CN108151876B - Optical fiber Fabry-Perot cavity microphone - Google Patents
Optical fiber Fabry-Perot cavity microphone Download PDFInfo
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- CN108151876B CN108151876B CN201810160878.XA CN201810160878A CN108151876B CN 108151876 B CN108151876 B CN 108151876B CN 201810160878 A CN201810160878 A CN 201810160878A CN 108151876 B CN108151876 B CN 108151876B
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/12—Generating the spectrum; Monochromators
- G01J3/26—Generating the spectrum; Monochromators using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
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Abstract
The invention provides an optical fiber Fabry-Perot cavity microphone with good stability, which comprises an optical fiber Fabry-Perot cavity microphone probe for inducing sound wave vibration, a monochromatic light source capable of emitting monochromatic light, a photoelectric detector for realizing photoelectric signal conversion, a three-port unidirectional light guide unit for realizing optical annular unidirectional propagation, an optical fiber, a pre-conditioning circuit and an optical fiber flange; the optical fiber Fabry-Perot cavity microphone probe is connected with a port II of the three-port unidirectional light guide unit, and the photoelectric detector is connected with the three-port unidirectional light guide unit; the optical fiber is used for connecting a monochromatic light source, a three-port unidirectional light guide unit, a probe and a photoelectric detector to form a light path; the optical fiber flange is used for connecting the probe optical fiber and the optical path optical fiber; the front-end adjusting circuit is connected with the output end of the photoelectric detector. The optical fiber Fabry-Perot cavity microphone has the advantages of simple structure, easiness in manufacturing, good stability and good application prospect.
Description
Technical Field
The invention belongs to the technical field of acoustic sensing, and particularly relates to an optical fiber Fabry-Perot cavity microphone with good stability, low cost and simple structure.
Background
With the development of optical fiber technology, especially optical fiber communication technology, optical fiber sensing technology has been rapidly developed, and has been widely used in the fields of automatic control, on-line detection, fault diagnosis, etc. of production processes in the fields of machinery, electronic instruments, aviation bodies, petroleum, chemical industry, food safety, etc. from the appearance of the concept of optical fiber sensor to the present decades.
Compared with the traditional various electric sensors, the optical fiber sensor has the advantages of high sensitivity, electromagnetic interference resistance, corrosion resistance, explosion resistance, low loss, long transmission distance and the like. As a branch of the optical fiber sensing device, since the 60 th century, the optical fiber microphone has been attracting attention and studied extensively. The optical fiber microphone is a novel microphone for picking up sound wave signals, and utilizes various optical structures to realize the modulation of parameters of sound waves to light, and obtains the sound wave signals through demodulation of the light signals. According to different modulated optical parameters, the current optical fiber microphone is mainly divided into: intensity modulation type, wavelength modulation type, phase modulation type, and polarization modulation type.
Among the optical fiber microphones of various principles, the optical fiber fabry-perot cavity microphone based on phase modulation has been widely studied because of its simple structure, high sensitivity, and simple demodulation method when monochromatic light is used as working light. However, the optical fiber fabry-perot cavity microphone of the existing structure has disadvantages. The optical fiber Fabry-Perot cavity microphone is based on a high-sensitivity optical interference detection method, which makes the optical fiber Fabry-Perot cavity microphone have high sensitivity, however, the stability of the optical fiber Fabry-Perot cavity microphone is poor, because the optical fiber Fabry-Perot cavity microphone is easy to influence from the outside, when the outside influence causes the length of the optical fiber Fabry-Perot cavity to change by one eighth of the wavelength of light, such as 1552nm light, the optical fiber Fabry-Perot cavity microphone can change from the most sensitive to the ineffective state, and the practical application of the optical fiber Fabry-Perot cavity microphone is greatly limited.
The main factors influencing the stability of the optical fiber Fabry-Perot cavity microphone are environmental temperature, and particularly, the optical fiber Fabry-Perot cavity microphone which adopts a monochromatic light source and utilizes intensity demodulation has the output signal very sensitive to the temperature, and the reason is that the cavity length of the optical fiber Fabry-Perot cavity can change along with the temperature change, so that the interference spectrum is shifted.
The main factors affecting the stability of the optical fiber Fabry-Perot cavity microphone are also external forces. In the existing probe structure of the optical fiber Fabry-Perot cavity microphone, a vibrating diaphragm is generally adopted as a reflecting surface of the Fabry-Perot cavity and is directly fixed on an outer structure; the end face of the fiber acts as another light reflecting surface and the fiber is held by another structure, typically with a portion of the structure being held inside the outer structure and another portion being outside the outer structure. The structure can lead the fixing structure of the optical fiber end face to be easily and directly acted by external force, so that the position of the optical fiber end face is slightly changed, and the stability of the interference structure is deteriorated.
The prior art does not address the stability problem of the fiber optic Fabry-Perot cavity microphone probe from the probe itself. An optical fiber FP cavity acoustic probe is described in patent CN104019884B, in which an inner core structure of one reflecting surface of an optical fiber FP cavity structure is supported, the thinner tail portion of the inner core is easily acted upon by external force, the inner core is fixed by a jackscrew, and mechanical stability for a long period of time is not ensured, and in this patent, a method for solving the temperature influence is not described.
Aiming at the problem that the stability of the optical fiber Fabry-Perot cavity microphone is poor, two main solutions exist at present: (1) The working wavelength of light is regulated, and the scheme is that a tunable laser is utilized to enable the working wavelength to change along with the change of the cavity length, so that the relative stability of an interference spectrum is ensured; (2) The method comprises the steps of generating an orthogonal signal by utilizing double working wavelengths and generating the orthogonal signal by utilizing double optical fibers, and obtaining an acoustic wave signal by utilizing an orthogonal signal demodulation method. Both schemes involve complex signal processing and system architecture, and are costly and unfavorable for application.
Disclosure of Invention
First, the technical problem to be solved
In order to solve the problems of poor stability, high cost, complex system, unfavorable use and the like in the prior art, the invention provides the optical fiber Fabry-Perot cavity microphone which has the characteristics of good stability, lower cost, simple structure, easy manufacture and the like.
(II) technical scheme
The invention relates to an optical fiber Fabry-Perot cavity microphone, which comprises:
optical fiber Fabry-Perot cavity microphone probe for inducing sound wave vibration;
a monochromatic light source capable of emitting monochromatic light;
a photodetector that realizes photoelectric signal conversion;
a three-port unidirectional light guide unit for realizing optical annular unidirectional propagation;
an optical fiber, a pre-conditioning circuit and an optical fiber flange;
the optical fiber Fabry-Perot cavity microphone probe is connected with a port II of the three-port unidirectional light guide unit, and the photoelectric detector is connected with a port III of the three-port unidirectional light guide unit; the optical fiber is used for connecting a monochromatic light source, a three-port unidirectional light guide unit, an optical fiber Fabry-Perot cavity microphone probe and a photoelectric detector to form a light path; the optical fiber flange is used for connecting the probe optical fiber and the optical path optical fiber; the front-end adjusting circuit is connected with the output end of the photoelectric detector;
monochromatic light emitted by the monochromatic light source enters the three-port unidirectional light guide unit from a port I of the three-port unidirectional light guide unit, and is emitted from a port II of the three-port unidirectional light guide unit into the optical fiber Fabry-Perot cavity microphone probe, so that interference light modulation of sound waves is realized; the modulated interference light enters the unidirectional light guide unit from the port II of the unidirectional light guide unit with three ports, and then is emitted from the port III of the unidirectional light guide unit with three ports to enter the photoelectric detector for converting optical signals into electric signals for processing;
the optical fiber Fabry-Perot cavity microphone probe comprises:
the shell is of a hollow structure, the middle part of the inner wall of the shell is provided with threads, the lower part of the shell is provided with fixed screw holes in the direction perpendicular to the shaft, the number of the holes is 2-4, and the holes are uniformly distributed along the circumference;
the vibrating diaphragm is a film and is arranged at the front end of the shell and used for sensing sound waves, and the surface of the vibrating diaphragm facing to one side of the inside of the shell has a light reflecting effect and is used as a light reflecting surface of the optical fiber Fabry-Perot cavity structure;
the optical fiber core insert is a hollow columnar structure and is formed by single materials or serial and composite of different materials;
the core inserting sleeve is of a hollow cylindrical structure, the outer side surface of the middle part of the core inserting sleeve is provided with threads, the core inserting sleeve is arranged in the shell, and one side of the core inserting sleeve, which faces towards the vibrating diaphragm, is used for installing an optical fiber core inserting; the side surface of the vibrating diaphragm is provided with an air vent groove from the top of the thread to the tail end of the core insert sleeve for balancing static pressure on the two sides of the vibrating diaphragm; the bottom of the shell is provided with a round table, the lower end face of the round table at the bottom is provided with a tool fixing hole, the tool is used for installing the core insert sleeve in the shell through the tool fixing hole, after the installation is finished, the outer side face of the round table at the bottom is contacted with the inner surface of the bottom of the shell, and the contact joint is welded by utilizing a laser welding process, so that the core insert sleeve and the shell are reliably connected, and the stability of the structure is improved;
the outer sleeve is of a cap-shaped structure with two open ends, is arranged outside the outer shell from the lower end of the outer shell, and is wrapped inside the outer shell, so that the outer force directly exerted on the outer core sleeve is avoided, and the stability of the optical fiber Fabry-Perot cavity microphone probe is improved;
the probe optical fiber is fixed in the optical fiber inserting core by the outer sleeve through the inserting core sleeve, and the upper end face of the probe optical fiber is used as the other reflecting face of the optical fiber Fabry-Perot cavity structure.
The number of the fixing screws is consistent with that of the fixing screw holes, and the fixing screws are arranged in the fixing screw holes and are used for assisting in fixing the core insert sleeve;
and the front cover is arranged outside the shell from one side of the vibrating diaphragm and is used for protecting the vibrating diaphragm, and the top end of the front cover is provided with an audio hole.
In the optical fiber Fabry-Perot cavity microphone structure, the diaphragm reflecting surface and the upper end surface of the probe optical fiber form an optical fiber Fabry-Perot cavity, and the thermal expansion coefficient of a combined structure formed by the core insert sleeve and the optical fiber core insert is larger than that of the shell.
(III) beneficial effects
As can be seen from the technical scheme and experimental results of the embodiment, the optical fiber Fabry-Perot cavity microphone has the following beneficial effects:
(1) Aiming at the problem of poor thermal stability caused by unsuitable material thermal expansion coefficient in the existing optical fiber Fabry-Perot cavity microphone probe structure, in the invention, a method that the thermal expansion coefficient of a combined structure formed by a ferrule sleeve and an optical fiber ferrule is larger than that of a shell is adopted, when the external temperature changes, the structure bearing the upper end face of an optical fiber can obtain a larger variation than the shell structure bearing the reflecting face of a vibrating diaphragm, so that the distance between the reflecting face of the vibrating diaphragm and the upper end face of the optical fiber is basically unchanged, namely the cavity length of an optical fiber Fabry-Perot cavity is basically unchanged, and the high stability of the optical fiber Fabry-Perot cavity structure is ensured, thereby ensuring that the optical fiber Fabry-Perot cavity microphone has good temperature adaptability;
(2) Aiming at the problems that the fixing structure of the end face of the optical fiber is easy to directly receive the effect of external force, so that the position of the end face of the optical fiber is slightly changed, and the stability of the probe is poor, the invention wraps the core insert sleeve in the shell through the outer sleeve structure, thereby avoiding the core insert sleeve from being directly acted by the effect of external force, and simultaneously, the core insert sleeve and the shell are welded together by utilizing the laser welding process to form reliable connection, thereby ensuring that the optical fiber Fabry-Perot cavity microphone has good stability;
(3) The system of the optical fiber Fabry-Perot cavity microphone has simple structure and low cost.
Drawings
Fig. 1 is a schematic diagram showing the composition of an optical fiber fabry-perot cavity microphone according to a first embodiment of the present invention;
fig. 2 is a schematic cross-sectional view of a probe structure of an optical fiber fabry-perot cavity microphone according to a first embodiment of the present invention;
fig. 3 is a schematic cross-sectional view showing a structure of a probe housing of an optical fiber fabry-perot cavity microphone according to a first embodiment of the present invention;
fig. 4 is a schematic three-dimensional structure of a probe core sleeve of an optical fiber fabry-perot cavity microphone according to a first embodiment of the present invention;
FIG. 5 is an interference spectrum of a conventional fiber Fabry-Perot cavity microphone probe at different temperatures;
fig. 6 is an interference spectrum of a probe of a fiber-optic fp cavity microphone at different temperatures according to a first embodiment of the present invention;
fig. 7 is a graph of normalized sensitivity of a fiber optic fabry-perot cavity microphone at different temperatures according to a first embodiment of the invention;
fig. 8 is a relationship of a probe cavity length of a fiber optic fabry-perot cavity microphone according to a first embodiment of the present invention over time;
fig. 9 is a schematic diagram of a three-port unidirectional light guiding unit of an optical fiber fabry-perot cavity microphone according to a second embodiment of the present invention;
fig. 10 is a schematic cross-sectional view of a probe structure of a fiber-optic fp cavity microphone according to a second embodiment of the present invention;
fig. 11 is a schematic view of a probe fiber ferrule of a fiber optic fp-type cavity microphone according to a second embodiment of the present invention.
[ main element symbols of the present invention ]
1-optical fiber Fabry-Perot cavity microphone probe 102 a-diaphragm reflecting surface
2-monochromatic light source 103-optical fiber core insert
3-three port unidirectional light guiding unit 103 a-ceramic or metal
301-three port unidirectional light guide unit port I103 b-hard polymer
302-three port unidirectional light guide unit port II 104-ferrule
301-three port unidirectional light guide unit port III 104 a-plug external thread
3 a-isolator 104 b-vent
3 b-fiber coupler 104 c-tool fixing hole
4-photodetector 104 d-bottom circular truncated cone
5-front conditioning circuit 105-jacket
6-optical fiber 106-probe optical fiber
7-optical fiber flange 106 a-probe optical fiber upper end face
101-housing 107-front cover
101 a-housing internal threads 107 a-access opening
101 b-fixing screw hole 108-fixing screw
102-diaphragm
Detailed Description
The present invention will be further described in detail below with reference to specific embodiments and with reference to the accompanying drawings, in order to make the objects, technical solutions and advantages of the present invention more apparent. In the drawings or description, like or identical parts are provided with the same reference numerals. Implementations not shown or described in the drawings are forms known to those of ordinary skill in the art. Additionally, while a parameter demonstration may be provided herein that includes a particular value, it should be appreciated that the parameter need not be exactly equal to the corresponding value, but may approximate the corresponding value within an acceptable margin of error or design constraint. Directional terms, such as "upper", "lower", "left", "right", etc., mentioned in the embodiments are merely directions referring to the drawings. Therefore, the directional terminology is used for the purpose of description and not of limitation of the scope of the invention.
First embodiment
In a first exemplary embodiment of the present invention, a fiber optic Fabry-Perot cavity microphone is provided. A schematic diagram of an optical fiber fabry-perot cavity microphone according to a first embodiment, as shown in fig. 1, includes: the optical fiber Fabry-Perot cavity microphone probe 1 inducing sound wave vibration, the monochromatic light source 2 capable of emitting monochromatic light, the three-port unidirectional light guide unit 3 realizing annular unidirectional propagation of light, the photoelectric detector 4 realizing photoelectric signal conversion, the pre-conditioning circuit 5, the optical fiber 6 and the optical fiber flange 7; the monochromatic light source 2 is connected with a port I301 of the three-port unidirectional light guide unit, the optical fiber Fabry-Perot cavity microphone probe 1 is connected with a port II302 of the three-port unidirectional light guide unit, and the photoelectric detector 4 is connected with a port III303 of the three-port unidirectional light guide unit; the optical fiber 6 is used for connecting the monochromatic light source 2, the three-port unidirectional light guide unit 3, the optical fiber Fabry-Perot cavity microphone probe 1 and the photoelectric detector 4 to form a light path; an optical fiber flange 7 for connecting the probe optical fiber 106 and the optical path optical fiber 6; the front-end adjusting circuit 5 is connected with the output end of the photoelectric detector 4; monochromatic light emitted by the monochromatic light source 2 enters the three-port unidirectional light guide unit 3 from the port I301 of the three-port unidirectional light guide unit through the optical fiber, and is emitted from the port II302 of the three-port unidirectional light guide unit into the optical fiber Fabry-Perot cavity microphone probe 1, so that the interference light modulation of sound waves is realized; the modulated interference light enters the three-port unidirectional light guide unit from the port II302 of the three-port unidirectional light guide unit, and then is emitted from the port III303 of the three-port unidirectional light guide unit to enter the photodetector 4 for converting optical signals into electric signals.
The following describes each part of a fiber optic fabry-perot cavity microphone in detail with respect to the first embodiment.
The monochromatic light source 2 is a laser or is composed of an ASE broad spectrum light source and an optical filter groove.
The three-port unidirectional light guiding unit 3 is a circulator or is composed of an isolator 3a and an optical fiber coupler 3 b.
A cross-sectional view of a probe structure of an optical fiber fp cavity microphone according to a first embodiment, as shown in fig. 2, the probe 1 of the optical fiber fp cavity microphone according to the present embodiment includes: the probe of the optical fiber Fabry-Perot cavity microphone is specifically described as follows:
the shell 101, as shown in fig. 3, is a schematic cross-sectional view of a structure of a probe shell of an optical fiber fabry-perot cavity microphone according to a first embodiment of the present invention, and is a hollow structure, wherein an inner thread 101a of the shell is provided in the middle of an inner wall of the hollow structure, and fixing screw holes 101b are provided in the lower part of the shell 101 in a direction perpendicular to an axis, wherein the number of the holes is 2-4, and the holes are uniformly distributed along the circumference;
the diaphragm 102 is a film and is arranged at the front end of the shell 101 and used for sensing sound waves, and the surface of the diaphragm facing the inner side of the shell has a light reflecting effect and is used as a light reflecting surface 102a of the optical fiber Fabry-Perot cavity structure;
the optical fiber ferrule 103 is a hollow columnar structure and is formed by single material or serial and composite of different materials;
the core-insert sleeve 104 is a hollow cylindrical structure, as shown in fig. 4, which is a three-dimensional structure schematic diagram of a probe core-insert sleeve of an optical fiber Fabry-Perot cavity microphone according to a first embodiment of the invention, wherein the outer side surface of the middle part is provided with a core-insert sleeve external thread 104a, and the side surface of the core-insert sleeve is provided with a ventilation slot 104b from the top of the thread to the tail end of the core-insert sleeve for balancing static pressure at two sides of the vibrating diaphragm; the bottom of the core insert sleeve is provided with a round table 104d, a tool fixing hole 104c is formed in the lower end face of the round table at the bottom, and the core insert sleeve 104 is installed inside the shell 101 through the tool fixing hole 104c by using a tool; the core insert 104 is installed inside the housing 101, one side of the core insert 104 facing the diaphragm 102 is used for installing the optical fiber core insert 103, after the installation of the core insert 104 is completed, the outer side surface of the bottom round table 104d contacts with the inner surface of the bottom of the housing 101, and the contact seam is welded by using a laser welding process, so that the core insert 104 and the housing 101 are reliably connected, and the stability of the structure is improved.
The outer sleeve 105 is a cap-shaped structure with two open ends, is arranged outside the outer shell 101 from the lower end of the outer shell 101, and wraps the core insertion sleeve 104 inside the outer sleeve, so that the core insertion sleeve 104 is prevented from being directly acted by external force;
the optical fiber 106 is fixed in the optical fiber insert core 103 by the outer sleeve 105 through the insert core sleeve 104, and the upper end surface 106a of the optical fiber is used as the other reflecting surface of the optical fiber Fabry-Perot cavity structure;
a front cover 107 installed outside the housing 101 from one side of the diaphragm for protecting the diaphragm 102, and having an inlet hole 107a at the top end thereof;
the number of the fixing screws 108 is equal to that of the fixing screw holes 101b, and the fixing screws are installed in the fixing screw holes 101b to assist in fixing the ferrule 104.
The reflecting surface 102a of the vibrating diaphragm is the surface of the vibrating diaphragm facing the inside of the shell; or the reflecting surface 102a of the diaphragm is a metal reflecting layer or a dielectric reflecting layer plated on one side of the diaphragm facing the inside of the shell.
The optical fiber ferrule 103 is made of a single material and is a ceramic ferrule or a metal ferrule; or the optical fiber ferrule 103 is formed by serial combination of different materials, and is formed by serial combination of ceramic or metal 103a and a hard polymer 103 b;
the optical fiber 106 is a single mode fiber or a polarization maintaining fiber.
The diaphragm 102 is one of the following diaphragms: metal film, silicon nitride film, silicon dioxide film, glass film, organic polymer film.
The shell 101 and the ferrule 104 are made of one or more metal materials selected from the following materials: stainless steel, titanium, copper, aluminum alloy, titanium alloy, nickel-copper alloy, nickel-chromium alloy.
In this embodiment, the monochromatic light source is a DFB semiconductor laser, and the three-port unidirectional light guiding unit is a circulator. In the probe structure, the shell material is made of titanium alloy material, and the thermal expansion coefficient of the shell material is about 9 multiplied by 10 -6 The number of the fixed screw holes at the lower part of the screw rod is 4; the diaphragm is a metal nickel diaphragm, and the reflecting surface of the diaphragm is the surface of the metal nickel diaphragm facing to one side of the inner part of the shell; the optical fiber core insert is a single material zirconia ceramic core insert with a thermal expansion coefficient of about 9.65X10 -6 a/DEG C; the probe optical fiber is a single-mode optical fiber; the core insert sleeve is made of nickel-copper alloy material with a thermal expansion coefficient of about14.4X10) -6 and/C. According to the data, the thermal expansion coefficient of the combined structure formed by the core insert sleeve and the optical fiber core is larger than that of the shell, so that when the external temperature changes, the structure bearing the upper end face of the probe optical fiber can obtain a larger change amount than the shell structure bearing the reflecting surface of the vibrating diaphragm, the distance between the reflecting surface of the vibrating diaphragm and the upper end face of the probe optical fiber is basically unchanged, the high stability of the optical fiber Fabry-Perot cavity structure is ensured, and the optical fiber Fabry-Perot cavity microphone has good temperature adaptability.
The temperature adaptability of the conventional optical fiber Fabry-Perot cavity microphone is poor because the cavity length of the optical fiber Fabry-Perot cavity can change along with the temperature change, so that the interference spectrum shifts. As shown in fig. 5, the interference spectrum of the conventional optical fiber fabry-perot cavity microphone recorded in the experiment at different temperatures is shown, and as the temperature changes, the interference spectrum is obviously shifted.
The optical fiber Fabry-Perot cavity microphone has good temperature adaptability, because the thermal expansion coefficient of the combined structure formed by the core insert sleeve and the optical fiber core insert is larger than that of the shell, when the external temperature changes, the structure bearing the upper end face of the probe optical fiber can obtain a larger change amount than the shell structure bearing the reflecting face of the vibrating diaphragm, and further, the distance between the reflecting face of the vibrating diaphragm and the upper end face of the probe optical fiber is basically unchanged, and the high stability of the optical fiber Fabry-Perot cavity structure is ensured. As shown in fig. 6, the interference spectra of the optical fiber fabry-perot cavity microphone according to the first embodiment of the present invention recorded in the experiment at different temperatures are shown, and as can be seen from the figure, the interference spectra are substantially coincident and have high stability when the temperature changes. The normalized sensitivity of the optical fiber Fabry-Perot cavity microphone at different temperatures in the first embodiment of the invention is recorded in experiments, as shown in fig. 7, as can be seen from the graph, the sensitivity is relatively changed to 9.2% in the temperature range of-20 ℃ to 40 ℃ by taking the sensitivity at 20 ℃ as reference sensitivity, the change is acceptable in engineering use, and the test result shows that the optical fiber Fabry-Perot cavity microphone has good temperature adaptability.
The optical fiber Fabry-Perot cavity microphone also has good long-term stability, because the core-inserting sleeve structure for fixing the end face of the optical fiber is arranged in the shell, the round table at the bottom of the core-inserting sleeve and the bottom of the shell are welded through a laser welding process, the core-inserting sleeve is firmly fixed in the shell, and meanwhile, the core-inserting sleeve is wrapped in the shell by the outer sleeve, so that the core-inserting sleeve is prevented from being directly acted by external force, and the long-term stability of the optical fiber Fabry-Perot cavity microphone probe is improved. As shown in fig. 8, in order to show the time-dependent change of the cavity length of an optical fiber fabry-perot cavity microphone according to the first embodiment of the present invention recorded in the experiment, it can be seen from the graph that the length of the optical fiber fabry-perot cavity does not change significantly in more than 30 days of test time, the length indicated by a scale on the ordinate in fig. 8 is 100nm, and as can be seen from fig. 8, the fluctuation value of the cavity length in more than 30 days is less than 15nm, and the offset of the operating point caused by the fluctuation value from the orthogonal operating point is less than 10%, which is sufficient to ensure the reliable operation of the optical fiber fabry-perot cavity microphone according to the present invention.
Second embodiment
The second embodiment of the present invention is an optical fiber fabry-perot cavity microphone, which is different from the first embodiment in that:
the monochromatic light source is composed of a wide-spectrum ASE light source and a DWDM wavelength division multiplexer with a filter function; the three-port unidirectional light guiding unit consists of an isolator 3a and a coupler 3b, as shown in fig. 9; the probe structure of the optical fiber Fabry-Perot cavity microphone is also different.
A schematic cross-sectional view of a probe structure of an optical fiber fabry-perot cavity microphone according to a second embodiment of the present invention is shown in fig. 10, and is different from the probe of the optical fiber fabry-perot cavity microphone according to the first embodiment in that:
the shell material is nickel-copper alloy with a thermal expansion coefficient of about 14.4X10 -6 a/DEG C; the core insert sleeve is made of nickel-copper alloy, and the thermal expansion coefficient of the core insert sleeve is about 14.4 multiplied by 10 -6 a/DEG C; the optical fiber ferrule 3 is composed of different materials in series, and is composed of a hard polymer epoxy resin 301 and zirconia ceramics 302 in series, wherein the thermal expansion coefficient of the epoxy resin is 54.77 multiplied by 10 -6 The thermal expansion coefficient of the zirconia ceramic is about 9.65X10 at a temperature of/DEG C -6 By controlling the ratio of the hard polymer epoxy resin and the zirconia ceramic, the thermal expansion coefficient of the optical fiber ferrule 3 formed by serially compounding the zirconia ceramic 301 and the hard polymer epoxy resin 302 is 20.2X10 -6 and/C. According to the data, the thermal expansion coefficient of the combined structure formed by the core insert sleeve and the optical fiber core is larger than that of the shell, so that when the external temperature changes, the structure bearing the upper end face of the optical fiber can obtain a shell structure with larger variation than that of the structure bearing the reflecting surface of the diaphragm, the distance between the reflecting surface of the diaphragm and the upper end face of the optical fiber is basically unchanged, the high stability of the structure of the optical fiber Fabry-Perot cavity is ensured, and the optical fiber Fabry-Perot cavity microphone has good temperature adaptability.
When the optical fiber core insert is formed by serially compounding ceramic or metal and a hard polymer, the thermal expansion coefficient of the optical fiber core insert is determined by the thermal expansion coefficients of two materials and the proportion of the two materials. FIG. 11 is a schematic view showing a structure of an optical fiber core insert of a probe of an optical fiber Fabry-Perot cavity microphone according to a second embodiment of the present invention, wherein a thermal expansion coefficient of a hard polymer is alpha 21 Having a length L 21 The thermal expansion coefficient of the ceramic or metal is alpha 22 Having a length L 22 The coefficient of thermal expansion α of the composite fiber ferrule is obtained by:
through the formula, proper materials can be selected, and the regulation and control of the thermal expansion coefficient can be realized by controlling the proportion of the materials, so that the thermal expansion coefficient of a combined structure formed by the ferrule sleeve and the optical fiber ferrule is ensured to be larger than that of the shell.
The foregoing embodiments have further described the objects, technical solutions and advantages of the present invention, and it should be understood that the foregoing embodiments are merely illustrative of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the present invention should be included in the scope of the present invention.
In conclusion, the optical fiber Fabry-Perot cavity microphone probe has the advantages of simple structure, easiness in manufacturing and good stability, and has a good application prospect.
Claims (5)
1. An optical fiber fabry-perot cavity microphone, comprising:
optical fiber Fabry-Perot cavity microphone probe for inducing sound wave vibration;
a monochromatic light source capable of emitting monochromatic light;
a photodetector that realizes photoelectric signal conversion;
a three-port unidirectional light guide unit for realizing optical annular unidirectional propagation;
the optical fiber Fabry-Perot cavity microphone probe is connected with a port II of the three-port unidirectional light guide unit, and the photoelectric detector is connected with a port III of the three-port unidirectional light guide unit;
monochromatic light emitted by the monochromatic light source enters the three-port unidirectional light guide unit from a port I of the three-port unidirectional light guide unit, and is emitted from a port II of the three-port unidirectional light guide unit into the optical fiber Fabry-Perot cavity microphone probe, so that interference light modulation of sound waves is realized; the modulated interference light enters the unidirectional light guide unit from the port II of the unidirectional light guide unit with three ports, and then is emitted from the port III of the unidirectional light guide unit with three ports to enter the photoelectric detector for converting optical signals into electric signals for processing;
the optical fiber Fabry-Perot cavity microphone probe comprises:
the shell is of a hollow structure, and threads are arranged in the middle of the inner wall of the shell;
the vibrating diaphragm is a film and is arranged at the front end of the shell and used for sensing sound waves, and the surface of the vibrating diaphragm facing to one side of the inside of the shell has a light reflecting effect and is used as a light reflecting surface of the optical fiber Fabry-Perot cavity structure;
the optical fiber core insert is a hollow columnar structure and is made of a single material and is a ceramic core insert or a metal core insert; or different materials are compounded in series; is formed by serially compounding ceramic or metal and a hard polymer;
the core inserting sleeve is of a hollow cylindrical structure, the outer side surface of the middle part of the core inserting sleeve is provided with threads, the core inserting sleeve is arranged in the shell, and one side of the core inserting sleeve, which faces towards the vibrating diaphragm, is used for installing an optical fiber core inserting;
the outer sleeve is of a cap-shaped structure with two open ends, is arranged outside the outer shell from the lower end of the outer shell, and is used for wrapping the core insert sleeve inside;
the probe optical fiber is fixed in the optical fiber insert core by the outer sleeve through the insert core sleeve, and the upper end surface of the probe optical fiber is used as the other reflecting surface of the optical fiber Fabry-Perot cavity structure;
in the probe structure of the optical fiber Fabry-Perot cavity microphone, the reflecting surface of the vibrating diaphragm and the upper end surface of the probe optical fiber form an optical fiber Fabry-Perot cavity, and the thermal expansion coefficient of a combined structure formed by the core insert sleeve and the optical fiber core insert is larger than that of the shell;
the reflecting surface of the vibrating diaphragm is the surface of the vibrating diaphragm facing the inside of the shell;
or the reflecting surface of the vibrating diaphragm is a metal reflecting layer or a medium reflecting layer plated on one side of the vibrating diaphragm facing the inside of the shell;
the side surface of the core insert sleeve is provided with a ventilation groove from the top of the thread to the tail end of the core insert sleeve, and the ventilation groove is used for balancing static pressure on two sides of the vibrating diaphragm; the bottom of the shell is provided with a round table, the lower end face of the round table at the bottom is provided with a tool fixing hole, the tool is used for installing the core inserting sleeve in the shell through the tool fixing hole, after the installation is finished, the outer side face of the round table at the bottom is contacted with the inner surface of the bottom of the shell, and the contact joint is welded by utilizing a laser welding process, so that the core inserting sleeve and the shell are reliably connected;
the lower part of the shell is provided with fixed screw holes in the direction perpendicular to the shaft, the number of the holes is 2-4, and the holes are uniformly distributed along the circumference; the fixing screws are arranged in the fixing screw holes and used for fixing the core insert sleeve, and the number of the fixing screws is identical to that of the fixing screw holes; the front cover is arranged outside the shell from one side of the vibrating diaphragm and is used for protecting the vibrating diaphragm, and the top end of the front cover is provided with an audio hole;
further comprises: the optical fiber is used for connecting a monochromatic light source, a three-port unidirectional light guide unit, an optical fiber Fabry-Perot cavity microphone probe and a photoelectric detector to form a light path; the optical fiber flange is used for connecting the probe optical fiber and the optical path optical fiber; the output end of the photoelectric detector is also connected with a front-end adjusting circuit;
the shell and the core insert sleeve are made of one or more of the following metal materials: stainless steel, titanium, copper, aluminum alloy, titanium alloy, nickel-copper alloy, nickel-chromium alloy.
2. The fiber optic fp-cavity microphone of claim 1, wherein the probe fiber is a single mode fiber or a polarization maintaining fiber.
3. The optical fiber fabry-perot cavity microphone of claim 1, wherein the diaphragm is one of the following diaphragms: metal film, silicon nitride film, silicon dioxide film, glass film, organic polymer film.
4. A fiber optic fp-cavity microphone according to claim 1, wherein the monochromatic light source is a laser or is formed by an ASE-broad spectrum light source and an optical filter trench.
5. A fiber optic fp cavity microphone according to claim 1, wherein the three-port single-direction light guide unit is a circulator or is comprised of an isolator and a fiber optic coupler.
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103152685A (en) * | 2013-03-12 | 2013-06-12 | 中国电子科技集团公司第三研究所 | F-P (Fabry-Perot) interference principle-based optical fiber microphone |
| CN104019884A (en) * | 2014-06-23 | 2014-09-03 | 中国科学院电子学研究所 | Optical fiber FP cavity sonic probe |
| CN105675114A (en) * | 2016-01-08 | 2016-06-15 | 杨志强 | Optical fiber EFPI ultrasonic sensor |
| CN105758434A (en) * | 2015-10-12 | 2016-07-13 | 北京信息科技大学 | FBG reflectance spectrum sensing demodulation method based on linear array InGaAs scanning |
| CN106482760A (en) * | 2015-10-14 | 2017-03-08 | 北京信息科技大学 | A kind of system of all-metal packaged fiber grating strain transducer |
| CN106644036A (en) * | 2016-12-26 | 2017-05-10 | 华中科技大学 | Sound wave detector based on polymer thin film and dual-wavelength demodulation method |
| CN208043243U (en) * | 2018-02-27 | 2018-11-02 | 北京信息科技大学 | A kind of optical fiber Fabry-Perot cavity microphone |
-
2018
- 2018-02-27 CN CN201810160878.XA patent/CN108151876B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103152685A (en) * | 2013-03-12 | 2013-06-12 | 中国电子科技集团公司第三研究所 | F-P (Fabry-Perot) interference principle-based optical fiber microphone |
| CN104019884A (en) * | 2014-06-23 | 2014-09-03 | 中国科学院电子学研究所 | Optical fiber FP cavity sonic probe |
| CN105758434A (en) * | 2015-10-12 | 2016-07-13 | 北京信息科技大学 | FBG reflectance spectrum sensing demodulation method based on linear array InGaAs scanning |
| CN106482760A (en) * | 2015-10-14 | 2017-03-08 | 北京信息科技大学 | A kind of system of all-metal packaged fiber grating strain transducer |
| CN105675114A (en) * | 2016-01-08 | 2016-06-15 | 杨志强 | Optical fiber EFPI ultrasonic sensor |
| CN106644036A (en) * | 2016-12-26 | 2017-05-10 | 华中科技大学 | Sound wave detector based on polymer thin film and dual-wavelength demodulation method |
| CN208043243U (en) * | 2018-02-27 | 2018-11-02 | 北京信息科技大学 | A kind of optical fiber Fabry-Perot cavity microphone |
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