The two light source laser ranging systems of mixing and method based on the same pacing chi of can tracing to the sourceTechnical 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 the machine-building of development large-scale precision, great scientific and technological engineering, aerospace industry, shipping industry and microelectronics equipment industry, wherein several meters of large-scale metrologies to hundreds of rice scope are large parts processing and the whole important foundations of assembling in aerospace vehicle and jumbo ship, the quality of its measuring method and equipment performance directly affects workpiece quality and assembly precision, and then running quality, performance and the life-span of a whole set of equipment of impact.The chi phase ranging methods of surveying utilize one group of survey chi wavelength from big to small to the measurement of refining step by step of tested distance more, solve conflicting between measurement range and measuring accuracy, can in hundreds of meters of overlength operating distances, reach submillimeter to micron-sized static measurement precision.
, survey in chi phase laser distance technology more, although the mode that many survey chis are measured has step by step been taken into account the demand of measurement range and measuring accuracy, but the restriction due to light source technology, bigness scale chi and accurate measurement chi can not produce the line phase of going forward side by side simultaneously and measure, caused Measuring Time long, the problem that measurement result real-time is poor, on the other hand due to take in surveying chi phase laser distance technology survey chi wavelength size and measure as benchmark, the stability of surveying chi wavelength directly affects the precision of laser ranging, therefore how to obtain bigness scale chi and the accurate measurement chi wavelength of high stability, and make it to participate in measuring is to improve at present the subject matter of surveying chi phase laser distance precision and real-time more simultaneously.
The stability of surveying chi is relevant with light source technology with synchronous generating technique, and by known to the analysis of phase laser distance method LASER Light Source technology, the modulation means of phasic difference method has directly modulation of electric current, optical modulation and intermode beat frequency modulation system etc. both at home and abroad at present.
Direct current modulation method is utilized semiconductor laser, and the feature of light intensity curent change comes the output intensity of noise spectra of semiconductor lasers to modulate, and has the advantages such as the modulation of being simple and easy to.Document [Siyuan Liu, Jiubin Tan and Binke Hou. Multicycle Synchronous Digital Phase Measurement Used to Further Improve Phase-Shift Laser Range Finding. 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 set forth a kind of current modulating method of based semiconductor laser instrument, it adopts the synthetic composite signal of multiple frequency synchronous to carry out synchronous modulation to laser output power, realized at synchronization and obtained in multifrequency modulation range finding each modulation frequency for the measurement result of tested distance, but in order to obtain linear modulation, make the straight line portion of working point in output characteristic curve, must when adding modulation signal electric current, add a suitable bias current makes its output signal undistorted, the introducing of direct current biasing has strengthened power consumption, when working long hours, temperature raises, can affect the stability of Output optical power, cause modulation waveform distortion, and the increase along with modulating frequency, depth of modulation can reduce, cause modulation waveform distortion, can not carry out high frequency modulated, size and the degree of stability of accurate measurement chi wavelength have been limited, on the other hand in the actual application of large-scale metrology, laser easily causes the loss of laser power in long Distance Transmission process, cause the impact on modulation waveform, and then accuracy and the degree of stability of impact survey chi, its frequency stability of surveying chi is generally less than 10-7.
Utilize light modulating method to be mainly acoustooptic modulation method and electro-optic modulation method, its modulation band-width is subject to the multifactorial impact of laser beam diameter etc., also can bring waveform distortion, particularly just even more serious when high frequency (Gigahertz), therefore it forms large survey chi, and measuring accuracy is difficult to improve owing to being subject to the restriction of maximum modulation frequency.
Utilize laser instrument different mode to export formed beat signal as the method for surveying chi, be called intermode modulation.The chamber long correlation of the modulation band-width of the method and laser instrument, He-Ne laser frequency stabilization technology is ripe, its frequency stability is high, the degree of stability of the survey chi being obtained by it is high, patent [high precision multiple frequency synchronous phase laser distance apparatus and method, publication number: CN 102419166] and patent [the multiple frequency synchronous phase laser distance apparatus and method based on dual-acousto-optic shift, publication number: CN 102305591A] all utilized the intermode modulation of He-Ne laser instrument and in conjunction with acousto-optic frequency translation technology, high-precision accurate measurement chi and bigness scale chi have been obtained, but the survey chi that the method produces does not possess tractability, when it is measured, absolute measuring chi length needs another detection system to provide, increased the complicacy of measuring, on the other hand, this method of utilizing process of heterodyning to obtain accurate measurement chi phase place, the frequency of its processing signals is higher, can follow-up phase measurement difficulty and measuring accuracy be affected, and supposes that phase-measurement accuracy is 0.05o, range measurement accuracy will reach 1um-10um, and signal frequency is at least 2GHz-20GHz, far exceeds the bandwidth of signal processing circuit.
Patent [superheterodyne device and method of reseptance and receiving trap SIC (semiconductor integrated circuit), publication number: CN102484492A] all introduced a kind of superhet interference signal treatment technology, Zhang Cunman [the Zhang Cunman etc. of Tsing-Hua University, superhet is interfered absolute distance measurement Review Study, optical technology 1998, (1): 7-9.] introduced superhet absolute distance measurement method, the method has reduced the processing frequency of signal, more easily reaches higher measuring accuracy.But this technology is on the one hand, can only obtain one and survey chi, and not possess tractability, can not carry out the chis of surveying more and measure, let alone survey the synchronism of chi more; To obtain surveying chi wavelength less for superhet on the other hand, generally in micron dimension, and can only be for the measurement of the micro-shape in surface.
In order to improve the stability of laser instrument output frequency, occurred usining that the Output of laser frequency of iodine saturated absorption frequency stabilization laser instrument, as the frequency-stabilizing method of frequency stabilization benchmark, utilizes the saturated absorption spectra of iodine to carry out rrequency-offset-lock control to He-Ne laser instrument and semiconductor laser.China is also studied, such as patent ZL200910072518.5 and patent ZL200910072519.X etc., a kind of rrequency-offset-lock device that utilizes iodine saturated absorption He-Ne frequency stabilized laser has all been described, make the laser output frequency after rrequency-offset-lock there is very high frequency stability, have advantages of that output frequency can trace to the source, but the output frequency of laser reaches 1014hz, corresponding survey chi is between 400-700nm, and measurement range, in nm rank, can not be found range for long distance laser, needs badly a kind ofly high frequency stability laser frequency is converted to the laser ranging on a large scale that can trace to the source surveys chi, and synchronizes them the technology of generation.
In sum, in phase laser distance technology, lack a kind of can taking into account at present and survey the synchronisms of chi and the precision distance measurement apparatus and method of tractability more.
Summary of the invention
The object of the invention is in existing phase laser distance technology, to lack a kind of problems that can take into account many survey synchronisms of chi and the apparatus and method of traceability in order to solve, a kind of mixing based on the same pacing chi of can tracing to the source pair light source laser ranging systems and method are provided, reach the object of increase range finding dirigibility, simplification range finding step, raising measurement efficiency and precision and degree of stability, real-time.
The two light source laser ranging systems of a kind of mixing based on the same pacing chi of can tracing to the source, by surveying chi generation unit, laser shift frequency unit, beam-expanding collimation mirror group and optical path and circuit unit, form, the Laser output that survey chi generation unit sends is to the input end of laser shift frequency unit, output Yi road, laser shift frequency unit laser outputs to an input end of optical path and circuit unit by beam-expanding collimation mirror group, another road laser of laser shift frequency unit output is directly inputted to another input end of optical path and circuit unit;
The structure of described survey chi generation unit is: the laser beam of frequency reference laser instrument transmitting arrives the input end of optical splitter, the first output terminal of optical splitter connects No. two spectroscopical input ends, No. two spectroscopical output terminals connect the input end of a photodetector, the second output terminal of optical splitter connects No. two spectroscopical input ends, No. two spectroscopical output terminals connect the input end of No. two photodetectors, No. one photodetector is connected the input end of single-chip microcomputer with the output terminal of No. two photodetectors, long two input ends adjusting actuator of two output terminal connection chambers of single-chip microcomputer, long two output terminals adjusting actuator in chamber connect respectively the input end of semiconductor laser and two longitudinal mode He-Ne laser instruments, an output terminal of semiconductor laser connects No. three spectroscopical input ends, No. three spectroscopical output terminals connect the input end of a catoptron, the output terminal of a catoptron connects the input end of a polaroid, an output terminal of two longitudinal mode He-Ne laser instruments connects No. two spectroscopical input ends,
The structure of described laser shift frequency unit is: an output terminal surveying chi generation unit connects the input end of No. nine catoptrons, the output terminal of No. nine catoptrons connects No. three spectroscopical input ends, No. three spectroscopical output terminal connects No. four spectroscopical input ends, another output terminal of surveying chi generation unit connects the input end of a polarization spectroscope, an output terminal of a polarization spectroscope connects the input end of a half-wave plate, the output terminal of a half-wave plate connects the input end of No. two polarization spectroscopes, an output terminal of No. two polarization spectroscopes connects an input end of No. three polarization spectroscopes, another output terminal of No. two polarization spectroscopes connects the input end of No. four catoptrons, the output terminal of No. four catoptrons connects an input end of a laser frequency shifter, the output terminal of a DDS signal source connects another input end of a laser frequency shifter, the output terminal of a laser frequency shifter connects the input end of No. five catoptrons, the output terminal of No. five catoptrons connects another input end of No. three polarization spectroscopes, the output terminal of No. three polarization spectroscopes connects No. three spectroscopical another input ends, No. three spectroscopical output terminal connects input end of No. four spectroscopes, another output terminal of a polarization spectroscope connects the input end of No. six catoptrons, the output terminal of No. six catoptrons is through the input end of No. four polarization spectroscopes of No. two half-wave plate connections, an output terminal of No. four polarization spectroscopes connects an input end of No. five polarization spectroscopes, another output terminal of No. four polarization spectroscopes connects the input end of No. seven catoptrons, the output terminal of No. seven catoptrons connects an input end of No. two laser frequency shifters, the output terminal of No. two DDS signal sources connects another input end of No. two laser frequency shifters, the output terminal of No. two laser frequency shifters connects the input end of No. eight catoptrons, the output terminal of No. eight catoptrons connects another input end of No. five polarization spectroscopes, the output terminal of No. five polarization spectroscopes connects No. four spectroscopical another input ends,
The structure of described optical path and circuit unit is: an output terminal of laser shift frequency unit connects the input end of ten No. two catoptrons, the output terminal of ten No. two catoptrons connects the input end of No. five catoptrons, an output terminal of No. five catoptrons is communicated with the input end of No. three photodetectors by No. two polaroids, the output terminal of No. three photodetectors connects the input end of a low-pass filter, the output terminal of a low-pass filter connects an input end of a frequency mixer, an output terminal of No. three DDS signal sources connects another input end of a frequency mixer, the output terminal of a frequency mixer connects an input end of a phase detector, another output terminal of No. five catoptrons is communicated with the input end of No. four photodetectors by No. three polaroids, the output terminal of No. four photodetectors connects the input end of No. two low-pass filters, the output terminal of No. two low-pass filters connects an input end of No. two phase detectors, the output terminal of beam-expanding collimation mirror group connects an input end of No. six polarization spectroscopes, an output terminal of No. six polarization spectroscopes is communicated with the input end of No. ten catoptrons by a quarter-wave plate, the output terminal of No. ten catoptrons is communicated with an input end of No. six polarization spectroscopes by a quarter-wave plate, an output terminal of No. six polarization spectroscopes is communicated with the input end of ride on Bus No. 11 catoptron by No. two quarter-wave plates, the output terminal of ride on Bus No. 11 catoptron is communicated with another input end of No. six polarization spectroscopes by No. two quarter-wave plates, another output terminal of No. six polarization spectroscopes connects No. eight spectroscopical input ends, No. eight a spectroscopical output terminal is communicated with the input end of No. five photodetectors by No. four polaroids, the output terminal of No. five photodetectors connects the input end of No. three low-pass filters, the output terminal of No. three low-pass filters connects an input end of No. three frequency mixer, another output terminal of No. three DDS signal sources connects another input end of No. three frequency mixer, the output terminal of No. three frequency mixer connects another input end of a phase detector, No. eight spectroscopical another output terminal is communicated with the input end of No. six photodetectors by No. five polaroids, the output terminal of No. six photodetectors connects the input end of No. four low-pass filters, the output terminal of No. four low-pass filters connects another input end of No. two phase detectors.
The two light source laser distance measurement methods of mixing based on the same pacing chi of can tracing to the source, its concrete steps are as follows:
Step 1, open frequency benchmark laser, semiconductor laser, two longitudinal mode He-Ne laser instrument, after through preheating and frequency stabilization, pass through FEEDBACK CONTROL, within semiconductor laser and two longitudinal mode He-Ne laser instrument output frequencies are locked in to the certain frequency scope of frequency reference laser instrument, semiconductor laser output frequency, through a polaroid, is adjusted polarization angle and is made only to allow frequency bev1laser pass through, two longitudinal mode He-Ne laser instrument output frequencies are v2and v3double-frequency laser;
Step 2, by the laser of the formed three kinds of frequencies of step 1, enter laser shift frequency unit, wherein a branch of double-frequency laser separates frequency with a polarization spectroscope and isv2withv3two bundle laser, separate two bundle double-frequency lasers with No. two polarization spectroscopes and No. four polarization spectroscopes respectively again through after half-wave plate, and wherein a road is through laser frequency shifter, and by DDS signal source driving laser frequency shifter, frequency is respectivelyf1withf2, the laser of last various frequencies merges, and wherein has five kinds of frequencies, is respectivelyv1,v2,v3,v2+f1withv3+f2,, this Shu Jiguang incides Amici prism and is divided into two-beam, and a branch of conduct is with reference to laser beam, and another Shu Zuowei measures laser beam and shines measurement target;
Step 3, reference laser beam are divided into two bundle laser beam through Amici prism, beam of laser bundle through polarization direction withv1after No. two identical polaroids, frequency isv1,v2withv3the polarization laser of horizontal direction enter into No. three photodetectors and change, its output electrical signals, its frequency isv1-v2,using this as bigness scale chi, another beam of laser through polarization direction withv1after becoming No. three polaroids of 45 degree, incide photodetector No. four, the electric signal of No. four photodetector outputs through low-pass filter filtering high frequency electrical signal, retain low frequency electric signal, its frequency isf1-f2, using this as accurate measurement chi;
When step 4, measurement start, No. ten catoptrons of reference surface maintain static, mobile ride on Bus No. 11 catoptron 53 is to destination end, measuring distance is L, measuring beam is after measuring catoptron reflection, and the light beam reflecting with reference surface converges at No. six polarization spectroscope places, enters metering circuit, measure laser beam and be divided into two bundle laser beam through Amici prism, wherein beam of laser bundle through polarization direction withv1after No. four identical polaroids, frequency isv1,v2withv3the polarization laser of horizontal direction enter into No. six photodetectors and change, its output electrical signals, its frequency isv1-v2,using this as bigness scale chi, and survey chi length is, another beam of laser through polarization direction withv1after becoming No. five polaroids of 45 degree, incide photodetector No. five, the electric signal of No. five photodetector outputs through low-pass filter filtering high frequency electrical signal, retain low frequency electric signal, its frequency isf1-f2, using this as accurate measurement chi, survey chi length is;
Step 5, by a phase detector and No. two phase detectors, obtain respectively frequency and bev1-v2withf1-f2the phase differential of two path signalφ1withφ2, according to formulatry to achieve the distance measure of bigness scale chilc, and its substitution formula is tried to achieve to the phase place round values of accurate measurement chi; Whereinfloor(x) function returnsxthe integral part of value, finally according to formula, try to achieve tested distance value:, in formula: c is the light velocity, the air refraction that n is environment.
Feature of the present invention and beneficial effect are:
The first, the present invention proposes, accurate measurement chi production method thick based on tracing to the source of mixing laser and device, these apparatus and method are utilized frequency reference type frequency reference laser instrument, and frequency stability reaches 10-11to 10-12magnitude, a semiconductor laser and a He-Ne laser instrument are carried out to rrequency-offset-lock control, and utilize semiconductor laser after frequency stabilization and He-Ne laser to form required thick of range finding, accurate measurement chi, make Output of laser frequency and formed laser ranging survey chi wavelength and can directly be traceable to frequency/wavelength benchmark, and can adjust according to actual needs lock point, and then regulate surveying chi wavelength, increased the dirigibility of range finding, overcome and in existing distance measuring equipment, surveyed the shortcoming that chi is not directly traced to the source, simplify general distance measuring equipment and when absolute measuring is long, surveyed the link that chi wavelength needs another detection system to detect, improved measurement efficiency and precision, this is that the present invention distinguishes one of innovative point of existing apparatus.
The second, the present invention proposes a kind of many surveys chi phase-locking acquisition methods and device of being combined with superhet based on heterodyne.These apparatus and method utilize laser frequency shifter to carry out shift frequency to the laser of component frequency, produce the laser of multi-frequency, and utilize heterodyne approach and superhet method to obtain respectively bigness scale chi and accurate measurement chi simultaneously, and then make it to participate in to measure simultaneously, realized the synchro measure of thick accurate measurement chi phase place, shorten Measuring Time, improved the real-time of measurement result.The laser interferometry combining with superhet by heterodyne obtains test phase signal, eliminate common mode interference, improved the degree of stability of surveying chi, reduced the frequency of phase measuring circuit reception signal simultaneously, reduce the difficulty of circuit design, this is two of the present invention's innovative point of distinguishing existing apparatus.
The 3rd, the present invention adopts He-Ne laser instrument and semiconductor laser to form thick accurate measurement chi generation hybrid light source, ensureing the complexity of having simplified light source under the prerequisite that survey chi can be traced to the source, and can make full use of semiconductor laser light resource and He-Ne laser instrument advantage separately, first utilize the large feature of semiconductor Output of laser energy, can guarantee light echo energy, improve signal to noise ratio (S/N ratio), next utilizes He-Ne laser instrument frequency stabilization process feature simply rapidly, can quick adjustment Output of laser frequency, and then regulate surveying chi, this is three of the present invention's innovative point of distinguishing existing apparatus.
Accompanying drawing explanation
Fig. 1 is the general structure schematic diagram of laser ranging system of the present invention;
Fig. 2 is for surveying the structural representation of chi generation unit;
Fig. 3 is the structural representation of laser shift frequency unit;
Fig. 4 is the structural representation of optical path and circuit unit.
Piece number explanation in figure: 1, survey chi generation unit, 2, laser shift frequency unit, 3, beam-expanding collimation mirror group, 4, optical path and circuit unit, 5, frequency reference laser instrument, 6, optical splitter, 7, a spectroscope, 8, No. two spectroscopes, 9, a photodetector, 10, No. two photodetectors, 11, single-chip microcomputer, 12, the long actuator of adjusting in chamber, 13, semiconductor laser, 14, two longitudinal mode He-Ne laser instruments, 15, No. three spectroscopes, 16, a catoptron, 17, a polaroid, 18, a polarization spectroscope, 19, a half-wave plate, 20, No. two polarization spectroscopes, 21, No. four catoptrons, 22, a DDS signal source, 23, a laser frequency shifter, 24, No. five catoptrons, 25, No. three polarization spectroscopes, 26, No. three spectroscopes, 27, No. six catoptrons, 28, a half-wave plate, 29, No. four polarization spectroscopes, 30, No. seven catoptrons, 31, No. two DDS signal sources, 32, No. two laser frequency shifters, 33, No. eight catoptrons, 34, No. five polarization spectroscopes, 35, No. nine catoptrons, 36, No. four spectroscopes, 37, ten No. two catoptrons, 38, No. five catoptrons, 39, No. two polaroids, 40, No. three photodetectors, 41, a low-pass filter, 42, a frequency mixer, 43, No. three DDS signal sources, 44, a phase detector, 45, No. three polaroids, 46, No. four photodetectors, 47, No. two low-pass filters, 48, No. two phase detectors, 49, No. six polarization spectroscopes, 50, a quarter-wave plate, 51, No. ten catoptrons, 52, No. two quarter-wave plates, 53, ride on Bus No. 11 catoptron, 54, No. eight spectroscopes, 55, No. four polaroids, 56, No. five photodetectors, 57, No. three low-pass filters, 58, No. three frequency mixer, 59, No. five polaroids, 60, No. six photodetectors, 61, No. four low-pass filters.
Embodiment
Below in conjunction with accompanying drawing, embodiment of the present invention is described in detail.
The two light source laser ranging systems of a kind of mixing based on the same pacing chi of can tracing to the source, comprise beam-expanding collimation mirror group 3, described device is by surveying chi generation unit 1, laser shift frequency unit 2, beam-expanding collimation mirror group 3 and optical path and circuit unit 4 form, the Laser output that survey chi generation unit 1 sends is to the input end of laser shift frequency unit 2, laser shift frequency unit 2 output Yi road laser output to an input end of optical path and circuit unit 4 by beam-expanding collimation mirror group 3, another road laser of laser shift frequency unit 2 outputs is directly inputted to another input end of optical path and circuit unit 4,
The structure of described survey chi generation unit 1 is: the laser beam of frequency reference laser instrument 5 transmittings arrives the input end of optical splitter 6, the first output terminal of optical splitter 6 connects an input end of No. two spectroscopes 7, an output terminal of No. two spectroscopes 7 connects the input end of a photodetector 9, the second output terminal of optical splitter 6 connects an input end of No. two spectroscopes 8, the output terminal of No. two spectroscopes 8 connects the input end of No. two photodetectors 10, No. one photodetector 9 is connected the input end of single-chip microcomputer 11 with the output terminal of No. two photodetectors 10, long two input ends adjusting actuator 12 of two output terminal connection chambers of single-chip microcomputer 11, long two output terminals adjusting actuator 12 in chamber connect respectively the input end of semiconductor laser 13 and two longitudinal mode He-Ne laser instruments 14, an output terminal of semiconductor laser 13 connects an input end of No. three spectroscopes 15, an output terminal of No. three spectroscopes 15 connects the input end of a catoptron 16, the output terminal of a catoptron 16 connects the input end of a polaroid 17, an output terminal of two longitudinal mode He-Ne laser instruments 14 connects an input end of No. two spectroscopes 8,
The structure of described laser shift frequency unit 2 is: an output terminal surveying chi generation unit 1 connects the input end of No. nine catoptrons 35, the output terminal of No. nine catoptrons 35 connects an input end of No. three spectroscopes 26, the output terminal of No. three spectroscopes 26 connects an input end of No. four spectroscopes 36, another output terminal of surveying chi generation unit 1 connects the input end of a polarization spectroscope 18, an output terminal of a polarization spectroscope 18 connects the input end of a half-wave plate 19, the output terminal of a half-wave plate 19 connects the input end of No. two polarization spectroscopes 20, an output terminal of No. two polarization spectroscopes 20 connects an input end of No. three polarization spectroscopes 25, another output terminal of No. two polarization spectroscopes 20 connects the input end of No. four catoptrons 21, the output terminal of No. four catoptrons 21 connects an input end of a laser frequency shifter 23, the output terminal of a DDS signal source 22 connects another input end of a laser frequency shifter 23, the output terminal of a laser frequency shifter 23 connects the input end of No. five catoptrons 24, the output terminal of No. five catoptrons 24 connects another input end of No. three polarization spectroscopes 25, the output terminal of No. three polarization spectroscopes 26 connects another input end of No. three spectroscopes 26, the output terminal of No. three spectroscopes 26 connects 36 1 input ends of No. four spectroscopes, another output terminal of a polarization spectroscope 18 connects the input end of No. six catoptrons 27, the output terminal of No. six catoptrons 27 is through the input end of No. four polarization spectroscopes 29 of No. two half-wave plate 28 connections, an output terminal of No. four polarization spectroscopes 29 connects an input end of No. five polarization spectroscopes 34, another output terminal of No. four polarization spectroscopes 29 connects the input end of No. seven catoptrons 30, the output terminal of No. seven catoptrons 30 connects an input end of No. two laser frequency shifters 32, the output terminal of No. two DDS signal sources 31 connects another input end of No. two laser frequency shifters 32, the output terminal of No. two laser frequency shifters 32 connects the input end of No. eight catoptrons 33, the output terminal of No. eight catoptrons 33 connects another input end of No. five polarization spectroscopes 34, the output terminal of No. five polarization spectroscopes 34 connects another input end of No. four spectroscopes 36,
The structure of described optical path and circuit unit 4 is: an output terminal of laser shift frequency unit 2 connects the input end of ten No. two catoptrons 37, the output terminal of ten No. two catoptrons 37 connects the input end of No. five catoptrons 38, an output terminal of No. five catoptrons 38 is communicated with the input end of No. three photodetectors 40 by No. two polaroids 39, the output terminal of No. three photodetectors 40 connects the input end of a low-pass filter 41, the output terminal of a low-pass filter 41 connects an input end of a frequency mixer 42, an output terminal of No. three DDS signal sources 43 connects another input end of a frequency mixer 42, the output terminal of a frequency mixer 42 connects an input end of a phase detector 44, another output terminal of No. five catoptrons 38 is communicated with the input end of No. four photodetectors 46 by No. three polaroids 45, the output terminal of No. four photodetectors 46 connects the input end of No. two low-pass filters 47, the output terminal of No. two low-pass filters 47 connects an input end of No. two phase detectors 48, the output terminal of beam-expanding collimation mirror group 3 connects an input end of No. six polarization spectroscopes 49, an output terminal of No. six polarization spectroscopes 49 is communicated with the input end of No. ten catoptrons 51 by a quarter-wave plate 50, the output terminal of No. ten catoptrons 51 is communicated with an input end of No. six polarization spectroscopes 49 by a quarter-wave plate 50, an output terminal of No. six polarization spectroscopes 49 is communicated with the input end of ride on Bus No. 11 catoptron 53 by No. two quarter-wave plates 52, the output terminal of ride on Bus No. 11 catoptron 53 is communicated with another input end of No. six polarization spectroscopes 49 by No. two quarter-wave plates 52, another output terminal of No. six polarization spectroscopes 49 connects an input end of No. eight spectroscopes 54, an output terminal of No. eight spectroscopes 54 is communicated with the input end of No. five photodetectors 56 by No. four polaroids 55, the output terminal of No. five photodetectors 56 connects the input end of No. three low-pass filters 57, the output terminal of No. three low-pass filters 57 connects an input end of No. three frequency mixer 58, another output terminal of No. three DDS signal sources 43 connects another input end of No. three frequency mixer 58, the output terminal of No. three frequency mixer 58 connects another input end of a phase detector 44, another output terminal of No. eight spectroscopes 54 is communicated with the input end of No. six photodetectors 60 by No. five polaroids 59, the output terminal of No. six photodetectors 60 connects the input end of No. four low-pass filters 61, the output terminal of No. four low-pass filters 61 connects another input end of No. two phase detectors 48.
One, No. two laser frequency shifter 23,32 of described laser shift frequency unit 2 comprises acousto-optic frequency shifters, electro-optic frequency translation device, and laser frequency can regulate.
Described survey chi generation unit 1 medium frequency benchmark laser 5 comprises iodine stabilized laser, femtosecond laser frequency comb laser instrument, and frequency stability is better than 10-12.
The two light source laser distance measurement methods of mixing based on the same pacing chi of can tracing to the source, its concrete steps are as follows:
Step 1, open frequency benchmark laser 5, semiconductor laser 13, two longitudinal mode He-Ne laser instrument 14, after through preheating and frequency stabilization, pass through FEEDBACK CONTROL, within semiconductor laser 13 and two longitudinal mode He-Ne laser instrument 14 output frequencies are locked in to the certain frequency scope of frequency reference laser instrument 5, semiconductor laser 13 output frequencies, through a polaroid 17, are adjusted polarization angle and are made only to allow frequency bev1laser pass through, two longitudinal mode He-Ne laser instrument 14 output frequencies are v2and v3double-frequency laser;
Step 2, by the laser of the formed three kinds of frequencies of step 1, enter laser shift frequency unit 2, wherein a branch of double-frequency laser separates frequency with a polarization spectroscope 18 and isv2withv3two bundle laser, separate two bundle double-frequency lasers with No. two polarization spectroscopes 20 and No. four polarization spectroscopes 29 respectively again through after half-wave plate, and wherein a road is through laser frequency shifter, and by DDS signal source driving laser frequency shifter, frequency is respectivelyf1withf2, the laser of last various frequencies merges, and wherein has five kinds of frequencies, is respectivelyv1,v2,v3,v2+f1withv3+f2,, this Shu Jiguang incides Amici prism and is divided into two-beam, and a branch of conduct is with reference to laser beam, and another Shu Zuowei measures laser beam and shines measurement target;
Step 3, reference laser beam are divided into two bundle laser beam through Amici prism, beam of laser bundle through polarization direction withv1after No. two identical polaroids 39, frequency isv1,v2withv3the polarization laser of horizontal direction enter into No. three photodetectors 40 and change, its output electrical signals, its frequency isv1-v2,using this as bigness scale chi, another beam of laser through polarization direction withv1the electric signal that becomes to incide after No. three polaroids 45 of 45 degree 46 outputs of 46, No. four photodetectors of No. four photodetectors through low-pass filter filtering high frequency electrical signal, retain low frequency electric signal, its frequency isf1-f2, using this as accurate measurement chi;
When step 4, measurement start, No. ten catoptrons 51 of reference surface maintain static, mobile ride on Bus No. 11 catoptron 53 is to destination end, measuring distance is L, measuring beam is after measuring catoptron 53 reflections, and the light beam reflecting with reference surface converges at No. six polarization spectroscope 49 places, enters metering circuit, measure laser beam and be divided into two bundle laser beam through Amici prism, wherein beam of laser bundle through polarization direction withv1after No. four identical polaroids 55, frequency isv1,v2withv3the polarization laser of horizontal direction enter into No. six photodetectors 56 and change, its output electrical signals, its frequency isv1-v2,using this as bigness scale chi, and survey chi length is, another beam of laser through polarization direction withv1the electric signal that becomes to incide after No. five polaroids 59 of 45 degree 60 outputs of 60, No. five photodetectors of No. five photodetectors through low-pass filter filtering high frequency electrical signal, retain low frequency electric signal, its frequency isf1-f2, using this as accurate measurement chi, survey chi length is;
Step 5, by a phase detector 44 and No. two phase detectors 48, obtain respectively frequency and bev1-v2withf1-f2the phase differential of two path signalφ1withφ2, according to formulatry to achieve the distance measure of bigness scale chilc, and its substitution formula is tried to achieve to the phase place round values of accurate measurement chi; Whereinfloor(x) function returnsxthe integral part of value, finally according to formula, try to achieve tested distance value:, in formula: c is the light velocity, the air refraction that n is environment.
Described two path signal phase differentialφ1with phase differentialφ2measurement at synchronization, carry out.
Accurate measurement chi used and bigness scale chi all can be traced to the source.