CN113124992A - Portable photoelectric conversion integrated optical fiber hydrophone and test system thereof - Google Patents
Portable photoelectric conversion integrated optical fiber hydrophone and test system thereof Download PDFInfo
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Abstract
The invention discloses a portable photoelectric conversion integrated optical fiber hydrophone and a test system thereof, which comprises a modulatable narrow-linewidth light source, an optical fiber hydrophone, a photoelectric detector, a transmission cable, a female power interface and two BNC interfaces, wherein the modulatable narrow-linewidth light source, the optical fiber hydrophone and the photoelectric detector are hermetically packaged, the transmission cable comprises a first signal transmission cable, a second signal transmission cable and a power cable, the modulatable narrow-linewidth light source is connected with the optical fiber hydrophone, the optical fiber hydrophone is connected with the photoelectric detector, the photoelectric detector is connected to one end of the first signal transmission cable, the other end of the first signal transmission cable is connected with one of the BNC interfaces, the modulation interface of the modulatable narrow-linewidth light source is connected with the second signal transmission cable, the second signal transmission cable is connected with two of the BNC interfaces, and power supply pins of the modulatable narrow-linewidth light source and the photoelectric detector are connected with the power cable, the power cable is connected with the female power interface. The device has the advantages of simple structure, portability, reliability and accurate calibration and detection.
Description
Technical Field
The invention belongs to the technical field of optical fiber sensing, and particularly relates to a portable photoelectric conversion integrated optical fiber hydrophone and a test system thereof, which are used for calibration test.
Background
The optical fiber hydrophone is an underwater acoustic signal sensor based on optical fiber and photoelectronic technology. The underwater sound vibration is converted into an optical signal through high-sensitivity optical coherent detection, and the optical signal is transmitted to a signal processing system through an optical fiber to extract sound signal information. The optical fiber hydrophone has the characteristics of high sensitivity, good frequency response characteristic and the like. And the test application of the optical fiber hydrophone system is complex, and the construction of correct and available optical fiber hydrophone test equipment is difficult under the condition of no professional optical engineer.
Disclosure of Invention
In order to enable non-optical researchers to normally use the optical fiber hydrophone to carry out test research in related fields, the invention provides a portable optical-to-electrical integrated optical fiber hydrophone and a test system thereof.
One of the purposes of the invention is realized by the following technical scheme: the portable photoelectric conversion integrated optical fiber hydrophone comprises a modulatable narrow-linewidth light source, an optical fiber hydrophone, a photoelectric detector, a transmission cable, a female power interface and two BNC interfaces, wherein the modulatable narrow-linewidth light source, the optical fiber hydrophone and the photoelectric detector are hermetically packaged, the transmission cable comprises a first signal transmission cable, a second signal transmission cable and a power cable, an optical fiber output end of the modulatable narrow-linewidth light source is connected with an optical fiber input end of the optical fiber hydrophone, an optical fiber output end of the optical fiber hydrophone is connected with an optical fiber input end of the photoelectric detector, an output end of the photoelectric detector is connected to one end of the first signal transmission cable, the other end of the first signal transmission cable is connected with one of the BNC interfaces, a modulation interface of the modulatable narrow-linewidth light source is connected with one end of the second signal transmission cable, and the other end of the second signal transmission cable is connected with two of the, the power supply pins of the modulatable narrow-linewidth light source and the photoelectric detector are connected with one end of a power cable, and the other end of the power cable is connected with a female power interface.
As a further improvement, the optical fiber hydrophone is a high-sensitivity mandrel type optical fiber hydrophone developed based on the michelson interference principle, and comprises an inner cylinder, an outer cylinder, a reference arm optical fiber, a sensing arm optical fiber, an elastic body, an optical fiber and an air cavity, wherein the inner cylinder and the outer cylinder are coaxially arranged, the inner cylinder is arranged in the outer cylinder, a support rigid body is arranged on the outer cylinder and used for external packaging and supporting stress, the reference arm optical fiber is wound on the inner cylinder, the sensing arm optical fiber is wound on the outer cylinder, the elastic body is sleeved in the inner cylinder, the optical fiber is wound on the elastic body, the inner layer of the elastic body is air, and the air cavity is arranged on the outer cylinder.
As a further improvement, the portable optical-to-electrical integrated fiber hydrophone further comprises a power amplifier arranged between the transmission cable and the photoelectric detector, wherein the output end of the photoelectric detector is connected with the input end of the power amplifier, and the output end of the power amplifier is connected with one end of the first signal transmission cable.
As a further improvement, the optical fiber hydrophone is packaged by adopting sound-transmitting rubber; the photoelectric detector and the modulatable narrow linewidth light source are integrally packaged by adopting stainless steel.
As a further improvement, the portable photoelectric conversion integrated optical fiber hydrophone further comprises a sealing device, the optical fiber hydrophone is packaged by sound-transmitting rubber and then placed in the sealing device, and the whole of the photoelectric detector and the modulable narrow-line-width light source is packaged by stainless steel and then placed in the sealing device.
As a further improvement, the power amplifier, the photoelectric detector and the modulable narrow-linewidth light source are integrally packaged by stainless steel.
As a further improvement, the modulatable narrow linewidth light source is a butterfly light source with the linewidth of 3kHz and the linewidth of 10 dBm; and/or the power amplifier model is AD 8021; and/or the photodetector has a bandwidth of 32MHz @3dB, a voltage responsivity of 130kV/W, and a length-diameter dimension of 13 x 7.8 mm.
As a further improvement, the portable optical-to-electrical integrated fiber hydrophone is manufactured by the following steps:
step 1: connecting an optical fiber output end of the light source with a narrow line width and an optical fiber input end of the optical fiber hydrophone;
step 2: connecting the optical fiber output end of the optical fiber hydrophone with the optical fiber input end of the photoelectric detector;
and step 3: connecting the power amplifier with the signal output end of the photoelectric detector;
and 4, step 4: connecting the output end of the photoelectric detector with the input end of the power amplifier, connecting the output end of the power amplifier to one end of a first signal transmission cable, and connecting the other end of the first signal transmission cable with one BNC interface;
and 5: connecting a modulation interface capable of modulating the narrow-linewidth light source with one end of a second signal transmission cable, and connecting the other end of the second signal transmission cable with two BNC interfaces;
step 6: connecting power supply pins of the light source, the power amplifier and the photoelectric detector with the adjustable narrow line width through a power cable in the transmission cable, wherein the other end of the power cable in the transmission cable is connected with a female power interface;
and 7: and the light source with the adjustable narrow line width, the optical fiber hydrophone, the photoelectric detector and the power amplifier are sealed and packaged in an acoustic transmission and waterproof manner.
The second purpose of the invention is realized by the following technical scheme: the portable photoelectric conversion integrated optical fiber hydrophone testing system comprises a computer, an acquisition card and any one of the portable photoelectric conversion integrated optical fiber hydrophone, wherein the optical fiber hydrophone is connected with an external power supply through a female power supply interface, two BNC connectors are connected to the acquisition card, and the acquisition card is connected with the computer.
As a further improvement, the computer realizes the calibration test of the portable photoelectric conversion integrated optical fiber hydrophone by direct frequency modulation and indirect phase modulation of a PGC algorithm, and the specific process is as follows:
firstly, extracting a pair of orthogonal terms in a PGC algorithm by a coherent demodulation method or a band-pass filtering method, namely separating a pair of odd frequency and even frequency;
and secondly, linearly extracting the phase to be tested in the pair of orthogonal terms by differential cross multiplication or an inverse tangent method, thereby realizing the calibration test of the portable photoelectric conversion integrated optical fiber hydrophone.
The invention provides a portable photoelectric conversion integrated optical fiber hydrophone which comprises a modulatable narrow-linewidth light source, an optical fiber hydrophone, a photoelectric detector, a transmission cable, a female power interface and two BNC interfaces, wherein the modulatable narrow-linewidth light source, the optical fiber hydrophone and the photoelectric detector are hermetically packaged, the transmission cable comprises a first signal transmission cable, a second signal transmission cable and a power cable, the optical fiber output end of the modulatable narrow-linewidth light source is connected with the optical fiber input end of the optical fiber hydrophone, the optical fiber output end of the optical fiber hydrophone is connected with the optical fiber input end of the photoelectric detector, the output end of the photoelectric detector is connected to one end of the first signal transmission cable, the other end of the first signal transmission cable is connected with one of the BNC interfaces, the modulation interface of the modulatable narrow-linewidth light source is connected with one end of the second signal transmission cable, and the other end of the second signal transmission cable is connected, the power supply pins of the modulatable narrow-linewidth light source and the photoelectric detector are connected with one end of a power cable, and the other end of the power cable is connected with a female power interface. Compared with the prior art, the integrated modulatable narrow-linewidth light source, the optical fiber hydrophone and the photoelectric detector are integrated, and then the integrated device is subjected to sound transmission and waterproof sealing packaging, so that the portable photoelectric conversion integrated optical fiber hydrophone which is portable and reliable and has an output signal of an electric signal is formed, and the portable photoelectric conversion integrated optical fiber hydrophone has the advantages of simple structure, reliability in carrying and simplicity and accuracy in calibration and testing.
Drawings
The invention is further illustrated by means of the attached drawings, but the embodiments in the drawings do not constitute any limitation to the invention, and for a person skilled in the art, other drawings can be obtained on the basis of the following drawings without inventive effort.
Fig. 1 is a schematic structural diagram of a portable optical-to-electrical integrated fiber hydrophone.
Fig. 2 is a cross-sectional view of a high sensitivity mandrel-type fiber optic hydrophone.
Fig. 3 is a schematic structural diagram of a photodetector.
Fig. 4 is a packaging style diagram of the portable optical-to-electrical integrated fiber hydrophone.
Fig. 5 is a flow chart of the manufacturing process of the portable optical-to-electrical integrated fiber hydrophone.
Fig. 6 is a portable optical-to-electrical integrated fiber optic hydrophone test system.
Fig. 7 is a schematic diagram of the testing software of the portable optical-to-electrical integrated fiber hydrophone.
FIG. 8 is a schematic diagram of a software algorithm for testing a portable optical-to-electrical integrated fiber hydrophone.
Fig. 9 is a phase sensitivity diagram of the portable optical-to-electrical integrated fiber optic hydrophone.
Fig. 10 is a graph of signal frequency versus maximum detected signal amplitude at a 50kHz carrier frequency.
Fig. 11 is a schematic diagram of phase noise of the portable optical-to-electrical integrated fiber optic hydrophone.
Fig. 12 is a schematic diagram of a portable photoelectric conversion integrated fiber optic hydrophone for acquiring demodulation signals.
Description of reference numerals:
1. a narrow linewidth light source can be modulated; 2. a fiber optic hydrophone; 3. a photodetector; 4. a sealing device; 5. amplifying power; 6. a BNC interface; 7. a female power interface; 8. a transmission cable; 9. an acoustically transparent rubber; 10. stainless steel; 21. an inner barrel; 22. an outer cylinder; 23. a reference arm optical fiber; 24. a sensing arm optical fiber; 25. an air chamber; 26. supporting the rigid body.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the following detailed description of the present invention is provided with reference to the accompanying drawings and specific embodiments, and it is to be noted that the embodiments and features of the embodiments of the present application can be combined with each other without conflict.
As shown in fig. 1, the portable optical-to-electrical integrated fiber hydrophone provided in the embodiment of the present invention is composed of a modulatable narrow line width light source, a fiber hydrophone 2, a photodetector 3, a sealing device 4, a power amplifier 5, two BNC (BayonetNut connectors) interfaces 6, a female power interface 7, and a transmission cable 8, wherein the power amplifier 5 is disposed between the transmission cable 8 and the photodetector 3, and an output signal form of a sensor of the fiber hydrophone 2 is an electrical signal. In this embodiment, a butterfly light source with a modulated narrow linewidth of 10dBm and a linewidth of 3kHz is preferably selected, the female power interface 7 is a female power interface with DC5.5 × 2.1mm, and the transmission cable 8 is selected to have a length of 100m and a diameter d3 of 9 mm. Specifically, in this embodiment, the modulatable narrow-linewidth light source, the optical fiber hydrophone 2, the power amplifier 5 and the photodetector 3 are hermetically packaged in the sealing device 4, the transmission cable 8 includes a first signal transmission cable, a second signal transmission cable and a power cable, an optical fiber output end of the modulatable narrow-linewidth light source is connected with an optical fiber input end of the optical fiber hydrophone 2, an optical fiber output end of the optical fiber hydrophone 2 is connected with an optical fiber input end of the photodetector 3, an output end of the photodetector 3 is connected with an input end of the power amplifier 5, an output end of the power amplifier 5 is connected with one end of the first signal transmission cable, the other end of the first signal transmission cable is connected with one of the BNC interfaces 6, a modulation interface of the modulatable narrow-linewidth light source is connected with one end of the second signal transmission cable, the other end of the second signal transmission cable is connected with two of the BNC interfaces 6, the modulatable narrow-linewidth light source and a power supply pin, the other end of the power cable is connected with the female power interface 7. Through the above arrangement, the integrated modulatable narrow linewidth light source, the optical fiber hydrophone 2 and the photoelectric detector 3 are integrated, then the integrated device is subjected to sound transmission and waterproof sealing packaging, so that the portable optical-to-electrical integrated optical fiber hydrophone is portable and reliable, the output signal is an electric signal, and even if the portable optical-to-electrical integrated optical fiber hydrophone is not assisted by an optical engineer, scientific research personnel can still normally perform calibration, test and other purposes, and the integrated optical fiber hydrophone has the advantages of simplicity and accuracy in calibration and test. It should be noted that, in the present invention, the transmission cable 8 may also be in a specification with a length of 30 meters and a diameter d3 of 9mm, at this time, the portable optical-to-electrical integrated optical fiber hydrophone does not need the power amplifier 5, the optical fiber output end of the optical fiber hydrophone 2 is connected to the optical fiber input end of the photodetector 3, and the output end of the photodetector 3 is connected to one end of the first signal transmission cable.
As shown in fig. 2, the optical fiber hydrophone 2 of the present invention is a high-sensitivity optical fiber hydrophone 2 developed based on michelson interference principle, and adopts a double-cavity design, and includes an inner cylinder 21, an outer cylinder 22, a reference arm optical fiber 23, a sensing arm optical fiber 24, an elastic body, an optical fiber, and an air cavity 25, wherein the inner cylinder 21 and the outer cylinder 22 are coaxially arranged, the inner cylinder 21 is disposed inside the outer cylinder 22, the outer cylinder 22 is provided with a support rigid body 26, the support rigid body 26 is used for external packaging and supporting stress, the reference arm optical fiber 23 is wound on the inner cylinder 21, the sensing arm optical fiber 24 is wound on the outer cylinder 22, the elastic body is sleeved inside the inner cylinder 21, the optical fiber is wound on the elastic body, the inner layer of the elastic body is air, the air cavity 25 is opened on the outer cylinder 22, the air cavity 25 is introduced to increase the sensitivity of the probe and. The sound pressure sensitivity of the optical fiber hydrophone 2 can reach-145 dB. The sound pressure sensitivity is a key index for evaluating the optical fiber hydrophone 2 and is also an important parameter for the structural design of the optical fiber hydrophone 2. The structure of the optical fiber hydrophone 2 is preferably longitudinal central axis symmetry, and the vertical central axis is a stress point, so that the structure of the optical fiber hydrophone 2 is bilaterally symmetrical.
Meanwhile, as a further preferred embodiment, the narrow-line-width light source can be modulated in the invention, the optical fiber hydrophone 2 and the photoelectric detector 3 can be sealed and packaged in an acoustic-transparent and waterproof manner, the optical fiber hydrophone 2 is preferably packaged by using acoustic-transparent rubber 9 and then placed in the sealing device 4, the diameter d1 of the packaged optical fiber hydrophone 2 is 36mm, and the length l1 is 100 mm; the photoelectric detector 3 and the adjustable narrow-line-width light source are integrally packaged by preferably adopting stainless steel 10 and then placed in the sealing device 4, the diameter d2 of the photoelectric detector 3 and the adjustable narrow-line-width light source after being integrally packaged is 36mm, and the length l2 is 80 mm; the total package size of all devices in the portable optronic integrated fiber optic hydrophone is 36 x 180mm in diameter and length, see fig. 4 in particular, but the package size of the devices is not limited thereto. It should be noted that, the power amplifier 5 of the present invention can also be sealed and packaged in an acoustic transparent and waterproof manner, and when the portable optical-to-electrical integrated fiber hydrophone includes the power amplifier 5, the whole of the photodetector 3, the power amplifier 5 and the modulatable narrow-line-width light source is packaged by the stainless steel 10 and then placed in the sealing device 4.
In addition, the power amplifier 5 is AD8021, the bandwidth of the photoelectric detector 3 is 32MHz @3dB, the voltage responsivity is 130kV/W, the size length a and the diameter b are 13 x 7.8mm, and the structure is shown in FIG. 3.
As a further preferred embodiment, referring to fig. 5, the portable optical-to-electrical integrated fiber hydrophone is manufactured by the following steps:
step 1: connecting the optical fiber output end of the light source with the optical fiber input end of the optical fiber hydrophone 2;
step 2: connecting the optical fiber output end of the optical fiber hydrophone 2 with the optical fiber input end of the photoelectric detector 3;
and step 3: connecting the power amplifier 5 with the signal output end of the photoelectric detector 3;
and 4, step 4: connecting the output end of the photoelectric detector 3 with the input end of the power amplifier 5, connecting the output end of the power amplifier 5 to one end of a first signal transmission cable, and connecting the other end of the first signal transmission cable with one BNC interface 6;
and 5: connecting a modulation interface capable of modulating the narrow-linewidth light source with one end of a second signal transmission cable, and connecting the other end of the second signal transmission cable with two BNC interfaces 6;
step 6: connecting the power supply pins of the light source with the adjustable narrow line width, the power amplifier 5 and the photoelectric detector 3 through a power cable in a transmission cable 8, and connecting the other end of the power cable in the transmission cable 8 with a female power interface 7;
and 7: carrying out acoustic transmission and waterproof sealing packaging on the modulable narrow-line-width light source, the optical fiber hydrophone 2, the photoelectric detector 3 and the power amplifier 5, wherein the optical fiber hydrophone 2 is partially packaged by adopting acoustic transmission rubber 9, and the packaged optical fiber hydrophone has the diameter of 36mm and the length of 100 mm; the photoelectric detector 3, the power amplifier 5 and the modulatable narrow-linewidth light source are packaged by stainless steel 10 so as to dissipate heat, and the diameter is 36mm, the length is 80mm after packaging, and the total packaging size of the devices in the portable photoelectric conversion integrated optical fiber hydrophone has the diameter and the length of 36-180 mm.
After the portable photoelectric conversion integrated optical fiber hydrophone is connected and packaged according to the steps, relevant performance tests are carried out, a test system is built as shown in the attached figure 6 and comprises a computer, an acquisition card and the portable photoelectric conversion integrated optical fiber hydrophone, the optical fiber hydrophone 2 is connected with an external power supply through a female power supply interface 7, two BNC connectors are connected to the acquisition card, and the acquisition card is connected with the computer. Specifically, the portable photoelectric conversion integrated optical fiber hydrophone is connected to a 5V power supply through a DC5.5 x 2.1mm female power supply interface 7, two BNC connectors are connected to an NI-6251 acquisition card, and the NI-6251 acquisition card is connected with a computer. The relevant test results can then be obtained by writing the relevant programs on the computer, see fig. 7.
Meanwhile, an algorithm of the portable optical-to-electrical integrated fiber optic hydrophone testing software provided by the embodiment is shown in fig. 8. In this embodiment, a Phase Generated Carrier (PGC) algorithm is used for implementation, and calibration test of the portable optical-to-electrical integrated fiber hydrophone is implemented through direct frequency modulation and indirect Phase modulation (i.e., laser frequency is directly modulated, and frequency modulation is converted into Phase modulation by an interferometer).
Specifically, a PGC phase carrier modulation is applied, and its interference fringes can be expressed as:
IPGC＝ηI0[1+k·cos(Ccos(ω0t)+Φ(t))]
＝A+B·cos(Ccos(ω0t)+Φ(t)) (1)
φ(t)＝φS(t)+φ0 (2)
wherein, I0Where η is the optical path loss, k is the visibility of the interference fringes, A, B are the dc and ac terms of the interference fringes, respectively, and C is the PGC phase modulation amplitude, set to 2.63rad, ω0For PGC modulation frequency, phi (t) is an interferometer phase signal containing an initial phase operating point phi0And the underwater acoustic phase signal phi to be measuredS(t)。
Bessel (Bessel) expansion of equation (1):
wherein k represents the order, J0(C) Represents a Bessel function of order 0, J2k(C) Representing an even-order Bessel function, J2k+1(C) Representing an odd order Bessel function.
As can be seen from equation (3), the odd and even frequencies of the carrier carry a pair of orthogonal terms including the phase to be measured, respectively. The PGC algorithm first needs to extract a pair of orthogonal terms, i.e. to separate a pair of odd-order frequencies and even-order frequencies, as shown in part (a) of fig. 8. The extraction method of the orthogonal term comprises a band-pass filtering method and a coherent demodulation method: the band-pass filtering method comprises the steps that two band-pass filters are used for locking one odd-order frequency and one even-order frequency respectively for filtering, and then amplitude detection is carried out; while coherent demodulation implements down conversion by mixing with a synchronous carrier, followed by low-pass filtering. Compared with a band-pass filter, the low-pass filter can obtain ideal filtering performance more easily, in addition, extra noise is introduced into amplitude detection, and coherent demodulation has a higher signal-to-noise ratio.
Preferably, the embodiment of the present invention employs coherent demodulation, as shown in part (a) of fig. 8, to combine equation (3) with the carrier signal cos (ω)0t) and a carrier frequency-doubled signal cos (2 ω)0t) are multiplied respectively, and then low-pass filtering is carried out, wherein the cut-off frequency is half of the PGC carrier frequency. In the portable photoelectric conversion integrated optical fiber hydrophone test system, a double-frequency carrier is obtained through double-frequency carrier operation. After two paths of low-pass filtering, the obtained orthogonal term is as follows:
L1(t)＝-BJ1(C)sinΦ(t)
L2(t)＝-BJ2(C)cosΦ(t) (4)
in the formula, L1(t)、L2(t) represents a pair of orthogonal terms, J1(C) Represents a Bessel function of order 1, J2(C) Representing a Bessel function of order 2.
The next step of the PGC algorithm is to linearly extract the phase to be measured from the pair of orthogonal terms. The method specifically comprises two methods:
1) differential Cross Multiplication (DCM)
As shown in part (b) of fig. 8, by differentiating equation (4), the following is obtained:
in the formula, D1(t)、D2(t) represents a pair of orthogonal term differential terms.
Calculating D1(t)×L2(t)-D2(t)×L1(t) obtaining:
equation (6) is then integrated to yield:
B2J1(C)J2(C)Φ(t) (7)
operating point drift phi due to initial phase0Is slowly changed and has extremely low frequencyTherefore, the equation (7) is high-pass filtered (band-pass filtered) to remove noise and interference outside the signal band, and the following results are obtained:
ΦPGC-DCM(t)＝B2J1(C)J2(C).φS(t) (8)
in the formula phiPGC-DCM(t) represents the phase demodulation result of the non-standard quantization.
Further, by calibrating the coefficients, the phase demodulation result can be obtained:
since the alternating term B of the interference fringes is a parameter related to the light intensity and the visibility of the interference fringes and is not easy to measure directly, B is usually normalized to a constant in the system before the PGC algorithm is performed2J1(C)J2(C) And combining the two into a constant, and calibrating the system to obtain the target.
2) Arctangent (Arctangent, Arctan)
As shown in part (c) of fig. 8, the orthogonal term L in the formula (4) is expressed1(t) and L2(t) divide to give:
the PGC phase modulation amplitude C value is adjusted to 2.63rad, which includes: j. the design is a square1(C)＝J2(C) Thus, there are:
then, after band-pass filtering, the phase demodulation result phi is obtainedS(t)。
An example of the demodulation results of the collected signals is shown in fig. 12.
The performance test of the optical fiber hydrophone 2 is shown in the attached figures 9, 10 and 11. Fig. 9 is a schematic diagram of phase sensitivity of the portable optical-to-electrical integrated fiber hydrophone, from which it can be seen that the influence of the variation of the sound pressure sensitivity of the ordinate with the frequency of the abscissa is small, the sound pressure sensitivity is-144.4 dB at a frequency of 40Hz, and the sound pressure sensitivity is-145.7 dB at a frequency of 160 Hz. Fig. 10 shows the relationship between the signal frequency and the maximum detection signal amplitude at a carrier frequency of 50kHz, from which it is understood that the maximum detection signal amplitude on the ordinate decreases as the value of the signal frequency on the abscissa increases, and the maximum detection signal amplitude is highest at a signal frequency of about 100Hz and is about 280 rad. Fig. 11 is a schematic diagram of phase noise of the portable optical-to-electrical integrated fiber hydrophone, from which it can be seen that the ordinate phase noise decreases as the value of the abscissa acoustic signal frequency gradually increases, and the phase noise is about-104 dBrad/v Hz when the frequency is 1000 Hz.
The portable photoelectric integrated optical fiber hydrophone integrates the modulatable narrow-linewidth light source 1, the optical fiber hydrophone 2 and the photoelectric detector 3, and then is sealed and packaged in an acoustic transparency and a waterproof manner, so that the portable photoelectric integrated optical fiber hydrophone which is portable and reliable and outputs an electric signal is formed, the structure is simple, the construction is convenient, and on one hand, scientific researchers can still normally perform calibration, test and other purposes without the assistance of optical engineers; on the other hand, the characteristics of high sensitivity, good frequency response characteristic, simplicity, easiness in use and the like of the optical fiber hydrophone can be obtained, and the accuracy of the calibration test is improved.
In the description above, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore should not be construed as limiting the scope of the present invention.
In conclusion, although the present invention has been described with reference to the preferred embodiments, it should be noted that, although various changes and modifications may be made by those skilled in the art, they should be included in the scope of the present invention unless they depart from the scope of the present invention.
Claims (10)
1. A portable photoelectric integrated optical fiber hydrophone is characterized by comprising a modulatable narrow-linewidth light source, an optical fiber hydrophone, a photoelectric detector, a transmission cable, a female power interface and two BNC interfaces, wherein the modulatable narrow-linewidth light source, the optical fiber hydrophone and the photoelectric detector are hermetically packaged, the transmission cable comprises a first signal transmission cable, a second signal transmission cable and a power cable, an optical fiber output end of the modulatable narrow-linewidth light source is connected with an optical fiber input end of the optical fiber hydrophone, an optical fiber output end of the optical fiber hydrophone is connected with an optical fiber input end of the photoelectric detector, an output end of the photoelectric detector is connected to one end of the first signal transmission cable, the other end of the first signal transmission cable is connected with one of the BNC interfaces, a modulation interface of the modulatable narrow-linewidth light source is connected with one end of the second signal transmission cable, the other end of the second signal transmission cable is connected with two of the BNC, the power supply pins of the modulatable narrow-linewidth light source and the photoelectric detector are connected with one end of a power cable, and the other end of the power cable is connected with a female power interface.
2. The portable photoelectric conversion integrated optical fiber hydrophone according to claim 1, wherein the optical fiber hydrophone is a high-sensitivity mandrel type optical fiber hydrophone developed based on the michelson interference principle, and comprises an inner cylinder, an outer cylinder, a reference arm optical fiber, a sensing arm optical fiber, an elastic body, an optical fiber and an air cavity, wherein the inner cylinder and the outer cylinder are coaxially arranged, the inner cylinder is arranged inside the outer cylinder, a support rigid body is arranged on the outer cylinder and used for supporting stress of external packaging, the reference arm optical fiber is wound on the inner cylinder, the sensing arm optical fiber is wound on the outer cylinder, the elastic body is sleeved in the inner cylinder, the optical fiber is wound on the elastic body, the inner layer of the elastic body is air, and the air cavity is arranged on the outer cylinder.
3. The portable optical-to-electrical integrated fiber hydrophone of claim 1, further comprising a power amplifier disposed between the transmission cable and the photodetector, wherein an output of the photodetector is connected to an input of the power amplifier, and an output of the power amplifier is connected to one end of the first signal transmission cable.
4. The portable opto-electric integrated fiber optic hydrophone of claim 1, wherein the fiber optic hydrophone is encapsulated in acoustically transparent rubber; the photoelectric detector and the modulatable narrow linewidth light source are integrally packaged by adopting stainless steel.
5. The portable optical-to-electrical integrated fiber optic hydrophone of claim 4, further comprising a sealing device, wherein the fiber optic hydrophone is encapsulated in the sealing device using an acoustically transparent rubber, and the photodetector and the modulatable narrow-linewidth light source are integrally encapsulated in stainless steel and then disposed in the sealing device.
6. The portable optical-to-electrical integrated fiber hydrophone of claim 3, wherein the power amplifier, photodetector and modulatable narrow linewidth light source are integrally encapsulated in stainless steel.
7. The portable optical-to-electrical integrated fiber hydrophone of claim 3, wherein the modulatable narrow linewidth light source is a butterfly light source with a linewidth of 3kHz and 10 dBm; and/or the power amplifier model is AD 8021; and/or the bandwidth of the photoelectric detector is 32MHz @3dB, the voltage responsivity is 130kV/W, and the size is 13 x 7.8 mm.
8. The portable optical-to-electrical integrated fiber optic hydrophone of claim 5, wherein the portable optical-to-electrical integrated fiber optic hydrophone is fabricated by:
step 1: connecting an optical fiber output end of the light source with a narrow line width and an optical fiber input end of the optical fiber hydrophone;
step 2: connecting the optical fiber output end of the optical fiber hydrophone with the optical fiber input end of the photoelectric detector;
and step 3: connecting the power amplifier with the signal output end of the photoelectric detector;
and 4, step 4: connecting the output end of the photoelectric detector with the input end of the power amplifier, connecting the output end of the power amplifier to one end of a first signal transmission cable, and connecting the other end of the first signal transmission cable with one BNC interface;
and 5: connecting a modulation interface capable of modulating the narrow-linewidth light source with one end of a second signal transmission cable, and connecting the other end of the second signal transmission cable with two BNC interfaces;
step 6: connecting power supply pins of the light source, the power amplifier and the photoelectric detector with the adjustable narrow line width through a power cable in the transmission cable, wherein the other end of the power cable in the transmission cable is connected with a female power interface;
and 7: and the light source with the adjustable narrow line width, the optical fiber hydrophone, the photoelectric detector and the power amplifier are sealed and packaged in an acoustic transmission and waterproof manner.
9. A portable photoelectric conversion integrated optical fiber hydrophone test system is characterized by comprising a computer, an acquisition card and the portable photoelectric conversion integrated optical fiber hydrophone in any one of claims 1-8, wherein the optical fiber hydrophone is connected with an external power supply through a female power supply interface, two BNC connectors are connected to the acquisition card, and the acquisition card is connected with the computer.
10. The system according to claim 9, wherein the computer performs direct frequency modulation and indirect phase modulation by using a PGC algorithm to perform a calibration test of the portable optical-to-electrical integrated fiber hydrophone, and the specific process is as follows:
firstly, extracting a pair of orthogonal terms in a PGC algorithm by a coherent demodulation method or a band-pass filtering method, namely separating a pair of odd frequency and even frequency;
and secondly, linearly extracting the phase to be tested in the pair of orthogonal terms by differential cross multiplication or an inverse tangent method, thereby realizing the calibration test of the portable photoelectric conversion integrated optical fiber hydrophone.
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