CN104049251B - The multifrequency laser ranging system of anti-light aliasing and method - Google Patents
The multifrequency laser ranging system of anti-light aliasing and method Download PDFInfo
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
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Abstract
The multifrequency laser ranging system of anti-light aliasing and method belong to phase laser distance technology, and described range unit includes surveying chi and generates unit, laser shift frequency unit, beam-expanding collimation mirror group, optical path and circuit unit；Its distance-finding method comprises the following steps that step one, open frequency benchmark laser and He-Ne laser instrument；Step 2, a branch of as reference laser beam, another Shu Zuowei Laser Measurement；Step 3, withAs accurate measurement chi；Step 4, withAs bigness scale chi；Step 5, traverse measurement angle vertebra prism, to destination end, respectively obtain the phase contrast of accurate measurement chi and bigness scale chi<i>Φ</i>1With<i>Φ</i>2, obtain tested distance value finally by formula；The invention solves overlength wavelength and ultrashort wavelength can not synchronize produce, Laser Measuring chi is not directly traced to the source and the problem of non-linear cycle error and frequency alias, has that measurement efficiency is high, precision is high, stability and a real-time feature.
Description
Technical field
The invention belongs to phase place laser measuring technique, relate generally to a kind of phase laser distance apparatus and method.
Background technology
Large-scale metrology receives much concern in the large-scale optical, mechanical and electronic integration equipment processing and manufacturings such as development large-scale precision machine-building, great science and technology engineering, aerospace industry, shipping industry and microelectronics equipment industry, wherein several meters of large-scale metrologies to hundreds of rice scope are the large parts processing in aerospace vehicle and jumbo ship and the overall important foundation assembled, the quality of its measuring method and equipment performance directly affects workpiece quality and assembly precision, and then affects the running quality of complete equipment, performance and life-span.Chi phase ranging methods of surveying utilize one group of survey chi wavelength from big to small that tested distance is carried out refining accuracy measurement more, what solve between measurement scope and certainty of measurement is conflicting, can reach submillimeter to micron-sized static measurement precision in hundreds of meters overlength operating distance.
Survey in chi phase laser distance technology more, although the mode that many survey chis are measured step by step has taken into account the demand of measurement scope and certainty of measurement, but the restriction due to light source technology, bigness scale chi and accurate measurement chi can not produce line phase measurement of going forward side by side simultaneously, cause measurement overlong time, the problem of measurement result poor real, on the other hand owing to being sized to benchmark survey in chi phase laser distance technology more and measure surveying chi wavelength, the stability surveying chi wavelength directly affects the precision of laser ranging, therefore bigness scale chi and the accurate measurement chi wavelength of high stability how are obtained, and measure, so as to simultaneously participate in, the subject matter being to improve many survey chi phase laser distance precision at present with real-time.
The stability surveying chi is relevant with light source technology with synchronization generation technology, by analyzing it can be seen that the modulation means of phase difference method has electric current directly modulation, light modulation and intermode beats frequency modulation etc. both at home and abroad at present phase laser distance method LASER Light Source technology.
Direct current modulation method utilizes semiconductor laser, the feature of light intensity curent change, and the output intensity carrying out noise spectra of semiconductor lasers is modulated, and has the advantages such as simple easily modulation.Document [SiyuanLiu, JiubinTanandBinkeHou.MulticycleSynchronousDigitalPhaseMe asurementUsedtoFurtherImprovePhase-ShiftLaserRangeFindin g.Meas.Sci.Technol.2007, 18:1756 1762] and patent [the large range high precision fast laser ranging apparatus and method of multiple frequency synchronous modulation, publication number: CN1825138] all elaborate the current modulating method of a kind of based semiconductor laser instrument, it adopts the composite signal that multiple frequency synchronous synthesizes that laser output power is carried out synchronous modulation, achieve and obtain in multifrequency modulation range finding each modulation frequency for the measurement result of tested distance at synchronization, but in order to obtain linear modulation, operating point is made to be in the straight line portion of output characteristic curve, must while adding modulation signal code the suitable bias current that add to make it export signal undistorted, the introducing of direct current biasing increases power consumption, when working long hours, temperature raises, the stability of Output optical power can be affected, cause that modulation waveform deforms, and along with the increase of modulating frequency, modulation depth can reduce, cause that modulation waveform deforms, high frequency modulated can not be carried out, limit size and the degree of stability of accurate measurement chi wavelength；On the other hand in the actual application of large-scale metrology, laser easily causes the loss of laser power in long range propagation process, causing the impact on modulation waveform, and then accuracy and the degree of stability of chi is surveyed in impact, its frequency stability surveying chi is generally less than 10-7。
Light modulating method is utilized to be mainly acousto-optic modulation method and electro-optic modulation method, its modulation bandwidth is subject to the multifactorial impact of laser beam spot sizes etc., also bring along waveform distortions, particularly just even more serious when high frequency (Gigahertz), therefore it is formed big survey chi, and certainty of measurement is difficult to improve owing to being subject to the restriction of maximum modulation frequency.
Utilize the beat signal that the output of laser instrument different mode is formed as the method surveying chi, be called that intermode is modulated.The chamber appearance of the modulation bandwidth of the method and laser instrument is closed, He-Ne laser frequency stabilization technology is ripe, its frequency stability is high, the degree of stability surveying chi obtained by it is high, patent [high accuracy multiple frequency synchronous phase laser distance apparatus and method, publication number: CN102419166] and patent [the multiple frequency synchronous phase laser distance apparatus and method based on dual-acousto-optic shift, publication number: CN102305591A] all make use of the intermode of He-Ne laser instrument to modulate and in conjunction with acousto-optic frequency translation technology, obtain high-precision accurate measurement chi and bigness scale chi, but the produced chi of surveying of the method does not possess tractability, when it is measured, absolute measuring chi length needs another detection system to provide, add the complexity of measurement；On the other hand, this method utilizing heterodyne method to obtain accurate measurement chi phase place, its frequency processing signal is higher, can follow-up phase measurement difficulty and certainty of measurement be affected, it is assumed that phase-measurement accuracy is 0.05o, range measurement accuracy to reach 1um-10um, then signal frequency is at least 2GHz-20GHz, the remote bandwidth beyond signal processing circuit.
Patent [superheterodyne device and method of reseptance and receive device semiconductor integrated circuit, publication number: CN102484492A] all describe a kind of superhet interference signal treatment technology, Tsing-Hua University Zhang Cunman [Zhang Cunman etc., superhet interferes absolute distance measurement Review Study, optical technology 1998, (1): 7-9.] describe superhet absolute distance measurement method, this method reduce the process frequency of signal, it is easier to reach higher certainty of measurement.But this technology has three aspects needing to improve: first, and this technology can only obtain one and surveys chi, and do not possess tractability, it is impossible to carry out chi of surveying more and measure, let alone the synchronicity surveying chi more；Second, it is less that superhet obtains surveying chi wavelength, is typically in micron dimension, is only used for the measurement of the micro-shape in surface.3rd, owing to using multi-frequency measurement and traditional anti-aliasing optical path with polarization spectroscope, inevitably produce non-linear cycle error and frequency alias, the certainty of measurement of phase place is impacted.
Nowadays, the laser instrument of 633nm and 543nm wave-length coverage has been successfully applied in the magnitude tracing system of various precision measurement system and geometry parameter, and the one second Allan variance of sampling has reached 2 × 10-13Below, therefore to improve the stability of laser instrument output frequency, occur in that using the Output of laser frequency of iodine saturated absorption frequency stabilization laser instrument as the frequency-stabilizing method of frequency stabilization benchmark, utilize the saturated absorption spectra of iodine that He-Ne laser instrument and semiconductor laser are carried out rrequency-offset-lock control.China has been also carried out research, such as patent ZL200910072518.5 and patent ZL200910072519.X etc. all describe a kind of rrequency-offset-lock device utilizing iodine saturated absorption He-Ne frequency stabilized carbon dioxide laser, the laser output frequency after rrequency-offset-lock is made to have significantly high frequency stability, there is the advantage that output frequency can be traced to the source, but the output frequency of laser reaches 1014Hz, corresponding survey chi is between 400-700nm, and scope of measuring is in nm rank, it is impossible to find range for long distance laser, needs a kind of survey chi of laser ranging on a large scale high frequency stability laser frequency being converted to and can tracing to the source badly, and synchronizes them the technology of generation.
In sum, in laser ranging field, there are three problems needs to solve, and first, the synchronization of overlength wavelength and ultrashort wavelength produces, so as to take into account certainty of measurement and measurement scope, second, high accuracy can be traced to the source and be surveyed the generation of chi, to improve the accuracy surveying chi wavelength, and reduce the step that measurement wavelength needs other system to provide, and the 3rd, reduce non-linear cycle error and the frequency alias impact on certainty of measurement.The present invention is directed to these three problem to propose a solution.
Summary of the invention
The invention aims to solve in existing phase laser distance technology exist overlength wavelength and ultrashort wavelength can not synchronize produce, Laser Measuring chi is not directly traced to the source and the problem of non-linear cycle error and frequency alias, a kind of superhet and the anti-light aliasing laser ranging system of heterodyne convolution and method are provided, reach to increase range finding motility, simplify ranging step, improve the purpose measuring efficiency, precision and real-time.
The object of the present invention is achieved like this:
A kind of multifrequency laser ranging system of anti-light aliasing, it is characterized in that: described device is formed by surveying chi generation unit, laser shift frequency unit, anti-aliasing optical path and phase measurement cells, the laser that wherein survey chi generation unit sends exports the input of laser shift frequency unit, the output reference laser light beam of laser shift frequency unit and measuring laser beam export anti-aliasing optical path, the output signal I of anti-aliasing optical path3, I4, I5, I6It is separately input to phase measurement cells；
Described survey chi generates the structure of unit: the laser beam that frequency reference laser instrument is launched arrives the input of beam splitter, first outfan of beam splitter connects a He-Ne laser input, a number He-Ne laser output connects the input of a polarization spectroscope, one direct Output of laser of outfan of a number polarization spectroscope, another outfan connects a reflecting mirror, second outfan of described beam splitter connects No. two He-Ne laser input, and the outfan of No. two He-Ne laser instrument connects the input of a polaroid；
The structure of described laser shift frequency unit is: the input of a half-wave plate connects the outfan of a polarization spectroscope, the outfan of a number half-wave plate connects the input of No. two polarization spectroscopes, one outfan of No. two polarization spectroscopes connects the input of No. two reflecting mirrors, another outfan of No. two polarization spectroscopes connects an input of laser splicer, the outfan of No. two reflecting mirrors connects an input of a laser frequency shifter, the outfan of a number DDS signal source connects another input of a laser frequency shifter, the outfan of a number laser frequency shifter connects an input of laser splicer, spectroscopical input connects the outfan of a reflecting mirror, a spectroscopical outfan connects the input of No. three reflecting mirrors, another outfan spectroscopical connects an input of laser splicer, the outfan of No. three reflecting mirrors connects an input of No. two laser frequency shifters, another input of No. two laser frequency shifters connects the outfan of No. two DDS signal sources, the outfan of No. two laser frequency shifters connects an input of laser splicer, one input of laser splicer connects the outfan of a polaroid；
The structure of described anti-aliasing optical path is: No. two spectroscopes of reference laser light beam directive, laser beam a is formed through No. two dichroic mirror entering angle cone prisms, it is transmitted into reference prism through No. two spectroscopes and forms laser beam b, laser beam a is reflected back into No. two spectroscopes by prism of corner cube, laser beam c is formed then through No. two spectroscope transmissions, reflect to form laser beam d, laser beam b is reflected back into No. two spectroscopes by reference prism, laser beam e is formed then through No. two spectroscope transmissions, reflect to form laser beam f, No. two spectroscopes of described measuring laser beam directive, it is transmitted into measuring prism through No. two spectroscopes and forms laser beam g, it is reflected into prism of corner cube and forms laser beam h, laser beam g is reflected into No. two spectroscopes through measuring prism, laser beam j is formed then through No. two spectroscope transmissions, reflect to form laser beam i, laser beam h is reflected into No. two spectroscopes through prism of corner cube, laser beam l is formed then through No. two spectroscope transmissions, reflect to form laser beam k, described laser beam c overlaps with laser beam i, and the input of a photelectric receiver is entered through No. two polaroids, described laser beam d overlaps with laser beam j, and the input of No. two photelectric receivers is entered through No. three polaroids, described laser beam e overlaps with laser beam k, and the input of No. three photelectric receivers is entered through No. four polaroids, described laser beam f overlaps with laser beam l, and the input of No. four photelectric receivers is entered through No. five polaroids；
The structure of described phase measurement cells is: the outfan of a photelectric receiver and No. four photelectric receivers is connected with the input of a low pass filter and No. two low pass filters respectively, a number low pass filter and the outfan of No. two low pass filters are connected with the input of frequency mixer, the outfan of frequency mixer connects the input of phase measurement meter, No. two photelectric receivers and No. three photelectric receivers are connected with the input of No. three low pass filters and No. four low pass filters respectively, the outfan of No. three low pass filters and No. four low pass filters is connected with the input of phase measurement meter.
The multifrequency laser distance measurement method of a kind of anti-light aliasing specifically comprises the following steps that
Step one, open frequency benchmark laser, He-Ne laser instrument, No. two He-Ne laser instrument, after preheating and frequency stabilization, output frequency is locked within the certain frequency scope of frequency reference laser instrument by No. two He-Ne laser instrument and He-Ne laser instrument by feedback control, and the laser sent from a He-Ne laser instrument is divided into frequency to be v after polarization spectroscope2Horizontal polarization direction laser and frequency are v3Vertical polarization laser, the rrequency-offset-lock laser sent from No. two He-Ne laser instrument after polaroid only surplus frequency be v1Vertical polarization laser；
Step 2, the three beams of laser formed by step one enter laser shift frequency unit, and its medium frequency is v2Laser beam, after a half-wave plate and No. two polarization spectroscopes, separate the two mutually perpendicular laser in bundle polarization direction, wherein a road is through a laser frequency shifter, a DDS signal source drive this laser frequency shifter, and shift frequency frequency is f1, another road not shift frequency, frequency is v3Laser after spectroscope, be also classified into two-way, a road is through No. two laser frequency shifters, and shift frequency frequency is f2, frequency is v1Laser be directly entered laser splicer, the laser of last various frequencies has five kinds of frequencies, respectively v2、v3、v1、v2+f1And v3+f2, the part through laser splicer closes light, is v by frequency2+f1And v3+f2Laser synthesizing a branch of, formed reference laser light beam, frequency is v2、v3、v1Laser synthesizing measuring laser beam, and shine anti-aliasing optical path respectively；
Step 3, reference laser light beam are divided into laser beam a and laser beam b through No. two spectroscopes, measuring laser beam is divided into laser beam g and laser beam h through No. two spectroscopes, laser beam b and laser beam h is respectively after reference prism and prism of corner cube reflect, a bit joining on No. two spectroscope light splitting surfaces forms two beam interferometer light beams, and wherein a light beam is through polarization direction and v1No. four polaroids becoming 45 degree enter No. three photodetectors and carry out opto-electronic conversion, and again through obtaining comprising the signal of telecommunication of accurate measurement chi signal phase information after No. four low pass filters, its frequency is f1-f2, corresponding survey chi length is, another light beam is through polarization direction and v1After No. five identical polaroids, obtaining frequency is v1、v2The laser of horizontal polarization direction, enter back into No. four photodetectors and carry out opto-electronic conversion, the signal of telecommunication obtained frequency of its output signal of telecommunication after No. two low pass filters is v1-v2, corresponding survey chi length is；
When step 4, measurement start, reference prism maintains static, traverse measurement prism is to destination end, measurement distance is L, laser beam g is after measuring prism reflects, converge at No. two another some places spectroscopical with laser beam a and form interfering beams, form two beam interferometer laser then through spectroscope light splitting, wherein a branch of through polarization direction and v1No. three polaroids becoming 45 degree enter No. two photodetectors and carry out opto-electronic conversion, and again through obtaining comprising the signal of telecommunication of accurate measurement chi signal phase information after No. three low pass filters, its frequency is f1-f2, corresponding survey chi length is, another light beam is through polarization direction and v1After No. two identical polaroids, obtaining frequency is v1、v2The laser of horizontal polarization direction, enter back into a photelectric receiver and carry out opto-electronic conversion, the signal of telecommunication obtained frequency of its output signal of telecommunication after a low pass filter is v1-v2, corresponding survey chi length is；
Step 5, it is v by frequency1-v2Two signals access frequency mixers, reduce the frequency of two signals, be then fed into phase measurement meter, obtain the phase contrast Φ of two frequencies1, it is f by frequency1-f2The signal of telecommunication send into phase measurement meter carry out survey phase, obtain the phase contrast Φ of two signals2, according to formulaTry to achieve the distance measure L of bigness scale chic, and substituted into formula and try to achieve the phase integer value of accurate measurement chi；Floor (x) function returns the integer part of x value, tries to achieve tested distance value finally according to formula:, in formula: c is the light velocity, n is the air refraction of environment.
The feature of the present invention and providing the benefit that:
First, the present invention proposes, accurate measurement chi production method thick based on tracing to the source of He-Ne laser instrument and device, and these apparatus and method utilize frequency reference type frequency stabilized carbon dioxide laser, and frequency stability reaches 10-12Magnitude, two He-Ne laser instrument are carried out rrequency-offset-lock control, and utilize the He-Ne laser after frequency stabilization to form required thick of range finding, accurate measurement chi, chi wavelength is surveyed in the laser ranging making Output of laser frequency and formed can directly be traceable to frequency/wavelength benchmark, and lock point can be adjusted according to actual needs, and then be adjusted surveying chi wavelength, add the motility of range finding, overcome and existing range unit is surveyed the shortcoming that chi is not directly traced to the source, simplify general range unit and survey the link that chi wavelength needs another detection system to detect when absolute measuring is long, improve measurement efficiency and precision, this is one of present invention innovative point distinguishing existing apparatus.
Second, the present invention proposes a kind of many surveys chi Phase synchronization acquisition methods being combined based on heterodyne and device with superhet.These apparatus and method utilize laser frequency shifter that the laser of component frequency is carried out shift frequency, produce the laser of multi-frequency, and utilize heterodyne approach and superhet approach to obtain bigness scale chi and accurate measurement chi respectively simultaneously, and then so as to simultaneously participate in measurement, achieve the synchro measure of coarse-fine survey chi phase place, shorten the measurement time, improve the real-time of measurement result.The laser interferometry combined with superhet by heterodyne obtains test phase signal, eliminate common mode disturbances, improve the degree of stability surveying chi, reduce phase measuring circuit simultaneously and receive the frequency of signal, reducing the difficulty of circuit design, this is that the present invention distinguishes the two of the innovative point of existing apparatus.
3rd, the present invention proposes a kind of multi-frequency anti-aliasing interference technique and device.In these apparatus and method, reference light and measurement light reach anti-aliasing optical path through different paths, in interferoscope group in anti-aliasing optical path, reference light and measurement light perform twice at through different paths and interfere the measurement realized tested distance, owing to two light beams are without aliasing, eliminate due to optics or light source polarization direction undesirable and produce polarized light reveal and aliasing, thus avoiding non-linear cycle error and frequency alias error in principle.This is that the present invention distinguishes the three of the innovative point of existing apparatus.
Accompanying drawing explanation
Fig. 1 is the population structure schematic diagram of the laser ranging system of the present invention；
Fig. 2 surveys chi to generate the structural representation of unit；
Fig. 3 is the structural representation of laser shift frequency unit；
Fig. 4 is reference signal beam interference schematic diagram；
Fig. 5 interferes schematic diagram for measuring signal beams；
Fig. 6 is anti-aliasing optical path structural representation；
Fig. 7 is phase measurement cells structural representation
In figure, piece number illustrates: 1, survey chi and generate unit, 2, laser shift frequency unit, 3, anti-aliasing optical path, 4, phase measurement cells, 5, frequency reference laser instrument, 6, beam splitter, 7, a number He-Ne laser instrument, 8, a number polarization spectroscope, 9, a number reflecting mirror, 10, No. two He-Ne laser instrument, 11, a number polaroid, 12, a number half-wave plate, 13, No. two polarization spectroscopes, 14, No. two reflecting mirrors, 15, a number laser frequency shifter, 16, a number DDS signal source, 17, spectroscope, 18, No. three reflecting mirrors, 19, No. two laser frequency shifters, 20, No. two DDS signal sources, 21, laser splicer, 22, reference laser light beam, 23, measuring laser beam, 24, No. two spectroscopes, 25, prism of corner cube, 26, measuring prism, 27, reference prism, 28, a number photelectric receiver, 29, No. two polaroids, 30, No. three polaroids, 31, No. two photelectric receivers, 32, No. four polaroids, 33, No. three photelectric receivers, 34, No. five polaroids, 35, No. four photelectric receivers, 36, a number low pass filter, 37, No. two low pass filters, 38, No. three low pass filters, 39, No. four low pass filters, 40, frequency mixer, 41, phase measurement meter.
Detailed description of the invention
Below in conjunction with accompanying drawing, embodiment of the present invention is described in detail.
A kind of multifrequency laser ranging system of anti-light aliasing, it is characterized in that: described device is formed by surveying chi generation unit 1, laser shift frequency unit 2, anti-aliasing optical path 3 and phase measurement cells 4, the laser that wherein survey chi generation unit 1 sends exports the input of laser shift frequency unit 2, anti-aliasing optical path 3, the output signal I of anti-aliasing optical path 3 are arrived in the output reference laser light beam 22 of laser shift frequency unit 2 and measuring laser beam 23 output3, I4, I5, I6It is separately input to phase measurement cells 4；
Described survey chi generates the structure of unit 1: the laser beam that frequency reference laser instrument 5 is launched arrives the input of beam splitter 6, first outfan of beam splitter 6 connects He-Ne laser instrument 7 input, number He-Ne laser instrument 7 outfan connects the input of a polarization spectroscope 8, one direct Output of laser of outfan of a number polarization spectroscope 8, another outfan connects a reflecting mirror 9, second outfan of described beam splitter 6 connects No. two He-Ne laser instrument 10 inputs, and the outfan of No. two He-Ne laser instrument 10 connects the input of a polaroid 11；
The structure of described laser shift frequency unit 2 is: the input of a half-wave plate 12 connects the outfan of a polarization spectroscope 8, the outfan of a number half-wave plate 12 connects the input of No. two polarization spectroscopes 13, one outfan of No. two polarization spectroscopes 13 connects the input of No. two reflecting mirrors 14, another outfan of No. two polarization spectroscopes 13 connects an input of laser splicer 21, the outfan of No. two reflecting mirrors 14 connects an input of a laser frequency shifter 15, the outfan of a number DDS signal source 16 connects another input of a laser frequency shifter 15, the outfan of a number laser frequency shifter 15 connects an input of laser splicer 21, the input of spectroscope 17 connects the outfan of a reflecting mirror 9, one outfan of spectroscope 17 connects the input of No. three reflecting mirrors 18, another outfan of spectroscope 17 connects an input of laser splicer 21, the outfan of No. three reflecting mirrors 18 connects an input of No. two laser frequency shifters 19, another input of No. two laser frequency shifters 19 connects the outfan of No. two DDS signal sources 20, the outfan of No. two laser frequency shifters 19 connects an input of laser splicer 21, one input of laser splicer 21 connects the outfan of a polaroid 11；
The structure of described anti-aliasing optical path 3 is: No. two spectroscopes 24 of reference laser light beam 22 directive, it is reflected into prism of corner cube 25 through No. two spectroscopes 24 and forms laser beam a22-1, it is transmitted into reference prism 27 through No. two spectroscopes 24 and forms laser beam b22-2, laser beam a22-1 is reflected back into No. two spectroscopes 24 by prism of corner cube 25, laser beam c22-3 is formed then through No. two spectroscope 24 transmissions, reflect to form laser beam d22-4, laser beam b22-2 is reflected back into No. two spectroscopes 24 by reference prism 27, laser beam e22-5 is formed then through No. two spectroscope 24 transmissions, reflect to form laser beam f22-6, described No. two spectroscopes 24 of measuring laser beam 23 directive, it is transmitted into measuring prism 26 through No. two spectroscopes 24 and forms laser beam g23-1, it is reflected into prism of corner cube 25 and forms laser beam h23-2, laser beam g23-1 is reflected into No. two spectroscopes 24 through measuring prism 26, laser beam j23-4 is formed then through No. two spectroscope 24 transmissions, reflect to form laser beam i23-3, laser beam h23-2 is reflected into No. two spectroscopes 24 through prism of corner cube 25, laser beam l23-6 is formed then through No. two spectroscope 24 transmissions, reflect to form laser beam k23-5, described laser beam c22-3 overlaps with laser beam i23-3, and the input of a photelectric receiver 28 is entered through No. two polaroids 29, described laser beam d22-4 overlaps with laser beam j23-4, and the input of No. two photelectric receivers 31 is entered through No. three polaroids 30, described laser beam e22-5 overlaps with laser beam k23-5, and the input of No. three photelectric receivers 33 is entered through No. four polaroids 32, described laser beam f22-6 overlaps with laser beam l23-6, and the input of No. four photelectric receivers 35 is entered through No. five polaroids 34；
The structure of described phase measurement cells 4 is: a photelectric receiver 28 is connected with the input of a low pass filter 36 and No. two low pass filters 37 respectively with the outfan of No. four photelectric receivers 35, a number low pass filter 36 is connected with the input of frequency mixer 40 with the outfan of No. two low pass filters 37, the outfan of frequency mixer 40 connects the input of phase measurement meter 41, No. two photelectric receivers 31 are connected with the input of No. three low pass filters 38 and No. four low pass filters 39 respectively with No. three photelectric receivers 33, No. three low pass filters 38 are connected with the input of phase measurement meter 41 with the outfan of No. four low pass filters 39.
One, No. two laser frequency shifters 15,19 of described laser shift frequency unit 2 include acousto-optic frequency shifters, electro-optic frequency translation device, and travel frequency can regulate.
It is the rrequency-offset-lock laser instrument based on frequency reference laser instrument that described survey chi generates a He-Ne laser instrument 7 and No. two He-Ne laser instrument 10 in unit 1.
It is iodine stabilizd laser or femtosecond laser frequency comb laser instrument that described survey chi generates unit 1 medium frequency benchmark laser 5, and frequency stability is better than 10-12。
The multifrequency laser distance measurement method of a kind of anti-light aliasing specifically comprises the following steps that
Step one, open frequency benchmark laser 7, No. two He-Ne laser instrument 10 of 5, He-Ne laser instrument, after preheating and frequency stabilization, output frequency is locked within the certain frequency scope of frequency reference laser instrument 5 by No. two He-Ne laser instrument 10 and He-Ne laser instrument 7 by feedback control, and the laser sent from a He-Ne laser instrument 7 is divided into frequency to be v after polarization spectroscope2Horizontal polarization direction laser and frequency are v3Vertical polarization laser, the rrequency-offset-lock laser sent from No. two He-Ne laser instrument 10 after polaroid only surplus frequency be v1Vertical polarization laser；
Step 2, the three beams of laser formed by step one enter laser shift frequency unit 2, and its medium frequency is v2Laser beam, after a half-wave plate 12 and No. two polarization spectroscopes 13, separate the two mutually perpendicular laser in bundle polarization direction, wherein a road is through a laser frequency shifter 15, a DDS signal source drive this laser frequency shifter, and shift frequency frequency is f1, another road not shift frequency, frequency is v3Laser after spectroscope, be also classified into two-way, a road is through No. two laser frequency shifters 19, and shift frequency frequency is f2, frequency is v1Laser be directly entered laser splicer 21, the laser of last various frequencies has five kinds of frequencies, respectively v2、v3、v1、v2+f1And v3+f2, the part through laser splicer 21 closes light, is v by frequency2+f1And v3+f2Laser synthesizing a branch of, formed reference laser light beam 22, frequency is v2、v3、v1Laser synthesizing measuring laser beam 23, and shine anti-aliasing optical path respectively；
Step 3, reference laser light beam 22 are divided into laser beam a22-1 and laser beam b22-2 through No. two spectroscopes 24, measuring laser beam 23 is divided into laser beam g23-1 and laser beam h23-2 through No. two spectroscopes 24, laser beam b22-2 and laser beam h23-2 is respectively after reference prism 27 and prism of corner cube 25 reflect, a bit joining on No. two spectroscope 24 light splitting surfaces forms two beam interferometer light beams, and wherein a light beam is through polarization direction and v1No. four polaroids 32 becoming 45 degree enter No. three photodetectors 33 and carry out opto-electronic conversion, and again through obtaining comprising the signal of telecommunication of accurate measurement chi signal phase information after No. four low pass filters 39, its frequency is f1-f2, corresponding survey chi length is, another light beam is through polarization direction and v1After No. five identical polaroids (34), obtaining frequency is v1、v2The laser of horizontal polarization direction, enter back into No. four photodetectors (35) and carry out opto-electronic conversion, the signal of telecommunication obtained frequency of its output signal of telecommunication after No. two low pass filters is v1-v2, corresponding survey chi length is；
When step 4, measurement start, reference prism 27 maintains static, traverse measurement prism 26 to destination end, measurement distance is L, laser beam g23-1 is after measuring prism 26 reflects, converge at another some place of No. two spectroscopes 24 with laser beam a22-1 and form interfering beam, form two beam interferometer laser then through spectroscope light splitting, wherein a branch of through polarization direction and v1No. three polaroids 30 becoming 45 degree enter No. two photodetectors 31 and carry out opto-electronic conversion, and again through obtaining comprising the signal of telecommunication of accurate measurement chi signal phase information after No. three low pass filters 38, its frequency is f1-f2, corresponding survey chi length is, another light beam is through polarization direction and v1After No. two identical polaroids 29, obtaining frequency is v1、v2The laser of horizontal polarization direction, enter back into a photelectric receiver 28 and carry out opto-electronic conversion, the signal of telecommunication obtained frequency of its output signal of telecommunication after a low pass filter 26 is v1-v2, corresponding survey chi length is；
Step 5, it is v by frequency1-v2Two signals access frequency mixers 40, reduce the frequency of two signals, be then fed into phase measurement meter 41, obtain the phase contrast Φ of two frequencies1, it is f by frequency1-f2The signal of telecommunication send into phase measurement meter 41 carry out survey phase, obtain the phase contrast Φ of two signals2, according to formulaTry to achieve the distance measure L of bigness scale chic, and substituted into formula and try to achieve the phase integer value of accurate measurement chi；Floor (x) function returns the integer part of x value, tries to achieve tested distance value finally according to formula:, in formula: c is the light velocity, n is the air refraction of environment.
Described two path signal phase contrast Φ1With phase contrast Φ2Measurement carry out at synchronization.
Described laser frequency v1、v2、v3Can trace to the source to frequency reference laser instrument.
Claims (7)
1. the multifrequency laser ranging system of an anti-light aliasing, it is characterized in that: described device is formed by surveying chi generation unit (1), laser shift frequency unit (2), anti-aliasing optical path (3) and phase measurement cells (4), the laser that wherein survey chi generation unit (1) sends exports the input of laser shift frequency unit (2), anti-aliasing optical path (3), the output signal I of anti-aliasing optical path (3) are arrived in output reference laser light beam (22) of laser shift frequency unit (2) and measuring laser beam (23) output3, I4, I5, I6It is separately input to phase measurement cells (4)；
Described survey chi generates the structure of unit (1): the laser beam that frequency reference laser instrument (5) is launched arrives the input of beam splitter (6), first outfan of beam splitter (6) connects He-Ne laser instrument (7) input, number He-Ne laser instrument (7) outfan connects the input of a polarization spectroscope (8), one direct Output of laser of outfan of a number polarization spectroscope (8), another outfan connects a reflecting mirror (9), second outfan of described beam splitter (6) connects No. two He-Ne laser instrument (10) inputs, the outfan of No. two He-Ne laser instrument (10) connects the input of a polaroid (11)；
The structure of described laser shift frequency unit (2) is: the input of a half-wave plate (12) connects the outfan of a polarization spectroscope (8), the outfan of a number half-wave plate (12) connects the input of No. two polarization spectroscopes (13), one outfan of No. two polarization spectroscopes (13) connects the input of No. two reflecting mirrors (14), another outfan of No. two polarization spectroscopes (13) connects an input of laser splicer (21), the outfan of No. two reflecting mirrors (14) connects an input of a laser frequency shifter (15), the outfan of a number DDS signal source (16) connects another input of a laser frequency shifter (15), the outfan of a number laser frequency shifter (15) connects an input of laser splicer (21), the input of spectroscope (17) connects the outfan of a reflecting mirror (9), one outfan of spectroscope (17) connects the input of No. three reflecting mirrors (18), another outfan of spectroscope (17) connects an input of laser splicer (21), the outfan of No. three reflecting mirrors (18) connects an input of No. two laser frequency shifters (19), another input of No. two laser frequency shifters (19) connects the outfan of No. two DDS signal sources (20), the outfan of No. two laser frequency shifters (19) connects an input of laser splicer (21), one input of laser splicer (21) connects the outfan of a polaroid (11)；
The structure of described anti-aliasing optical path (3) is: No. two spectroscopes (24) of reference laser light beam (22) directive, it is reflected into prism of corner cube (25) through No. two spectroscopes (24) and forms laser beam a(22-1), it is transmitted into reference prism (27) through No. two spectroscopes (24) and forms laser beam b(22-2), laser beam a(22-1) reflected back into No. two spectroscopes (24) by prism of corner cube (25), laser beam c(22-3 is formed) then through No. two spectroscope (24) transmissions, reflect to form laser beam d(22-4), laser beam b(22-2) reflected back into No. two spectroscopes (24) by reference prism (27), laser beam e(22-5 is formed) then through No. two spectroscope (24) transmissions, reflect to form laser beam f(22-6), No. two spectroscopes (24) of described measuring laser beam (23) directive, it is transmitted into measuring prism (26) through No. two spectroscopes (24) and forms laser beam g(23-1), it is reflected into prism of corner cube (25) and forms laser beam h(23-2), laser beam g(23-1) it is reflected into No. two spectroscopes (24) through measuring prism (26), laser beam j(23-4 is formed) then through No. two spectroscope (24) transmissions, reflect to form laser beam i(23-3), laser beam h(23-2) it is reflected into No. two spectroscopes (24) through prism of corner cube (25), laser beam l(23-6 is formed) then through No. two spectroscope (24) transmissions, reflect to form laser beam k(23-5), described laser beam c(22-3) with laser beam i(23-3) overlap, and the input of a photelectric receiver (28) is entered through No. two polaroids (29), described laser beam d(22-4) with laser beam j(23-4) overlap, and the input of No. two photelectric receivers (31) is entered through No. three polaroids (30), described laser beam e(22-5) with laser beam k(23-5) overlap, and the input of No. three photelectric receivers (33) is entered through No. four polaroids (32), described laser beam f(22-6) with laser beam l(23-6) overlap, and the input of No. four photelectric receivers (35) is entered through No. five polaroids (34)；
The structure of described phase measurement cells (4) is: a photelectric receiver (28) is connected with the input of a low pass filter (36) and No. two low pass filters (37) respectively with the outfan of No. four photelectric receivers (35), a number low pass filter (36) is connected with the input of frequency mixer (40) with the outfan of No. two low pass filters (37), the outfan of frequency mixer (40) connects the input of phase measurement meter (41), No. two photelectric receivers (31) are connected with the input of No. three low pass filters (38) and No. four low pass filters (39) respectively with No. three photelectric receivers (33), No. three low pass filters (38) are connected with the input of phase measurement meter (41) with the outfan of No. four low pass filters (39).
2. the multifrequency laser ranging system of anti-light aliasing according to claim 1, it is characterised in that: one, No. two laser frequency shifters (15,19) of described laser shift frequency unit (2) include acousto-optic frequency shifters, electro-optic frequency translation device, and travel frequency can regulate.
3. the multifrequency laser ranging system of anti-light aliasing according to claim 1, it is characterised in that: it is the rrequency-offset-lock laser instrument based on frequency reference laser instrument that described survey chi generates No. one, No. two He-Ne laser instrument (7) (10) in unit (1).
4. the multifrequency laser ranging system of anti-light aliasing according to claim 1, it is characterised in that: it is iodine stabilizd laser or femtosecond laser frequency comb laser instrument that described survey chi generates unit (1) medium frequency benchmark laser (5), and frequency stability is better than 10-12。
5. the distance-finding method of the multifrequency laser ranging system of an anti-light aliasing as claimed in claim 1, it is characterised in that: specifically comprise the following steps that
Step one, open frequency benchmark laser (5), He-Ne laser instrument (7), No. two He-Ne laser instrument (10), after preheating and frequency stabilization, output frequency is locked within the certain frequency scope of frequency reference laser instrument (5) by No. two He-Ne laser instrument (10) and He-Ne laser instrument (7) by feedback control, and the laser sent from a He-Ne laser instrument (7) is divided into frequency to be v after polarization spectroscope2Horizontal polarization direction laser and frequency are v3Vertical polarization laser, the rrequency-offset-lock laser sent from No. two He-Ne laser instrument (10) after polaroid only surplus frequency be v1Vertical polarization laser；
Step 2, the three beams of laser formed by step one enter laser shift frequency unit (2), and its medium frequency is v2Laser beam, the two mutually perpendicular laser in bundle polarization direction are separated after a half-wave plate (12) and No. two polarization spectroscopes (13), wherein a road is through a laser frequency shifter (15), a DDS signal source (16) drive this laser frequency shifter, and shift frequency frequency is f1, another road not shift frequency, frequency is v3Laser after spectroscope, be also classified into two-way, a road is through No. two laser frequency shifters (19), and shift frequency frequency is f2, frequency is v1Laser be directly entered laser splicer (21), the laser of last various frequencies has five kinds of frequencies, respectively v2、v3、v1、v2+f1And v3+f2, the part through laser splicer (21) closes light, is v by frequency2+f1And v3+f2Laser synthesizing a branch of, formed reference laser light beam (22), frequency is v2、v3、v1Laser synthesizing measuring laser beam (23), and shine anti-aliasing optical path respectively；
Step 3, reference laser light beam (22) are divided into laser beam a(22-1 through No. two spectroscopes (24)) and laser beam b(22-2), measuring laser beam (23) is divided into laser beam g(23-1 through No. two spectroscopes (24)) and laser beam h(23-2), laser beam b(22-2) and laser beam h(23-2) respectively after reference prism (27) and prism of corner cube (25) reflect, a bit joining on No. two spectroscope (24) light splitting surfaces forms two beam interferometer light beams, and wherein a light beam is through polarization direction and v1No. four polaroids (32) becoming 45 degree enter No. three photodetectors (33) and carry out opto-electronic conversion, and again through obtaining comprising the signal of telecommunication of accurate measurement chi signal phase information after No. four low pass filters (39), its frequency is f1-f2, corresponding survey chi length is, another light beam is through polarization direction and v1After No. five identical polaroids (34), obtaining frequency is v1、v2The laser of horizontal polarization direction, enter back into No. four photodetectors (35) and carry out opto-electronic conversion, the signal of telecommunication obtained frequency of its output signal of telecommunication after No. two low pass filters is v1-v2, corresponding survey chi length is；
When step 4, measurement start, reference prism (27) maintains static, traverse measurement prism (26) is to destination end, measurement distance is L, laser beam g(23-1) after measuring prism (26) reflects, with laser beam a(22-1) converge at another some place of No. two spectroscopes (24) and to form interfering beam, form two beam interferometer laser then through spectroscope light splitting, wherein a branch of through polarization direction and v1No. three polaroids (30) becoming 45 degree enter No. two photodetectors (31) and carry out opto-electronic conversion, and again through obtaining comprising the signal of telecommunication of accurate measurement chi signal phase information after No. three low pass filters (38), its frequency is f1-f2, corresponding survey chi length is, another light beam is through polarization direction and v1After No. two identical polaroids (29), obtaining frequency is v1、v2The laser of horizontal polarization direction, enter back into a photelectric receiver (28) and carry out opto-electronic conversion, the signal of telecommunication obtained frequency of its output signal of telecommunication after a low pass filter (26) is v1-v2, corresponding survey chi length is；
Step 5, it is v by frequency1-v2Two signals access frequency mixer (40), reduce the frequency of two signals, be then fed into phase measurement meter (41), obtain the phase contrast Φ of two frequencies1, it is f by frequency1-f2The signal of telecommunication send into phase measurement meter (41) carry out survey phase, obtain the phase contrast Φ of two signals2, according to formulaTry to achieve the distance measure L of bigness scale chic, and substituted into formula and try to achieve the phase integer value of accurate measurement chi；Floor (x) function returns the integer part of x value, tries to achieve tested distance value finally according to formula:, in formula: c is the light velocity, n is the air refraction of environment.
6. the distance-finding method of the multifrequency laser ranging system of anti-light aliasing according to claim 5, it is characterised in that: described two path signal phase contrast Φ1With phase contrast Φ2Measurement carry out at synchronization.
7. the distance-finding method of the multifrequency laser ranging system of anti-light aliasing according to claim 5, it is characterised in that: described laser frequency v1、v2、v3Can trace to the source to frequency reference laser instrument.
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