CN1099128A - Carry out difference interference measuring absolute distance system with dual-wavelength laser - Google Patents
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Abstract
The present invention relates to a kind ofly carry out the system of difference interference measuring absolute distance, belong to the Technology of Precision Measurement field with dual-wavelength laser.This range measurement system comprises the laser instrument of two wavelength that produce the polarization direction quadrature, realizes the heterodyne ineterferometer of dual wavelength difference interference, and heterodyne signal is carried out the acousto-optic modulator of opto-electronic conversion and the phase detecting circuit and the data processing unit of heterodyne signal.Range measurement system of the present invention has that Measuring Time is short, measuring accuracy is high, it is affected by environment to be difficult for, antijamming capability is strong and advantage such as interferometer structure is simple.
Description
The present invention relates to a kind ofly carry out the system of difference interference measuring absolute distance, belong to the Technology of Precision Measurement field with dual-wavelength laser.
Laser interferometer is because its measuring accuracy height, good stability, dependable performance are widely used in production practices, is that the double-frequency laser measurement system of representative is a most frequently used laser measurement system at present with U.S. Hewlett-Packard Corporation.But this laser measurement system is when carrying out linear measure longimetry, must finish by a guide rail along direction of measurement, makes laser interferometer use under some occasions for this reason and is restricted.In order to address the above problem, people begin to be devoted to the absolute distance measurement Study of interferometer.The maximum characteristics of absolute distance interferometer are exactly to need not to use any guide rail when measuring distance between two points.
The absolute distance measurement interferometer overlaps theoretical based on decimal.Be provided with two wavelength and be respectively λ
1, λ
2Light beam, by the effect of Michelson interferometer, just having formed a synthetic wavelength is λ
sThe space composite wave.If at this moment the optical path difference of Michelson interferometer two arms is L, so, it can be expressed as following formula:
L＝（m+e）· (λ
s)/2 （1）
Wherein m is the integer level time of synthetic wavelength, and e is the decimal level time of synthetic wavelength, λ
sBe synthetic wavelength, and have:
λ
2= ｜ (λ
1λ
2)/(λ
1- λ
2) ｜（2）
By theoretical analysis, if when tested length can be pre-estimated with the precision that a △ represents, as long as this △ satisfies such numerical value, m just can uniquely determine so:
That is:
△＜ (λ
S)/4 （3）
As long as just measure L with suitable method, measure the decimal level time e of (1) formula by clapping the wave interference instrument like this, so tested length L just is determined uniquely.
At present existing this principle of many utilizations is carried out the method for absolute distance measurement: for example utilize CO
2Laser instrument, He-Xe, laser instrument and He-Ne3.39 mu m waveband laser device are realized absolute distance measurement.China institute of metrology has then adopted transverse zeeman to divide 633 nanometer He-Ne laser instruments, utilizes and claps the decimal level time realization absolute distance measurement that the ripple method is measured synthetic wavelength.So-called clap the ripple that the ripple method is exactly two wavelength that laser is sent, incide and clap in the wave interference instrument, just obtain the bat ripple-composite wave of two wavelength so at the output terminal of clapping the wave interference instrument, by changing the length of the reference arm of clapping the wave interference instrument, find the bat ripple zero point of composite wave, at this moment, the length change value of clapping wave interference instrument reference arm is exactly the decimal level time of synthetic wavelength.
Realize that the decimal level time measures owing to clap the ripple method and is by changing the space light path of clapping interferometer, therefore, its Measuring Time is long, is subject to the influence that external environment changes in measuring process, and with the interferometer measuration system complex structure of this kind method formation.
The present invention proposes a kind of novel absolute distance heterodyne ineterferometer, it utilizes has the LASER Light Source that two wavelength can separate, and realizes the optical heterodyne interference with acousto-optic modulator, and the decimal level of directly measuring synthetic wavelength is inferior.Therefore, it is short to have Measuring Time, and the measuring accuracy height is not subject to the influence of environment, and antijamming capability is strong, and interferometer structure is simple.
Content of the present invention is: carry out difference interference measuring absolute distance system with dual-wavelength laser, this system is through diffracted after the acoustooptic modulation from the orthogonal linearly polarized light in two bundle polarization directions that laser head sends, this diffraction light by behind the beam expanding lens by beam-expanding collimation, zero order light behind the acousto-optic modulator diffraction incides as measuring beam measures the target mirror, after measuring the target mirror reflection, incide on the spectroscope, behind the acousto-optic modulator diffraction+1 grade of light is as reference light, through inciding after the mirror reflects on the above-mentioned spectroscope, and converge the formation difference interference with above-mentioned reference light; The two-beam of outgoing from the spectroscope, a branch of light have polarization by one and select to obtain a wavelength X behind the photoelectric receiving system
1The difference interference signal, another Shu Guang has after polarization selects photoelectric receiving system by another, the acquisition wavelength is λ
2The difference interference signal, these two difference interference signal entering signal processing units can obtain by the distance value of finding range.
Description of drawings:
Fig. 1 is a range measurement system block diagram of the present invention.
Fig. 2 is a signal processing unit theory diagram among the present invention.
Below in conjunction with accompanying drawing, introduce content of the present invention in detail.
As shown in Figure 1, the only frequency stabilization of sending from laser head 1, and be orthogonal two linearly polarized lights in polarization direction, this two light is diffracted through acousto-optic modulator 2 backs, by beam expanding lens 3 beam-expanding collimations.Zero order light behind acousto-optic modulator 2 diffraction incides as measuring beam measures target mirror 4, and target mirror 4 is kaleidoscope prisms, and the light that target mirror 4 reflects incides on the spectroscope 5; Behind acousto-optic modulator 2 diffraction+1 grade of light is as reference light, and it incides on the spectroscope 5 after reflecting through catoptron 6, converges the formation difference interference with measuring beam.Outgoing two-beam from the spectroscope 5, a branch of light obtains a wavelength X by after having polarization and selecting photoelectric receiving system 7
1The difference interference signal; Then by after having polarization selection photoelectric receiving system 8, the acquisition wavelength is λ to another bundle light
2The difference interference signal of light wave, these two signals can be represented with following two formulas:
i
1＝I
01cos（2πf
0t-k
1x） （4）
i
2＝I
02cos（2πf
0t-k
2x） （5）
In the formula: I
01, I
02Be the amplitude of photosignal, f
0Be the driving frequency of acousto-optic modulator, k
1, k
2Be respectively the wave number of two wavelength, x is the optical path difference between two interference arms.
Find out that from (4) formula and (5) formula these two signals are that frequency is identical and sinusoidal signal that phase place is different is carried out the phase bit comparison with this two signal, its phase differential △ ψ is so:
△ψ＝k
1x-k
2x
= x( (2π)/(λ
1) - (2π)/(λ
2) )
= (2πx)/(λ
1) (6)
Because phase difference measurement can only be measured the phase differential in the one-period, the decimal level that obvious following formula is a synthetic wavelength is inferior, and promptly decimal level time e is:
E=| (x)/(λ
s) |
Mould=(△ ψ)/(2 π) (7)
From (7) formula as seen, as long as measure the phase differential of two signals that (4) formula, (5) formula represent, can measure the decimal level time of synthetic wavelength.According to the theoretical numerical value that just can obtain tested distance of aforesaid synthetic wavelength.
Therefore, from the photosignal of 7,8 outputs, by signal processing unit 9, carry out phase measurement and handle, the decimal level of measuring synthetic wavelength is inferior, and the first guess according to tested length obtains tested distance value through data processing again.
Shown in Figure 2 is the block diagram of signal processing unit 9.Because the driving frequency of acousto-optic modulator is than higher, what the present invention used is the acousto-optic modulator of a 40MHz, therefore in order to obtain a high measure phase difference precision, the photosignal of 7,8 outputs is carried out mixing through 10,11 and local oscillation signals 12 near the signal of acousto-optic modulator driving frequency of electronics mixting circuit, obtain the phase differential of two wavelength difference interference signals so again through phase comparison unit 13 through the low frequency signal after the mixing, this phase differential obtains tested distance value with the first guess of input through data processing unit 14 effects.
In one embodiment of the present of invention, laser instrument 1 has adopted the He-Ne double-longitudinal-mode laser of 633 nanometers, 2 is 40MHz acousto-optic modulators that Shanghai silicate research institute produces, and photoelectric receiving system the 7, the 8th selects polaroid and high frequency photelectric receiver to form by a wavelength.10, the 11st, the MC1496 integrated circuit constitutes, and its effect is that 7,8 signals of exporting are carried out mixing with 10 signals of exporting respectively.13 is ratio circuitry phases of realizing with interpolation method, and the phase signal of the output signal with 10,11 extracts; The 14th, with data acquisition and processing unit that single-chip microcomputer 8098 constitutes, it reads the phase difference value of comparer 13 on the one hand, according to the first guess of keyboard input, uses aforementioned algorithm on the other hand, calculates the distance that will survey.
Claims (2)
1, carry out difference interference measuring absolute distance system with dual-wavelength laser, it is characterized in that this system is through diffracted after the acoustooptic modulation from the orthogonal linearly polarized light in two bundle polarization directions that laser head sends, this diffraction light by behind the beam expanding lens by beam-expanding collimation, zero order light behind the acousto-optic modulator diffraction incides as measuring beam measures the target mirror, after measuring the target mirror reflection, incide on the spectroscope, behind the acousto-optic modulator diffraction+1 grade of light is as reference light, through inciding after the mirror reflects on the above-mentioned spectroscope, and converge the formation difference interference with above-mentioned measuring light; Outgoing two-beam from the spectroscope, a branch of light has the difference interference signal that polarization selects to obtain behind the photoelectric receiving system wavelength by one, after another Shu Guang has polarization selection photoelectric receiving system by another, obtain the difference interference signal of another wavelength, these two difference interference signal entering signal processing units can obtain by the distance value of finding range.
2, measurement absolute distance as claimed in claim 1 system, it is characterized in that wherein said signal processing unit is with the electronics mixting circuit photosignal and the local oscillation signal near acousto-optic modulator driving frequency signal to be carried out mixing, low frequency signal after mixing obtains the phase differential of above-mentioned two photosignals through phase comparison unit, this phase differential through data processing unit, obtains tested distance value with the first guess of input.
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| CN 94101493 CN1099128A (en) | 1994-03-04 | 1994-03-04 | Carry out difference interference measuring absolute distance system with dual-wavelength laser |
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| CN 94101493 CN1099128A (en) | 1994-03-04 | 1994-03-04 | Carry out difference interference measuring absolute distance system with dual-wavelength laser |
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|---|---|---|---|---|
| CN1095542C (en) * | 2000-02-25 | 2002-12-04 | 清华大学 | Dual-vacuum chamber and dual-frequency phase measurement air refractivity interferometer |
| CN1111734C (en) * | 1997-05-09 | 2003-06-18 | 代尔夫特技术大学 | Use the ellipsometer test of two laser instruments |
| CN1297797C (en) * | 2002-12-17 | 2007-01-31 | 北京航空航天大学 | Apparatus and method for raising location accuracy of laser heterodyne difference interferometer |
| CN100362366C (en) * | 2006-04-30 | 2008-01-16 | 太原理工大学 | Apparatus and method for distance measurement using chaos laser of optical fiber laser device |
| CN100439858C (en) * | 2005-05-12 | 2008-12-03 | 恪纳腾技术公司 | Interferometry measurement in disturbed environments |
| CN100465595C (en) * | 2000-04-24 | 2009-03-04 | 周晟 | Phase difference measurer and heterodyne interference measuring system using it |
| CN101128717B (en) * | 2005-02-23 | 2010-04-14 | 莱卡地球系统公开股份有限公司 | Phase noise compensation for interferometric absolute distance measuring |
| CN101825458A (en) * | 2010-03-31 | 2010-09-08 | 北京航空航天大学 | Absolute distance measurement system based on interferometric phase comparison method |
| CN102022977A (en) * | 2010-10-26 | 2011-04-20 | 中国航天科工集团第三研究院第八三五八研究所 | Double-shaft MEMS scanning-based heterodyne interference system and method |
| CN102183234A (en) * | 2011-03-21 | 2011-09-14 | 清华大学 | Method and device for measuring frequency scanning absolute distance based on femtosecond optical frequency comb |
| CN102288103A (en) * | 2011-06-27 | 2011-12-21 | 清华大学 | Folding-fabry-perot-cavity-based absolute distance measurement method and device |
| CN101660924B (en) * | 2009-09-28 | 2012-05-09 | 中国科学院长春光学精密机械与物理研究所 | Method for improving measurement precision by using acousto-optic device in optical heterodyne interferometry |
| CN102478418A (en) * | 2011-04-29 | 2012-05-30 | 国家大容量第一计量站 | Novel method for measuring liquid level by combining laser interference technology and free-state floater |
| CN101438126B (en) * | 2005-09-27 | 2013-01-02 | 真实仪器公司 | Self referencing heterodyne reflectometer and method for implementing |
| CN103234461A (en) * | 2013-05-07 | 2013-08-07 | 北京交通大学 | Novel laser interference length measuring method |
| WO2014043984A1 (en) * | 2012-09-19 | 2014-03-27 | Harbin Institute Of Technology | High speed high resolution heterodyne interferometric method and system |
| CN103954922A (en) * | 2014-05-15 | 2014-07-30 | 黑龙江大学 | Device and method for measuring magnetostriction coefficient through linear frequency modulation double-beam laser heterodyning |
| CN104635237A (en) * | 2013-11-08 | 2015-05-20 | 波音公司 | Synthetic wave laser ranging sensors and methods |
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1994
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Cited By (34)
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|---|---|---|---|---|
| CN1111734C (en) * | 1997-05-09 | 2003-06-18 | 代尔夫特技术大学 | Use the ellipsometer test of two laser instruments |
| CN1095542C (en) * | 2000-02-25 | 2002-12-04 | 清华大学 | Dual-vacuum chamber and dual-frequency phase measurement air refractivity interferometer |
| CN100465595C (en) * | 2000-04-24 | 2009-03-04 | 周晟 | Phase difference measurer and heterodyne interference measuring system using it |
| CN1297797C (en) * | 2002-12-17 | 2007-01-31 | 北京航空航天大学 | Apparatus and method for raising location accuracy of laser heterodyne difference interferometer |
| CN101128717B (en) * | 2005-02-23 | 2010-04-14 | 莱卡地球系统公开股份有限公司 | Phase noise compensation for interferometric absolute distance measuring |
| CN100439858C (en) * | 2005-05-12 | 2008-12-03 | 恪纳腾技术公司 | Interferometry measurement in disturbed environments |
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| CN101825458A (en) * | 2010-03-31 | 2010-09-08 | 北京航空航天大学 | Absolute distance measurement system based on interferometric phase comparison method |
| CN102022977A (en) * | 2010-10-26 | 2011-04-20 | 中国航天科工集团第三研究院第八三五八研究所 | Double-shaft MEMS scanning-based heterodyne interference system and method |
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