing provided by the invention has installed two independently fibre-optical probes of becoming one of Fibre Optical Sensor 1 and constitute test macro.
With reference to Fig. 6; Test macro comprises first amplifier 15 that links to each other with concentration detector 5 and second amplifier 18, first bright detecting device 9 that links to each other with LASER Light Source 7 and the second bright detecting device 10 that links to each other with led light source 8 that link to each other with hygrosensor 6, and a dsp processor 19.The output signal of first amplifier 5, second amplifier, 15, the first bright detecting device 9 and the second bright detecting device 10 is connected to dsp processor 19 respectively, and dsp processor 19 is connected with display 26 and output port 27.First amplifier 5 is connected with first sensitivity controller 16 and is connected with second sensitivity controller 24 and second zero adjuster 25 with first zero regulator 17, the second amplifiers 15.Concentration detector 5 converts electric signal to two light signals that hygrosensor 6 is accepted, and is input to dsp processor 19 respectively through the signal of regulating back output at amplifier amplification, sensitivity adjusting, zero point and carries out data processing.Dsp processor 19 comprises A/D conversion and DSP data processing module.
Laser Power Devices 7 are provided with luminous energy control circuit 28, with reference to Fig. 7, are the semiconductor lasers with luminous energy control; When the luminous power of semiconductor laser improves, to be accepted by detector PIN, the light intensity that it is accepted is strong more; Then the voltage on triode 2SA1015 reduces, and the electric current of triode 2SC1545 is descended, so the photocurrent of semiconductor laser also descends; The luminous power of semiconductor laser also descends, otherwise same.
In order to improve measuring accuracy, directly from light source, be guided out a branch of light and carry out the light detection.LASER Light Source 7 is connected with the first bright detecting device 9 through optical fiber, and led light source 8 is connected with second bright detecting device 10, the first bright detecting devices 9 and the second bright detecting device 10 is exported bright detection signal separately respectively through another optical fiber.With reference to Fig. 8, the first bright detecting device 9 is made up of chip circuit TLO72 and AD620, and acceptance is input to dsp processor 19 and is carried out data processing by the light that light guide bundles returns, in order to improve measuring accuracy.For carrying out temperature detection, the second bright detecting device 10 that also has a route TLO72 and AD620 to form.Foregoing circuit is known technology, so be not described further.
Fibre-optical probe of the present invention is following with the combined type liquid fiber densimeter advantage that adopts this fibre-optical probe:
1 because the test side of contact liq is a fibre-optical probe, and separates between the main frame, thereby can realize Distance Test, directly includes in and carries out The real time measure on the technological process production line.
2 owing to being optical quantities, so explosion-proof, anti-electromagnetic interference (EMI) needs can both use in the explosion-proof technological process in the abominable field of test environment in one's power.
3 because the test side is directly inserted sample and just can be measured, and does not need special reconstitute device.Probe size is little, and because optical fiber is flexible, need not select special place, high easy mounting.
4 Optical Fiber Transmission do not receive the influence of electromagnetic field, big electric current and high temperature, so distribution mustn't special consideration, and safe reliability is high.
Embodiment recited above describes preferred implementation of the present invention, is not that design of the present invention and scope are limited.Under the prerequisite that does not break away from design concept of the present invention; Various modification and improvement that this area ordinary person makes technical scheme of the present invention; All should drop into protection scope of the present invention, the technology contents that the present invention asks for protection all is documented in claims.