CN109029775A - A kind of system for detecting temperature based on Michelson interference structure - Google Patents
A kind of system for detecting temperature based on Michelson interference structure Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
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Abstract
A kind of system for detecting temperature based on Michelson interference structure of the invention belongs to fiber optic sensor technology field.Its primary structure has pumping source (1), the first photo-coupler (2), light wavelength division multiplexing (3) etc..The present invention uses sinusoidal signal as modulated signal, will not generate High-frequency Interference, has the characteristics that work is more reliable, sensing accuracy is high, has a wide range of application.
Description
Technical field
The invention belongs to the technical field of fibre optical sensor, in particular to a kind of temperature based on Michelson interference structure
Detection system.
Background technique
Electromagnetism interference, resistant to chemical etching, transmission loss is small, weight small in size because having for bragg grating (FBG)
Gently, convenient for large-scale production the advantages that, and it is widely used in field of sensing technologies.Currently, temperature sensor is in safety in production
Play a significant role, especially such as mine Different high risk sites, it is most important to the monitoring of temperature.But traditional temperature sensor is most
It is all the variation realization by electric signal, and the temperature sensor based on change in electric is in practical applications by very big limit
System, the use of one side electric signal can cause additional security risk to certain environment (such as coal mine), on the other hand in severe ring
Interference when using under border by environment is larger and transmission is inconvenient.And bragg grating makes its composition due to its above-mentioned advantage
Temperature sensor compared to other sensors have higher reliability, the use being also more suitable under mal-condition.
It is doctor's thesis " fiber grating sensing system of Nankai University Liu Bo with the immediate prior art of the present invention
Research and realization ", the document provides a kind of bragg fiber light based on non-equilibrium Michelson fiber-optic interferometry demodulation techniques
Grid sensor-based system (referring to Fig. 3 .4 of page 24 of the document), the optical fiber sensing system use non-equilibrium Michelson fiber-optic principle of interference,
Change the length of the arm on a wherein arm in interferometer two-arm using the modulated signal that piezoelectric ceramics (PZT) is provided, thus
Changing interferometer output intensity, interferometer output intensity is regular in cosine function with the variation of PZT modulated signal, if using
Modulated signal of the ideal sawtooth wave as PZT, then the output of optical fiber sensing system is directly cosine wave.Optical fiber sensing system passes through
Bragg grating perceives the variation of measurement point stress or temperature, and is reflected as the variation of reflectance spectrum central wavelength, middle cardiac wave
Long variation is presented as the variation of output cosine wave phase after above-mentioned non-equilibrium Michelson fiber-optic interferometer, finally by cosine wave
Phase compare with the phase of sawtooth wave, can reflect the variation of bragg grating reflectance spectrum central wavelength, thus
Realize the variation of measurement extraneous stress (or temperature).
In above-mentioned sensor-based system, existing greatest problem is that sawtooth wave can not accomplish absolute idealization, preferably
Sawtooth wave failing edge is vertical, and the failing edge of actual sawtooth wave always has certain gradient, so that rear class can be made defeated
There are a high dithers for cosine wave out, generally necessary in grade demodulator circuit behind in order to eliminate the high-frequency jitter signal
Using bandpass filter (BPF), DC component and high fdrequency component are filtered out.But on the one hand the high fdrequency component inherently can be to remaining
The phase-detection of string wave impacts (zero crossing change in location)；On the other hand the frequency of the high-frequency jitter signal is driven by PZT
(electrical characteristics of PZT are equivalent to capacitor to the lagging characteristics of circuit performance, PZT itself, and both end voltage cannot jump, therefore
The failing edge of sawtooth wave be do not accomplish it is unlimited short) and the factors such as optical fiber elasticity itself influence, frequency size is indefinite, very
Difficulty filters out completely；Moreover, when using filter, it, can also be simultaneously other than it can be had an impact to the amplitude-frequency characteristic of output signal
The phase-frequency characteristic of signal is had an impact, i.e., filtering is that phase will receive influence near cutoff frequency, this is for relying on phase
It is very unfavorable for changing for the fibre optical sensor to measure stress variation.Therefore, existing bragg grating temperature
Sensor also requires further improvement.
Summary of the invention
In order to overcome existing bragg grating temperature sensor there are the shortcomings that, the present invention provides a kind of using just
System for detecting temperature based on Michelson interference structure of the string signal as PZT driving signal, so as to avoid High-frequency Interference
The generation of signal, and when handling the signal received without using filter, so as to avoid filtering to phase
The influence that position generates.
The purpose of the present invention is achieved through the following technical solutions:
A kind of system for detecting temperature based on Michelson interference structure, structure have, pumping source 1 and the first photo-coupler
2 input terminal is connected, and 90% output end of the first photo-coupler 2 is connected with the end 980nm of light wavelength division multiplexing 3, and light wave point is multiple
It is connected with the end 1550nm of device 3 with one end of delay line adjustable optic fibre 12, the other end of delay line adjustable optic fibre 12 and the first light
The input terminal of isolator 11 is connected, and the control terminal of delay line adjustable optic fibre 12 is connected with the output port of electrical level transferring chip 13,
The input port of electrical level transferring chip 13 is connected with single-chip microcontroller 19；The output end of first optoisolator 11 and the light of optical filter 10
Input terminal is connected, and the electric control end of optical filter 10 is connected with single-chip microcontroller 19, the light output end and optical circulator of optical filter 10
7 first port is connected, and the second port of optical circulator 7 is connected with one end of Bragg grating group 9, the third of optical circulator 7
Port is connected with the input terminal of third photo-coupler 6, and 90% output end of third photo-coupler 6 is defeated with the second optoisolator 5
Enter end to be connected, the output end of the second optoisolator 5 is connected with one end of Er-doped fiber 4, the other end and light wave point of Er-doped fiber 4
The common end of multiplexer 3 is connected；The input terminal phase of 10% the output end output and the 4th photo-coupler 8 of third photo-coupler 6
Even, an output end of the 4th photo-coupler 8 is connected with the input terminal of the second faraday rotation mirror 26, the 4th photo-coupler 8
Another output is connected with the one end for the optical fiber being wrapped on piezoelectric ceramics 24, is wrapped in the another of the optical fiber on piezoelectric ceramics 24
One end is connected with the input terminal of the first faraday rotation mirror 25, another input terminal and the second photoelectricity of the 4th photo-coupler 8 turn
The input terminal for changing circuit 27 is connected；
It is characterized in that, structure in addition, the output end and function translation circuit 28 of the second photoelectric conversion circuit 27 input
End is connected, and the output end of functional transformation circuit 28 is connected with an input terminal of adaptive amplitude normalizing circuit 29, adaptive width
The output end of degree normalizing circuit 29 is connected with an input terminal of phase-comparison circuit 30；The frequency output terminal in controllable frequency source 22
It is connected with single-chip microcontroller 19, the signal output end in controllable frequency source 22 is connected with another input terminal of phase-comparison circuit 30, also
It is connected with the input terminal of PZT driving circuit 23, the output end of phase-comparison circuit 30 is connected with single-chip microcontroller 19, PZT driving circuit
23 output end is connected with the control terminal of piezoelectric ceramics 24；10% output end of the first photo-coupler 2 and the second photo-coupler 16
An input terminal be connected, another input terminal of the second photo-coupler 16 and dehydrated alcohol filling photonic crystal fiber 15
One end is connected, and the other end of dehydrated alcohol filling photonic crystal fiber 15 is connected with an output end of the second photo-coupler 16,
The another output of second photo-coupler 16 is connected with the input terminal of the first photoelectric conversion circuit 17, the first photoelectricity shifting circuit 17
Output end be connected with the input terminal of analog to digital conversion circuit 18, the output end of analog to digital conversion circuit 18 is connected with single-chip microcontroller 19；It is single
Piece machine 19 is also connected with input key 14, serial communication modular 20, display screen 21 respectively；
The structure of the functional transformation circuit 28 is, one end of capacitor C3 and the pin 12 of trigonometric function converter U1 and
One end of resistance R2 is connected, and input terminal of the other end of capacitor C3 as functional transformation circuit 28 is denoted as port ACOS_in, with
The output end of second photoelectric conversion circuit 27 is connected；The other end of resistance R2 is grounded；The pin 2 of trigonometric function converter U1,3,
4,5,8,11,13 ground connection, pin 9,10 are connected with one end of capacitor C2 and -12V power supply, the other end ground connection of capacitor C2；Triangle
The pin 6 of function converter U1 is connected with pin 7, and pin 16 is connected with one end of+12V power supply and capacitor C1, capacitor C1's
Other end ground connection；The pin 1 of trigonometric function converter U1 is connected with the sliding end of slide rheostat W1, and the one of slide rheostat W1
End is connected with one end of resistance R1, and the other end of resistance R1 is connected with the pin 14 of trigonometric function converter U1, slide rheostat
Output end of the sliding end of W1 as functional transformation circuit 28, is denoted as port ACOS_out, with adaptive amplitude normalizing circuit 29
Input terminal be connected；The model AD639 of the trigonometric function converter U1；
The structure of the adaptive amplitude normalizing circuit 29 is one end of capacitor C9 and one end of resistance R3 and chip U2
Pin 3 be connected, the other end of resistance R3 ground connection, input of the other end of capacitor C9 as adaptive amplitude normalizing circuit 29
End, is denoted as port ADAPT_in, and the port ACOS_out of and function translation circuit 28 is connected；The pin 1 of chip U2, pin 7,
Pin 8, pin 14 are grounded, and pin 2 is connected with+5V power supply with pin 4, pin 11 be connected with pin 12 and with capacitor C5
One end and+5V power supply be connected, the other end of capacitor C5 ground connection；The pin 13 of chip U2 is connected with one end of capacitor C4, capacitor
The other end of C4 is grounded；The pin 9 of chip U2 is connected with one end of capacitor C6, the other end ground connection of capacitor C6；The pipe of chip U2
Foot 5 is connected with one end of resistance R12 and resistance R11, and the other end ground connection of resistance R12, the other end of resistance R11 is with amplifier U4's
One end of output end and capacitor C8 are connected, the positive supply termination+5V power supply of amplifier U8, negative power end ground connection；Capacitor C8's is another
End is connected with one end of resistance R10, and the other end of resistance R10 is connected with the non-inverting input terminal of amplifier U4；The reverse phase of amplifier U4 is defeated
Enter end and be connected with the sliding end for sliding variohm W3, one end of slide rheostat W3 is connected with+5V power supply, slide rheostat W3
The other end ground connection；One end of capacitor C7 is connected with the non-inverting input terminal of one end of resistance R9 and amplifier U4, and capacitor C7's is another
End ground connection, the other end of resistance R9 are connected with the output end of one end of resistance R7 and amplifier U3, the other end and amplifier of resistance R7
The inverting input terminal of U3 is connected；One end of resistance R8 is connected with the non-inverting input terminal of amplifier U3, other end ground connection；Amplifier U3's
Positive supply termination+5V power supply, negative power end ground connection；Output of the pin 10 of chip U2 as adaptive amplitude normalizing circuit 29
End, is denoted as port ADAPT_out, is connected with an input terminal of phase-comparison circuit 30；The pin 10 and diode of chip U2
The anode of D1 is connected, and the cathode of diode D1 is connected with one end of resistance R4, the other end of resistance R4 and one end of resistance R5 and
The inverting input terminal of amplifier U3 is connected, and the other end of resistance R5 is connected with the anode of diode D2, the cathode and cunning of diode D2
The sliding end of dynamic rheostat W2 is connected；One end of slide rheostat W2 is connected and is grounded with the cathode of diode D3, slides variable resistance
The other end of device W2 is connected with the anode of one end of resistance R6 and diode D3, another termination -5V power supply of resistance R6；Described
Chip U2 is variable gain amplifier chip, and model is AD8367；
The structure of the phase-comparison circuit 30 is one end of capacitor C10 and the non-inverting input terminal and resistance of amplifier U5
One end of R13 is connected, and an input terminal of the other end of capacitor C10 as phase-comparison circuit 30 is denoted as port PHASE_
In1 is connected with the port ADAPT_out of adaptive amplitude normalizing circuit 29；The other end of resistance R13 is grounded；Amplifier U5 is just
Power supply termination+5V power supply, negative power end ground connection, reverse inter-input-ing ending grounding, the end CLK of output termination d type flip flop U6A；D type flip flop
The port D of U6A is grounded；The one end capacitor C11 ground connection, the end PR of another termination d type flip flop U6A；Resistance R14 mono- terminates d type flip flop
The end PR of U6A, the end Q of another termination d type flip flop U6A；CLR termination+5V the power supply of d type flip flop U6A, the Q of d type flip flop U6A are non-
Terminate the end PR of d type flip flop U8A；One end of capacitor C12 is connected with one end of the non-inverting input terminal of amplifier U7 and resistance R15, electricity
Hold another input terminal of the other end of C12 as phase-comparison circuit 30, port PHASE_in2 is denoted as, with controllable frequency source
22 port SineM_out is connected；The other end of resistance R15 is grounded；Positive supply termination+5V the power supply of amplifier U7, negative power end
Ground connection, reverse inter-input-ing ending grounding, the end CLK of output termination d type flip flop U6B；The port D of d type flip flop U6B is grounded；Capacitor C13
One end ground connection, the end PR of another termination d type flip flop U6B；Resistance R16 mono- terminates the end PR of d type flip flop U6B, another termination D triggering
The end Q of device U6B；CLR termination+5V the power supply of D trigger U6B, the end CLR of the Q non-terminated d type flip flop U8A of d type flip flop U6B；
The end D and the end CLK of d type flip flop U8A is grounded, and output end of the end Q as phase-comparison circuit 30 is denoted as port PHASE_
Out is connected with the input terminal of single-chip microcontroller 19；
The structure in the controllable frequency source 22 is the non-inverting input terminal of a termination amplifier U9 of resistance R21, another termination
Ground；The non-inverting input terminal of a termination amplifier U9 of capacitor C19, signal output end of the other end as controllable frequency source 22 are denoted as
Port SinM_out is connected with the input terminal of port PHASE_in2 and the PZT driving circuit 23 of phase-comparison circuit 30；Electricity
Hinder the inverting input terminal of a termination amplifier U9 of R20, other end ground connection；Positive supply termination+5V the power supply of amplifier U9, negative power end
Ground connection, frequency output terminal of the output end as controllable frequency source 22 are denoted as port FrqM_out, are connected with single-chip microcontroller 19；Inductance
A termination+12V power supply of L1, the collector of another termination triode Q1；The anode of electrolytic capacitor C14 connects+12V power supply, cathode
Ground connection；The collector of a termination triode Q1 of resistance R17, the base stage of another termination triode Q1；A termination three of capacitor C18
The base stage of pole pipe Q1, the anode of another termination electrolytic capacitor C17；The base stage of a termination triode Q1 of resistance R18, another termination
Ground；Resistance R19 mono- terminates the emitter of triode Q1, other end ground connection；The anode of electrolytic capacitor C15 connects the transmitting of triode Q1
Pole, cathode ground connection；The collector of a termination triode Q1 of capacitor C16, one end of another termination controllable impedance L2, controllable impedance
The other end of L2 is grounded；A termination port SinM_out of inductance L3, the anode of another termination electrolytic capacitor C17, electrolytic capacitor
The cathode of C17 is grounded；The collector of triode Q1 meets port SinM_out.
The preferred 980nm laser light source of pumping source 1.
The Bragg grating group 9 is preferably made of 3 Bragg gratings, and the reflectivity of each grating is 90%,
Bandwidth is 0.6nm, and central wavelength is respectively 1550nm, 1560nm and 1630nm.
The utility model has the advantages that
1, the present invention uses sinusoidal signal as modulated signal, compared with the prior art is modulated using sawtooth signal,
High-frequency Interference will not be generated, so that sensor-based system work is more reliable.
2, the present invention uses adaptive amplitude normalizing circuit by the amplitude auto-changing of signal after demodulation at suitable phase ratio
Compared with the size that circuit is compared, so that phase-detection error is smaller, the sensing accuracy of entire sensor-based system is effectively increased.
3, compared with prior art, frequency modulating signal of the invention is adjustable, so that sensor-based system applied field of the invention
It closes wider.
4, the present invention has temperature compensation function, effectively overcomes influence of the environment temperature to parameter sensing.
Detailed description of the invention
Fig. 1 is whole functional block diagram of the invention.
Fig. 2 is the basic circuit diagram for the functional transformation circuit that the present invention uses.
Fig. 3 is the basic circuit diagram for the adaptive amplitude normalizing circuit that the present invention uses.
Fig. 4 is the basic circuit diagram for the phase-comparison circuit that the present invention uses.
Fig. 5 is the basic circuit diagram in the controllable frequency source that the present invention uses.
Specific embodiment
The working principle of the invention is further illustrated with reference to the accompanying drawing, it should be appreciated that the component marked in attached drawing
Parameter is the preferred parameter that following embodiment uses, rather than limiting the scope of the invention.
As shown in Figure 1, overall structure of the invention has, pumping source 1 (the LC962U type pumping source of OCLARO company, center
Wavelength 980nm, maximum single-mode output optical power are 750mW) (OZ-OPTICS company produces, model with the first photo-coupler 2
FUSED-12-1064-7/125-90/10-3U-3mm, splitting ratio 90:10) input terminal be connected, the first photo-coupler 2
The end 980nm of 90% output end and light wavelength division multiplexing 3 (COMCORE company 980/1060nm single mode optical fiber wavelength division multiplexer)
It is connected, the end 1550nm of light wavelength division multiplexing 3 and delay line adjustable optic fibre 12 be (Sichuan space fixed star Micron Technology Co., Ltd
The electronic fibre delay line of VDL-40-15-S9-1-FA type) one end be connected, the other end of delay line adjustable optic fibre 12 and the first light
The input terminal of isolator 11 (THORLABS company IO-H-1064B single mode optoisolator) is connected, the control of delay line adjustable optic fibre 12
End processed is connected with the output port of electrical level transferring chip 13 (MAX232), the input port and single-chip microcontroller 19 of electrical level transferring chip 13
(STC89C51 single-chip microcontroller) is connected；(Micron Optics company is raw for the output end and optical filter 10 of first optoisolator 11
Produce, model FFP-TF-1060-010G0200-2.0) light input end be connected, the electric control end of optical filter 10 and monolithic
Machine 19 is connected, and the of the light output end of optical filter 10 and optical circulator 7 (Shanghai Han Yu company PIOC3-15 type optical circulator)
Single port is connected, the second port of optical circulator 7 and Bragg grating group 9 (reflectivity is 90%, and bandwidth is 0.6nm, in
Cardiac wave is long be respectively 1550nm, 1560nm and 1630nm three Bragg gratings) one end be connected, the third of optical circulator 7
(OZ-OPTICS company produces, model FUSED-12-1064-7/125-90/10-3U- for port and third photo-coupler 6
3mm, splitting ratio 90:10) input terminal be connected, 90% output end of third photo-coupler 6 and the second optoisolator 5
The input terminal of (THORLABS company IO-H-1064B single mode optoisolator) is connected, the output end of the second optoisolator 5 and er-doped
One end of the optical fiber 4 SM-ESF-7/125 Er-doped fiber of production (Nufern company of the U.S.) is connected, the other end of Er-doped fiber 4 with
The common end of light wavelength division multiplexing 3 is connected, and above structure constitutes basic luminaire part and the transducing part of fibre optical sensor.The
The 10% output end output of three photo-couplers 6 and the 4th photo-coupler 8 (2 × 2 standard single mode photo-couplers, splitting ratio 50:
50) input terminal is connected, and (THORLABS company is raw for an output end of the 4th photo-coupler 8 and the second faraday rotation mirror 26
The MFI-1310 of production) input terminal be connected, the another output of the 4th photo-coupler 8 and be wrapped in piezoelectric ceramics 24 (circle
Cylindricality piezoelectric ceramics, outer diameter 50mm, internal diameter 40mm, high 50mm) on optical fiber one end be connected, be wrapped on piezoelectric ceramics 24
The other end of optical fiber is connected with the input terminal of the first faraday rotation mirror 25 (MFI-1310 of THORLABS company production), the
Another input terminal of four photo-couplers 8 is connected with the input terminal of the second photoelectric conversion circuit 27；Above-mentioned 4th photo-coupler 8,
First faraday rotation mirror 25, the second faraday rotation mirror 26 and piezoelectric ceramics 24 collectively constitute Michelson interference structure.
Structure of the invention in addition, the output end and function translation circuit 28 of the second photoelectric conversion circuit 27 input terminal phase
Even, the output end of functional transformation circuit 28 is connected with an input terminal of adaptive amplitude normalizing circuit 29, and adaptive amplitude is returned
The output end of one circuit 29 is connected with an input terminal of phase-comparison circuit 30；The frequency output terminal and list in controllable frequency source 22
Piece machine 19 is connected, and the signal output end in controllable frequency source 22 is connected with another input terminal of phase-comparison circuit 30, and also and PZT
The input terminal of driving circuit 23 is connected, and the output end of phase-comparison circuit 30 is connected with single-chip microcontroller 19, PZT driving circuit 23 it is defeated
Outlet is connected with the control terminal of piezoelectric ceramics 24, and above structure constitutes the demodulation part of sensor.First photo-coupler 2
One input terminal phase of 10% output end and the second photo-coupler 16 (2 × 2 standard single mode photo-couplers, splitting ratio 50:50)
Even, another input terminal of the second photo-coupler 16 and dehydrated alcohol filling photonic crystal fiber 15 are (by NKT Photonics
Company production PM-1550-01 photonic crystal fiber airport filling dehydrated alcohol constitute) one end be connected, dehydrated alcohol
The other end of filling photonic crystal fiber 15 is connected with an output end of the second photo-coupler 16, the second photo-coupler 16
Another output is connected with the input terminal of the first photoelectric conversion circuit 17, the output end and modulus of the first photoelectricity shifting circuit 17
The input terminal of conversion circuit 18 is connected, and the output end of analog to digital conversion circuit 18 is connected with single-chip microcontroller 19, and above structure is the present invention
Provide temperature compensation function.Single-chip microcontroller 19 is also connected with input key 14, serial communication modular 20, display screen 21 respectively.
2 functional transformation circuit of embodiment
The structure of the functional transformation circuit 28 is, one end of capacitor C3 and the pin 12 of trigonometric function converter U1 and
One end of resistance R2 is connected, and input terminal of the other end of capacitor C3 as functional transformation circuit 28 is denoted as port ACOS_in, with
The output end of second photoelectric conversion circuit 27 is connected；The other end of resistance R2 is grounded；The pin 2 of trigonometric function converter U1,3,
4,5,8,11,13 ground connection, pin 9,10 are connected with one end of capacitor C2 and -12V power supply, the other end ground connection of capacitor C2；Triangle
The pin 6 of function converter U1 is connected with pin 7, and pin 16 is connected with one end of+12V power supply and capacitor C1, capacitor C1's
Other end ground connection；The pin 1 of trigonometric function converter U1 is connected with the sliding end of slide rheostat W1, and the one of slide rheostat W1
End is connected with one end of resistance R1, and the other end of resistance R1 is connected with the pin 14 of trigonometric function converter U1, slide rheostat
Output end of the sliding end of W1 as functional transformation circuit 28, is denoted as port ACOS_out, with adaptive amplitude normalizing circuit 29
Input terminal be connected；The model AD639 of the trigonometric function converter U1.The circuit has the function of anti-cosine transform, will
The signal of second photoelectric conversion circuit 27 output carries out anticosine processing.
The adaptive amplitude normalizing circuit of embodiment 3
Since the signal amplitude that functional transformation circuit 28 exports is smaller, and influenced by multiple parameters in optical path and circuit,
Size is indefinite, therefore the present invention devises adaptive amplitude normalizing circuit 29, for the signal for exporting functional transformation circuit 28
Amplitude normalization at best size, to further increase the precision of demodulation.The specific structure is shown in FIG. 3, one end of capacitor C9
It is connected with the pin 3 of one end of resistance R3 and chip U2, the other end ground connection of resistance R3, the other end of capacitor C9 is as adaptive
The input terminal of amplitude normalizing circuit 29, is denoted as port ADAPT_in, and the port ACOS_out of and function translation circuit 28 is connected；Core
Pin 1, pin 7, pin 8, the pin 14 of piece U2 is grounded, and pin 2 is connected with+5V power supply with pin 4, pin 11 and pin
12 are connected and are connected with one end of capacitor C5 and+5V power supply, the other end ground connection of capacitor C5；The pin 13 and capacitor C4 of chip U2
One end be connected, the other end of capacitor C4 ground connection；The pin 9 of chip U2 is connected with one end of capacitor C6, the other end of capacitor C6
Ground connection；The pin 5 of chip U2 is connected with one end of resistance R12 and resistance R11, the other end ground connection of resistance R12, resistance R11's
The other end is connected with one end of the output end of amplifier U4 and capacitor C8, the positive supply termination+5V power supply of amplifier U8, negative supply termination
Ground；The other end of capacitor C8 is connected with one end of resistance R10, and the other end of resistance R10 is connected with the non-inverting input terminal of amplifier U4；
The inverting input terminal of amplifier U4 is connected with the sliding end of sliding variohm W3, one end and the+5V power supply phase of slide rheostat W3
Even, the other end ground connection of slide rheostat W3；One end of capacitor C7 and one end of resistance R9 and the non-inverting input terminal phase of amplifier U4
Even, the other end ground connection of capacitor C7, the other end of resistance R9 are connected with the output end of one end of resistance R7 and amplifier U3, resistance R7
The other end be connected with the inverting input terminal of amplifier U3；One end of resistance R8 is connected with the non-inverting input terminal of amplifier U3, the other end
Ground connection；Positive supply termination+5V the power supply of amplifier U3, negative power end ground connection；The pin 10 of chip U2 is used as adaptive amplitude normalizing
The output end of circuit 29 is denoted as port ADAPT_out, is connected with an input terminal of phase-comparison circuit 30；The pipe of chip U2
Foot 10 is connected with the anode of diode D1, and the cathode of diode D1 is connected with one end of resistance R4, the other end and electricity of resistance R4
The inverting input terminal of one end and amplifier U3 for hindering R5 is connected, and the other end of resistance R5 is connected with the anode of diode D2, diode
The cathode of D2 is connected with the sliding end of slide rheostat W2；One end of slide rheostat W2 is connected and connects with the cathode of diode D3
The other end on ground, slide rheostat W2 is connected with the anode of one end of resistance R6 and diode D3, another termination -5V of resistance R6
Power supply；The chip U2 is variable gain amplifier chip, and model is AD8367.
4 phase-comparison circuit of embodiment
As shown in figure 4, the structure for the phase-comparison circuit 30 that the present invention uses is, one end of capacitor C10 is with amplifier U5's
One end of non-inverting input terminal and resistance R13 are connected, an input terminal of the other end of capacitor C10 as phase-comparison circuit 30,
It is denoted as port PHASE_in1, is connected with the port ADAPT_out of adaptive amplitude normalizing circuit 29；Another termination of resistance R13
Ground；Positive supply termination+5V the power supply of amplifier U5, negative power end ground connection, reverse inter-input-ing ending grounding, output termination d type flip flop U6A's
The end CLK；The port D of d type flip flop U6A is grounded；The one end capacitor C11 ground connection, the end PR of another termination d type flip flop U6A；Resistance R14
The end PR of one termination d type flip flop U6A, the end Q of another termination d type flip flop U6A；CLR termination+5V the power supply of D trigger U6A, D
The end PR of the Q non-terminated d type flip flop U8A of trigger U6A；One end of capacitor C12 and the non-inverting input terminal and resistance of amplifier U7
One end of R15 is connected, another input terminal of the other end of capacitor C12 as phase-comparison circuit 30 is denoted as port PHASE_
In2 is connected with the port SineM_out in controllable frequency source 22；The other end of resistance R15 is grounded；The positive supply termination of amplifier U7+
5V power supply, negative power end ground connection, reverse inter-input-ing ending grounding, the end CLK of output termination d type flip flop U6B；The end D of d type flip flop U6B
Mouth ground connection；The one end capacitor C13 ground connection, the end PR of another termination d type flip flop U6B；The PR of the termination of resistance R16 mono- d type flip flop U6B
End, the end Q of another termination d type flip flop U6B；CLR termination+5V the power supply of d type flip flop U6B, the Q non-terminated D touching of d type flip flop U6B
Send out the end CLR of device U8A；The end D and the end CLK of d type flip flop U8A is grounded, output end of the end Q as phase-comparison circuit 30, note
For port PHASE_out, it is connected with the input terminal of single-chip microcontroller 19.Standard sine wave that the circuit exports controllable frequency source 22 with
The sine wave (environment that its phase is detected by Bragg grating group 9 is influenced) of adaptive 29 output of amplitude normalizing circuit carries out phase
Bit comparison, and comparison result is sent into single-chip microcontroller 19, single-chip microcontroller 19 calculates at Bragg grating group 9 according to the phase differential
Temperature change.
5 controllable frequency source of embodiment
The structure in the controllable frequency source 22 is the non-inverting input terminal of a termination amplifier U9 of resistance R21, another termination
Ground；The non-inverting input terminal of a termination amplifier U9 of capacitor C19, signal output end of the other end as controllable frequency source 22 are denoted as
Port SinM_out is connected with the input terminal of port PHASE_in2 and the PZT driving circuit 23 of phase-comparison circuit 30；Electricity
Hinder the inverting input terminal of a termination amplifier U9 of R20, other end ground connection；Positive supply termination+5V the power supply of amplifier U9, negative power end
Ground connection, frequency output terminal of the output end as controllable frequency source 22 are denoted as port FrqM_out, are connected with single-chip microcontroller 19, are used to
The frequency of monitoring output signal；A termination+12V power supply of inductance L1, the collector of another termination triode Q1；Electrolytic capacitor
The anode of C14 connects+12V power supply, cathode ground connection；The collector of a termination triode Q1 of resistance R17, another termination triode Q1
Base stage；The base stage of a termination triode Q1 of capacitor C18, the anode of another termination electrolytic capacitor C17；One end of resistance R18
Connect the base stage of triode Q1, other end ground connection；Resistance R19 mono- terminates the emitter of triode Q1, other end ground connection；Electrolytic capacitor
The anode of C15 connects the emitter of triode Q1, cathode ground connection；The collector of a termination triode Q1 of capacitor C16, another termination
One end of controllable impedance L2, the other end ground connection of controllable impedance L2；A termination port SinM_out of inductance L3, another termination
The anode of electrolytic capacitor C17, the cathode ground connection of electrolytic capacitor C17；The collector of triode Q1 meets port SinM_out.The electricity
The adjustable standard sine wave of road output frequency, required sinusoidal signal is provided for demodulation part of the invention.
6 the working principle of the invention of embodiment
In conjunction with the various embodiments described above and each attached drawing, illustrate the working principle of the invention.When work, by bragg grating
Group 9 is placed on each position (sensitive position in such as mine) for needing monitoring temperature to change.By Er-doped fiber 4, optoisolator 5
The optical fiber laser annular chamber of equal compositions is that bragg grating group 9 provides wideband light source, each bragg grating meeting
There is a specific reflectance spectrum, the peak wavelength of different gratings, reflectance spectrum is different, and temperature changes when some measured point
When, the reflectance spectrum peak wavelength of the bragg grating at this can occur to deviate accordingly, and reflected light enters by the 4th light
The Michelson's interferometer that coupler 8, piezoelectric ceramics 24, the first faraday rotation mirror 25 and the second faraday rotation mirror 26 are constituted
In, while controllable frequency source 22 provides a control signal sin (ω t) for Michelson's interferometer, the signal is in interferometer
It is influenced by the light that bragg grating reflects, then is converted into electric signal and by functional transformation through the second photoelectric conversion circuit 27
It is obtained sin (ω t+ Δ θ) after the anti-cosine transform of circuit 28, which is adjusted through adaptive 29 amplitude of amplitude normalizing circuit
It saves to a suitable size, signal at this time is compared with the sinusoidal signal sin (ω t) that controllable frequency source 22 generates, phase hair
Variation has been given birth to, the phase difference detection of the two is come out to by phase-comparison circuit 30 and is sent into single-chip microcontroller 19, the phase difference is practical
The temperature change of measured point has been reacted, the detection to measured point temperature is finally realized.The present invention is during modulation and demodulation
Also just it is not required in demodulator circuit using sawtooth wave so as to avoid sawtooth wave failing edge bring high-frequency jitter signal
It to be filtered using bandpass filter, avoid and the amplitude-frequency characteristic and phase-frequency characteristic of output signal are had an impact.The present invention
Using standard sine wave signal as PZT modulated signal, when demodulating to modulated signal, functional transformation is dexterously used
Circuit 28 and adaptive amplitude normalizing circuit 29, recover phase is controlled by Bragg grating group 9 and width for modulated signal
Spend suitable sinusoidal signal so that in phase-comparison circuit 30 carry out phase bit comparison when, can highly precisely compare by
The phase difference of signal and original signal is controlled, thus the environment ginseng that accurately reaction sensing head (i.e. Bragg grating group 9) is detected
Number.
Since optical fiber laser annular chamber (is generally sensed with bragg grating group 9 vulnerable to environment temperature at work
Pop one's head in not in same position) influence, therefore temperature compensation function has also been devised in the present invention, fills photonic crystal by dehydrated alcohol
Optical fiber 15, the second photo-coupler 16, the first photoelectric conversion circuit 17 and analog to digital conversion circuit 18 are constituted.Dehydrated alcohol fills photon
Crystal optical fibre 15 is temperature sensor, can cause to generate variation by the phase of its laser when the environmental temperature is changed, into
And change the output electric current of the first photoelectric conversion circuit 17, then be converted into digital signal input single-chip microcontroller through analog to digital conversion circuit 18
19, measurement result bring error is given in the variation for environment temperature locating for compensated optical fiber laser annular chamber.
Claims (3)
1. a kind of system for detecting temperature based on Michelson interference structure, structure have, pumping source (1) and the first photo-coupler
(2) input terminal is connected, and 90% output end of the first photo-coupler (2) is connected with the end 980nm of light wavelength division multiplexing (3), light
The end 1550nm of wavelength division multiplexer (3) is connected with one end of delay line adjustable optic fibre (12), delay line adjustable optic fibre (12) it is another
One end is connected with the input terminal of the first optoisolator (11), the control terminal and electrical level transferring chip of delay line adjustable optic fibre (12)
(13) output port is connected, and the input port of electrical level transferring chip (13) is connected with single-chip microcontroller (19)；First optoisolator
(11) output end is connected with the light input end of optical filter (10), electric control end and single-chip microcontroller (19) phase of optical filter (10)
Even, the light output end of optical filter (10) is connected with the first port of optical circulator (7), the second port of optical circulator (7) and
One end of Bragg grating group (9) is connected, and the third port of optical circulator (7) is connected with the input terminal of third photo-coupler (6),
90% output end of third photo-coupler (6) is connected with the input terminal of the second optoisolator (5), the second optoisolator (5) it is defeated
Outlet is connected with the one end of Er-doped fiber (4), and the other end of Er-doped fiber (4) is connected with the common end of light wavelength division multiplexing (3)；
The 10% output end output of third photo-coupler (6) is connected with the input terminal of the 4th photo-coupler (8), the 4th photo-coupler (8)
An output end be connected with the input terminal of the second faraday rotation mirror (26), the another output of the 4th photo-coupler (8)
It is connected with the one end for the optical fiber being wrapped on piezoelectric ceramics (24), is wrapped in the other end and of the optical fiber on piezoelectric ceramics (24)
The input terminal of one faraday rotation mirror (25) is connected, another input terminal of the 4th photo-coupler (8) and the second photoelectric conversion electricity
The input terminal on road (27) is connected；
It is characterized in that, structure in addition, the output end and function translation circuit (28) of the second photoelectric conversion circuit (27) input
End is connected, and the output end of functional transformation circuit (28) is connected with an input terminal of adaptive amplitude normalizing circuit (29), adaptive
The output end of amplitude normalizing circuit (29) is answered to be connected with an input terminal of phase-comparison circuit (30)；Controllable frequency source (22)
Frequency output terminal is connected with single-chip microcontroller (19), and the signal output end of controllable frequency source (22) is another with phase-comparison circuit (30)
A input terminal is connected, and is also connected with the input terminal of PZT driving circuit (23), the output end and single-chip microcontroller of phase-comparison circuit (30)
(19) it is connected, the output end of PZT driving circuit (23) is connected with the control terminal of piezoelectric ceramics (24)；First photo-coupler (2)
10% output end is connected with an input terminal of the second photo-coupler (16), another input terminal of the second photo-coupler (16) with
Dehydrated alcohol fill photonic crystal fiber (15) one end be connected, dehydrated alcohol fill photonic crystal fiber (15) the other end with
One output end of the second photo-coupler (16) is connected, the another output and the first photoelectric conversion of the second photo-coupler (16)
The input terminal of circuit (17) is connected, the input terminal phase of the output end and analog to digital conversion circuit (18) of the first photoelectricity shifting circuit (17)
Even, the output end of analog to digital conversion circuit (18) is connected with single-chip microcontroller (19)；Single-chip microcontroller (19) also respectively with input key (14), string
Port communications module (20), display screen (21) are connected；
The structure of the functional transformation circuit (28) is one end of capacitor C3 and the pin 12 and electricity of trigonometric function converter U1
The one end for hindering R2 is connected, and input terminal of the other end of capacitor C3 as functional transformation circuit (28) is denoted as port ACOS_in, with
The output end of second photoelectric conversion circuit (27) is connected；The other end of resistance R2 is grounded；The pin 2 of trigonometric function converter U1,
3,4,5,8,11,13 ground connection, pin 9,10 are connected with one end of capacitor C2 and -12V power supply, the other end ground connection of capacitor C2；Three
The pin 6 of angle function converter U1 is connected with pin 7, and pin 16 is connected with one end of+12V power supply and capacitor C1, capacitor C1's
Other end ground connection；The pin 1 of trigonometric function converter U1 is connected with the sliding end of slide rheostat W1, and the one of slide rheostat W1
End is connected with one end of resistance R1, and the other end of resistance R1 is connected with the pin 14 of trigonometric function converter U1, slide rheostat
Output end of the sliding end of W1 as functional transformation circuit (28), is denoted as port ACOS_out, with adaptive amplitude normalizing circuit
(29) input terminal is connected；The model AD639 of the trigonometric function converter U1；
The structure of the adaptive amplitude normalizing circuit (29) is, one end of capacitor C9 and one end of resistance R3 and chip U2's
Pin 3 is connected, the other end ground connection of resistance R3, input of the other end of capacitor C9 as adaptive amplitude normalizing circuit (29)
End, is denoted as port ADAPT_in, and the port ACOS_out of and function translation circuit (28) is connected；The pin 1 of chip U2, pin 7,
Pin 8, pin 14 are grounded, and pin 2 is connected with+5V power supply with pin 4, and pin 11 is connected with pin 12 and with capacitor C5's
One end and+5V power supply are connected, the other end ground connection of capacitor C5；The pin 13 of chip U2 is connected with one end of capacitor C4, capacitor C4
The other end ground connection；The pin 9 of chip U2 is connected with one end of capacitor C6, the other end ground connection of capacitor C6；The pin 5 of chip U2
It is connected with one end of resistance R12 and resistance R11, the other end of resistance R12 ground connection, the other end of resistance R11 is defeated with amplifier U4's
One end of outlet and capacitor C8 are connected, the positive supply termination+5V power supply of amplifier U8, negative power end ground connection；The other end of capacitor C8
It is connected with one end of resistance R10, the other end of resistance R10 is connected with the non-inverting input terminal of amplifier U4；The anti-phase input of amplifier U4
It holds and is connected with the sliding end of sliding variohm W3, one end of slide rheostat W3 is connected with+5V power supply, slide rheostat W3's
Other end ground connection；One end of capacitor C7 is connected with the non-inverting input terminal of one end of resistance R9 and amplifier U4, the other end of capacitor C7
Ground connection, the other end of resistance R9 are connected with the output end of one end of resistance R7 and amplifier U3, the other end and amplifier U3 of resistance R7
Inverting input terminal be connected；One end of resistance R8 is connected with the non-inverting input terminal of amplifier U3, other end ground connection；The positive electricity of amplifier U3
Source connects+5V power supply, negative power end ground connection；Output end of the pin 10 of chip U2 as adaptive amplitude normalizing circuit (29),
It is denoted as port ADAPT_out, is connected with an input terminal of phase-comparison circuit (30)；The pin 10 and diode D1 of chip U2
Anode be connected, the cathode of diode D1 is connected with one end of resistance R4, the other end of resistance R4 and one end of resistance R5 and fortune
The inverting input terminal for putting U3 is connected, and the other end of resistance R5 is connected with the anode of diode D2, the cathode of diode D2 and sliding
The sliding end of rheostat W2 is connected；One end of slide rheostat W2 is connected and is grounded with the cathode of diode D3, slide rheostat
The other end of W2 is connected with the anode of one end of resistance R6 and diode D3, another termination -5V power supply of resistance R6；The core
Piece U2 is variable gain amplifier chip, and model is AD8367；
The structure of the phase-comparison circuit (30) is one end of capacitor C10 and the non-inverting input terminal of amplifier U5 and resistance R13
One end be connected, an input terminal of the other end of capacitor C10 as phase-comparison circuit (30) is denoted as port PHASE_in1,
It is connected with the port ADAPT_out of adaptive amplitude normalizing circuit (29)；The other end of resistance R13 is grounded；The positive electricity of amplifier U5
Source connects+5V power supply, negative power end ground connection, reverse inter-input-ing ending grounding, the end CLK of output termination d type flip flop U6A；D type flip flop
The port D of U6A is grounded；The one end capacitor C11 ground connection, the end PR of another termination d type flip flop U6A；Resistance R14 mono- terminates d type flip flop
The end PR of U6A, the end Q of another termination d type flip flop U6A；CLR termination+5V the power supply of d type flip flop U6A, the Q of d type flip flop U6A are non-
Terminate the end PR of d type flip flop U8A；One end of capacitor C12 is connected with one end of the non-inverting input terminal of amplifier U7 and resistance R15, electricity
Hold another input terminal of the other end of C12 as phase-comparison circuit (30), port PHASE_in2 is denoted as, with controllable frequency
The port SineM_out in source (22) is connected；The other end of resistance R15 is grounded；Positive supply termination+5V the power supply of amplifier U7, negative electricity
Source ground connection, reverse inter-input-ing ending grounding, the end CLK of output termination d type flip flop U6B；The port D of d type flip flop U6B is grounded；Capacitor
The one end C13 ground connection, the end PR of another termination d type flip flop U6B；Resistance R16 mono- terminates the end PR of d type flip flop U6B, another termination D
The end Q of trigger U6B；CLR termination+5V the power supply of d type flip flop U6B, the CLR of the Q non-terminated d type flip flop U8A of d type flip flop U6B
End；The end D and the end CLK of d type flip flop U8A is grounded, and output end of the end Q as phase-comparison circuit (30) is denoted as port
PHASE_out is connected with the input terminal of single-chip microcontroller (19)；
The structure in the controllable frequency source (22) is the non-inverting input terminal of a termination amplifier U9 of resistance R21, another termination
Ground；The non-inverting input terminal of a termination amplifier U9 of capacitor C19, signal output end of the other end as controllable frequency source (22), note
Input terminal phase for port SinM_out, with port PHASE_in2 and the PZT driving circuit (23) of phase-comparison circuit (30)
Even；The inverting input terminal of a termination amplifier U9 of resistance R20, other end ground connection；Positive supply termination+5V the power supply of amplifier U9 is born
Power end ground connection, frequency output terminal of the output end as controllable frequency source (22) is denoted as port FrqM_out, with single-chip microcontroller (19)
It is connected；A termination+12V power supply of inductance L1, the collector of another termination triode Q1；The anode of electrolytic capacitor C14 meets+12V
Power supply, cathode ground connection；The collector of a termination triode Q1 of resistance R17, the base stage of another termination triode Q1；Capacitor C18
One termination triode Q1 base stage, it is another termination electrolytic capacitor C17 anode；The base of a termination triode Q1 of resistance R18
Pole, other end ground connection；Resistance R19 mono- terminates the emitter of triode Q1, other end ground connection；The anode of electrolytic capacitor C15 connects three
The emitter of pole pipe Q1, cathode ground connection；The collector of a termination triode Q1 of capacitor C16, another termination controllable impedance L2's
One end, the other end ground connection of controllable impedance L2；A termination port SinM_out of inductance L3, another termination electrolytic capacitor C17's
Anode, the cathode ground connection of electrolytic capacitor C17；The collector of triode Q1 meets port SinM_out.
2. a kind of system for detecting temperature based on Michelson interference structure according to claim 1, which is characterized in that institute
The pumping source (1) stated is 980nm laser light source.
3. a kind of system for detecting temperature based on Michelson interference structure according to claim 1 or 2, feature exist
In the Bragg grating group (9) is made of 3 Bragg gratings, and the reflectivity of each grating is 90%, and bandwidth is
0.6nm, central wavelength are respectively 1550nm, 1560nm and 1630nm.
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| US20110255078A1 (en) * | 2007-10-23 | 2011-10-20 | Us Sensor Systems, Inc. | Interrogator for a plurality of sensor fiber optic gratings |
| CN102564317A (en) * | 2011-12-23 | 2012-07-11 | 北京交通大学 | High-accuracy remote absolute displacement measurement system based on optical fiber composite interference |
| CN103940361A (en) * | 2014-04-30 | 2014-07-23 | 中国科学院半导体研究所 | Fiber bragg grating low-frequency strain sensing demodulation system |
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