CN1204048A - Unbalanced fiber optic michelson interferometer as optical pick-off - Google Patents

Unbalanced fiber optic michelson interferometer as optical pick-off Download PDF

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Publication number
CN1204048A
CN1204048A CN 98101500 CN98101500A CN1204048A CN 1204048 A CN1204048 A CN 1204048A CN 98101500 CN98101500 CN 98101500 CN 98101500 A CN98101500 A CN 98101500A CN 1204048 A CN1204048 A CN 1204048A
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China
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optical
light
variation
fiber
pin
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戴维B·霍尔
塞谬阿尔N·弗雷什特
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Northrop Grumman Guidance and Electronics Co Inc
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Litton Systems Inc
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Priority to CN 98101500 priority Critical patent/CN1204048A/en
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Abstract

A system for measuring changes in an environmental parameter, such as velocity or pressure, includes an optical signal source for providing a coherent light signal, and an interferometer having a first and second optical legs of unequal optical path lengths. The signal is split into first and second beams that are respectively directed into the first and second optical legs of the interferometer. A fixed mirror reflects the first beam received at the end of the first optical leg. An optical pick-off includes a movable mirror, positioned to reflect the second beam received from the end of the second optical leg. The movable mirror is movable in response to changes in the value of the parameter to be measured. An optical coupler combines the first and second beams after they have been reflected back into their respective optical legs, producing an interference signal, which is detected by an optical detector. The detector generates an electronic signal having a value indicative of the value of the interference signal.

Description

A kind of uneven fiber optics Michelson's interferometer is as an optical sensor
The present invention and optical interference are the variations that is used for measurement environment parameter such as pressure or speed in respect of the pass.The present invention includes an optical sensor, it is interferometric parts, and interferometer can be used for acoustic sensor or accelerometer.
Michelson or Mach-Zehnder interferometer use in some applications, as acoustic sensor, are known.The Mach-Zehnder interferometer is described in people's such as Arab-Sadeghabadi U.S. Patent No. 5,448,058 to some extent with the acoustic sensor that uses under water.
The optical interference meter of known type comprises by light signal of a single light source transmission to a pair of optical fiber.Light signal is respectively through these two fiber guides, and the light path through different length when these two signal beams combine, has produced a phase differential between this two barss light beam.In conjunction with light beam can detect by photodetector.After their combinations, if this two barss light beam has identical polarized state,, signal forms the candy strip of bright or dark lines just disturbing, this can be detected by fluorescence detector.
Arbitrary or two fibers are exposed in the variation of environmental parameter, and as sound pressure variations, striated pattern changes all the reflection phenomenon on fluorescence detector.By analyzing the variation of detected these striated patterns of fluorescence detector, can record the variation of the environmental parameter that fiber is exposed to.In such cases, when interferometer was used in the acoustic sensor, the characteristic of the sound wave that contacts on the optical fiber just can be determined.
When Mach-Zehnder or Michelson interferometer use in the acoustic transducer system under water (acousimeter under water), tens meters long optical fibers are on an axle.The stretching of fiber can produce a kind of hysteresis that records phase place, and the pressure of it and sound wave is varied to direct ratio.Interferometer has a unmatched optical path length between its two optical fiber terminal pins, it allows standard operation and carry out signal Processing with phase place generation Carrier at one meter the order of magnitude.For example, referring to " fiber sensing element of distribution and multichannel " literary composition of Kersey, Udd, ED.Fiber Optic Sensors:AnIntroduction for Engineers and Scientists (New York 1991), pp.347~363.
The sensing system of above-mentioned fiber optic interferometric meter, survey sound system under water than piezoelectric type is superior, because its advantage is: exempted electromagnetic interference (EMI), can on towboat rather than under water, in the environment all electronics and electric component and system be set, and easily record vector.But relatively more expensive when existing fiber optic sensor system is made, be not better than piezoelectric system, and the comparatively cheap measure of same advantage is provided.The silicon chip sensing element of batch processing, it have one in response in the environment as pressure and acceleration change and mobile detection bodies, be used as the sensor of acceleration and speed.Such silicon sensing element is very cheap and solid.This silicon sensing element is surveyed when using in the sound system under water, inserts detection bodies with optic fiber transmission system, will reduce cost than existing fibre system.But, this silicon chip sensing element and the existing fiber structure of using in Mach-Zehnder and Michelson interferometer measurement sensor-based system or similar system are complementary, in practice, prove and have any problem.
Therefore, provide an optical fibre interference sensor-based system in acousimeter or similar the application under water, it can use the silicon sensing element of common batch processing, concerning present technology obvious improvement is arranged.
The present invention is a test macro, uses cheap silicon chip sensing element to come gaging pressure, speed, acceleration in the optical interferometry meter, or the characteristic of other environment or parameter.One movable detection bodies is arranged in the sensing element, and a terminal pin end in the interferometer that two unequal terminal pins of length are arranged is as movable minute surface.The mobile variation of the detection bodies of silicon chip sensing element in response to a certain special environmental parameter, the optical length of change interferometer terminal pin.
The present invention includes an optical signal source so that a light signal pulse, that can interfere to be provided; The first and second fiber-optic wire pin interferometers that different light path lengths is arranged.Signal is separated into first and second light beams, and they are directed to respectively in the first and second fiber-optic wire pin.A fixing end mirror is placed in the end of the first fiber-optic wire pin, to be reflected in first light beam that first light lead-in wire foot is accepted.An optical sensor is fixed on the far-end of the second fiber-optic wire pin.Optical sensor includes a sensing element, and it has one to detect physical efficiency and move with respect to the end of the second fiber-optic wire pin.The surface of detection bodies can be reflected, and is positioned at and can reflects second light beam of being accepted from the second fiber terminal pin end.An optical coupler is the first and second light beam combinations that reflect back from fixedly end mirror and detection bodies, to produce an interference signal.A fluorescence detector is attached to coupling mechanism with optical mode, with the interference signal of detection in conjunction with light beam, and produces an electronic signal, its value representation interference signal value.Electronic signal by analysis, make it value and the variation of measured environmental parameter numerical value between produce mutual relationship.
Measuring system of the present invention can provide one accurately, fibre optic interferometric sensor system that relative cost is low, under water in survey sound or similar the application, can use silicon sensing element common, batch processing, and fully can be compatible mutually with existing fiber optics member.
Shown in Figure 1 is the measurement mechanism that constitutes according to the present invention, has used a plurality of interferometers; Fig. 2 is the silicon chip sensing element that can be used as a velocity pick-up component type according to of the present invention, and a fixing embodiment cross-sectional view of the optical fiber end of the support member of sensing element sheet and optical sensor;
Fig. 3 is Fig. 2 silicon vane and is the cross-sectional view of second embodiment of the optical fiber end of the back-up block of fixing sensing element and the optical sensor that constitutes according to the present invention;
Fig. 4 is the cross-sectional view that can used in this inventionly change the silicon vane of structure.
The present invention will be described as follows according to the context of its preferred embodiment:
The test macro 10 that constitutes according to the present invention, as shown in Figure 1, it comprises that one or more interferometers is used for measuring from the variation of the interference of light figure that the end reflected of optic fibre light path that different length is arranged.
Specifically, test macro 10 includes a light source 11, and it is laser instrument preferably, produces the optical signalling of interfering of a ultrared or visible spectrum.Laser instrument 11 can directly be sent out pulse, or continuous pump, and its signal is again by lithium niobium amplitude modulaor 12, as an optical gates, or other suitable mechanisms, cause pulse.So be transferred to the fluctuating signal fiber optics phase-modulator 13, thereby produce the carrier wave that a phase place takes place with selected carrier frequency.
The signal with after the phase modulation (PM) of pulse propagates into an independent interferometer along first direction through optical fiber transmission line 15, or many interferometers that sequence is provided with on the transmission line 15.In the embodiment shown, for the ease of explanation later on three interferometers 31,101 are arranged, 121 illustrate.In order to carry out simple and clear discussion, so only first interferometer 31 is described.
Interferometer 31 is attached on the transmission line 15 with method of optics by optical fiber tie line 36 and first optical coupler 37, and interferometer includes a pair of fiber-optic wire pin 33,35 that is uneven in length.Optical signalling from laser instrument 11 transmits along first direction through transmission line 15, visits light beams by two inquiries that second optical coupler 38 is separated into.Second optical coupler 38 can be with existing 3dB optical coupler, and it guides first light beam to the first terminal pin 33 and second light beam to the second terminal pin 35.
The optical path length of the second optical lead pin 35 is much larger than first optics, 31 stitches.For example, the optical path length of first terminal pin 33 should be lacked as much as possible, and better length is no more than about 10 centimetres.And the optical path length of second terminal pin 35 is about 1 meter.
As following detailed explanation, first and second light beams are at the first and second fiber-optic wire pin 33,35 end is reflected back toward respectively, be back to second optical coupler 38 through the optical lead pin, it makes it deliver to photodetector 39 along transmission line 15 with the second direction passback again in conjunction with the optical signalling that is reflected.The variation of optical path length is relatively got back on the transmission line 15 at reflected light between two terminal pins, and catoptrical conoscope image is changed.Will illustrate that as following person skilled in the art also can approve, by analyzing conoscope image and its variation, make the variation of the environmental parameter (as pressure and motion) that interferometer 31 is exposed to determine.
The first fiber-optic wire pin 33 (short terminal pin) has the end mirror 41 of a high reflectance, and it is fixed on the far-end or second end of lead-in wire.These fixing end mirror 41 reflections make it return first terminal pin along second direction, promptly to light source 11 (also to detecting device 39) through first light beam that first terminal pin 33 transmits.At the far-end or second end of second terminal pin 35, an optical sensor 51 (will describe in detail in the back) is arranged, it includes the silicon chip sensing element of detection bodies movably.Detection bodies has a movably end mirror, and reflection is propagated second light beam of coming through second terminal pin 35, makes it return second terminal pin along second direction, and light source 11 and detecting device 39 promptly lead.
Now, used the silicon chip sensing element 54 that is installed on the sensing back-up block 54 in the optical sensor 51 referring to Fig. 2.Be applicable to that silicon chip sensing element of the present invention is that everybody generally knows with available.They are relatively cheap a large amount of productions that also are easy to.The silicon chip sensing element uses the variation that removable detection bodies is come sensing environment such as speed, acceleration or pressure.The silicon chip sensing element 53 of a demonstration is shown in figure two, it has the silicon cell of an integral body, contain a movably detection bodies 55, use the flexible parts 58 that link, at least two opposed edges of detection bodies along detection bodies are anchored on the peripheral fixed part 57.Fixed part 57 is firmly to be fixed between first 59a of shell portion and second 59b of shell portion, is limited with an internal cavities 60 like this and holds detection bodies 55 between them.59a of shell portion and 59b more preferably have the stupalith plate of low thermal coefficient of expansion, better are Pyrex Glass (by Corning Glass listing, Corning, NY) or certain suitable material.Detection bodies must be able to move in cavity 60, because it mobile is used for the variation of testing environment parameter, will illustrate as following.On second 59b of shell portion a perforate 62 is arranged, the center of it and detection bodies 55 is arranged closely, is directed on the detection bodies 55 by its second light beam, and this will be illustrated below.
The distal portion of the second fiber-optic wire pin 35 is provided with in a sleeve pipe 63, can use ceramic pipe.Sleeve pipe 63 has an axial passageway holding the distal portion of the second fiber-optic wire pin 35, and the diameter of path the diameter with optical fiber 35 is identical substantially.The far-end of the second fiber-optic wire pin 35 that the far-end of sleeve pipe 63 includes with it inserts in the opening 62 of the second body shell 59b of portion of silicon sensing element 53.Detection bodies has a high plane of reflection 64, and it locatees the end face 65 that separation in sight regards to the second optical fiber terminal pin 35 again, and end face 65 is concordant mutually in perforate 62 with the end face of sleeve pipe 63.Be that this plane of reflection 64 has the very thin metallic coating of one deck preferably, gold for example can be near 100% with the cremasteric reflex rate.Only coming out from fiber end face 65 and passing air by surface 64 reflections of detection bodies and when turning back to fiber from the light beam of fiber 35 like this.Light also might twist the material of light beam without other.
Gap between the plane of reflection 64 of the end face 65 of fiber 35 and detection bodies 55 should be enough little, like this when light when fiber end comes out and reflect back into fiber, the light loss meeting of beam divergence is minimum.Be several wavelength that gap width is no more than the light of propagating through fiber preferably.For example, for the wavelength of discussing, gap width preferably greatly about 2.5 emblem rice between the 20 emblem rice, the distance back and forth of light process in air is greatly in the scope of 5~40 emblem rice like this.Be coated with coating (not shown) at the end face 65 of the second fiber terminal pin 35, make and reduce undesirable etalon reflection between detection bodies 55 and the fiber end face 65, and guarantee that all reflected signals all enter fiber with a kind of antireflection.And needing anti-reflection coating also is to eliminate retro-reflection to the second fiber-optic wire pin 35 for basic.Anti-reflection coating on end face 65 should have one less than about 10% reflectivity, is to be not more than about 0.1% preferably.Manufacturing has low reflecting properties optical coating, and as U.S. Patent No. 5,529, shown in 671, its content just is combined in here as a reference in known technology.
Sensing element 53 is mounted in to be supported to make the perforate 62 on the second body shell 59b of portion consistent with axial hole 74 centers of back-up block 54 like this on the piece 54.Axis hole 74 holds sleeve pipe 63.The length that the second fiber terminal pin 35 stays outside sleeve pipe 63 can place (not shown) in the typical fiber overcoat.Sensor supports that piece 54 can be annular, though its distinctive appearance and size are the things in the design alternative, is in order to be applicable to special application.
Like this, second light beam emits from fiber end face 65 through the second fiber-optic wire pin 35, passes the clearance between the reflecting surface 64 of fiber end face 65 and removable detection bodies 55.Reflecting surface 64 is got back to beam reflection in the fiber-optic wire pin 35.
Use the optical sensor of a silicon sensing element, can be used to measuring speed or acceleration, or be used for the variation of measuring pressure.As the one skilled in the art as can be known, in cavity 60, during with respect to the body shell 59a of portion and 59b motion, can detect acceleration when the detection bodies in the sensing element 53 55.Because body shell 59a and 59b fix with respect to the second light light terminal pin 35, the motion of detection bodies 55 in cavity 60 is just with respect to the motion of the second optical lead pin 35.This motion has changed the reflecting surface 64 of detection bodies 55 and the width of the optical gap between the second optical lead pin, 35 end faces 65.The first body shell 59a of the portion inside surface is from detection bodies 55 a little distance to be arranged, and moves along a single axial in cavity 60 to allow detection bodies 55.Total can be accommodated in the neutral floating box (not illustrating in the drawings).
Referring to Fig. 3, that shown is amended sensor 51 ', has an altered sensor to support piece 82, is in order to use in sensor 51 ' of a basic flat structure of needs.Sensor supports piece 82 to hold the far-end of the second optical lead pin 35, and provides a light path for second light beam between the end of the second optical lead pin 35 and the detection bodies 55 in the silicon sensing element 53.Sensor supports piece 82 better to form by the stupalith sheet of dish type or by a kind of thermal stability material (that is to say low thermal expansivity) of equivalence basically, though its profile and size are according to being applied as the thing that the deviser selects.
The distal portion of the second smooth terminal pin 35 is to wrap in the sleeve pipe 83, it and support piece 82 the same should formation by the almost negligible as suitable stupalith of a kind of hot expansion system.Sleeve pipe 83 is to be inserted in first lateral aperture 85 of supporting piece 82, and it has enough gaps and allows lasso 83 axially to rotate in hole 85, and the direction of light beam can be adjusted to the optimum condition running like this, and this will illustrate below.The axial hole that passes sleeve pipe 83 holds the distal portion of second fiber-optic wire 35, and holding level with both hands of distal portion and sleeve pipe 83 is neat, perhaps is that the distal process than sleeve pipe 83 goes out a little slightly as shown in the figure preferably.Second fiber-optic wire 35 has end face 86, and it better is to have about 8 ° angle, with basic elimination retro-reflection in second fiber-optic wire 35.
Cylindrical grading index lens (grin lens) 87 are optically harmonized with the end face 86 of second fiber lead-in wire 35, thereby second fiber lead-in wire, 35 light beams that send are focused on the reflecting surface 64 of detection bodies 55.Better be to have a gap to be approximately 0.2 millimeter between the surface of the end face 86 of second fiber-optic wire 35 and the grin lens of facing 87.Grin lens 87 is to be contained in second side opening 89 supporting piece 82, and it and first side opening 85 are on same axle.
Sensing element 53 is to be contained on the surface of supporting piece 82, and the optics perforate 62 on such second sensing element body shell 59b of portion forms a line with the optics energy circuit 91 that air is arranged, and channel axis is to passing through to support piece 82.In order to admit sleeve pipe 83, grin lens 87 and below with the parts of narration, path 91 might not be at the center of supporting piece 82.
A mirror rod 93 is installed in the eccentric orfice 94 of tubulose assembly parts 95, and assembly parts 95 install in the 3rd lateral aperture 97 supporting piece 82, and purpose is to be the energy axial rotation.The inner termination of mirror rod 93 is one to be cut into the minute surface 99 of 45 degree, and it is given prominence in path 91 so that the light beam of accepting to send from grin lens.Second light beam from the end 86 of second fiber-optic wire 35 sends by grin lens 87, has reflected 90 ° of angles in the termination of mirror rod 93 by minute surface 99 then, again by path 91.Tubulose assembly parts 95 can rotate in second side opening 97, so that the striking point of light beam on minute surface 99 can be adjusted to reach optimum operation, that is to say to reach least disadvantage and undesirable reflection.Additional degree of adjusted can reach in the axial rotation in the eccentric orfice 94 when installation mirror rod 93 is to tubulose assembly parts 95.
The arrangement of the optics perforate 62 of the second sensing element body shell 59b of portion makes light path not pass the body shell material.Because perforate 62 supports that with sensor path 91 covers of piece 82 are neat, second light beam comes out only can pass through air from grin lens 87.Second light beam comes out through second fiber-optic wire 35 and from fiber end 86, passes through the clearance between fiber end 86 and grin lens 87 again, enters into grin lens.Grin lens 87 will be imaged on from the light beam of fiber end 86 on the reflecting surface 64 of detection bodies 55.After 90 ° of minute surface 99 folded light beams, make light beam pass through perforate 62 among the second body shell 59b of portion of sensing element 53, hit on the reflecting surface 64 of detection bodies 55.Reflecting surface 64 folded light beams make it to turn back on the mirror rod 99.Mirror rod 99 makes it to turn back in the grin lens 87 with 90 ° of reflections light beam that is reflected again.Reflected beams enters second fiber-optic wire 35 once more through grin lens 87 like this.The efficient coupling of the light beam that comes out from fiber 35 to detection bodies surface 64 and when returning is very important to the top efficiency that obtains this device.It should reduce the back reflection in fiber end 86 or other places.
Minute surface 99 should be adjusted to the reflected light that makes from reflecting surface 64, and same circuit is propagated when hitting reflecting surface 64 as light beam accurately.Minute surface 99 answers lead beam as much as possible near the center of detection bodies 55 like this, if the detection bodies 55 when using is always in bending.
For the various application (for example surveying sound system under water for) that measurement environment pressure changes, the structure of sensing element can adopt and be different from shown in Fig. 2 and Fig. 3.The one skilled in the art will understand that in this application, the detection bodies structure 55 shown in the figure and 58 can be cancelled.The structure of such replacement sensing element 53 as shown in Figure 4.In this change, sensing element 53 ' have a silicon diaphragm 100 that plays the detection bodies effect, and it has the area district, center of a flexibility, but corresponding bending is done in the variation of response environment pressure.Diaphragm 100 is fenced up by a peripheral rim 102, and wheel rim 102 is attached on the solid substrate 104, has formed internal optics cavity 60 ' between diaphragm 100 and substrate 104.Substrate 104 has optics perforate 62 ', as the passage of second light beam, second light beam is hit on reflecting surface 64 ', and it is the inside surface (in the face of cavity 60 ') that directly affacts diaphragm 100.The variation of pressure impels the area district, center of diaphragm 100 to move, and has changed the road length of the optical gap that is limited by internal cavities 60 ' width.
Referring again to Fig. 1, second light beam that reflects from sensor 51 (it may be the above-mentioned embodiment any) is propagated to second direction through second fiber-optic wire 35; And reflect from fixed mirror 41, also propagate through first light beam of first fiber-optic wire 33 to second direction.The combination once more in second photo-coupler 38 of first and second light beams so just forms an interference signal, and this signal changes with the motion of removable minute surface in the sensor 51, and should move in response to the variation of environmental parameter value.This interference signal is propagated through tie line 36, and by first photo-coupler 37 and transmission line 15 couplings.This interference signal is transferred to photodetector 39 by an optical fiber tie line 75 again through transmission line 15, and connecting line 75 is coupled to transmission line by a photo-coupler 73.
Because second light beam that reflects from sensor 51, passed through different length than first light beam that reflects from end mirror 41, therefore interfere from sensor 51 light that reflects and the light that reflects from end mirror 41, thereby produced a conoscope image, conoscope image is with the motion change of detection bodies, and this motion is in response to the variation of environmental parameter.The variation of conoscope image shows the variation with light photodetector 39 detected interference signal values; The variation of the electrical output signal indication interference signal value of the definite value that confused survey device sends.This electrical output signal is input to microcomputer 77 (after suitable and traditional signal arrangement and digitizing), it is handled electric signal with the technology that everybody knows, be associated between the variation that makes the interference signal value and the environmental parameter changing value, thereby produce the measurement result of the variation that can represent parameter value.
Using the present invention to do under the situation of an accelerometer, attaching has optical sensor 51 on the object of motion, thereby the detection bodies 55 that is contained among body shell 59a and the 59b is moved in sensor cavities 60.The motion of detection bodies 55 changes the optical path length of the light of propagating through second lead-in wire 35.Therefore, the variation of optical path length also changes the conoscope image of the interference signal that is reflected that is detected by photodetector 39.Can determine the motion of detection bodies 55 from the variation of these catoptrical conoscope images.
The present invention also can be used as a pressure transducer, as acousimeter under water, then better is to use sensing element 53 ' as shown in Figure 4.Pressure changes (for example sound wave is through sensor 51) and impels the deformable first 59a ' of the body shell portion bending (in this change, it is a conduct detection bodies as previously described), has changed the optical path length of the light of propagating through second lead-in wire 35.Therefore, the variation of optical path length changes the conoscope image of the interference signal that is reflected that is detected by photodetector 39.From the variation of these catoptrical conoscope images, just can record the variation of environmental pressure.Change from these pressure that record, just can obtain to cause the information of the sound wave of these variations.
Different with existing technology, the fiber optics parts do not play the function of sensing element among the present invention.Sensing is all finished by silicon sensing element 53 in the sensor 51.Be higher than a few tenths of hertz environmental change for sensing has a frequency, the phase delay owing to elongate fiber in fiber-optic wire 33,35 is negligible.
One to described system needed phase place generation carrier wave, and requiring has an enough unmatched optical path length between two fibers lead-in wires 33 and 35.At present the state of the art about passive fine light sensing element shows, the optical path length between two fiber lead-in wires 33 and 35 is inconsistent should be at about 10 centimetres to about 1 meter.The inconsistent scope of such optical path length also is compatible with the stable narrow-linewidth laser light source in the present technology, and uses interior frequency modulation (PFM) and compound or outer phase place modulation of time division multiplex and the compound fiber optics structure of frequency separation multichannel.
Optical sensor 51 is measured detection bodies 55 with respect to fixing silicon sensing element body shell 59a and the displacement of 59b, and its survey frequency certain about 1~5 hertz is more than the minimum value.Slowly drift may take place with temperature in optical path length in time in the fiber lead-in wire 33,35, but such error that variation produced is very low from frequency, so be negligible to measuring needed degree of accuracy.For example, temperature had 1 ℃ variation in 1 minute, and when about one meter of the line length difference between this two fibers lead-in wire 33 and 35, the fringe motion of generation is equivalent to 0.1 hertz, is significantly less than minimum value recited above.When as accelerometer, 55 of the detection bodies in given sensor 51 have response in one direction.Therefore can use three interferometer sensing elements, each has its silicon chip vane, with measurement of x, and y, three axial motions of z.This ternary sensing element can be installed on the individual block.
System shown in Figure 1 is made up of three sensing elements, so just might measure three speed and acceleration on the direction.As the second and the 3rd interferometer 101 and 121 of accelerometer, each is identical with interferometer 31 basically, though they may be any embodiments among Fig. 2 or Fig. 3.In a specific system, all interferometric schemes should be identical, but do not limit the interferometer how many particular number are this system should have.
In Fig. 1, second interferometer 101 contains the fiber lead-in wire 103 and 105 that is uneven in length.Wherein fiber lead-in wire 103 is significantly shorter than fiber lead-in wire 105, and these two lead-in wires carry out optical coupled by an optical coupler 106.Short lead-in wire 103 terminates in the fixing end mirror 107.Long lead-in wire 105 terminals in an optical sensor 109, it basically with optical sensor 51 recited above or 51 ' in any identical be favourable.Second interferometer is by fiber optics connecting line 111 and optical coupler 113 and transmission line 15 optical coupled.Similarly, the 3rd interferometer 121 contains the lead-in wire 123 and 125 of different length, is connect by optical coupler 126.First fiber lead-in wire 123 is significantly shorter than second fiber lead-in wire 125.Short lead-in wire 123 terminals are on fixing end mirror 127.Long lead-in wire 125 terminals are in an optical sensor 129.The 3rd interferometer 121 usefulness fiber optics connecting lines 131 and optical coupler 133 and transmission line 15 optical coupled.The interferometer of additional same spline structure can be added to system, is coupled with optics coupling process and main transmission line 15.
When surveying under water when using on the acoustic device, the interferometer of larger amt (uses sensing element 53 ', can form a line as shown in Figure 4) and drag back at a ship.With the lasing light emitter of an enough power, a laser instrument just can promote tens such devices.If to obtain the gain that distributes, hundreds of such device can be promoted by a signal laser of a pump at optical fiber chosen part doping bait.
Though several preferred embodiments are narrated in the above, these schemes are exemplary.Many changes and modification are producible to person skilled in the art, for example, support the profile of piece 54 (Fig. 2) and 82 (Fig. 3) can change to be suitable for different application with size.Simultaneously, above narration as the aligning adjusting mechanism of the mirror rod 93 in Fig. 3 scheme, also can revise to make in the other direction and also can adjust, perhaps it also can save together.Change of these and other and modification should be considered among the spirit and scope of the present invention, as what following claim limited.

Claims (29)

1. system that is used for the testing environment parameter value variation comprises:
The coherent light signal source of a pulsation;
An interferometer is coupled to described light source optically, so that accept the optical signalling of a pulsation therefrom; This interferometer comprises:
First device is in order to be separated into described optical signalling the first and second two light beams;
Second device is respectively first and second light beams and forms first and second optics pin, and is longer than the length through another optics pin through the optical path length of one of them optics pin;
A fixed mirror is in the terminal of the first optics pin, so that first beam reflection is got back in the first optics pin;
A movable mirror is in the terminal of the second optics pin, so that second beam reflection is got back in the second optics pin; The mobile variation of movable mirror in response to parameter value;
The optical coupled apparatus combines first and second light beams that reflected by fixed mirror and movable mirror edge optics pin separately respectively, so that form an interference signal again;
Optical detector means responds to interference signal, represents the value of interference signal to produce an electric signal;
The 3rd device responds with described electric signal, sets up the variation of interference signal value and the corresponding relation of parameter value variation.
2. the system in the claim 1, wherein interferometer also comprises:
One sensing element has a detection bodies, can move in response to the variation of parameter value;
Reflecting surface on the detection bodies forms described movable mirror.
3. the system in the claim 1, wherein the optical path length of the second optics pin is obviously greater than the optical path length of the first optics pin.
4. the system in the claim 3, wherein the optical path length of the first optics pin is not greater than about 10 centimetres, and the optical path length of the second optics pin is at least about 1 meter.
5. the system in the claim 2, wherein said sensing element includes the first and second box portions and limits a cavity, and the described detection bodies that is placed in wherein can move, and the described second box portion is provided with a unthreaded hole, reflects the path of second light beam as reflecting surface.
6. the system in the claim 2, wherein said sensing element includes the first and second box portions and limits an internal cavities is arranged each other, described detection bodies constitutes a pressure-responsive portion of the first box portion, this pressure-responsive portion has a reflecting surface to face described internal cavities to form movable minute surface, and described second box portion is provided with a unthreaded hole, provides path for reflecting described second light beam for described reflecting surface.
7. optical sensor that is used for interferometry sensor-based system or similar system comprises:
One supporting structure includes the light path of an end,
One movable mirror, move in response to specific physical parameter changes, described movable mirror is for the setting of described light path end, and the light beam that the light path end is sent hits on the movable mirror, and reflect back into from movable mirror in the end of light path, thereby the motion of movable mirror has changed optical path length.
8. the optical sensor in the claim 7, wherein movable mirror comprises:
The detection bodies that one reflecting surface is arranged.
9. the optical sensor in the claim 8, also include the box of an internal cavities, what described detection bodies was movable is supported in the cavity, and described box has a unthreaded hole and light path to be complementary, so that provide an optical channel for the light beam between described reflecting surface and the described light path end.
10. the optical sensor in the claim 8, wherein said detection bodies is one to have the pressure-responsive diaphragm of periphery, wherein said sensor also comprises a substrate, the periphery of described diaphragm is supported in the described substrate, thereby form an internal cavities between diaphragm and substrate, diaphragm arrangement makes reflecting surface face inside cavity, and described substrate has a unthreaded hole and light path to be complementary, like this between described reflecting surface and described light path end, for light beam provides a path.
11. the optical sensor in the claim 9, wherein said optical routing one optical fiber limits, and the end of wherein said light path is the end face of described optical fiber, and wherein supporting structure should comprise:
Support piece for one;
One fiber retaining element optical fiber is anchored at support in the piece, thereby the end face of optical fiber is arranged in the described unthreaded hole.
12. the optical sensor in the claim 11, wherein support piece to have a thorax hole and described unthreaded hole to form a line, and wherein the fiber retaining element comprises a ferrule configuration in described thorax hole, and sleeve pipe has an axial passageway holding described fiber optics, thereby the end face of optical fiber is configured in the described unthreaded hole.
13. the optical sensor in the claim 10, wherein said light path are limited by an optical fiber, wherein the end of light path is the end face of optical fiber, and wherein supporting structure should comprise:
One supports piece;
One fiber retaining element optical fiber is anchored at support in the piece, thereby the end face of optical fiber is configured in the described unthreaded hole.
14. the optical sensor in the claim 13, wherein said support piece has a thorax hole and described unthreaded hole to form a line, and wherein said fiber retaining element comprises that a ferrule configuration is in described thorax hole, described sleeve pipe has an axial passageway to come receiving optical fiber, thereby the end face of optical fiber is configured in the unthreaded hole.
15. the optical sensor in the claim 9, wherein supporting structure comprises that one supports piece, it has an axial optical path and described unthreaded hole to form a line, wherein said light path primary orientation is in lateral light paths, and wherein supporting structure comprises that also the beam direction device enters described optical channel to guide the light beam from the light path end, and reaches on the described reflecting surface through described unthreaded hole.
16. the optical sensor in the claim 15, wherein locate the light path end, and to guide described light beam to the passage of light, the direction of described light beam is the axle that crosses passage substantially, and described beam direction device comprises:
At an angled mirror of supporting to be provided with on the piece, so that accept described light beam in optical channel, and its directional energy reflects described light beam through described unthreaded hole and reach to described reflecting surface.
17. the optical sensor in the claim 15 also should comprise:
In supporting piece and the imaging len that between the end of described light path and optical channel, is provided with, so that described light beam is imaged on the described reflecting surface.
18. the optical sensor in the claim 16, wherein said angled mirror is rotary, changes the striking point of light beam on reflecting surface like this.
19. the optical sensor in the claim 18, wherein be installed in and support rotating described angle mirror on the piece, have the end face of a reflection to be arranged on the described optical channel, described end face is towards an angle is arranged, so that the light beam in the reception optical channel, and with beam reflection in described unthreaded hole.
20. the optical sensor in the claim 19, wherein said angle mirror comprise a rod, axially are installed in the eccentric thorax hole of supporting a sleeve pipe in the piece so that can axial rotation.
21. a kind of method of the variation of measurement environment parameter comprises the steps:
The coherent light signal of a pulsation is provided;
An interferometer is provided, and it has a movable mirror of a fixed mirror, the variation of described movable mirror response environment parameter value and moving;
The direct light signal is in described interferometer, to obtain an interference signal as interferometer output; The motion that the value of interference signal is in response to movable mirror changes;
Detect the variation of described interference signal value;
The variation of interference signal value and the variation foundation of environmental parameter value are got in touch.
22. the method in the claim 21, wherein environmental parameter is a speed.
23. the method in the claim 21, wherein environmental parameter is a pressure.
24. the method in the claim 21, wherein interfere in respect of one first optics pin, its end points place is a fixed mirror, interferometer also has one second optics pin, its end points place is described movable mirror, and wherein guides step to comprise that elder generation becomes first light beam with separate optical signals, and first pin leads, with second light beam, second pin leads.
25. the method in the claim 21 wherein detects step and comprises the step that produces an electrical output signal, the value of its value indication interference signal; And wherein set up the step of contact, comprise the mutual relationship of determining between electronic output signal value and the variation of environmental parameter value.
26. the method for measurement environment parameter comprises the steps:
The coherent light signal of a pulsation is provided;
Described separate optical signals is become first and second light beams;
Guide respectively in the smooth pin of first and second light beams to the first and second, the first and second smooth pins have different optical path lengths, and the optical path length of one of them light pin changes in response to the variation of environmental parameter value;
Reflect first and second light beams that the first and second smooth pins come out, thereby produce an interference signal, its value changes in response to the variation of a light pin optical path length;
Detect the variation of undesired signal value, set up the variation of interference signal value and the corresponding relation that the environmental parameter value changes.
27. the method in the claim 26, wherein environmental parameter is a speed.
28. the method in the claim 26, wherein environmental parameter is a pressure.
29. the method in the claim 26 wherein detects step and comprises electronic output signal of generation, the value of its value indication interference signal, and comprise the corresponding relation of setting up between electronic output signal value and the variation of environmental parameter value.
CN 98101500 1997-06-06 1998-06-04 Unbalanced fiber optic michelson interferometer as optical pick-off Pending CN1204048A (en)

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Application Number Priority Date Filing Date Title
US08/848,090 1997-06-06
CN 98101500 CN1204048A (en) 1997-06-06 1998-06-04 Unbalanced fiber optic michelson interferometer as optical pick-off

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CN102103011A (en) * 2010-11-09 2011-06-22 山东省科学院海洋仪器仪表研究所 High-precision laser interference hydrophone
CN102460102A (en) * 2009-06-05 2012-05-16 西美亚光学公司 A fibre optical system and use thereof

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CN102460102A (en) * 2009-06-05 2012-05-16 西美亚光学公司 A fibre optical system and use thereof
CN102460102B (en) * 2009-06-05 2014-11-12 西美亚光学公司 A fibre optical system and use thereof
CN102103011A (en) * 2010-11-09 2011-06-22 山东省科学院海洋仪器仪表研究所 High-precision laser interference hydrophone
CN102103011B (en) * 2010-11-09 2013-05-15 山东省科学院海洋仪器仪表研究所 High-precision laser interference hydrophone
CN102065365A (en) * 2010-12-03 2011-05-18 中国电子科技集团公司第四十九研究所 Silicon micro-composite thin film chip manufacture method and optical fiber sound pressure sensor using the silicon micro-composite thin film chip
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