CN102053283B - White-light interferometric optical fiber gravimeter - Google Patents
White-light interferometric optical fiber gravimeter Download PDFInfo
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- CN102053283B CN102053283B CN2010105369423A CN201010536942A CN102053283B CN 102053283 B CN102053283 B CN 102053283B CN 2010105369423 A CN2010105369423 A CN 2010105369423A CN 201010536942 A CN201010536942 A CN 201010536942A CN 102053283 B CN102053283 B CN 102053283B
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- polarization
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- beam splitter
- optical fibre
- maintaining optical
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Abstract
The invention discloses a white-light interferometric optical fiber gravimeter which comprises a white light source, a polarization-maintaining beam splitter, a gravity sensing device, a phase modulator and a photoelectric detector; the white light source is connected with one inlet end of the polarization-maintaining beam splitter through a polarization-maintaining fiber; two outlet ends of the polarization-maintaining beam splitter are connected with two inlet ends of the gravity sensing device respectively through polarization-maintaining fibers; two outlet ends of the gravity sensing device are connected with two inlet ends of the phase modulator respectively through polarization-maintaining fibers; an outlet end of the phase modulator is connected with the photoelectric detector through a polarization-maintaining fiber; and the white light source is connected with the polarization-maintaining beam splitter through a 0-degree counter shaft of the polarization-maintaining fiber, and the polarization-maintaining beam splitter is connected with the gravity sensing device through the 0-degree counter shaft of the polarization-maintaining fiber. By using the white-light interferometry, the white-light interferometric optical fiber gravimeter reduces the impact of backscattering and reduces the coherent noise by adopting the broadband light source, and greatly improves the polarization error caused by polarization cross-coupling and greatly enhances the system accuracy (The accuracy can reach 10-9 g) by adopting the all-polarization-maintaining system.
Description
Technical field
The present invention relates to a kind of optical fiber sensing technology, particularly relate to a kind of white light interference type optical fiber gravity meter.
Background technology
Gravity meter is an instrument of measuring acceleration of gravity, is the main means of surveying the terrestrial gravitation field information.It is bringing into play key effect at the aspects such as accurate mensuration, crustal vertical deformation and national defense construction of national gravity base station foundation, earthquake and sea level monitoring, geoid surface.
High-precision gravity is surveyed and can accurately be obtained and relevant variation characteristics such as the migration of earth interior material, earth movement, for geodetic surveying, geophysics, earth interior dynamical mechanism, environment and disaster monitoring provide important evidence.Many in the world at present countries set up the absolute gravity net one after another; The non-tidal fluctuations of monitoring gravity field, and in the environmental impact research of sea level variation, earthquake, volcano, tectonic movement and relevant environmental change, geologic hazard and relevant Important Project, be applied.
Except the research and application of geophysics aspect, in national economy, people's productive life, the accurate measurement of terrestrial gravitation also will be brought into play more and more important, crucial effect.
Traditional mechanical formula gravity meter is simple in structure, but precision is low, is prone to temperature influence and electromagnetic interference (EMI).
Adopt common narrow spectrum light source, like the LD light source, spectrum width is little, and coherent length is long, and the length difference of two interference arms reaches the requirement of coherent length easily.But the control that do not add of brachium causes the influence of environment (like temperature) to phase place easily, introduces coherent noise (like backscattering).The phase error that the polarization cross of narrow-band light source coupling simultaneously causes also can greatly influence the precision of optical fiber gravity meter.
Summary of the invention
In order to solve the problem that exists in the background technology, the object of the present invention is to provide a kind of white light interference type optical fiber gravity meter.
The technical scheme that the present invention adopts is:
Comprise white light source, polarization-maintaining beam splitter, gravity sensitive device, phase-modulator and photodetector; White light source is connected with an inlet end of polarization-maintaining beam splitter through polarization maintaining optical fibre; Two endpiece of polarization-maintaining beam splitter are connected through two inlet ends of polarization maintaining optical fibre and gravity sensitive device respectively; Two endpiece of gravity sensitive device are connected through two inlet ends of polarization maintaining optical fibre and phase-modulator respectively, and the endpiece of phase-modulator is connected with photodetector through polarization maintaining optical fibre; White light source, polarization-maintaining beam splitter and gravity sensitive device be connected all be polarization maintaining optical fibre 0 the degree be connected by shaft.
Described gravity sensitive device comprises elastic plate, supporter, polarization maintaining optical fibre sensor coil and housing; Elastic plate is by the supporter center support, and it is also gluing fixing in the upper and lower surface coiling of elastic plate respectively that the polarization maintaining optical fibre sensor coil is protected inclined to one side polarization maintaining optical fibre by two; Two inlet ends of polarization maintaining optical fibre sensor coil are connected with two endpiece of polarization-maintaining beam splitter, and two endpiece of polarization maintaining optical fibre sensor coil are connected with two inlet ends of phase-modulator; Polarization-maintaining beam splitter and phase-modulator are fixed on the housing with laser bonding, are evacuated in the shell.
The present invention compares with background technology, and the beneficial effect that has is:
The present invention utilizes white light interference technique; Adopt the short wide spectrum light source of coherent length, can reduce the influence of backscattering, reduce coherent noise; Adopt the inclined to one side system of all risk insurance simultaneously; Greatly improved the polarization error that the polarization cross coupling brings, improved system accuracy greatly, its precision can reach 10-9gm/s2.In addition, the system design of adopting sealing to vacuumize has reduced drift, has suppressed the influence of external environment factor to measuring to a great extent.
Description of drawings
Fig. 1 is the structural principle synoptic diagram of white light interference type optical fiber gravity meter.
Fig. 2 is the structural principle synoptic diagram of gravity sensitive device.
Fig. 3 is the vertical view of polarization maintaining optical fibre sensor coil.
Fig. 4 is the graph of a relation of white light interference type precision of gravimeter and length.
Among the figure: 1, white light source, 2, polarization-maintaining beam splitter, 3, the gravity sensitive device, 4, phase-modulator, 5, photodetector, 3-1, elastic plate, 3-2, supporter, 3-3, polarization maintaining optical fibre sensor coil, 3-4, housing.
Embodiment
Below in conjunction with accompanying drawing and embodiment the present invention is further described.
As shown in Figure 1, the present invention includes white light source 1, polarization-maintaining beam splitter 2, gravity sensitive device 3, phase-modulator 4 and photodetector 5; White light source 1 is connected with an inlet end of polarization-maintaining beam splitter 2 through polarization maintaining optical fibre; Two endpiece of polarization-maintaining beam splitter 2 are connected through two inlet ends of polarization maintaining optical fibre and gravity sensitive device 3 respectively; Two endpiece of gravity sensitive device 3 are connected through two inlet ends of polarization maintaining optical fibre and phase-modulator 4 respectively, and the endpiece of phase-modulator 4 is connected with photodetector 5 through polarization maintaining optical fibre; Being connected of white light source 1, polarization-maintaining beam splitter 2 and gravity sensitive device 3 all is that 0 degree of polarization maintaining optical fibre is connected by shaft, and is output as the line polarisation and is on the birefringence axis of tail optical fiber.
Like Fig. 2, shown in Figure 3, described gravity sensitive device 3 comprises elastic plate 3-1, supporter 3-2, polarization maintaining optical fibre sensor coil 3-3 and housing 3-4; Elastic plate 3-1 is by supporter 3-2 center support, and polarization maintaining optical fibre sensor coil 3-3 is also gluing fixing in the upper and lower surface coiling of elastic plate 3-1 respectively by two polarization maintaining optical fibres; Two inlet ends of polarization maintaining optical fibre sensor coil 3-3 are connected with two endpiece of polarization-maintaining beam splitter 2, and two endpiece of polarization maintaining optical fibre sensor coil 3-3 are connected with two inlet ends of phase-modulator 4; Polarization-maintaining beam splitter 2 is fixed on the housing 3-4 with phase-modulator 4 usefulness laser bonding, is evacuated in the shell.
The light signal that white light source 1 sends gets into two polarization maintaining optical fibre sensor coil 3-3 up and down of gravity sensitive device 3 through the beam splitting device; Because the effect of gravity; Make elastic plate 3-1 that deformation take place, make two the polarization maintaining optical fibre sensor coil 3-3 up and down that stick on the elastic plate 3-1 receive different stress simultaneously, the polarization maintaining optical fibre sensor coil 3-3 above the elastic plate 3-1 receives a tension; Polarization maintaining optical fibre sensor coil 3-3 below the elastic plate 3-1 receives a compressive stress; Cause that polarization maintaining optical fibre length and refractive index change, two ways of optical signals has produced a phase differential, introduces a phase modulated signal through lithium niobate list polarized waveguides device; Convert electric signal to through the PIN pipe at last, and read and demodulation by lock-in amplifier.
It is the SLD light source of 30nm that white light source 1 can adopt spectrum width, the polarization-maintaining beam splitter that polarization-maintaining beam splitter 2 adopts with wave band, and phase-modulator 4 can adopt lithium niobate list polarized waveguides device, and photodetector 5 can adopt the PIN pipe to carry out the photosignal conversion.
Adopt wide spectrum light source to build gravity meter, need interfere the length difference of arm to carry out extremely strict control two.The coherent length of SLD light source is 20 μ m---50 μ m, therefore need interfere the length difference of arm to be controlled in this scope to two.
Take all risk insurance folk prescription case simultaneously; Transmission Fibers all adopts polarization maintaining optical fibre; The polarization-maintaining beam splitter that polarization-maintaining beam splitter 2 adopts with wave band; Phase-modulator 4 adopts lithium niobate list polarized waveguides device, and the optical fiber connection between the device all is that 0 degree of polarization maintaining optical fibre is connected by shaft, in order to control transmission polarisation of light error.
Adopt lithium niobate list polarized waveguides device to carry out phase modulation (PM), traditional piezoelectric ceramic devices of comparing, not only the scope of modulating frequency has obtained expansion significantly, and polarization state has also obtained control well simultaneously.
The thickness of the length of polarization maintaining optical fibre sensor coil 3-3 and the quality size of supporter 3-2 and elastic plate 3-1 all is the key factor that influences precision of gravimeter.The Circular Plate that the employing inside circumference bears even distributed force is as physical model; Under gravity condition; The hoop deformation of elastic plate 3-1 in the time of can deriving certain radius by the amount of deflection of elastic plate 3-1 uses the glue of certain Young modulus that polarization maintaining optical fibre is fixed on the elastic plate 3-1, through certain conducting system; Integration is carried out in hoop deformation to the elastic plate 3-1 of different radii, just can obtain the length variations of the polarization maintaining optical fibre of certain-length on the Circular Plate that inside circumference bears even distributed force.If polarization maintaining optical fibre is only at radial force, its change of refractive is about 0.21 times of length variations, and length variations plays opposite influence to phase place.By the variation of length and phase place, can release the sensitivity formula of gravity meter.
Wherein, length variations Δ l does
Wherein, Δ ψ is a phase differential, and n is a refractive index, and λ is a wavelength, and ω is an amount of deflection, and z is the half the of thickness of elastic plates, and Ω is the polarization maintaining optical fibre diameter, and r is the radius of elastic plate, and c and d are respectively the internal diameter and the external diameter of polarization maintaining optical fibre sensor coil.
With the experimental system is example.Elastic plate 3-1 adopts disc structure, uses the 1J-36 alloy material, and elastic plate 3-1 thickness is 0.5mm, the internal diameter 10mm external diameter 40mm of elastic plate 3-1, and the fine long 12.5m of single face, sensitivity can reach 29.9rad/g.If adopt 10mm---the circle ring disk of 100mm radius, to coil fine length and can reach 100m, theoretical sensitivity can reach 451.42rad/g, and precision can reach 10
-9The g magnitude.Can know that by Fig. 4 when polarization maintaining optical fibre length reached 100 meters, precision had reached 10
-9The g magnitude, promptly high-precision requirement also meets the requirement that can operate miniaturization simultaneously, is desirable length.
Two lithium niobate list polarized waveguides devices are fixed on the housing 3-4 through laser bonding, and laser bonding can connect the alloy material of difficult weldering in the industry, and deformation of members is little, and joint quality is high, and favorable reproducibility forms high-quality weld seam.Realize laser bonding in vacuum workshop, simultaneously with being evacuated in the housing, can further guarantee not affected by environment, thereby improve the precision of gravity meter.
Claims (1)
1. a white light interference type optical fiber gravity meter is characterized in that: comprise white light source (1), polarization-maintaining beam splitter (2), gravity sensitive device (3), phase-modulator (4) and photodetector (5); White light source (1) is connected with an inlet end of polarization-maintaining beam splitter (2) through polarization maintaining optical fibre; Two endpiece of polarization-maintaining beam splitter (2) are connected through two inlet ends of polarization maintaining optical fibre and gravity sensitive device (3) respectively; Two endpiece of gravity sensitive device (3) are connected through two inlet ends of polarization maintaining optical fibre and phase-modulator (4) respectively, and the endpiece of phase-modulator (4) is connected with photodetector (5) through polarization maintaining optical fibre; White light source (1), polarization-maintaining beam splitter (2) and being connected of gravity sensitive device (3) all are that 0 degree of polarization maintaining optical fibre is connected by shaft;
Described gravity sensitive device (3) comprises elastic plate (3-1), supporter (3-2), polarization maintaining optical fibre sensor coil (3-3) and housing (3-4); Elastic plate (3-1) is by supporter (3-2) center support, and polarization maintaining optical fibre sensor coil (3-3) is also gluing fixing in the upper and lower surface coiling of elastic plate (3-1) respectively by two polarization maintaining optical fibres; Two inlet ends of polarization maintaining optical fibre sensor coil (3-3) are connected with two endpiece of polarization-maintaining beam splitter (2), and two endpiece of polarization maintaining optical fibre sensor coil (3-3) are connected with two inlet ends of phase-modulator (4); Polarization-maintaining beam splitter (2) is fixed on the housing (3-4) with laser bonding with phase-modulator (4), is evacuated in the housing.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2010105369423A CN102053283B (en) | 2010-11-09 | 2010-11-09 | White-light interferometric optical fiber gravimeter |
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| Application Number | Priority Date | Filing Date | Title |
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| CN2010105369423A CN102053283B (en) | 2010-11-09 | 2010-11-09 | White-light interferometric optical fiber gravimeter |
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| CN102053283B true CN102053283B (en) | 2012-08-08 |
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| CN106125131B (en) * | 2016-09-08 | 2018-08-17 | 哈尔滨工程大学 | A kind of rotation seismic wave measuring device based on compound interferometer |
| CN112083476A (en) * | 2020-09-10 | 2020-12-15 | 北京大学 | Rotary seismograph based on dual-polarization light path structure |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5216920A (en) * | 1992-02-11 | 1993-06-08 | Austin Charles T | Multifold shipboard gravity upgraded with still readings |
| CN101509789A (en) * | 2008-12-18 | 2009-08-19 | 浙江大学 | Guidefree optical fiber Fabry-Perot interference sensor |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5216920A (en) * | 1992-02-11 | 1993-06-08 | Austin Charles T | Multifold shipboard gravity upgraded with still readings |
| CN101509789A (en) * | 2008-12-18 | 2009-08-19 | 浙江大学 | Guidefree optical fiber Fabry-Perot interference sensor |
Non-Patent Citations (1)
| Title |
|---|
| 戴旭涵等.光纤陀螺的信号处理方案评述.《光子学报》.1999,第28卷(第11期),1043-1048. * |
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