CN102150007B - Compact optical fiber structure for anti-Continuous Wave with frequency modulation coherent laser radar of warbling - Google Patents

Abstract

One is used for determining the system and method for the measurement distance between measurement apparatus (20A) and object (21), and this system includes: have first lasing light emitter (13) of first light beam (13A) of first waveform (32) and first frequency for generation；For producing second lasing light emitter (11) of second light beam (11A) with second frequency, described second light beam (11A) has the second waveform (36), wherein second frequency with the second speed warble decline time first frequency warble risings with first rate, first frequency second frequency of warbling with first rate when declining is warbled rising with the second speed；For the first light beam (13A) and the second light beam (11A) are combined into the optical element (15) combining beam path (17), the returning part in conjunction with beam path (17) is separated into the 3rd light beam (24) by described optical element (15)；And be used for receiving the single detector (23) of described 3rd light beam (24), the 3rd light beam (24) include two from measure apart from proportional different difference frequency.

Description

Compact optical fiber structure for anti-Continuous Wave with frequency modulation coherent laser radar of warbling

Background technology

The present invention generally relates to measure the optical pickocff of the distance of object (target).

It is known that light is transmitted by optical fiber, but due to the environment impact on optical fiber itself, essence Degree can be affected.These environmental effects can change the polarization of the optical path length in optical fiber and light, and Certainty of measurement can be had adverse effect on.Use optical heterodyne detection can allow quantum noise level Light radiation detects.Therefore, amplitude under Coherent Optical can improve environment light condition, precision, Reliability, sweep amplitude, the work depth of field and operation.Additionally, coherent system can obtain rapidly Enough characteristic informations about target location.

Optical heterodyne detection includes target goal and from the source beam of target reflection.Then, the light beam of return Mix to provide interference of light striped on photoelectric detector with local oscillator beam, this light can be processed Interference fringe is to provide the details about target.Light heterodyne technology can utilize source beam and reflection The interaction of light beam.Such as, these light beams can substantially have phase co-wavelength and be directed at same On one optical axis.In this case, the highest due to signal to noise ratio (SNR), it is possible to use little Receiving aperture, such as, can insert the least lens of limited entrance area.Due to little receiver hole Footpath can provide the details about target, so the optical module of coherent system can be made to non- The least.

Accurate FM laser radar can load a linear frequency modulation (chirp warbles) lasing light emitter and tool There is the polarization maintaining optical fibre structure of separate local oscillator (LO) path and signal path.Need one Anti-configuration of warbling, due to accurate doppler correction, the impact of its most vibrated caused range error. Also need to be that LO path and signal path are incorporated in an optical fiber by two laser instrument, so that optical fiber Optical circuit becomes less complicated and cheap due to less element, and by due to environment because of The impact of the error caused by change of element local oscillator caused by such as variations in temperature and signal path lengths. Such as, the manufacturing industry of the environmental condition that there is background vibration and change can be the candidate of this laser structure User.The combination of LO path and signal path can provide extra benefit, that is, due to unit Sensor head can be arbitrarily away from other parts of unit, therefore it can be placed on capacity constraint Region.

In a word, need one to measure the most accurately and fast, small space can be entered, flexibly and Practical optics precision measurement system reliably.

Summary of the invention

The demand and other further needs and advantage are solved by below example.

The present embodiment relates to a kind of optical distance measurement apparatus, and it can include but not limited to: for generation the First lasing light emitter of one light beam, for producing the second lasing light emitter of the second light beam, wherein, the first light beam With the phase contrast of the waveform phase mutual 180 degree of the second light beam so that the first light when the second light beam is warbled downward Bundle is warbled upwards, and vice versa；First optical element, it is for by the first light beam and the second light Binding is combined into and combines light beam, and any returning part combining light beam is separated into the 3rd light beam；With In the first detector receiving the 3rd light beam.In another embodiment, one is devised for determining The method of distant objects distance, comprising: produce the first light beam from the first lasing light emitter and swash from second Light source produces the second light beam, wherein, the phase of the waveform phase mutual 180 degree of the first light beam and the second light beam Potential difference, so that first light beam is warbled upwards and vice versa when the second light beam is warbled downward, will be penetrated from source The light directing object gone out, receives reflection LO path and the signal path of target reflection for each source, for Detection LO path, each source and signal path, and it is poor to generate for each source, path to carry out heterodyne Frequently, the distance difference between this difference frequency and two paths is proportional, LO path and corresponding signal road Path length difference between footpath is equal to distance to be measured.

The method being used for determining the measurement distance between the output of measurement apparatus and object of the present embodiment Following steps can be included, but are not limited to: produce first light with first frequency from the first lasing light emitter Restrainting and produce second light beam with second frequency from the second lasing light emitter, second frequency is with the second speed When warbling downward, first frequency is warbled upwards with first rate, and first frequency is warbled downwards with first rate Time second frequency warble upwards with the second speed, in conjunction with the first light beam and the second light beam, thing is pointed in detection The combination beam path of body, receives the local oscillator (LO) of the reflection relevant with combining beam path Path light beam, receives the signal path light beam of the target reflection relevant with combining beam path, and will The signal path light beam of LO path light beam and target reflection carries out heterodyne to produce two and to measure distance Proportional different difference frequency, is detected two difference frequencies by single detector.

For determining that the system of the measurement distance between measurement apparatus and object includes but not limited to: be used for Produce first lasing light emitter of the first light beam with first waveform and first frequency, have for generation Second lasing light emitter of the second light beam of two frequencies, the second light beam has the second waveform, wherein second frequency With the second speed warble decline time first frequency warble rising with first rate, and first frequency is with the One speed warble decline time second frequency warble risings with the second speed, be used for the first light beam and second Light beam is combined into the optical element combining beam path, and this optical element will combine the return of beam path Being partially separated is the 3rd light beam, and for receiving the single detector of the 3rd light beam, the 3rd light beam Including from measure apart from two proportional different difference frequencies.

Specifically, the present invention is for accurately measuring the double chirped laser instrument of the duplex of absolute distance, It comprises launches first coherent light with the first tranmitting frequency by the first chirped modulation signal modulation First FM laser of bundle and transmitting have by the second transmitting of the second chirped modulation signal modulation Second FM laser of the second coherent beam of frequency.Second chirped modulation signal and first is warbled tune Signal processed has constant phase difference, preferably 180 degree phase contrasts.Additionally, the warbling of the second lasing light emitter Rate is different from the chirp rate of the first lasing light emitter obvious measurable to being enough to produce in a detector two Difference frequency.The present embodiment may further include the optical fiber coupling being connected with the first FM laser optics Device, wherein, the first coherent beam be divided into two be respectively designated as 50% part.It addition, optical fiber coupling Device and the second laser of frequency modulation source optics connect, and wherein the second coherent beam is divided into two and is respectively designated as 50% Part.

The linear beam outlet end protecting inclined fiber also has an interface, from the first coherent beam and the The sub-fraction transmission light of two coherent beams be reflected back whereby fiber coupler and transmit therefrom into Enter photoelectric detector, and, another part of transmission light is transferred to target and returns to interface from target； Fluorescence detector is connected with fiber coupler optics；Reflection at the transmission light from the first coherent beam Partly and set up the first interference, and therefore optics between the return of the first associated beam of target Detector detection, from the first the first difference frequency interfered and from the second the second difference frequency interfered, is coming From setting up between the reflecting part and the return of the second coherent beam of the transmission light of the second coherent beam Two interfere.Then, difference frequency signal is sent to being set to produce the first beat measurement value and the second difference frequency The digital signal processing device of measured value.In the present embodiment, the reference arm standard of calibration can be with light Fine coupler optical connects and can receive the part of two nominals 50% of the first coherent beam One of them, and also produce the first reference arm output；This reference arm also receives the second coherent beam The part of two nominals 50% one of them and produce the second output frequency further.Computer installation Can export in conjunction with the first beat measurement value and the first reference arm and produce the first absolute distance measurements, and And can be combined with the second beat measurement value and the second reference arm output generation the second absolute distance measurement Value.Computer installation can be combined with the first absolute distance measurements and the second absolute distance measurements produces Raw comprehensive absolute distance measurements, wherein the unreliability of comprehensive absolute distance measurements is substantially reduced.

Selectively, calibration reference arm standard is fibre optic interferometer.Optionally also, fiber optic interferometric Instrument can include the first fiber coupler, and it is connected with the second fiber coupler optics, the first optical fiber coupling Input light can be divided into two parts by clutch；There are two of the different optical path lengths calibrating path length difference Optical fiber, every optical fiber receives a part for the input light from the first fiber coupler；It is positioned at every light The bonder terminal of fine end, luminous reflectance back into optical fibers bonder whereby, from the two of the light of two optical fiber Part recombines whereby, thus sets up interference and thing followed difference frequency；The detector of detection difference frequency. Result is sent to be set to each laser instrument and produces the digital signal processing device of beat measurement value, often The reference arm that the described beat measurement value of individual laser instrument comprises for reference arm standard exports.

The present embodiment can be at unstable environment, the noncontact being such as present in aircraft and automobile factory essence Really range finding application uses, such as the measurement in upright arrangement when assembling parts.

In order to the present embodiment and other embodiments are better understood from, refer to accompanying drawing real with concrete Execute mode.

Accompanying drawing explanation

Fig. 1 is laser optical frequency and the schematic diagram of heterodyne radio frequency (RF) signal of coherent laser radar；

Fig. 2 is linear frequency modulation, " warbles " in other words, with the schematic diagram of corresponding " poor " frequency, " poor " Frequency is when occurring that relative target moves, and is the first lasing light emitter 13 and the second lasing light emitter 11 combines LO Signal and the result of target light signal；

Fig. 3 is the schematic diagram of the structure in anti-device of warbling with two lasing light emitters；

Fig. 4 is the schematic diagram of an alternative embodiment, and it can minimize back reflection (back And circuit can also be made to be easier at planar optical waveguide (Planar Lightwave reflections) Circuit) upper realization；

Fig. 5 A is the schematic diagram of another alternative embodiment, and it has 3 × 3 polarization-maintaining couplers, and this is real Execute example and can increase the spirit of system by reducing the noisiness of the light generation along output optical fibre backscattering Sensitivity；

Fig. 5 B is the schematic diagram of another alternative embodiment, and it has 2 × 2 polarization-maintaining couplers, and this is real Execute example and also can increase system by reducing the noisiness of the light generation along output optical fibre backscattering Sensitivity；

Fig. 6 is the schematic diagram of another alternative embodiment with multiple output beam；

Fig. 7 is the schematic diagram of a kind of structure, and it uses delay line various output signals to be multiplexed into One detector, therefore reduces cost and the complexity of radar；

Fig. 8 is the schematic diagram of an alternative embodiment of multiple beam concept structure.

Fig. 9 is the schematic diagram of another optional multi output embodiment；

Figure 10 be by from have optical fiber pigtail visible laser diode be optically coupled to output optical fibre Schematic diagram；And

Figure 11 is local oscillator path and the schematic diagram of signal path generation.

Detailed description of the invention

Describing before the present embodiment, it should be understood that the disclosure be not limited to described specific device, Method and assembly, because they can change.Only it will also be appreciated that term used herein For describing specific embodiment, and it is not limiting as the scope of the present disclosure.Appear below retouches structure State the purpose being merely to illustrate.Any meet the structure herein required and framework may be suitable for implementing The system and method for the present embodiment.

It will also be appreciated that unless clear stipulaties, that be used herein and in rights to independence Singulative " 1 ", " one " and " being somebody's turn to do " in profit requirement also include plural number.It is therefoie, for example, " one Individual isolating device " include multiple this isolating device, " lens combination " represents one or more lens And its equivalent known to those skilled in the art.Define unless otherwise other, make here All technology there is be generally understood that with those of ordinary skill in the art identical with scientific terminology Implication.

With reference to Fig. 1, using diode laser being concerned with or in FM laser radar as light source, The frequency of laser is directly regulated by the input current of regulation laser instrument.Generally, use has generation line Property modulation target waveform carry out modulating frequency.This modulation type is commonly called warble (chirp). Send to two laser instrument to regulate two chirped modulation input signals or the ripple of their output wavelength Shape differs.How each laser instrument regulates is unique, it is therefore necessary to produce one for each laser instrument Individual unique waveform.Shape and the amplitude of the waveform of each laser instrument are different.It is important to Generate the input current waveform of the linear chrip producing wavelength specific change during warbling.For this Planting in the conventional modulation format of application, the injection current modulated signal of each laser instrument has unique shape Shape and be deformed into sawtooth waveforms think laser instrument output produce linear saw tooth frequency modulation(PFM) envelope curve.Relevant The basis of FMCW reflexometer is two signal heterodynes from same linear chrip source to be mixed, one Individual signal is along local oscillator " LO " path, and another is returned from target reflection.Along test Any time between signal and the signal come with reference to reflection that path slave site reflects postpones The difference frequency in mixing output will be caused.The value of difference frequency is proportional to time delay, and signal at difference frequency Size proportional with corresponding reflection coefficient.Therefore, the spectrum analysis of this output discloses along survey The position of any pip (relative to reference path lengths) in examination path and intensity.

With reference now to Fig. 1, the first lasing light emitter 13 and the LO light of the second lasing light emitter 11 and flashlight, Frequency diagram is shown as waveform 32,34,36 and 38.For radar and target 21 (at this and object 21 Be used interchangeably) between there is no the situation of relative motion, there is not Doppler frequency shift, and mix Difference frequency produced by LO and flashlight is for each of the first lasing light emitter 13 and the second lasing light emitter 11 Raising and lowering be identical.For the first lasing light emitter 13, difference frequency is f133, swashs for second Light source 11, difference frequency is f235.For the first lasing light emitter 13 and the second lasing light emitter 11, modulation period 42Tmod is identical, and the first lasing light emitter 13 has the phase of 180 ° with the second lasing light emitter 11 Potential difference.The ascending curve of the first lasing light emitter 13 occurs in the decline curve process at the second lasing light emitter 11 In.The curve of both laser is same rated frequency, but the curve and second of the first lasing light emitter 13 The Δ f2 46 of lasing light emitter compares has higher value Δ f1 44.In this embodiment, f1 33 and f2 35 Ratio identical with the ratio of Δ f1 44 and Δ f2 46.By with different rate modulation the first laser Source 13 and the second lasing light emitter 11, it is possible to use a single detector 23 detects the letter of two mixing Number to reduce the quantity of required element.Two signals in different frequencies and can use digital signal Treatment technology measures each signal.

With reference now to Fig. 2, it is illustrated that linear frequency is modulated, and " warbles " in other words, and corresponding " poor " Frequently, " poor " frequency is to occur when relative target moves, and is the first lasing light emitter 13 and the second lasing light emitter 11 Produced by LO signal and target light signal.In exemplary plot 2, the fundamental frequency of laser is about 200 Terahertz, " poor " frequency is in the range of 1Mhz.If measured surface is moved relative to the first lasing light emitter 13 Dynamic, due to Doppler frequency shift, difference frequency corresponding with laser ascending curve will differ from and decline curve phase The difference frequency answered.The difference on the frequency measured between two signals can make the determination of speed be possibly realized.If In a modulation period, the distance of target and speed are constant, then f1up and f1down can To be expressed as:

f_1up=| f₁-f_d| (1)

f_1down=| f₁+f_d| (2)

Wherein, f1 is the frequency produced because of distance, and fd is the frequency because of Doppler frequency shift. If f1 is ＞ fd, then

$f_1=\frac{f_{1\mathrm{up}}+f_{1\mathrm{down}}}{2}---\left(3\right)$

$f_d=\frac{f_{1\mathrm{up}}-f_{1\mathrm{down}}}{2}---\left(4\right)$

Distance and speed can be expressed as

$f_1=\frac{f_{1\mathrm{up}}+f_{1\mathrm{down}}}{2}=\frac{2\mathrm{R\Δ}{f}_1}{c{T}_{\mathrm{mod}}}---\left(5\right)$

$f_d=\frac{f_{1\mathrm{up}}-f_{1\mathrm{down}}}{2}=\frac{2\mathrm{\ν}}{\mathrm{\λ}}---\left(6\right)$

Wherein, λ is optical wavelength, and ν is relative velocity.

Similarly,

$f_2=\frac{f_{2\mathrm{up}}+f_{2\mathrm{down}}}{2}=\frac{2\mathrm{R\Δ}{f}_2}{c{T}_{\mathrm{mod}}}---\left(7\right)$

$f_d=\frac{f_{2\mathrm{down}}-f_{2\mathrm{up}}}{2}=\frac{2v}{\mathrm{\λ}}---\left(8\right)$

With continued reference to Fig. 2, if measured surface is moved relative to lasing light emitter, due to Doppler frequency shift, Difference frequency corresponding with laser ascending curve will differ from difference frequency corresponding with decline curve.Measure these letters Difference on the frequency between number can make the determination of speed be possibly realized.Although rising or falling of single laser Warble and allow to detect respectively distance and the speed of target, but vibrate if there is any such as target Time there will be in warble velocity variations, range data may be affected.By using two anti-Zhou Sing laser, the range error that these speed cause can be compensated.It is then possible to process the signal produced With the immunity that offer is bigger to velocity error.As shown in equation below (9), can pass through The corresponding decline with another laser that rise only using a laser makes the amplitude of correction by how general Strangle and compensate rather than as aforesaid equation (5) and (7) uses the rising from a laser to warble The amplitude of doppler correction is determined with declining to warble.

$f_1=\frac{f_{1\mathrm{up}}+\frac{\mathrm{\Δ}{f}_1}{\mathrm{\Δ}{f}_2}{f}_{2\mathrm{down}}}{2}=\frac{f_{1\mathrm{down}}+\frac{\mathrm{\Δ}{f}_1}{\mathrm{\Δ}{f}_2}{f}_{2\mathrm{up}}}{2}---\left(9\right)$

The method not only considerably reduces Doppler error, but also effectively makes measuring rate add Times, the one-shot measurement time is reduced to from Tmod the half of Tmod.

If the precision that the fm linearity limiting distance on the counting interval is measured, then, if target One meter of distant place, the precision that the most millesimal linearity is provided that is 1mm.If can detect And compensate the real-time difference of the linearity, then the range measurement of a few micrometers precision can be realized.Due to FM laser radar can carry out computed range according to the difference frequency not relying on signal amplitude, so FM swashs Light can not be changed by ambient lighting conditions and surface reflectivity to be affected.This can make FM be concerned with System uses the return laser light energy of the least such as 1 micromicrowatt, or has the dynamic spirit of 9 exponent number magnitudes Sensitivity range is measured reliably.

The basis of relevant FMCW reflexometer is by two signal heterodynes from same linear chrip source Mixing, one of them signal is along local oscillator " LO " path, and another signal is from target Reflect.The signal reflected along test path slave site and come self-reference reflection signal it Between any time postpone can cause mixing output difference frequency.The value of difference frequency becomes ratio with time delay Example, the difference frequency size of signal is proportional with corresponding reflection coefficient.Therefore, the spectrum analysis of this output Disclose position and the intensity of any pip (relative to reference path lengths) along test path.

Referring now to Fig. 3, system 100 shows the structure in anti-configuration of warbling with two lasing light emitters The laser radar optical texture formed.In heterodyne mixing scheme, use two different tuning rates Regulation laser instrument is with the embodiment of the double coherent laser radar of warbling of structure, and it can be in planar optical waveguide (PLC) realize and the most protected from environmental on.In this embodiment, laser can be, but not limited to Protected (PM) optical fiber pigtail laser diode LD 1 13 and LD2 11 partially by two to produce.With one Speed carries out frequency modulation to the light from laser instrument LD1 13, and this speed is the tuning speed of LD2 11 Function.The light that each laser instrument sends is sharp to prevent back-reflections from upsetting by fiber optic isolator 12 The tuning characteristic of light device.Each laser instrument is combined in such as but not limited to 3 × 3PM bonder 15 The light sent, this bonder uses 5 in 6 available ports.Then, light can be along combination Light path light beam 17 (alternately using with optical fiber 17 here) is propagated and can be by being had geometry The interval 18 of motility is sent to measure position.At the end of optical fiber 17, light is from combining light path light beam 17 injections, leave optical fiber in output 19 and are partly reflected back in optical fiber at optical fiber connector.Each The reflected light path of laser radar becomes local oscillator (LO) path.Penetrate from optical fiber 17, by mesh Mark 21 reflection and return to the light of optical fiber 17 and define the signal path of laser radar.Selectively, Lens combination 27 can be used to focus light at measured zone interested so that returning the light of optical fiber 17 Total amount maximize.Lens combination 27 can e.g. fixed focal length system or can be according to required optics The system of depth of field focusing.Additionally, light is after lens combination 27 penetrates, can be by optional scanning mirror The different piece of (not shown) target goal 21 is to provide two dimension or three-dimensional measurement.Once from output 19 injections, the light from laser instrument LD1 13 and LD2 11 is linearly polarized in a direction.From After target 21 reflection, the light from each laser instrument comes back to carry the combination light of same polarization axis In the optical fiber of road light beam 17.Light in LO path and signal path passes back to light by bonder 15 Detector 23, in fluorescence detector, the light from two paths is mixed to form between two paths The proportional RF signal of range difference.RF signal can comprise can be with the tuning speed of each laser instrument Two relevant frequencies.Owing to LO path and signal path combine the light of light path light beam 17 in carrying Fibre and optical fiber 24 are propagated, it may be considered that occur at interface 20 interfering, which create LO signal, And therefore, the path length difference between LO path and its respective signal path equal to measure away from From.Accordingly, because the carrying that environmental effect such as variations in temperature is caused combines light path light beam 17 Optical fiber and carrying combine the optical path change in the optical fiber 24 of light path light beam will not be to measuring signal Produce impact.Therefore, combine the optical fiber of light path light beam 17 to the carrying of output 19 from bonder 15 Length can be arbitrary, measurement can't be made to deteriorate.This allows to include but not limited to output 19, the position of the sensor head of lens combination 27 and sweep mechanism is in the region of capacity constraint, And other parts of system 100, include but not limited to: other optics, electronic device and power supply, can To separate with sensor head.Additionally, all optical fibre structure can provide the content can resisted in air to draw The deviation risen or the robust unit of degeneration.

With continued reference to Fig. 3, in order to accurately measure, can include that reference standard 41/42 is for definitely Range accuracy also contributes to linearisation and the monitoring of laser chip waveform.Reference standard 41/42 can be adopted By the form of the fibre optic interferometer that such as Michelson (Michaelson) configures, but it is not limited to this. If the length of optical fiber is calibrated in reference arm, reference standard 41/42 can exhausted as system 100 Useful to the waveform linearisation of the first lasing light emitter 13 and the second lasing light emitter 11 to length standard and offer Signal.In a similar fashion, reference detector 29 can provide the linearisation to the two laser Useful signal.The purposes that the another kind of reference standard 41/42 is useful is detection particular moment laser Precision tuning, it may be used to determine doppler difference.Isolator 25 can be by flashlight electro-detection Optically isolated with from reference standard 41/42 of device 23.2 × 2 bonders 41 and the combination of optical fiber 42 Being Michelson reference arm, its operating is as follows: light enters 2 × 2 bonders 41 from isolator 25, and And separated between output optical fibre 42.Light once encounters the air/glass interface of optical fiber 42 end, Its part reflects in each optical fiber, is then return to 2 × 2 bonder 41 and reference detectors On 29.Length difference between the mixed signal and the tuning speed of each laser and the optical fiber 42 that produce Relevant.

Continue Primary Reference Fig. 3, for determining between the interface 20 of measurement apparatus 20A and object 21 The method of measurement distance can include but not limited to following steps: produce tool from the first lasing light emitter 13 There is the first light beam 13A of first frequency, and from the second lasing light emitter 11 generation, there is second frequency Second light beam 11A, when second frequency warbles decline with the second speed, first frequency is with first rate Zhou Sing rising, on when first frequency warbles decline with first rate, second frequency is warbled with the second speed Rise, in conjunction with the first light beam 13A and the second light beam 11A, will in conjunction with beam path 17 UDeflector 21, Receive the local oscillator relevant with combining beam path 17 (LO) the path light beam 461 of reflection (Figure 11) the signal path light beam 469 relevant with combining beam path 17 of target reflection, is received (Figure 11), and by LO path light beam 461 (Figure 11) and target echo path light beam 469 (Figure 11) heterodyne is carried out to generate two with measurement apart from proportional different difference frequency, by individually Detector 23 detects two difference frequencies.

Continue further Primary Reference Fig. 3, for determining between measurement apparatus 20A and object 21 The system 100 measuring distance can include but not limited to: has first waveform 32 and for generation First lasing light emitter 13 of the first light beam 13A of one frequency, has the second of second frequency for producing Second lasing light emitter 11 of light beam 11A, the second light beam 11A has the second waveform 36, wherein, second Frequency with the second speed warble decline time first frequency warble rising, and first frequency with first rate With first rate warble decline time second frequency warble rising with the second speed.System 100 can also be wrapped Include for the first light beam 13A and the second light beam 11A being combined into the optics unit combining beam path 17 Part 15.The returning part combining beam path 17 can be divided into the 3rd light beam 24 by optical element 15 (being used interchangeably with optical fiber 24 here), and individually detector 23, it includes two for reception Individual from the 3rd light beam 24 measured apart from proportional different difference frequency.

Referring now primarily to Fig. 4, system 150 shows an alternative embodiment.This configuration can be Littleization back reflection, and circuit can also be made to be prone on a planar lightwave circuit implement.Couple 3 × 2 Device 15 (Fig. 3) replaces with three 2 × 1 bonders 43,45 and 47, and by 2 × 2 bonders 41 (Fig. 3) replace with two 2 × 1 bonders 49 and 51.Note that the first lasing light emitter 13/ Isolator 12 between two laser sources 11 and 2 × 1 bonder 47 is not shown, but it is system 150 A part.

With reference now to Fig. 5 A and Figure 11, system 200 shows another alternative embodiment.This configuration Based on polarization duplexing schemes, it can be by reducing light along noise produced by output optical fibre back scattering Amount increases the sensitivity of system.In the structure shown here, combine in 3 × 3 polarization-maintaining couplers 15 from The light of each laser instrument.Then, light from uppermost spread fiber to polarization separator 57.Separator 63 make the light propagated from optical fiber 61 disappear.Then, the light from optical fiber 55 output leaves optical fiber 55 also Enter lens combination 27.In this embodiment, optical fiber connector is angled so that do not have light from interface 20 are reflected back in optical fiber 55.Light polarization can be converted to circularly polarized light by quarter wave plate 463 (Figure 11). Optical fiber connector can be angled so that does not has light to be reflected back optical fiber 55 from air/glass interface.Portion Divide reflector 465 (Figure 11) that fraction light can be reflected back to go forward side by side through quarter wave plate 463 (Figure 11) Enter the orthogonal polarization axes of output optical fibre 55.Using this light as local oscillator (LO).From lens System 27 sends, reflects from target 21 and passes through quarter wave plate 463 (Figure 11) and returns to the light of optical fiber 55 The signal path of laser radar can be defined.This light also is located in orthogonal polarization axes.LO and signal Light in path is passed back through polarization separator 57, and along the second optical fiber 62 by separator 63 Guide bonder 15, then arrive photodetector 23, in photodetector 23, the light in two paths The RF signal that the range difference that is mixed to form between two paths is proportional.RF signal packet containing two with The corresponding frequency of tuning speed of each laser instrument.In the structure shown here, the backscattered light in output optical fibre with LO light beam cross-polarization and its will not phase dry blending, therefore will not produce noise signal.

Referring now primarily to Fig. 5 B, system 450 shows another alternative embodiment.This configuration base In polarization duplexing schemes, it can be by reducing light along noise produced by output optical fibre backscattering Amount increases the sensitivity of system.In the structure shown here, the light from each laser instrument passes through isolator 12 And combine in 2 × 2 polarization-maintaining couplers 41.Then, light travels to polarization separator 57.From that In, output light propagates to optical fiber 17A and is then departed from optical fiber output 19.Optical fiber output end is angled To prevent in optical back scattering back into optical fibers 17A.Being all that guarantor is inclined due to all elements, optical fiber exports The just linear polarization of 19 injections.Then, light is through quarter wave plate 463 (Figure 11), and it can be by linear Polarized light is converted to circularly polarized light, such as right hand circular polarization.Part reflector 465 (Figure 11) is permissible It is reflected back fraction light through quarter wave plate 463 (Figure 11) the orthogonal polarization axes that enters output optical fibre 19. This light is used as local oscillator (LO).Through lens combination 27, penetrate from lens combination 27, The remainder of the light reflecting from target 21 and returning to optical fiber 17A through quarter wave plate 463 can be determined The signal path of justice laser radar.This light is also in orthogonal polarization axes.In LO and signal path Light pass and be directed to photodetector 23 back through polarization separator 57, at photodetector 23, The RF signal that range difference that the light in two paths is mixed to form between two paths is proportional.RF Signal will comprise two frequencies corresponding with the tuning speed of each laser instrument.In the structure shown here, output Backscattered light in optical fiber 19 and LO light beam cross-polarization and its will not phase dry blending, therefore Noise signal will not be produced.

Referring now primarily to Fig. 5 B and Fig. 3, an alternative of this structure is to use to have Fig. 3 The angled optical fiber/quarter wave plate/part reflector lens arrangement of optical fiber structure.This structure is possible to prevent The noise that causes due to back-scattering light and number of elements can be reduced.Part reflector can reflect Return fraction light pass through quarter wave plate 463 (Figure 11) and enter the orthogonal polarization axes of output optical fibre 17.Will This light is as local oscillator.Penetrate from lens combination 27, reflect from target 21 and by 1/4 Wave plate 463 (Figure 11) returns to the light of optical fiber 17 and defines the signal path of laser radar.This light It is also in orthogonal polarization axes.Laser is by PM optical fiber pigtail laser diode LD 1 13 and LD2 11 Produce.From the light of laser instrument LD1 13 to be different from the rate modulated frequency of the chirp rate of LD2 11. From the light of each laser instrument through optical fiber optically isolated 12 to prevent back-scattering light from upsetting laser instrument Tuning characteristic.The light from each laser instrument is combined in 3 × 3 polarization-maintaining couplers 15.Then light warp Cross optical fiber 17 to propagate and propagate to can having geometric flexibility measure place.At optical fiber 17 End, light penetrates from optical fiber, through quarter wave plate 463 (Figure 11) and be partially reflected device 465 (figure 11) partially reflective.Reflected light path footpath becomes local oscillator (LO) path of each laser radar. The light penetrating, reflect from target 21 and returning to optical fiber 17 from optical fiber 17 defines laser radar Signal path.Selectively, it is possible to use lens combination 27 focuses on light in measured zone interested To maximize the total amount of the light returning optical fiber 17.Such as, lens combination 27 can be fixed focal length system System or the system can focused according to the required optics depth of field.Further, optionally, light is from lens combination After 27 injections, the different piece of target 21 can be directed to provide two dimension by using scanning mirror Or three-dimensional measurement.

With reference now to Fig. 6, represent the application that can benefit from this technology with multiple output beam.System System 250 is another alternative embodiment based on main concept of the present invention.In system 250, two The output of laser instrument mixes in 2 × 2 bonders 65.The output 67 and 69 of bonder 65 is sent into There is provided in the bonder 71 and 73 of multiple output channel.In this embodiment, 1 × 3 coupling is used Device 71 and 73 is to provide five output beams 75,77,79,81 and 85 and reference arm 83.Often Individual output channel by direct the light to lens combination 75A, the 1 × 2 of 77A, 79A, 81A and 83A Bonder, the optical fiber/glass interface of generation LO and the detector group for two signal frequencies of detection Become.Also show the optical fiber 93 and 95 that by 2 × 2 bonders 91, there are two deflected lengths and The Michelson reference arm of reference detector 97 composition.Other reference arms, such as horse can also be used The reference arm of conspicuous Zeng Deer (Mach Zehnder) structure, but it is not limited to this.

With reference now to Fig. 7, system 300 shows a kind of structure, and it uses delay line by various outputs Signal is multiplexed into a detector, therefore decreases cost and the complexity of radar.In this enforcement In example, in 2 × 2 bonders 101, combine laser.The output 103 feed-in reference of bonder 101 Arm bonder 105.In this embodiment, reference arm is shown as such as but not limited to being Michelson structure. Output 107 is directed to 2 × 2 bonders 109, and it is presented further through 1 × 3 bonder 111 and 113 Enter multiple output optical fibre.In this embodiment, output 115 is for by the reflection of air/glass interface Produce LO.Output 117,119,121,123 and 125 be have different fiber retardation (D1, D2, D3, D4 and D5) optical fiber.The end of these optical fiber is angled, so other LO will not be produced. Owing to there is different delays, produced by the light of target reflection, signal returns difference at detector 23 Frequency.And owing to laser is modulated with different rates, so from the signal of laser instrument in frequency Also it is separate.

With reference now to Fig. 8, system 350 gives the alternative embodiment of multiple beam concept structure.System 350 can minimize back reflection and circuit can also be made to be easier to realize on a planar lightwave circuit.? In system 350, light combines in 2 × 1 bonders 201 and then separates in 2 × 1 bonders 203, Optical fiber 207 is connected to reference arm, and optical fiber 205 is connected to signal arm.Optical fiber 205 is guided separator 2x (n+1) 209, wherein n is the quantity of light beam.Optical fiber 211 carry LO path and optical fiber 213A, 213B ..., 213n carrying has the output beam of different fiber lengths, so that photoelectric detector 23 can carry all signals that can depend on different delay transits.

With reference now to Fig. 9, system 400 gives another optional multi output embodiment.In system In 400, two PM optical fiber pigtail laser diodes 401 and 403 produce laser.From indicating The light of laser instrument 401 for slow laser instrument aligns with the slow axis of PM optical fiber.From being marked as fast laser The light of the laser instrument 403 of device aligns with the fast axle of PM optical fiber.In system 400, from laser instrument The light of L1401 and L2403 is after respectively through isolator 405 and 407, by polarization separator 409 In conjunction with.Polarization separator 409 can be by the fast axle of the light in the slow axis of optical fiber 411 and optical fiber 413 The corresponding axle optically coupling to optical fiber 415 in.Light from laser instrument LD1 401 and LD2 403 By using 1 × 2 fiber coupler 421 to be segregated into optical fiber 417 and 419 to maintain them just Hand over polarization.Then, light is segregated into multiple output by 1 × 3 bonder 423 and 425.Each Output channel can include can directing the light to 1 × 2 bonder of lens combination 27, producing LO's Optical fiber/glass interface, two separate polarization separators of signal 427 that each laser instrument is produced and For detecting the detector 429 of signal frequency.The luminous reflectance being in slow axis from laser instrument L1401 Returning in slow axis, the luminous reflectance being in fast axle from laser instrument L2 403 returns in fast axle.These Reflected light path footpath becomes local oscillator (LO) path of each laser radar.Penetrate from optical fiber, From target reflection and return to the light of optical fiber and define the signal path of each laser radar.Once from output Optical fiber penetrates, and the light from laser instrument L1 401 is linearly polarized in a direction, from laser instrument The light of L2 403 is linearly polarized in the direction orthogonal with the light of laser instrument L1 401.Once from target Reflection, the light from each laser instrument re-enters and returns in optical fiber and be positioned at the axle that it is original.LO Propagate through 1 × 2 bonder 431 and polarization point with the light of the laser instrument L1 in signal path Arriving fluorescence detector 428 from device 427, here, the light in two paths is mixed to form and Liang Ge road The RF signal that range difference between footpath is proportional.Similarly, from LO and the laser of signal path The light of device L2 propagates to L2 detector 429.Owing to being in orthogonal all the time from the light of two laser instrument Polarization state, two laser radar signals that therefore they will not interfere and produce only occur in In the detector of each of which.Figure also show by 1 × 2 bonder 435, deflected length optical fiber 437, by two separate polarization separators of reference arm signal 439 and two reference detector compositions Mach zhender reference arm.The reference arm of Michelson structure can also be used.In this applications Normally used source laser device is the diode that output wavelength concentrates on about 1550nm (near-infrared) Laser instrument.Owing to this wavelength is sightless for human vision, therefore optical fiber circuit can increase Add the second, visible laser frequency, with by target provide position identical with infrared survey point Visible dots helps user.

With reference now to Figure 10, the light from optical fiber pigtail visible laser diode 451 can be by using Wavelength duplex bonder 455 is coupled into output optical fibre 453.Bonder 455 can be by from visible The visible ray of laser diode 451 and the IR light from polarization separator 457 are combined into exporting light Fine 453.

With reference now to Figure 11, the end of optical fiber output 19 is angled.This is air and optical fiber Interface between glass.If not angled, it will the reflection returned along optical fiber occurs.Fig. 5 A Middle LO path so produces.Light penetrates from optical fiber 19, through quarter wave plate 463 and wherein Some reflect from part reflector 465.A part for reflection light returns through quarter wave plate 463 again Enter optical fiber 19.This is LO path.Now, owing to twice through quarter wave plate 463, light is just in Hand over polarization.Quarter wave plate 463 have an angle to prevent spurious reflections to be again introduced into optical fiber.Selectively, The side 465A of part reflector 465 can also be angled maybe can to scribble anti-reflecting layer.

Therefore, foregoing is only for illustrating the principle of the present invention.Additionally, due to people in the art Member can easily make numerous modifications and variations, so the present invention should not necessarily be limited by shown and description The most structurally and operationally, therefore, all suitable amendments and equivalent all fall at the model in the present invention In enclosing.

Claims (17)

1. for the method determining the measurement distance between the output of measurement apparatus and object, including Following steps:

Produce from the first lasing light emitter and there is the first light beam of first frequency and produce from the second lasing light emitter There is the second light beam of second frequency；The modulation period of the first lasing light emitter and the second lasing light emitter is identical, and And first lasing light emitter and the second lasing light emitter there is the phase contrast of 180 °；

When second frequency is warbled downward with the second speed, first frequency is warbled upwards with first rate, described Second speed is different from first rate；

When first frequency is warbled downward with first rate, second frequency is warbled upwards with the second speed；First Speed and the second speed are different speed；

Optics polarization-maintaining coupler is used to combine the first light beam and the second light beam；

Will in conjunction with light path light beam along output optical fibre propagate, by the angled end of output optical fibre, 1/4 Wave plate and part reflector, UDeflector；Part reflector provides the local oscillator path light of reflection Bundle；

Receive the local oscillator path light beam of the reflection relevant with combining light path light beam；

Receive the signal path light beam of the target reflection relevant with combining light path light beam；Wherein, return to defeated After going out optical fiber, the signal path light beam of target reflection is in the local oscillator path light beam of reflection Carry in the output optical fibre of identical orthogonal polarization axes；And wherein back-scattering light in output optical fibre The polarized orthogonal of the local oscillator path light beam of polarization and reflection；

By optics polarization-maintaining coupler by the local oscillator path light beam of reflection and with combine light path light The signal path light beam of the target reflection of Shu Youguan is sent to single detector by the second optical fiber；

The signal path light beam of local oscillator path light beam and target reflection is carried out heterodyne to produce Two different difference frequencies proportional from the distance measured, are detected two difference frequencies by single detector.

Method the most according to claim 1, it is characterised in that by the guarantor as the first lasing light emitter Optical fiber pigtail laser diode partially produces the first light beam and by the polarization maintaining optical fibre tail as the second lasing light emitter Fine laser diode produces the second light beam.

Method the most according to claim 1, it is characterised in that also comprise the steps of and prevent The light of backscattering upsets the first light beam and the tuning characteristic of the second light beam.

Method the most according to claim 3, it is characterised in that described in prevent step from comprising following Step: be optically isolated and combine light path light beam.

Method the most according to claim 1, it is characterised in that also comprise the steps of and will tie Close light path light beam to focus on to the measured zone of object.

Method the most according to claim 5, it is characterised in that described focus steps comprises: from Selective focus device in fixed focal length system and adjustable focus system.

Method the most according to claim 1, it is characterised in that also comprise the steps of and pass through Reference standard is used to produce absolute distance measurement.

Method the most according to claim 7, it is characterised in that described reference standard is Michael The fibre optic interferometer of inferior configuration.

9. for determining a system for the measurement distance between measurement apparatus and object, including:

For producing the first lasing light emitter of first light beam with first waveform and first frequency；

For producing the second lasing light emitter of second light beam with second frequency, described second light beam has Second waveform, wherein second frequency with the second speed warble decline time first frequency warble with first rate Rise, first frequency with first rate warble decline time second frequency warble rising with the second speed, institute State first rate and the second speed is different speed；Wherein, the first lasing light emitter and the second lasing light emitter Modulation period is identical, and the first lasing light emitter and the second lasing light emitter have the phase contrast of 180 °；

For the first light beam and the second light beam being combined into the optics polarization-maintaining coupler combining light path light beam, Described optics polarization-maintaining coupler provides and combines light path light beam, and described combination light path light beam passes along output optical fibre Broadcast, arrive target, part by the angled end of output optical fibre to quarter wave plate and part reflector Reflector provides the local oscillator path light beam of reflection, and the signal path light beam of target reflection passes through 1/4 Wave plate and output optical fibre are propagated and are back to described optics polarization-maintaining coupler, and described optics polarization-maintaining coupler is by mesh The signal path light beam of mark reflection and the local oscillator path beam direction of reflection are the 3rd light beam；Its In, after returning to output optical fibre, the signal path light beam of target reflection and the local oscillator road of reflection Footpath light beam is in the output optical fibre carrying identical orthogonal polarization axes；And the wherein back of the body in output optical fibre Polarized orthogonal to the polarization of scattered light with the local oscillator path light beam of reflection；And

For receiving the single detector of described 3rd light beam, the 3rd light beam include two with measure away from From proportional different difference frequency；Wherein, described 3rd light beam passes through second from optics polarization-maintaining coupler Fiber-optic transfer is to single detector.

System the most according to claim 9, it is characterised in that for producing the first light beam First lasing light emitter and the second lasing light emitter being used for producing the second light beam are polarization maintaining fiber pigtail laser two pole Pipe.

11. systems according to claim 10, it is characterised in that also comprise: for isolation junction Close the optoisolator of light path light beam.

12. systems according to claim 9, it is characterised in that also comprise: will be in conjunction with light path The lens combination that light beam focuses on to the measured zone of object.

13. systems according to claim 12, it is characterised in that described lens combination comprise from The focusing arrangement selected in fixed focal length system and adjustable focus system.

14. systems according to claim 9, it is characterised in that also comprise: produce definitely away from From the reference standard measured.

15. systems according to claim 14, it is characterised in that described reference standard is mikey The fibre optic interferometer of Er Xun configuration.

16. systems according to claim 9, it is characterised in that described optics polarization-maintaining coupler It is to provide multiple bonders of multiple output beam.

17. systems according to claim 9, it is characterised in that described output optical fibre has light Fine delay.