CN104655025A - Laser interferometric wavelength lever-type absolute distance measurement method and device - Google Patents

Abstract

The invention discloses a laser interferometric wavelength lever-type absolute distance measurement method and device. The system comprises a light source system, a wavelength lever-type laser interference system and an interference signal processing and controlling system, wherein orthogonal-line polarized beams with the wavelengths of lambda 1 and lambda 2 are output by the light source system and emitted to the wavelength lever-type laser interference system to form interference beams which are emitted to the interference signal processing and controlling system; in the wavelength lever-type laser interference system, a wavelength lever-type absolute distance measurement relationship between measured absolute distance and motion displacement of a cube-corner prism of a reference arm is formed through corresponding relationship between synthetic wavelength and single wavelength; the interference signal processing and controlling system is used for detecting a phase difference of two single-wavelength interference signals, calculating the measured absolute distance and controlling change of the wavelength of lambda 2 in the light source system. Any absolute distance can be measured, transition from synthetic wavelength to single wavelength can be realized, and the method and the device are suitable for large-length or large-size and high-accuracy absolute distance measurement in the field of large precision assembly manufacture, spatial engineering, measurement technique and the like.

Description

Laser interference wavelength lever absolute distance measurement method and apparatus

Technical field

The present invention relates to and adopt measuring method and device, especially relate to a kind of laser interference wavelength lever absolute distance measurement method and apparatus.

Background technology

Along with the development of science and technology, the application of accurate measurement in high-end equipment manufacturing, space engineering and measurement technology etc. of large length, high-precision absolute distance is more and more extensive.As in the measurement of Aircraft Jig installation site in the measurement of the measurement of the measurement of heavy-duty machine frame, large-scale precision bed piece, steam turbine and hydraulic turbine main shaft measurement of length, power station turbine-generator units stators and rotators diameter, aerospace industry, satellite formation flying to the position of satellite with attitude is monitored and high-resolution ratio range finding etc., not being only required in range measurement accuracy in tens meters even scope of up to a hundred meters, can to reach micron dimension even lower, also need the efficiency of surveying instrument device high simultaneously, dirigibility is good, can adapt to none guidance measurement condition.

The method of absolute distance measurement is mainly divided into two large classes: flight time measurement method and interferometry.In flight time measurement method, laser pulse ranging is limited to the time resolution of picosecond, and range measurement accuracy is at grade; Although the optics balance cross-correlation method measuring accuracy overlapped based on femtosecond pulse can reach submicron order, measuring distance must be the integral multiple of femtosecond pulse spacing distance, can not realize the measurement of any absolute distance; The phase delay that phase-shift method comes and goes tested distance generation by the light wave measuring modulation records the flight time, the method Measurement Resolution depends on the phase resolution that maximum modulating frequency is corresponding, and measuring distance is limited to non-fuzzy distance corresponding to lowest modulation frequency.Laser interference absolute distance measurement method mainly comprises frequency scanning interference method, femtosecond pulse dispersion interferometric method and multi-wavelength interference method.For frequency sweep method, in frequency sweeping process, the change of tested distance or fluctuation can introduce larger error, and range measurement accuracy is 10 ^-6; Femtosecond pulse dispersion interferometric method is limited to the resolution of frequency spectrograph, and range measurement accuracy is 10 ^-5; Multi-wavelength interference utilizes some wavelength to form the composite wave long-chain that increases step by step of length, according to tested distance just measured value and fractional interference order corresponding to synthetic wavelength at different levels, from highest synthetic wavelength, solves tested distance step by step.When adopting multi-wavelength interference method, the measurement of fractional interference order time normally adopts claps ripple method, process of heterodyning and Super heterodyne etc. and records, and wherein clap ripple method light strong dc drift effect, range measurement accuracy is less than 10 ^-6, in the light channel structure of process of heterodyning and Super heterodyne, heterodyne light source affects by frequency modulation (PFM) device, synthetic wavelength less stable, and range measurement accuracy is difficult to improve.

Summary of the invention

The object of the present invention is to provide a kind of laser interference wavelength lever absolute distance measurement method and apparatus, one-to-one relationship between the synthetic wavelength utilizing two Single wavelength to be formed and Single wavelength, the moving displacement of prism of corner cube in tested absolute distance and reference arm is formed lever relation, obtained the absolute distance of tested large length by the motion bit in-migration detecting prism of corner cube in reference arm, measurement range of the present invention is large, measuring accuracy is high and can be traceable to meter Ding Yi.

The technical solution adopted for the present invention to solve the technical problems is:

One, a laser interference wavelength lever absolute distance measurement method, the step of the method is as follows:

1) the first laser instrument exports fixing wavelength X ₁, control second laser and export variable wavelength X ₂, make wavelength X ₁and wavelength X ₂the chopped-off head synthetic wavelength λ formed _s1half to be greater than tested absolute distance L, L be distance between the second prism of corner cube and pyrometric cone prism;

2) the first shutter open, the second shutter close, the proximal measurement light beam now returned from the second prism of corner cube and reference beam form interference signal, and mobile first prism of corner cube, makes the wavelength X that the first photodetector and the second detector detect ₂and wavelength X ₁interference signal phase differential be

3) the first shutter close, the second shutter are opened, and the far-end measuring light beam now returned from pyrometric cone prism and reference beam form interference signal, the two-way interference signal phase differential that the first photodetector and the second detector receive change, mobile first prism of corner cube makes the phase differential of two-way interference signal again equal 0, the moving displacement recording the first prism of corner cube is Δ l;

4) chopped-off head synthetic wavelength λ _s1, wavelength X ₁, tested absolute distance L and the first prism of corner cube moving displacement Δ l there is following wavelength lever relationshhip:

$\frac{L}{{\mathrm{\λ}}_{S1}}=\frac{\mathrm{\Δl}}{{\mathrm{\λ}}_1},$

Wherein λ _s1=λ ₁λ ₂/ | λ ₁-λ ₂| be wavelength X ₁and wavelength X ₂the chopped-off head synthetic wavelength formed, λ ₁and λ ₂for the optical maser wavelength in air, according to above-mentioned wavelength lever relationshhip, calculated the bigness scale value first of tested absolute distance by computing machine:

$L_1=\frac{{\mathrm{\λ}}_{S1}}{{\mathrm{\λ}}_1}\·\mathrm{\Δl};$

5) computing machine changes the wavelength X of second laser output by controller ₂, make wavelength X ₁and wavelength X ₂form a series of synthetic wavelength λ _s2> λ _s3> ... > λ _sn, and every grade of synthetic wavelength λ _si> 4u (L ' _i-1), i=2,3 ..., n, wherein u (L ' _i-1) be when synthetic wavelength is λ _si-1time tested distance estimated value L ' _i-1uncertainty of measurement, the L ' as i=2 _i-1=L ₁, repeat step 2), step 3), record is each changes second laser wavelength X ₂time the first prism of corner cube moving displacement be Δ l _i, according to step 4) and medium wavelength lever relationshhip, calculate corresponding synthetic wavelength λ by computing machine _sithe bigness scale value of the tested absolute distance of fraction part:

$L_i=\frac{{\mathrm{\λ}}_{\mathrm{Si}}}{{\mathrm{\λ}}_1}\·\mathrm{\Δ}{l}_i;$

Computing machine calculates the synthetic wavelength λ comprised in tested absolute distance L according to following formula _sifractional interference order sub-value:

${\mathrm{\ϵ}}_{\mathrm{Si}}=\frac{2L_i}{{\mathrm{\λ}}_{\mathrm{Si}}},$

Computing machine calculates the synthetic wavelength λ comprised in tested absolute distance L according to following formula _siinteger order of interference sub-value:

$M_{\mathrm{Si}}=\mathrm{int}[\frac{2L_{i-1}^{\′}}{{\mathrm{\λ}}_{\mathrm{Si}}}+0.5-{\mathrm{\ϵ}}_{\mathrm{Si}}],$

Wherein int [] expression rounds downwards;

Computing machine calculates each estimated value of tested absolute distance L according to following formula:

$L_i^{\′}=(M_{\mathrm{Si}}+{\mathrm{\ϵ}}_{\mathrm{Si}})\·\frac{{\mathrm{\λ}}_{\mathrm{Si}}}{2};$

When 4u (L ' _n) < λ ₁time, computing machine calculates tested absolute distance according to following formula:

$L=(M_n+{\mathrm{\&epsiv;}}_n)\&CenterDot;\frac{{\mathrm{\&lambda;}}_1}{2},$

Wherein: ${\mathrm{\&epsiv;}}_n=\frac{2\mathrm{\&Delta;}{l}_i}{{\mathrm{\&lambda;}}_1},M_n=\mathrm{int}[\frac{2L_n^{\&prime;}}{{\mathrm{\&lambda;}}_1}+0.5-{\mathrm{\&epsiv;}}_n];$

Terminate to measure.

Two, a kind of laser interference wavelength lever absolute distance measurement device

The present invention includes light-source system, wavelength lever laser interference system and interference signal process and control system; Light-source system output wavelength is respectively λ ₁and λ ₂orhtogonal linear polarizaiton light beam, after spectroscope in directive wavelength lever laser interference system, spectroscopical near-end in wavelength lever laser interference system or the measuring beam of far-end are after dichroic mirror, with the polarization spectroscope in the interfering beam directive interference signal process formed through spectroscopical reference beam and control system, the laser output wavelength that the controller in interference signal process and control system controls in light-source system is λ ₂linearly polarized light.

Described light-source system, comprises the first laser instrument, second laser, the first collimator and extender device, the second collimator and extender device, the first catoptron and the first polarization spectroscope; First laser instrument exports fixing wavelength X ₁and polarization direction is parallel to the linearly polarized light of paper, directive first polarization spectroscope after the first collimator and extender device, second laser exports variable wavelength X ₂and polarization direction is perpendicular to the linearly polarized light of paper, directive first catoptron after the second collimator and extender device, directive first polarization spectroscope after the first catoptron reflection; Wavelength is λ ₁linearly polarized light through after the first polarization spectroscope and wavelength be λ ₂linearly polarized light through first polarization spectroscope reflection after, synthesize a branch of orthogonal linearly polarized light beam.

Described wavelength lever laser interference system, comprises the first spectroscope, the second polarization spectroscope, the first prism of corner cube, the second spectroscope, the first shutter, the second shutter, the second catoptron, the 3rd catoptron, the 3rd spectroscope, the second prism of corner cube and pyrometric cone prism; Be divided into the reference beam of reflection and the measuring beam of transmission after orthogonal linearly polarized light beam directive first spectroscope, reference beam directive second polarization spectroscope, its medium wavelength is λ ₂linearly polarized light by second polarization spectroscope reflection after directive first spectroscope, wavelength is λ ₁linearly polarized light return after being reflected through the second polarization spectroscope, directive first prism of corner cube, again through directive first spectroscope after the second polarization spectroscope, the proximal measurement light beam of reflection and the far-end measuring light beam of transmission is divided into after measuring beam directive second spectroscope, proximal measurement light beam is directive first spectroscope after the first shutter, the second catoptron, the second prism of corner cube and the 3rd spectroscope successively, and far-end measuring light beam is directive first spectroscope after the second shutter, pyrometric cone prism, the 3rd catoptron and the 3rd spectroscope successively; The measuring beam of directive first spectroscope near-end or far-end, after the first dichroic mirror, forms interfering beam with through first spectroscopical reference beam.

Described interference signal process and control system, comprise the 3rd polarization spectroscope, the first photodetector, the second photodetector, data acquisition module, computing machine and controller; Interfering beam directive the 3rd polarization spectroscope that reference beam is formed, wherein its medium wavelength is λ ₂interfering beam by the 3rd polarization spectroscope reflection after, by the first photoelectric detector, wavelength is λ ₁interfering beam through after the 3rd polarization spectroscope, by the second photoelectric detector, the interference signal that two photodetectors export delivers to data acquisition module respectively, after data acquisition module process, be transferred to computing machine, computing machine changes the wavelength X of second laser output by controller according to result of calculation ₂value.

In described light-source system, the laser wavelength lambda that the first laser instrument exports ₁fixed value, the wavelength X that second laser exports ₂variable.

In described wavelength lever laser interference system, form reference arm by the second polarization spectroscope and the first prism of corner cube; Gage beam is formed by the second spectroscope, the first shutter, the second shutter, the second catoptron, the 3rd catoptron, the 3rd spectroscope, the second prism of corner cube and pyrometric cone prism.

In described wavelength lever laser interference system, wavelength is λ ₁linearly polarized light and wavelength be λ ₂the synthetic wavelength λ that formed at gage beam of linearly polarized light _swith the wavelength X of the linearly polarized light of directive in reference arm first prism of corner cube ₁have one-to-one relationship, in the tested absolute distance in gage beam and reference arm, the moving displacement of the first prism of corner cube forms lever relation.

Compared with background technology, the beneficial effect that the present invention has is:

(1) utilize wavelength lever principle, tested for large length distance is converted into the measurement of prism of corner cube moving displacement in the reference arm being easy to detect, instead of obtain synthetic wavelength fractional fringe level time by phase-detection, the method is easy to realize;

(2) the method can realize the absolute measurement of any distance, and when synthetic wavelength reduces gradually and is transitioned into Single wavelength, the measuring accuracy of tested distance can reach nanoscale, and measuring accuracy is high.

(3) the method can realize the transition of synthetic wavelength to Single wavelength, and structure is simple, and cost is low, easy to use.

The present invention is mainly applicable to the large length involved by field such as large-scale precision equipment manufacturing, space engineering and measurement technology or large scale, high-precision absolute distance measurement and detection.

Accompanying drawing explanation

Fig. 1 is laser interference wavelength lever absolute distance measurement device block diagram.

Fig. 2 is wavelength lever absolute distance measurement schematic diagram.

In figure: 10, first laser instrument, 11, second laser, 12, first collimator and extender device, 13, second collimator and extender device, 14, first catoptron, 15, first polarization spectroscope, 20, first spectroscope, 21, second polarization spectroscope, 22, first prism of corner cube, 23, second spectroscope, 24, first shutter, 25, second shutter, 26, second catoptron, 27, 3rd catoptron, 28, 3rd spectroscope, 29, second prism of corner cube, 210, pyrometric cone prism, 30, 3rd polarization spectroscope, 31, first photodetector, 32, second photodetector, 33, data acquisition module, 34, computing machine, 35, controller.

Embodiment

Below in conjunction with drawings and Examples, the invention will be further described.

As shown in Figure 1, the present invention includes light-source system I, wavelength lever laser interference system II and interference signal process and control system III; Light-source system I output wavelength is respectively λ ₁and λ ₂orhtogonal linear polarizaiton light beam, after spectroscope in directive wavelength lever laser interference system II, spectroscopical near-end in wavelength lever laser interference system II or the measuring beam of far-end are after dichroic mirror, with the polarization spectroscope in the interfering beam directive interference signal process formed through spectroscopical reference beam and control system III, the laser output wavelength that the controller in interference signal process and control system III controls in light-source system I is λ ₂linearly polarized light.

Described light-source system I, comprises the first laser instrument 10, second laser 11, first collimator and extender device 12, second collimator and extender device 13, first catoptron 14 and the first polarization spectroscope 15; First laser instrument 10 exports fixing wavelength X ₁and polarization direction is parallel to the linearly polarized light of paper, directive first polarization spectroscope 15 after the first collimator and extender device 12, second laser 11 exports variable wavelength X ₂and polarization direction is perpendicular to the linearly polarized light of paper, directive first catoptron 14 after the second collimator and extender device 13, directive first polarization spectroscope 15 after the first catoptron 14 reflects; Wavelength is λ ₁linearly polarized light through after the first polarization spectroscope 15 and wavelength be λ ₂linearly polarized light through first polarization spectroscope 15 reflect after, synthesize a branch of orthogonal linearly polarized light beam.

Described wavelength lever laser interference system II, comprises the first spectroscope 20, second polarization spectroscope 21, first prism of corner cube 22, second spectroscope 23, first shutter 24, second shutter 25, second catoptron 26, the 3rd catoptron 27, the 3rd spectroscope 28, second prism of corner cube 29 and pyrometric cone prism 210, be divided into the reference beam of reflection and the measuring beam of transmission after orthogonal linearly polarized light beam directive first spectroscope 20, reference beam directive second polarization spectroscope 21, its medium wavelength is λ ₂linearly polarized light reflected rear directive first spectroscope 20 by the second polarization spectroscope 21, wavelength is λ ₁linearly polarized light through the second polarization spectroscope 21, return after directive first prism of corner cube 22 is reflected, again through directive first spectroscope 20 after the second polarization spectroscope 21, the proximal measurement light beam of reflection and the far-end measuring light beam of transmission is divided into after measuring beam directive second spectroscope 23, proximal measurement light beam is successively through the first shutter 24, second catoptron 26, second prism of corner cube 29 and rear directive first spectroscope 20 of the 3rd spectroscope 28, far-end measuring light beam is successively through the second shutter 25, pyrometric cone prism 210, 3rd catoptron 27 and rear directive first spectroscope 20 of the 3rd spectroscope 28, the measuring beam of directive first spectroscope 20 near-end or far-end, after the first spectroscope 20 reflects, forms interfering beam with the reference beam through the first spectroscope 20.

Described interference signal process and control system III, comprise the 3rd polarization spectroscope 30, first photodetector 31, second photodetector 32, data acquisition module 33, computing machine 34 and controller 35; Interfering beam directive the 3rd polarization spectroscope 30 that reference beam is formed, wherein its medium wavelength is λ ₂interfering beam reflected by the 3rd polarization spectroscope 30 after, received by the first photodetector 31, wavelength is λ ₁interfering beam through after the 3rd polarization spectroscope 30, received by the second photodetector 32, the interference signal that two photodetectors export delivers to data acquisition module 33 respectively, after data acquisition module 33 processes, be transferred to computing machine 34, computing machine 34 changes the wavelength X of second laser 11 output by controller 35 according to result of calculation ₂value.

In described light-source system I, the laser wavelength lambda that the first laser instrument 10 exports ₁fixed value, the wavelength X that second laser 11 exports ₂variable.

In described wavelength lever laser interference system II, form reference arm by the second polarization spectroscope 21 and the first prism of corner cube 22; Gage beam is formed by the second spectroscope 23, first shutter 24, second shutter 25, second catoptron 26, the 3rd catoptron 27, the 3rd spectroscope 28, second prism of corner cube 29 and pyrometric cone prism 210.

In described wavelength lever laser interference system II, wavelength is λ ₁linearly polarized light and wavelength be λ ₂the synthetic wavelength λ that formed at gage beam of linearly polarized light _swith the wavelength X of the linearly polarized light of directive in reference arm first prism of corner cube 22 ₁have one-to-one relationship, in the tested absolute distance in gage beam and reference arm, the moving displacement of the first prism of corner cube 22 forms lever relation.

In described wavelength lever laser interference system II, when the first shutter 24 open, the second shutter 25 close time, the proximal measurement light beam of directive first spectroscope 20 and the reference beam of directive first spectroscope 20 are formed interferes; When the first shutter 24 close, the second shutter 25 open time, the far-end measuring light beam of directive first spectroscope 20 and the reference beam of directive first spectroscope 20 are formed interferes; Namely opened and closed by the first shutter 24 and replacing of the second shutter 25, proximal measurement light beam and far-end measuring light beam are formed with reference beam respectively interferes.

The first laser instrument 10 in concrete enforcement adopts a DL Pro 633 type semiconductor laser with tunable of German Toptica company, exports fixed wave length λ ₁for 631nm, second laser 11 adopts another DL Pro 633 type semiconductor laser with tunable of German Toptica company, output wavelength λ ₂scope be 630nm-637nm, first photodetector 31 and the second photodetector 32 adopt the S09105 type PIN photoelectric detector of Beijing Suoyang photoelectricity technology corporation, Ltd., data acquisition module 33 adopts the PCI-9820 type data collecting card of Ling Hua Science and Technology Ltd., computing machine 34 adopts the Pro4500 desktop computer of Hewlett-Packard, and controller 35 adopts the Digilock110 type controller of German Toptica company.

In FIG, it is λ that the vertical short-term in light path represents that polarization direction is parallel to paper wavelength ₁light beam, stain represents that polarization direction is λ perpendicular to paper wavelength ₂light beam.

Shown in composition graphs 2, the specific implementation process of laser interference wavelength lever absolute distance measurement of the present invention is as follows:

(1) first laser instrument 10 exports fixed wave length λ ₁linearly polarized light, control second laser 11 export a variable wavelength λ ₂linearly polarized light, make wavelength X ₁and wavelength X ₂the chopped-off head synthetic wavelength λ formed _s1half be greater than tested absolute distance L (L is the distance between the second prism of corner cube 29 and pyrometric cone prism 210);

(2) first shutters 24 are opened, the second shutter 25 is closed, and the proximal measurement light beam now returned from the second prism of corner cube 29 and reference beam are formed interferes, the wavelength X that the first detector 31 and the second detector 32 detect ₂and wavelength X ₁interference signal be respectively:

Mobile first prism of corner cube 22, the phase differential between the two-way interference signal that data acquisition module 33 is detected is zero, namely has:

In formula: L _rbe the range difference of the first spectroscope 20 to the second prism of corner cube 29 and the first spectroscope 20 to the second polarization spectroscope 21, L _mbe the range difference between the second polarization spectroscope 21 and the first prism of corner cube 22, λ ₁and λ ₂for the optical maser wavelength in air, λ ₁=λ ₁₀/ n ₁, λ ₂=λ ₂₀/ n ₂(λ ₁₀and λ ₂₀for vacuum laser wavelength, n ₁and n ₂for air refraction, n ₁and n ₂calculated by Edl é n formula by measuring the temperature of air, humidity, pressure and carbon dioxide content), λ _s1=λ ₁λ ₂/ | λ ₁-λ ₂| be wavelength X ₁and λ ₂the chopped-off head synthetic wavelength formed;

(3) first shutters 24 are closed, the second shutter 25 is opened, and the measuring beam now returned from pyrometric cone prism 210 and reference beam are formed interferes, and the introducing of tested distance L makes the phase difference variable between two-way interference signal to be:

(4) in order to record this tested distance L, the first prism of corner cube 22 moves a slight distance Δ l, i.e. L _m→ L _m± Δ l, the phase difference variable now between two-way interference signal is:

Work as λ ₂> λ ₁time, the first prism of corner cube 22 moves near the direction of the second polarization spectroscope 21, and the symbol before Δ l gets positive sign; Work as λ ₂< λ ₁time, the first prism of corner cube 22 moves to the direction away from the second polarization spectroscope 21, and the symbol before Δ l gets negative sign;

The slight distance Δ l of the first prism of corner cube 22 movement should meet in conjunction with formula (3) and formula (5), synthetic wavelength λ _s1, wavelength X ₁, establish following wavelength lever relationshhip between tested absolute distance L and the moving displacement Δ l of the first prism of corner cube 22:

$\frac{L}{{\mathrm{\&lambda;}}_{S1}}=\frac{\mathrm{\&Delta;l}}{{\mathrm{\&lambda;}}_1}---\left(6\right)$

This wavelength lever relationshhip, as shown in Figure 2, according to this wavelength lever relationshhip, is calculated the bigness scale value first of tested absolute distance by computing machine 34:

$L_1=\frac{{\mathrm{\&lambda;}}_{S1}}{{\mathrm{\&lambda;}}_1}\&CenterDot;\mathrm{\&Delta;l}---\left(7\right)$

(5) computing machine 34 changes the output wavelength λ of second laser 11 by controller 35 ₂, make wavelength X ₁and wavelength X ₂form a series of synthetic wavelength λ _s2> λ _s3> ... > λ _sn, and every grade of synthetic wavelength λ _si> 4u (L ' _i-1) (i=2,3 ..., n), wherein u (L ' _i-1) be when synthetic wavelength is λ _si-1time tested distance estimated value L ' _i-1uncertainty of measurement (as i=2 L ' _i-1=L ₁), to every one-level synthetic wavelength λ _si, repeat step (2) and step (3), record is each changes second laser 11 wavelength X ₂time the first prism of corner cube 22 moving displacement be Δ l _i, formula (5) becomes:

When tested distance L is greater than λ in formula (8) _siwhen/2, comprise integral multiple and the fraction part of 2 π, be expressed as another form:

In conjunction with formula (8) and formula (9), the estimated value L ' of tested distance _ibe expressed as:

$L_i^{\&prime;}=(M_{\mathrm{Si}}+{\mathrm{\&epsiv;}}_{\mathrm{Si}})\&CenterDot;\frac{{\mathrm{\&lambda;}}_{\mathrm{Si}}}{2}---\left(10\right)$

In formula: M _siand ε _sirepresent the synthetic wavelength λ comprised in tested distance respectively _siinteger and fractional interference order time;

Repeat step (4), calculate corresponding synthetic wavelength λ by computing machine 34 _sithe bigness scale value of the tested absolute distance of fraction part:

$L_i=\frac{{\mathrm{\&lambda;}}_{\mathrm{Si}}}{{\mathrm{\&lambda;}}_1}\&CenterDot;\mathrm{\&Delta;}{l}_i---\left(11\right)$

The synthetic wavelength λ comprised in tested absolute distance L _sifractional interference order sub-value be:

${\mathrm{\&epsiv;}}_{\mathrm{Si}}=\frac{2L_i}{{\mathrm{\&lambda;}}_{\mathrm{Si}}}---\left(12\right)$

The synthetic wavelength λ comprised in tested absolute distance L _siinteger interfere line level time M _sithe estimated value L ' of the tested absolute distance recorded by upper level synthetic wavelength _i-1with the current fractional interference order recorded time ε _sitry to achieve according to following formula:

$M_{\mathrm{Si}}=\mathrm{int}[\frac{2L_{i-1}^{\&prime;}}{{\mathrm{\&lambda;}}_{\mathrm{Si}}}+0.5-{\mathrm{\&epsiv;}}_{\mathrm{Si}}]---\left(13\right)$

Wherein int [] expression rounds downwards;

By the M tried to achieve _siand ε _sisubstitute into formula (10), calculating synthetic wavelength by computing machine 34 is λ _sitime the estimated value L of tested absolute distance _{' i};

Formula (11) is substituted into formula (12), obtains:

${\mathrm{\&epsiv;}}_{\mathrm{Si}}=\frac{2\mathrm{\&Delta;}{l}_i}{{\mathrm{\&lambda;}}_1}---\left(14\right)$

Formula (14) is substituted into formula (14), obtains:

$L_i^{\&prime;}=M_{\mathrm{Si}}\&CenterDot;\frac{{\mathrm{\&lambda;}}_{\mathrm{Si}}}{2}+\frac{{\mathrm{\&lambda;}}_{\mathrm{Si}}}{{\mathrm{\&lambda;}}_1}\&CenterDot;\mathrm{\&Delta;}{l}_i---\left(15\right)$

By formula (15), obtain the estimated value L ' of tested absolute distance _iuncertainty of measurement be:

$u\left(L_i^{\&prime;}\right)=\sqrt{{(\frac{M_{\mathrm{Si}}}{2}\&CenterDot;u\left({\mathrm{\&lambda;}}_{\mathrm{Si}}\right))}^2+{(\frac{{\mathrm{\&lambda;}}_{\mathrm{Si}}}{{\mathrm{\&lambda;}}_1}\&CenterDot;u\left(\mathrm{\&Delta;}{l}_i\right))}^2+{(\frac{\mathrm{\&Delta;}{l}_i}{{\mathrm{\&lambda;}}_1}\&CenterDot;u\left({\mathrm{\&lambda;}}_{\mathrm{Si}}\right))}^2+{(\frac{\mathrm{\&Delta;}{l}_i{\mathrm{\&lambda;}}_{\mathrm{Si}}}{{{\mathrm{\&lambda;}}_1}^2}\&CenterDot;u\left({\mathrm{\&lambda;}}_1\right))}^2}---\left(16\right)$

Formula (16) shows: the estimated value L ' of tested absolute distance _iuncertainty of measurement u (L ' _i) depend on synthetic wavelength λ _siround values M _si, synthetic wavelength λ _siuncertainty u (λ _si), wavelength X ₁uncertainty u (λ ₁) and the moving displacement Δ l of the first prism of corner cube 22 _iuncertainty u (Δ l _i);

For different i, repeat step (5), when 4u (L ' _n) < λ ₁time, computing machine 34 calculates tested absolute distance according to following formula:

$L=(M_n+{\mathrm{\&epsiv;}}_n)\&CenterDot;\frac{{\mathrm{\&lambda;}}_1}{2}---\left(17\right)$

Wherein: ${\mathrm{\&epsiv;}}_n=\frac{2\mathrm{\&Delta;}{l}_i}{{\mathrm{\&lambda;}}_1},M_n=\mathrm{int}[\frac{2L_n^{\&prime;}}{{\mathrm{\&lambda;}}_1}+0.5-{\mathrm{\&epsiv;}}_n];$

To measure the absolute distance of 50m, when the wavelength X that the first laser instrument 10 exports ₁=631nm, u (Δ l _i)=0.0003 μm, vacuum wavelength λ ₁₀and λ ₂₀relative uncertainty degree be 10 ^-10with air refraction measure relative uncertainty degree be 10 ^-9time, air medium wavelength λ ₁, λ ₂and λ _sirelative uncertainty degree be 10 ^-9, after 4 grades of synthetic wavelengths are measured, the uncertainty of measurement of tested absolute distance reaches 0.06 μm, meet 4u (L ' _n) < λ ₁, concrete data are as table 1.

Level Four composite wave long value during table 1. tested absolute distance L=50m and corresponding measurement result

Calculate tested absolute distance L=49999999.98 μm according to formula (17), the relative accuracy of absolute distance measurement is 3.54 × 10 ^-10.

As can be seen here, present invention achieves the precision measurement of large length absolute distance, measuring accuracy is high; And light channel structure is simple, easy to use, has outstanding significant technique effect.

Above-mentioned embodiment is used for explaining and the present invention is described, instead of limits the invention, and in the protection domain of spirit of the present invention and claim, any amendment make the present invention and change, all fall into protection scope of the present invention.

Claims (8)

1. a laser interference wavelength lever absolute distance measurement method, is characterized in that, the step of the method is as follows:

1) the first laser instrument (10) exports fixing wavelength X ₁, control second laser (11) and export variable wavelength X ₂, make wavelength X ₁and wavelength X ₂the chopped-off head synthetic wavelength λ formed _s1half to be greater than tested absolute distance L, L be distance between the second prism of corner cube (29) and pyrometric cone prism (210);

2) the first shutter (24) open, the second shutter (25) close, the proximal measurement light beam now returned from the second prism of corner cube (29) and reference beam form interference signal, mobile first prism of corner cube (22), makes the wavelength X that the first photodetector (31) and the second detector (32) detect ₂and wavelength X ₁interference signal phase differential be

3) the first shutter (24) closedown, the second shutter (25) are opened, the far-end measuring light beam now returned from pyrometric cone prism (210) and reference beam form interference signal, the two-way interference signal phase differential that the first photodetector (31) and the second detector (32) receive change, mobile first prism of corner cube (22) makes the phase differential of two-way interference signal again equal 0, the moving displacement recording the first prism of corner cube (22) is Δ l;

4) chopped-off head synthetic wavelength λ _s1, wavelength X ₁, tested absolute distance L and the first prism of corner cube (22) moving displacement Δ l there is following wavelength lever relationshhip:

$\frac{L}{{\mathrm{\&lambda;}}_{S1}}=\frac{\mathrm{\&Delta;l}}{{\mathrm{\&lambda;}}_1},$

Wherein λ _s1=λ ₁λ ₂/ | λ ₁-λ ₂| be wavelength X ₁and wavelength X ₂the chopped-off head synthetic wavelength formed, λ ₁and λ ₂for the optical maser wavelength in air, according to above-mentioned wavelength lever relationshhip, calculated the bigness scale value first of tested absolute distance by computing machine (34):

$L_1=\frac{{\mathrm{\&lambda;}}_{S1}}{{\mathrm{\&lambda;}}_1}\&CenterDot;\mathrm{\&Delta;l};$

5) computing machine (34) changes second laser (11) wavelength X that exports by controller (35) ₂, make wavelength X ₁and wavelength X ₂form a series of synthetic wavelength λ _s2> λ _s3> ... > λ _sn, and every grade of synthetic wavelength λ _si> 4u (L ' _i-1), i=2,3 ..., n, wherein u (L ' _i-1) be when synthetic wavelength is λ _si-1time tested distance estimated value L ' _i-1uncertainty of measurement, the L ' as i=2 _i-1=L ₁, repeat step 2), step 3), record change second laser (11) wavelength X at every turn ₂time the first prism of corner cube (22) moving displacement be Δ l _i, according to step 4) and medium wavelength lever relationshhip, calculate corresponding synthetic wavelength λ by computing machine (34) _sithe bigness scale value of the tested absolute distance of fraction part:

$L_i=\frac{{\mathrm{\&lambda;}}_{\mathrm{Si}}}{{\mathrm{\&lambda;}}_1}\&CenterDot;\mathrm{\&Delta;}{l}_i;$

Computing machine (34) calculates the synthetic wavelength λ comprised in tested absolute distance L according to following formula _sifractional interference order sub-value:

${\mathrm{\&epsiv;}}_{\mathrm{Si}}=\frac{2L_i}{{\mathrm{\&lambda;}}_{\mathrm{Si}}},$

Computing machine (34) calculates the synthetic wavelength λ comprised in tested absolute distance L according to following formula _siinteger order of interference sub-value:

$M_{\mathrm{Si}}=\mathrm{int}[\frac{2L_{i-1}^{\&prime;}}{{\mathrm{\&lambda;}}_{\mathrm{Si}}}+0.5-{\mathrm{\&epsiv;}}_{\mathrm{Si}}],$

Wherein int [] expression rounds downwards;

Computing machine (34) calculates each estimated value of tested absolute distance L according to following formula:

$L_i^{\&prime;}=(M_{\mathrm{Si}}+{\mathrm{\&epsiv;}}_{\mathrm{Si}})\&CenterDot;\frac{{\mathrm{\&lambda;}}_{\mathrm{Si}}}{2};$

When 4u (L ' _n) < λ ₁time, computing machine (34) calculates tested absolute distance according to following formula:

$L=(M_n+{\mathrm{\&epsiv;}}_n)\&CenterDot;\frac{{\mathrm{\&lambda;}}_1}{2},$

Wherein: ${\mathrm{\&epsiv;}}_n=\frac{2\mathrm{\&Delta;}{l}_i}{{\mathrm{\&lambda;}}_1},M_n=\mathrm{int}[\frac{2L_n^{\&prime;}}{{\mathrm{\&lambda;}}_1}+0.5-{\mathrm{\&epsiv;}}_n];$

Terminate to measure.

2. a kind of laser interference wavelength lever absolute distance measurement device of method according to claim 1, is characterized in that: comprise light-source system (I), wavelength lever laser interference system (II) and interference signal process and control system (III); Light-source system (I) output wavelength is respectively λ ₁and λ ₂orhtogonal linear polarizaiton light beam, after spectroscope in directive wavelength lever laser interference system (II), spectroscopical near-end in wavelength lever laser interference system (II) or the measuring beam of far-end are after dichroic mirror, with the polarization spectroscope in the interfering beam directive interference signal process formed through spectroscopical reference beam and control system (III), the laser output wavelength that the controller in interference signal process and control system (III) controls in light-source system (I) is λ ₂linearly polarized light.

3. a kind of laser interference wavelength lever absolute distance measurement device according to claim 2, it is characterized in that: described light-source system (I), comprise the first laser instrument (10), second laser (11), the first collimator and extender device (12), the second collimator and extender device (13), the first catoptron (14) and the first polarization spectroscope (15); First laser instrument (10) exports fixing wavelength X ₁and polarization direction is parallel to the linearly polarized light of paper, directive first polarization spectroscope (15) after the first collimator and extender device (12), second laser (11) exports variable wavelength X ₂and polarization direction is perpendicular to the linearly polarized light of paper, directive first catoptron (14) after the second collimator and extender device (13), directive first polarization spectroscope (15) after the first catoptron (14) reflection; Wavelength is λ ₁linearly polarized light be λ with wavelength afterwards through the first polarization spectroscope (15) ₂linearly polarized light through the first polarization spectroscope (15) reflection after, synthesize a branch of orthogonal linearly polarized light beam.

4. a kind of laser interference wavelength lever absolute distance measurement device according to claim 2, it is characterized in that: described wavelength lever laser interference system (II), comprise the first spectroscope (20), the second polarization spectroscope (21), the first prism of corner cube (22), the second spectroscope (23), the first shutter (24), the second shutter (25), the second catoptron (26), the 3rd catoptron (27), the 3rd spectroscope (28), the second prism of corner cube (29) and pyrometric cone prism (210), be divided into the reference beam of reflection and the measuring beam of transmission after orthogonal linearly polarized light beam directive first spectroscope (20), reference beam directive second polarization spectroscope (21), its medium wavelength is λ ₂linearly polarized light by the second polarization spectroscope (21) reflection after directive first spectroscope (20), wavelength is λ ₁linearly polarized light through the second polarization spectroscope (21), return after directive first prism of corner cube (22) is reflected, again through the second polarization spectroscope (21) directive first spectroscope (20) afterwards, the proximal measurement light beam of reflection and the far-end measuring light beam of transmission is divided into after measuring beam directive second spectroscope (23), proximal measurement light beam is successively through the first shutter (24), second catoptron (26), second prism of corner cube (29) and the 3rd spectroscope (28) directive first spectroscope (20) afterwards, far-end measuring light beam is successively through the second shutter (25), pyrometric cone prism (210), 3rd catoptron (27) and the 3rd spectroscope (28) directive first spectroscope (20) afterwards, the measuring beam of directive first spectroscope (20) near-end or far-end, after the first spectroscope (20) reflection, forms interfering beam with the reference beam through the first spectroscope (20).

5. a kind of laser interference wavelength lever absolute distance measurement device according to claim 2, it is characterized in that: described interference signal process and control system (III), comprise the 3rd polarization spectroscope (30), the first photodetector (31), the second photodetector (32), data acquisition module (33), computing machine (34) and controller (35); The interfering beam directive the 3rd polarization spectroscope (30) that reference beam is formed, wherein its medium wavelength is λ ₂interfering beam by the 3rd polarization spectroscope (30) reflection after, by the first photodetector (31) receive, wavelength is λ ₁interfering beam through after the 3rd polarization spectroscope (30), received by the second photodetector (32), the interference signal that two photodetectors export delivers to data acquisition module (33) respectively, computing machine (34) is transferred to, the wavelength X that computing machine (34) is exported by controller (35) change second laser (11) according to result of calculation after data acquisition module (33) process ₂value.

6. a kind of laser interference wavelength lever absolute distance measurement device according to claim 3, is characterized in that: in described light-source system (I), the laser wavelength lambda that the first laser instrument (10) exports ₁fixed value, the wavelength X that second laser (11) exports ₂variable.

7. a kind of laser interference wavelength lever absolute distance measurement device according to claim 4, it is characterized in that: in described wavelength lever laser interference system (II), form reference arm by the second polarization spectroscope (21) and the first prism of corner cube (22); Gage beam is formed by the second spectroscope (23), the first shutter (24), the second shutter (25), the second catoptron (26), the 3rd catoptron (27), the 3rd spectroscope (28), the second prism of corner cube (29) and pyrometric cone prism (210).

8. a kind of laser interference wavelength lever absolute distance measurement device according to claim 4, is characterized in that: in described wavelength lever laser interference system (II), wavelength is λ ₁linearly polarized light and wavelength be λ ₂the synthetic wavelength λ that formed at gage beam of linearly polarized light _swith the wavelength X of the linearly polarized light of directive in reference arm first prism of corner cube (22) ₁have one-to-one relationship, in the tested absolute distance in gage beam and reference arm, the moving displacement of the first prism of corner cube (22) forms lever relation.