CN109029772B - A kind of temperature sensors of high precision - Google Patents
A kind of temperature sensors of high precision Download PDFInfo
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- CN109029772B CN109029772B CN201810888833.4A CN201810888833A CN109029772B CN 109029772 B CN109029772 B CN 109029772B CN 201810888833 A CN201810888833 A CN 201810888833A CN 109029772 B CN109029772 B CN 109029772B
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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
Abstract
A kind of temperature sensors of high precision of the invention belongs to fiber optic sensor technology field.Its primary structure has pumping source (1), light wavelength division multiplexing (2), Er-doped fiber (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 sensors of high precision.
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 based on your interferometry demodulation techniques of non-equilibrium Mach Zehnder
Grating sensing system (referring to Fig. 3 .6 of page 26 of the document), the optical fiber sensing system use Mach Zehnder that principle of interference,
Change the length of the arm using the modulated signal that piezoelectric ceramics (PZT) is provided on a wherein arm in interferometer two-arm, to change
Exsiccation interferometer output intensity, interferometer output intensity is regular in cosine function with the variation of PZT modulated signal, if using ideal
Modulated signal of the sawtooth wave as PZT, then the output of optical fiber sensing system is directly cosine wave.Optical fiber sensing system passes through Bradley
Lattice grating perceives the variation (principle is similar when measurement temperature) of measurement point stress, and is reflected as the change of reflectance spectrum central wavelength
Change, the variation of central wavelength is presented as the variation of output cosine wave phase after your interferometer of above-mentioned Mach Zehnder, finally will
The phase of cosine wave compares with the phase of sawtooth wave, can reflect the change of bragg grating reflectance spectrum central wavelength
Change, to 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 temperature change.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
Temperature sensors of high precision of the string signal as PZT driving signal so as to avoid the generation of high-frequency interferencing signal, and is being docked
Without using filter when the signal received is handled, the influence that phase is generated so as to avoid filtering.
The purpose of the present invention is achieved through the following technical solutions:
A kind of temperature sensors of high precision, structure have, and pumping source 1 is connected with the end 980nm of light wavelength division multiplexing 2, light
The end 1550nm of wavelength division multiplexer 2 is connected with one end of delay line adjustable optic fibre 11, the other end of delay line is adjustable light 11 with
The input terminal of first optoisolator 10 is connected, the control terminal of light 11 that delay line is adjustable and the output port of electrical level transferring chip 12
It is connected, electrical level transferring chip 12 is connected with single-chip microcontroller 15；The output end of first optoisolator 10 and the light input end of optical filter 9
It is connected, the electric control end of optical filter 9 is connected with single-chip microcontroller 15, the light output end of optical filter 9 and the first end of optical circulator 7
Mouth is connected, and the second port of optical circulator 7 is connected with one end of Bragg grating group 8, the third port of optical circulator 7 and first
The input terminal of photo-coupler 5 is connected, and 90% output end of the first photo-coupler 5 is connected with the input terminal of the second optoisolator 4, the
The output end of two optoisolators 4 is connected with one end of Er-doped fiber 3, the other end of Er-doped fiber 3 and the public affairs of light wavelength division multiplexing 2
End is connected altogether；The 10% output end output of first photo-coupler 5 is connected with the input terminal of the second photo-coupler 6, the second optical coupling
One output end of device 6 is connected with an input terminal of third photo-coupler 22, the another output of the second photo-coupler 6 with
The one end for being wrapped in the optical fiber on piezoelectric ceramics 21 is connected, and is wrapped in the other end and third optocoupler of the optical fiber on piezoelectric ceramics 21
Another input terminal of clutch 22 is connected, the input terminal phase of the output end and the first optical detector 23 of third photo-coupler 22
Even, another output is connected with the input terminal of the second optical detector 24；
It is characterized in that, structure is in addition, the output end of the first optical detector 23 and the homophase input of differential amplifier circuit 25
End is connected, and the second optical detector 24 is connected with the inverting input terminal of differential amplifier circuit 25, the output end of differential amplifier circuit 25
The input terminal of and function translation circuit 26 is connected, and the output end of functional transformation circuit 26 is defeated with adaptive amplitude normalizing circuit 27
Enter end to be connected, the output end of adaptive amplitude normalizing circuit 27 is connected with an input terminal of phase-comparison circuit 28；Digital-to-analogue turns
The input terminal for changing circuit 18 is connected with single-chip microcontroller 15, and output end is connected with the input terminal in controllable frequency source 19, controllable frequency source 19
Output end be connected with another input terminal of phase-comparison circuit 28, output end and 15 phase of single-chip microcontroller of phase-comparison circuit 28
Even；The output end in controllable frequency source 19 is also connected with the input terminal of PZT driving circuit 20, the output end of PZT driving circuit 20 with
The control terminal of piezoelectric ceramics 21 is connected；Single-chip microcontroller 15 also respectively with input key 13, temperature sensor 14, serial communication modular
16, display screen 17 is connected；
The structure of the functional transformation circuit 26 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 26 is denoted as port ACOS_in, with
The output end of differential amplifier circuit 25 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；Trigonometric function
The pin 6 of converter U1 is connected with pin 7, and pin 16 is connected with one end of+12V power supply and capacitor C1, the other end of capacitor C1
Ground connection；The pin 1 of trigonometric function converter U1 is connected with the sliding end of slide rheostat W1, one end of slide rheostat W1 and electricity
The one end for hindering R1 is connected, and the other end of resistance R1 is connected with the pin 14 of trigonometric function converter U1, the cunning of slide rheostat W1
Output end of the moved end as functional transformation circuit 26, is denoted as port ACOS_out, the input with adaptive amplitude normalizing circuit 27
End is connected；The model AD639 of the trigonometric function converter U1；
The structure of the adaptive amplitude normalizing circuit 27 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 27
End, is denoted as port ADAPT_in, and the port ACOS_out of and function translation circuit 26 is connected；Pin 1, pin 7, the pipe of chip U2
Foot 8, pin 14 are grounded, and pin 2 is connected with+5V power supply with pin 4, and pin 11 is connected and one with capacitor C5 with pin 12
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's
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 with
One end of resistance R12 and resistance R11 are connected, the other end ground connection of resistance R12, the output of the other end and amplifier U4 of resistance R11
End and one end of 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 with
One end of resistance R10 is connected, 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
It is connected with the sliding end of sliding variohm W3, one end of slide rheostat W3 is connected with+5V power supply, and slide rheostat W3's is another
One 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, another termination of capacitor C7
The other end on ground, resistance R9 is connected with the output end of one end of resistance R7 and amplifier U3, and the other end of resistance R7 is with amplifier U3's
Inverting input terminal is connected；One end of resistance R8 is connected with the non-inverting input terminal of amplifier U3, other end ground connection；The positive supply of amplifier U3
Termination+5V power supply, negative power end ground connection；Output end of the pin 10 of chip U2 as adaptive amplitude normalizing circuit 27, is denoted as
Port ADAPT_out is connected with an input terminal of phase-comparison circuit 28；The pin 10 of chip U2 and the anode of diode D1
It is 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 amplifier U3's
Inverting input terminal is connected, and the other end of resistance R5 is connected with the anode of diode D2, the cathode and slide rheostat of diode D2
The sliding end of W2 is connected；One end of slide rheostat W2 is connected and is grounded with the cathode of diode D3, and slide rheostat W2's is another
One end is connected with the anode of one end of resistance R6 and diode D3, another termination -5V power supply of resistance R6；The chip U2 is
Variable gain amplifier chip, model are AD8367；
The structure of the phase-comparison circuit 28 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 28 is denoted as port PHASE_
In1 is connected with the port ADAPT_out of adaptive amplitude normalizing circuit 27；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 28, port PHASE_in2 is denoted as, with controllable frequency source
19 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 mono-
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 type flip flop
The end Q of U6B；CLR termination+5V the power supply of d type flip flop U6B, the end CLR of the Q non-terminated d type flip flop U8A of d type flip flop U6B；D touching
The end D and the end CLK for sending out device U8A are grounded, and output end of the end Q as phase-comparison circuit 28 is denoted as port PHASE_out；
The structure in the controllable frequency source 19 is a termination+12V power supply of slide rheostat W4, the other end and sliding
Terminate the base stage of triode Q1；The base stage of a termination triode Q1 of capacitor C14, other end ground connection；A termination three of resistance R17
The base stage of pole pipe Q1, other end ground connection；A termination+12V power supply of resistance R18, the collector of another termination triode Q1；Resistance
The emitter of a termination triode Q1 of R19, other end ground connection；The emitter of a termination triode Q1 of capacitor C15, the other end
Connect the collector of triode Q1；The emitter of a termination triode Q1 of capacitor C16, other end ground connection；The current collection of triode Q1
Output end of the pole as controllable frequency source 19, is denoted as port SineM_out；The collector of a termination triode Q1 of capacitor C17,
The other end is connected with one end of one end of capacitor C18 and inductance L1, another termination varactor D4 cathode of capacitor C18, becomes
Hold the plus earth of diode D4, the other end ground connection of inductance L1；One end of capacitor C19 is grounded, and the other end is as controllable frequency
The input terminal in source 19 is denoted as port SineM_in；One end of resistance R20 is connected with port SineM_in, the other end and transfiguration two
The cathode of pole pipe is connected.
The preferred 980nm laser light source of pumping source 1.
The preferred DS18B20 digital temperature sensor of temperature sensor 14.
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.
The overall structure of the invention of embodiment 1
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) and (the COMCORE company 980/1060nm single mode of light wavelength division multiplexing 2
Optical fibre wavelength division multiplexer) the end 980nm be connected, the end 1550nm of light wavelength division multiplexing 2 and (the Sichuan space of delay line adjustable optic fibre 11
The electronic fibre delay line of VDL-40-15-S9-1-FA type of fixed star Micron Technology Co., Ltd) one end be connected, delay line tunable optical
The other end of line 11 is connected with the input terminal of the first optoisolator 10 (1550nm polarization independent optical isolator), delay line tunable optical
The control terminal of line 11 is connected with the output port of electrical level transferring chip 12 (MAX232), electrical level transferring chip 12 and single-chip microcontroller 15
(single-chip microcontroller STC89C51) is connected；The output end of first optoisolator 10 and optical filter 9 (Micron Optics company produces,
Model FFP-TF-1060-010G0200-2.0) light input end be connected, electric control end and 15 phase of single-chip microcontroller of optical filter 9
Even, the light output end of optical filter 9 is connected with the first port of optical circulator 7 (PIOC3-15 of Shanghai Han Yu company), the ring of light
(reflectivity is 90% to the second port of shape device 7, and bandwidth is 0.6nm, and central wavelength is respectively with Bragg grating group 8
Three Bragg gratings of 1550nm, 1560nm and 1630nm) one end be connected, the third port of optical circulator 7 and the first light
Coupler 5 (the model FUSED-12-1060-7/125-50/50-3U-3mm of OZ-OPTICS company production, splitting ratio 10:
90 1 × 2 fiber coupler) input terminal be connected, 90% output end of the first photo-coupler 5 and the second optoisolator 4
The input terminal of (1550nm polarization independent optical isolator) is connected, the output end of the second optoisolator 4 and the 3 (U.S. of Er-doped fiber
Nufern company production SM-ESF-7/125 Er-doped fiber) one end be connected, the other end and optical wavelength division multiplexing of Er-doped fiber 3
The common end of device 2 is connected；Above structure constitutes basic luminaire part and the transducing part of fibre optical sensor.First photo-coupler
5 10% output end output is connected with the input terminal of the second photo-coupler 6,6 (the OZ-OPTICS company production of the second photo-coupler
Model FUSED-12-1060-7/125-50/50-3U-3mm, splitting ratio be 50:50 1 × 2 fiber coupler) one
An input terminal of output end and third photo-coupler 22 (2 × 2 standard single mode photo-couplers, splitting ratio 50:50) are connected, the
The another output of two photo-couplers 6 is connected with the one end for the optical fiber being wrapped on piezoelectric ceramics 21, is wrapped in piezoelectric ceramics
The other end and third photo-coupler 22 of optical fiber on 21 (cylindrical piezoelectric ceramics, outer diameter 50mm, internal diameter 40mm, high 50mm)
Another input terminal is connected, and (the quick light science and technology in Beijing is limited with the first optical detector 23 for an output end of third photo-coupler 22
The LSIPD-LD50 type optical detector of company) input terminal be connected, another output and 24 (the quick light in Beijing of the second optical detector
The LSIPD-LD50 type optical detector of Science and Technology Ltd.) input terminal be connected.Above-mentioned second photo-coupler 6, third optical coupling
Device 22, piezoelectric ceramics 21 and the first optical detector 23 and the second optical detector 24 collectively constitute Mach Zehnder that interference structure.
Structure of the invention in addition, the output end and differential amplifier circuit 25 of the first optical detector 23 non-inverting input terminal phase
Even, the LSIPD-LD50 type optical detector of the quick Micron Technology Co., Ltd in 24 Beijing of the second optical detector) and differential amplifier circuit 25
Inverting input terminal be connected, the input terminal of the output end and function translation circuit 26 of differential amplifier circuit 25 is connected, functional transformation
The output end of circuit 26 is connected with the input terminal of adaptive amplitude normalizing circuit 27, the output end of adaptive amplitude normalizing circuit 27
It is connected with an input terminal of phase-comparison circuit 28；The input terminal of D/A converting circuit 18 is connected with single-chip microcontroller 15, output end
It is connected with the input terminal in controllable frequency source 19, the output end in controllable frequency source 19 and another input terminal of phase-comparison circuit 28
It is connected, the output end of phase-comparison circuit 28 is connected with single-chip microcontroller 15；The output end in controllable frequency source 19 also with PZT driving circuit
20 input terminal is connected, and the output end of PZT driving circuit 20 is connected with the control terminal of piezoelectric ceramics 21；Above structure constitutes biography
The demodulation part of sensor.Single-chip microcontroller 15 is also connected with temperature sensor 14 (DS18B20), and above structure is that the present invention provides temperature
Spend compensation function.Single-chip microcontroller 15 is also connected with input key 13, serial communication modular 16 (MAX232), display screen 17 respectively；With
In setting parameter, the functions such as information are communicated and shown with computer.
2 functional transformation circuit of embodiment
As shown in Fig. 2, the structure of functional transformation circuit 26 used in the present invention is one end of capacitor C3 and trigonometric function
The pin 12 of converter U1 and one end of resistance R2 are connected, input terminal of the other end of capacitor C3 as functional transformation circuit 26,
It is denoted as port ACOS_in, is connected with the output end of differential amplifier circuit 25；The other end of resistance R2 is grounded；Trigonometric function conversion
The pin 2,3,4,5,8,11,13 of device U1 is grounded, and pin 9,10 is connected with one end of capacitor C2 and -12V power supply, and capacitor C2's is another
One end ground connection；The pin 6 of trigonometric function converter U1 is connected with pin 7, one end phase of pin 16 and+12V power supply and capacitor C1
Even, the other end ground connection of capacitor C1；The pin 1 of trigonometric function converter U1 is connected with the sliding end of slide rheostat W1, sliding
One end of rheostat W1 is connected with one end of resistance R1,14 phase of pin of the other end and trigonometric function converter U1 of resistance R1
Even, output end of the sliding end of slide rheostat W1 as functional transformation circuit 26 is denoted as port ACOS_out, with adaptive width
The input terminal for spending normalizing circuit 27 is connected；The model AD639 of the trigonometric function converter U1；The circuit has anticosine
Mapping function, the signal that differential amplifier circuit 25 is exported carry out anticosine processing.
The adaptive amplitude normalizing circuit of embodiment 3
Since the signal amplitude that functional transformation circuit 26 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 27, for the signal for exporting functional transformation circuit 26
Amplitude normalization at best size, to further increase the precision of demodulation.The knot of the adaptive amplitude normalizing circuit 27
Structure is that one end of capacitor C9 is connected with the pin 3 of one end of resistance R3 and chip U2, the other end ground connection of resistance R3, capacitor C9
Input terminal of the other end as adaptive amplitude normalizing circuit 27, be denoted as port ADAPT_in, and function translation circuit 26
Port ACOS_out is connected；Pin 1, pin 7, pin 8, the pin 14 of chip U2 is grounded, and pin 2 and pin 4 are electric with+5V
Source is connected, and pin 11 is connected with pin 12 and is connected with one end of capacitor C5 and+5V power supply, the other end ground connection of capacitor C5；Core
The pin 13 of piece U2 is connected with one end of capacitor C4, the other end ground connection of capacitor C4；The pin 9 of chip U2 and one end of capacitor C6
It is connected, the other end ground connection of capacitor C6；The pin 5 of chip U2 is connected with one end of resistance R12 and resistance R11, and resistance R12's is another
One end ground connection, the other end of resistance R11 are connected with one end of the output end of amplifier U4 and capacitor C8, the positive supply termination of amplifier U8
+ 5V power supply, negative power end ground connection；The other end of capacitor C8 is connected with one end of resistance R10, the other end and amplifier of resistance R10
The non-inverting input terminal of U4 is connected；The inverting input terminal of amplifier U4 is connected with the sliding end of sliding variohm W3, slide rheostat
One end of W3 is connected with+5V power supply, the other end ground connection of slide rheostat W3；One end of capacitor C7 and one end of resistance R9 and fortune
The non-inverting input terminal for putting U4 is connected, the other end ground connection of capacitor C7, the other end of resistance R9 and one end of resistance R7 and amplifier U3
Output end be connected, the other end of resistance R7 is connected with the inverting input terminal of amplifier U3；One end of resistance R8 is same with amplifier U3's
Phase input terminal is connected, 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
As the output end of adaptive amplitude normalizing circuit 27, it is denoted as port ADAPT_out, an input with phase-comparison circuit 28
End is connected；The pin 10 of chip U2 is connected with the anode of diode D1, and the cathode of diode D1 is connected with one end of resistance R4, electricity
The other end of resistance R4 is connected with the inverting input terminal of one end of resistance R5 and amplifier U3, and the other end of resistance R5 is with diode D2's
Anode is connected, and the cathode of diode D2 is connected with the sliding end of slide rheostat W2；One end of slide rheostat W2 and diode
The cathode of D3 is connected and is grounded, and the other end of slide rheostat W2 is connected with the anode of one end of resistance R6 and diode D3, electricity
Hinder another termination -5V power supply of R6；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 28 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 28,
It is denoted as port PHASE_in1, is connected with the port ADAPT_out of adaptive amplitude normalizing circuit 27；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 type flip flop U6A, D touching
Send out the end PR of the Q non-terminated d type flip flop U8A of device U6A；One end of capacitor C12 and the non-inverting input terminal of amplifier U7 and resistance R15's
One end is connected, another input terminal of the other end of capacitor C12 as phase-comparison circuit 28 is denoted as port PHASE_in2, with
The port SineM_out in controllable frequency source 19 is connected；The other end of resistance R15 is grounded；Positive supply termination+5V the electricity of amplifier U7
Source, 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 connects
Ground；The one end capacitor 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, separately
The end Q of one termination d type flip flop U6B；CLR termination+5V the power supply of d type flip flop U6B, the Q non-terminated d type flip flop of d type flip flop U6B
The end CLR of U8A；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 28 is denoted as end
Mouth PHASE_out, is connected with the input terminal of single-chip microcontroller 15.Standard sine wave that the circuit exports controllable frequency source and adaptive
The sine wave (environment that its phase is detected by Bragg grating group 8 is influenced) of amplitude normalizing circuit output carries out phase bit comparison,
And comparison result is sent into single-chip microcontroller 15, single-chip microcontroller calculates the temperature at Bragg grating group 8 and becomes according to the phase differential
Change.
5 controllable frequency source of embodiment
As shown in figure 5, the structure in controllable frequency source 19 used in the present invention is, a termination+12V of slide rheostat W4
Power supply, the base stage of the other end and sliding termination triode Q1；The base stage of a termination triode Q1 of capacitor C14, other end ground connection；
The base stage of a termination triode Q1 of resistance R17, other end ground connection；A termination+12V power supply of resistance R18, three poles of another termination
The collector of pipe Q1；The emitter of a termination triode Q1 of resistance R19, other end ground connection；A termination triode of capacitor C15
The emitter of Q1, the collector of another termination triode Q1；The emitter of a termination triode Q1 of capacitor C16, another termination
Ground；Output end of the collector of triode Q1 as controllable frequency source 19, is denoted as port SineM_out；A termination of capacitor C17
The collector of triode Q1, the other end are connected with one end of one end of capacitor C18 and inductance L1, and another termination of capacitor C18 becomes
Hold diode D4 cathode, the plus earth of varactor D4, the other end ground connection of inductance L1；One end of capacitor C19 is grounded, separately
Input terminal of the one end as controllable frequency source 19, is denoted as port SineM_in；One end of resistance R20 and port SineM_in phase
Even, the other end is connected with the cathode of varactor.Control of the module by D/A converting circuit 18, the adjustable mark of output frequency
Quasi-sine-wave provides required sinusoidal signal for demodulation part of the invention.
7 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 8 is placed on each position (sensitive position in such as mine) for needing monitoring temperature to change, by Er-doped fiber 3, optoisolator 4
The optical fiber laser annular chamber of equal compositions is that bragg grating group 8 provides wideband light source, each bragg grating meeting
There is a specific reflectance spectrum, the peak wavelength of different gratings, reflectance spectrum is different, when some measurand temperature becomes
When change, the reflectance spectrum peak wavelength of the bragg grating at this can occur to deviate accordingly, and reflected light enters by second
In the Mach Zehnder that interferometer that photo-coupler 6, piezoelectric ceramics 21, third photo-coupler 22 are constituted, while controllable frequency source 19
For Mach Zehnder, your interferometer provides a control signal sin (ω t), and the signal is anti-by bragg grating in interferometer
The influence for the light penetrated, then it is converted into electric signal through the first optical detector 23 and the second optical detector 24, by differential amplifier circuit 25
It carries out differential amplification and is obtained sin (ω t+ Δ θ) later by the anti-cosine transform of functional transformation circuit 26, the signal is through adaptive
27 amplitude of amplitude normalizing circuit is adjusted to a suitable size (being controlled by reference voltage circuit 32), signal at this time with
Controllable frequency source 19 generates sinusoidal signal sin (ω t) and compares, and phase is changed, by phase-comparison circuit 28 by the two
Phase difference detection come out and be sent into single-chip microcontroller 15, the phase difference real reaction temperature change of measured point finally realizes
Detection to measured point temperature.The present invention is no during modulation and demodulation to use sawtooth wave, so as to avoid under sawtooth wave
Drop is along bring high-frequency jitter signal, also there is no need to use bandpass filter to be filtered in demodulator circuit, avoids pair
The amplitude-frequency characteristic and phase-frequency characteristic of output signal have an impact.The present invention using standard sine wave signal as PZT modulated signal,
When demodulating to modulated signal, functional transformation circuit 26 and adaptive amplitude normalizing circuit 27 are dexterously used, it will
Modulated signal recovers phase is controlled by the Bragg grating group 8 and suitable sinusoidal signal of amplitude, so that in phase bit comparison electricity
When carrying out phase bit comparison in road 28, the phase difference of controlled signal and original signal can be highly precisely compared, thus accurately
The environmental parameter that ground reaction sensing head (i.e. Bragg grating group 8) is detected.
Since optical fiber laser annular chamber (is generally sensed with bragg grating group 8 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, by temperature sensor 14 by environment temperature
The variation of degree is converted into digital signal input single-chip microcontroller 15, the change for environment temperature locating for compensated optical fiber laser annular chamber
Change and gives measurement result bring error.
Claims (3)
1. a kind of temperature sensors of high precision, structure have, pumping source (1) is connected with the end 980nm of light wavelength division multiplexing (2),
The end 1550nm of light wavelength division multiplexing (2) is connected with one end of delay line adjustable optic fibre (11), delay line adjustable optic fibre (11)
The other end is connected with the input terminal of the first optoisolator (10), the control terminal and electrical level transferring chip of delay line adjustable optic fibre (11)
(12) output port is connected, and electrical level transferring chip (12) is connected with single-chip microcontroller (15)；The output end of first optoisolator (10)
It is connected with the light input end of optical filter (9), the electric control end of optical filter (9) is connected with single-chip microcontroller (15), optical filter (9)
Light output end be connected with the first port of optical circulator (7), the second port of optical circulator (7) and Bragg grating group (8)
One end be connected, the third port of optical circulator (7) is connected with the input terminal of the first photo-coupler (5), the first photo-coupler (5)
90% output end be connected with the input terminal of the second optoisolator (4), the output end and Er-doped fiber of the second optoisolator (4)
(3) one end is connected, and the other end of Er-doped fiber (3) is connected with the common end of light wavelength division multiplexing (2)；First photo-coupler
(5) 10% output end is connected with the input terminal of the second photo-coupler (6), an output end of the second photo-coupler (6) and
One input terminal of three photo-couplers (22) is connected, and the second photo-coupler (6) another output and is wrapped in piezoelectric ceramics
(21) one end of the optical fiber on is connected, and is wrapped in the other end and third photo-coupler (22) of the optical fiber on piezoelectric ceramics (21)
Another input terminal is connected, and an output end of third photo-coupler (22) is connected with the input terminal of the first optical detector (23),
Another output is connected with the input terminal of the second optical detector (24)；
It is characterized in that, structure is in addition, the output end of the first optical detector (23) and the homophase input of differential amplifier circuit (25)
End is connected, and the second optical detector (24) is connected with the inverting input terminal of differential amplifier circuit (25), differential amplifier circuit (25)
The input terminal of output end and function translation circuit (26) is connected, the output end of functional transformation circuit (26) and adaptive amplitude normalizing
The input terminal of circuit (27) is connected, and one of the output end of adaptive amplitude normalizing circuit (27) and phase-comparison circuit (28) is defeated
Enter end to be connected；The input terminal of D/A converting circuit (18) is connected with single-chip microcontroller (15), and output end is defeated with controllable frequency source (19)
Enter end to be connected, the output end of controllable frequency source (19) is connected with another input terminal of phase-comparison circuit (28), phase bit comparison
The output end of circuit (28) is connected with single-chip microcontroller (15)；The output end in controllable frequency source (19) also with PZT driving circuit (20)
Input terminal is connected, and the output end of PZT driving circuit (20) is connected with the control terminal of piezoelectric ceramics (21)；Single-chip microcontroller (15) is also distinguished
It is connected with input key (13), temperature sensor (14), serial communication modular (16), display screen (17)；
The structure of the functional transformation circuit (26) 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 (26) is denoted as port ACOS_in, with
The output end of differential amplifier circuit (25) 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 letter
The pin 6 of number converter U1 is connected with pin 7, and pin 16 is connected with one end of+12V power supply and capacitor C1, and capacitor C1's is another
End ground connection；The pin 1 of trigonometric function converter U1 is connected with the sliding end of slide rheostat W1, one end of slide rheostat W1 with
One end of resistance R1 is connected, and the other end of resistance R1 is connected with the pin 14 of trigonometric function converter U1, slide rheostat W1's
Output end of the sliding end as functional transformation circuit (26), is denoted as port ACOS_out, with adaptive amplitude normalizing circuit (27)
Input terminal be connected；The model AD639 of the trigonometric function converter U1；
The structure of the adaptive amplitude normalizing circuit (27) 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 (27)
End, is denoted as port ADAPT_in, and the port ACOS_out of and function translation circuit (26) 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 (27),
It is denoted as port ADAPT_out, is connected with an input terminal of phase-comparison circuit (28)；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 (28) 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 (28) is denoted as port PHASE_in1,
It is connected with the port ADAPT_out of adaptive amplitude normalizing circuit (27)；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 (28), port PHASE_in2 is denoted as, with controllable frequency
The port SineM_out in source (19) 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 (28) is denoted as port
PHASE_out；
The structure in the controllable frequency source (19) is a termination+12V power supply of slide rheostat W4, the other end and sliding end
Connect the base stage of triode Q1；The base stage of a termination triode Q1 of capacitor C14, other end ground connection；Three poles of termination of resistance R17
The base stage of pipe Q1, other end ground connection；A termination+12V power supply of resistance R18, the collector of another termination triode Q1；Resistance
The emitter of a termination triode Q1 of R19, other end ground connection；The emitter of a termination triode Q1 of capacitor C15, the other end
Connect the collector of triode Q1；The emitter of a termination triode Q1 of capacitor C16, other end ground connection；The current collection of triode Q1
Output end of the pole as controllable frequency source (19), is denoted as port SineM_out；The current collection of a termination triode Q1 of capacitor C17
Pole, the other end are connected with one end of one end of capacitor C18 and inductance L1, another termination varactor D4 cathode of capacitor C18,
The plus earth of varactor D4, the other end ground connection of inductance L1；One end of capacitor C19 is grounded, and the other end is as controllable frequency
The input terminal in rate source (19), is denoted as port SineM_in；One end of resistance R20 is connected with port SineM_in, the other end and change
The cathode for holding diode is connected.
2. a kind of temperature sensors of high precision according to claim 1, which is characterized in that the pumping source (1) is
980nm laser light source.
3. a kind of temperature sensors of high precision according to claim 1 or 2, which is characterized in that the temperature sensor
It (14) is DS18B20 digital temperature sensor.
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| 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 |
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