CN103322922A - Optical heterodyne interference method for eliminating non-linear errors based on FFT algorithm - Google Patents
Optical heterodyne interference method for eliminating non-linear errors based on FFT algorithm Download PDFInfo
- Publication number
- CN103322922A CN103322922A CN2013102313881A CN201310231388A CN103322922A CN 103322922 A CN103322922 A CN 103322922A CN 2013102313881 A CN2013102313881 A CN 2013102313881A CN 201310231388 A CN201310231388 A CN 201310231388A CN 103322922 A CN103322922 A CN 103322922A
- Authority
- CN
- China
- Prior art keywords
- signal
- road
- light
- drive test
- test amount
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Landscapes
- Instruments For Measurement Of Length By Optical Means (AREA)
Abstract
The invention provides an optical heterodyne interference method for eliminating non-linear errors based on an FFT algorithm, and belongs to the field of optical heterodyne interference. The method comprises the steps that on optical paths with the non-linear errors interference elements, at least three paths of signals are managed to acquire, the respective periodic non-linear error interference elements in the at least three paths are different from the corresponding circumference angle range of a phase angle on a signal frequency element to be eliminated or in the corresponding circumference angle range after integral multiple circumferential angles are eliminated, a filter is used for filtering signals in an analog electric signal channel, after analog-to-digital conversion is conducted, the FFT algorithm is adopted to conduct phase position interpretation on not less than three paths of signals respectively, and follow-up treatment is further conducted to eliminate or control the interference elements after displacement is calculated through a displacement calculating part. The optical heterodyne interference method can eliminate the non-linear errors or interferential specific harmonic wave elements, the adjusting process is easy to conduct, the system performance is improved, and cost is reduced.
Description
Technical field
The invention belongs to laser heterodyne interferometry (Heterodyne Interferometry) fields of measurement, be specifically related to a kind of exempt from accurate adjustment based on the FFT(Fast Fourier Transform (FFT)) algorithm eliminates the laser heterodyne interferometry measuring method of nonlinearity erron fundamental frequency.
Background technology
The laser heterodyne interference system can be used for measuring the physical quantitys such as displacement, length, is one of best nano measurement method.This system is converted to tested displacement in the frequency or phase place variation of heterodyne signal, again with this measure of the change out, because the frequency ratio optical frequency of heterodyne signal is much lower, photosignal is easily processed, can be through electronic fine-grained and reach higher Measurement Resolution, resolution can reach micromicron (pm) or better.
But ubiquity non-linear (nonlinearity) problem in the laser heterodyne interferometry method, these factors can be the main source of error of displacement measurement, make its precision generally only have nanoscale to tens nanometer, its reason is that the different light beam of frequency can not well separate.These periodic nonlinearity erron problems are the obstacles of this art development always.
Constantly invent for many years the method for some improvement both at home and abroad, but also have some restrictions or problems more, for example Badami and Pattersom use ratemeter and frequency spectrograph are directly measured the nonlinearity erron composition and are compensated in mobile system; Tae Bong Eom and Tae Young Choi etc. come the compensating non-linear error to the method for carrying out ellipse fitting behind the phase signal integration.These methods can be when the auxiliary interferometer that does not have other exists the compensating non-linear error, but system complex, and need a large amount of fluctuation signal cycle and relative a large amount of computing, the real-time of impact measurement.In being the Chinese invention patent of CN101660924, publication number announced a kind of new method, the method can address this problem effectively, if but wish to obtain very accurate result, also need point-device optics to regulate, this precise optical is regulated usually relatively difficulty.
Summary of the invention
The system complex, the operand that have the existence of laser heterodyne interference system now are large, real-time is poor, the coarse technical matters of result in order to solve, the invention provides a kind of laser heterodyne interferometry method based on resonator, filter and fft algorithm elimination nonlinearity erron, can eliminate the particular harmonic composition of nonlinearity erron or interference, and remove the needed precision optics regulating device of nonlinearity erron and the minute adjustment process eliminated from, make this adjustment become very easy, significantly improve simultaneously system performance, reduce cost.
The AC signal that the photodetector output terminal of laser heterodyne interference systematic survey light arm obtains is take the poor electric signal as frequency of alien frequencies optical frequency, and its additional phase differential and measured position moves into accurate proportionate relationship.But wherein comprising so-called nonlinearity erron, mainly be distributed on the first harmonic (also can be called fundamental frequency according to Fourier series character generally speaking, be a kind of spatial frequency) of Fourier spectrum.Method of the present invention can be eliminated the fundamental component of nonlinearity erron; In fact method of the present invention all is effectively to a certain frequency arbitrarily, and need not optical system is done special minute adjustment.
In the laser heterodyne interference system, exist on the signal light path of nonlinearity erron interference component, obtain at least 3 road signals (passage), obtain these signals by carrying the method that at least 3 interference light photodetection parts are set on the light arm that is detected signal, and make and have wherein that the phase angle of contained nonlinearity erron first harmonic (or other frequency content) is different in the circumference of a correspondence separately in 3 the tunnel at least, so just obtained sufficient information, enable pass later face the processing such as weighted sum stack and eliminate fundamental frequency (or any one frequency) composition in the nonlinearity erron.The phase angle of realizing first harmonic (or other frequency content) different method in the circumference of a correspondence is a lot, for example can change the phase angle of corresponding first harmonic by adjusting light path, by the error measurement method of disclosed first harmonic in the prior art, can be easy to obtain amplitude and the starting phase angle of first harmonic.Generally speaking, the phase angle of the several signals error of different light paths is usually unequal, if the situation that has phase angle to equate can be known by the method for measurement phase angle in the prior art, and pass through to adjust light path so that they are unequal.Furtherly, our optical system of setting up at random generally speaking, do not have in any 2 the tunnel nonlinearity erron phasing degree identical in a corresponding circumference, if but finish after the adjusting of optical system, the phase angle of 2 road nonlinearity erron first harmonics in 3 tunnel (or other frequency content that will be eliminated) is more or less the same then can affect the amplitude of weighted stacking useful signal afterwards, thereby affect the signal to noise ratio (S/N ratio) of output signal, at this moment we can roughly adjust the phase angle of the frequency content that will be eliminated in wherein the 1-2 road with respect to the difference of (frequency content that will be eliminated of nonlinearity erron) signal phase angle corresponding in other passages, and it is increased to fully till (namely enough) to some extent.The method that a lot of detection nonlinearity erron first harmonics (or other frequency content that will be eliminated) phase place and amplitude are arranged now is such as " measuring method of laser heterodyne interference nonlinearity erron " " Beijing University of Technology's journal " the 6th phase in 2010 of Chen Hongfang etc.; " the novel measuring method of a kind of laser heterodyne interference nonlinearity erron " of Zhong Zhi etc., photoelectron laser, 2005, etc.The method of adjusting phase angle can realize by the optical path difference of regulating between two light that participate in interfering.
Based on the periodicity of hamonic function, certainly can several integral multiple angles of circumference eliminatings that comprise in the above-mentioned phase differential be disregarded as usually (following no longer do similar prompting).
Adopt and carry out in the following method subsequent treatment: at first hypothesis only has the situation of 3 road signals, 3 road signals is carried out the phase bit comparison with reference signal respectively, until solve 3 displacements.At this moment the phase place of the nonlinearity erron in each passage is different.
By following proof as can be known, have non-vanishing weighting coefficient array can so that after the stack amplitude of the fundamental frequency of nonlinearity erron or other frequency contents be zero, and keep useful signal.
In above-mentioned 3 displacements that solve, the displacement measurement on i road can be expressed as:
Wherein, first χ of equal sign right-hand member is real physical displacement, and second is the primary components of nonlinearity erron, certainly with first harmonic content of the present invention is described here and is without loss of generality; A is coefficient, expresses the nonlinearity erron amplitude, is an a small amount of generally speaking, but does not make approximate processing in the derivation afterwards.
Be the initial phase angle of nonlinearity erron, λ is optical wavelength.Here the wave number in the nonlinearity erron item
Expression be the first harmonic composition, and by the situation of measuring prism individual reflection.For the situation of second harmonic, this can become
With 3 weighted stacking as a result, be normalized into:
One group of new ki just for pro forma clean and tidy, can be regarded as new weighting coefficient.Our purpose be find one group of ki so that: X=x.
We can obtain following system of linear equations by above-mentioned condition:
k
1 +k
2 +k
3 =b
Wherein, b ≠ 0
The factor arrays of variable ki is 3 rank square formations of full rank, about the system of equations of ki untrivialo solution is arranged.That is, can make
To sum up, verified after such weighted stacking, the first harmonic composition of nonlinearity erron is eliminated.
If
In have any 2 to differ 180 °, can make problem become simple and favourable, this situation generally needs accurate optics adjusting just can obtain, and only need non-linear component to differ 180 ° the 2 road signals enough nonlinearity erron composition of elimination characteristic frequency just, in this that patent of invention of in background technology, having mentioned than being illustrated in more detail.
We have solved the nonlinearity erron problem in the laser heterodyne interference in 3 dimensional linear spaces of electronics to this.
For having the above situation of 3 road signals (passage), but we are the different signal of advance reservation 3 road phase angles at least, again with all the other several signals and reservation 3 the tunnel in the stack of any one road signal, and with its change on certain frequency of nonlinearity erron phase angle difference each non-vanishing 3 the tunnel.So just dissolve the problem that has solved above becoming, i.e. the situation of 3 passages, and be proven.Certainly also can not adopt recited abovely at first to be simplified to 3 tunnel processing procedure, but in weighted overlap-add procedure, together finish.
Can obtain correct weighting coefficient array by following method in practice and eliminate error percentage: (1) incites somebody to action 2 route stacks wherein, because in 2 dimension spaces of this nonlinear certain harmonic components, this two paths of signals is one group of substrate of Special composition, so can generate any one vector by adjusting the stack coefficient, we allow the vector and the 3rd signal (vector) that generate just in time be opposite directions on nonlinear certain harmonic components, then with the signal and the 3rd signal (vector) linear superposition that generate, adjust weighting coefficient and just can make nonlinear certain harmonic components be kept to fully mutually zero, and useful signal can still be retained.(2) weighting coefficient that can electricity consumption accent method repeats alternate sweep at least 2 tunnel is measured nonlinearity erron value in the output after the stack simultaneously, it is constantly reduced, until be zero.(3) adopt the most basic method, after measuring phase angle described in every road and amplitude, directly calculated by analytic method, also can adopt the thinking in (1) here, but be not to decompose to adjust, but calculate step by step, no longer carefully separate here.That is to say, can cancel each other by weighted stacking having found the first harmonic error, thereby remove after the above-mentioned principle of error percentage, the related content of record can be selected the weighted stacking mode that is fit to according to the present invention, just can realize the elimination of first harmonic error.The method of above-mentioned multiple acquisition weighting coefficient only is for the ease of enumerating of understanding, and is not the fully restriction to technical scheme.
In order to remove corresponding optics accurate adjustment from, eliminate or the inhibition nonlinearity erron, and be conducive to keep useful signal and select rational parameter, as preferred version, make the difference between the phase angle on the signal frequency composition that will be eliminated of 3 periodicity nonlinearity errons at least 3 road signals be not less than 60 degree.This is because we always can easily by regulating or arranging, make the declinate between any two-phase not too little in practice.Theoretical and experiment all illustrates, a rational numerical value with 60 ° of lower limits as this angle, this is beneficial to the signal to noise ratio (S/N ratio) after processing, can not make the useful signal of output be lower than the amplitude of single channel after the weighted stacking, simultaneously as long as attempt blindly device 3 to 5 times on the random fixing light path that can affect phase differential between 3 tunnel, roughly just once chance meet this condition, thereby realize mechanically " adjustment-free ", and saved corresponding adjuster, so that adjusting or the work that arranges become simple and easy.Can judge whether to meet this condition according to the method for the starting phase angle of the aforementioned measurement first harmonic error of mentioning, thereby stop to adjust.Also can nonlinear certain harmonic components be transferred nothing by the similar aforementioned actual method (1) (2) of eliminating error percentage, and then the amplitude of inspection useful signal, if excessively low, just " 60 degree condition " or similar standard are not satisfied in explanation.It is complete whether check is adjusted, and having eliminated error can be by relatively waiting method to judge such as adopting more accurate surveying instrument to carry out the result.
This " minute adjustment " by electronics replaces the release precision optical machinery of " minute adjustment " of optics to regulate or exempts from the method for optics accurate adjustment, and cost is significantly reduced, and the accuracy requirement that optics is regulated can descend 2-3 more than the order of magnitude.And the precision that whole system shows on the nonlinearity erron characteristic frequency also can be significantly improved.
Clearly, whether advantage and meaning that the ultimate principle of the method and itself exist and adopt the integrated optics mode, comprise the optical fiber mode, or bulk wave mode etc. is irrelevant.The method all is effectively for the periodic error in all laser heterodyne interferometry systems, as long as we can access the different signal of at least 3 road its interference component phase places.
Adopt digital processing for the interpretation that is no less than 3 road signal phases, then the result according to these processing is weighted and overlap-add procedure after the displacement calculating section calculates displacement again.The laser heterodyne interferometry signal is special weak signal, and is this very large by instantaneous amplitude noise and phase noise in the light wave ray of radiation generation, but can obtain accurate result of calculation by fft algorithm, and can directly carry out the follow-up processing such as weighted stacking.In the inner disposable digital processing processes such as digit phase interpretation, displacement calculating and weighted stacking of finishing continuously of single numerical portion, system is had advantages of efficiently, quick, cost is low, volume is little, simple for structure.
Based on foregoing, the invention provides a kind of first harmonic or other frequency content that can eliminate or reduce the periodicity nonlinearity erron, improve measuring accuracy, the laser heterodyne interferometry method that the corresponding precision optics that omits is adjusted, namely eliminate the laser heterodyne interferometry method of nonlinearity erron based on fft algorithm, the method is: on the light path that exists the nonlinearity erron interference component, obtain at least 3 drive test amount signals and 1 tunnel reference signal by light splitting, and make at least 3 drive test amount signals wherein periodically nonlinearity erron is different in the angle of circumference scope of the phasing degree on the frequency content that will be eliminated a correspondence separately; At least 3 drive test amount signals and 1 tunnel reference signal are separately converted to corresponding at least 3 drive test amount analog electrical signals and 1 tunnel with reference to analog electrical signal; The first filtering and analog to digital conversion are carried out respectively in each road of described at least 3 drive test amount analog electrical signals, and correspondence obtains at least 3 drive test amount digital electric signals; Carry out the second filtering and analog to digital conversion with 1 the tunnel with reference to analog electrical signal, correspondence obtains 1 road reference number electric signal; Described at least 3 drive test amount digital electric signals are inputted respectively corresponding FFT phase place reading module with 1 road reference number electric signal, calculate at least 3 drive test amount signal phase angles and 1 tunnel reference signal phasing degree; The cycle count of phase bit comparison and phase differential is carried out respectively with 1 tunnel reference signal phasing degree in described at least 3 drive test amount signal phase angles, and is converted into displacement, obtains at least 3 tunnel displacement measurement, and contain nonlinearity erron in each road displacement measurement this moment; At least 3 tunnel displacement measurement that obtain are carried out the real number ranking operation, carry out again additive operation and can obtain final measurement; Described the first filtering adopts the single-stage resonance filter.
Above-mentioned single-stage resonance filter comprises the inductance capacitance resonant tank of parallel connection or series connection.
The phase differential of at least 3 periodicity nonlinearity errons in the above-mentioned at least 3 drive test amount signals is not less than 60 °.
Above-mentioned the first filtering and the second filtering adopt different types of wave filter.
Above-mentioned the first filtering and the second filtering adopt the wave filter of identical type.
Above-mentioned step by light splitting acquisition at least 3 drive test amount signals and 1 tunnel reference signal comprises: the A road light signal of output obtains respectively A1, A2...An road light signal, wherein n 〉=4 by at least 4 light-dividing devices successively; The B road light signal that has frequency difference with the A road light signal of exporting obtains B1 road light signal by light-dividing device, and all the other light signals of B road obtain B2...Bn road light signal, wherein n 〉=4 by light-dividing device after reflecting by reflection unit successively; A1 road light signal and B1 road light signal are interfered the formation reference signal, and the respectively corresponding interference of A2...An road light signal and B2...Bn road light signal forms n-1 drive test amount signal.
In fact the laser heterodyne interference signal is typical weak signal, particularly more requires signal pure in the exquisite system of this elimination nonlinearity erron, and the wave filter in the analog electrical signal is a very important link in the machine system, and effect is unique.The useful signal of considering this system is single some frequency composition, be operated on the natural frequency of single-point with the wave filter of in parallel in the analog electronics or the inductance capacitance resonant tank formation of connect and just in time be mapped, the resonance characteristic of this wave filter that is made of resonant tank and narrow bandwidth can make the logical outer spectrum component of band that various noises, non-linear intermodulation and sampling thheorem require etc. be suppressed greatly, and this purpose that will reach just.The key property of this resonant tank is level and smooth, clear and definite, simple, the noiseless of circuit own, radioresistance, be easy to control, so no matter whether exist in order to guarantee the set low-pass filter of sampling thheorem (such as Tchebyscheff filter) in the system, in the analog electrical signal passage, add this resonant tank signal is carried out filtering, all be very desirable with thinking that follow-up weighted overlap-add procedure obtains high-quality signal, this wave filter also can reduce guaranteeing the requirement of the low-pass filter that sampling thheorem is set.This filters solutions can make machine system become accurately, stablize, reliable, be easy to adjust and produce.So the wave filter that we can adopt the inductance capacitance resonant tank of in parallel or series connection to consist of in the analog electrical signal passage carries out filtering to signal, in order to process by electronics such as follow-up weighting, stacks.
The quality factor in radio frequency inductive capacitor resonance loop can reach dozens or even hundreds of, from the angle of filtering, are enough to that system is reached and are better than the precision of nanometer scale and satisfy most of user's requests.
Adding resistance or equivalent resistance adjustment quality factor are carried out filtering in resonant tank, in order to make quality factor adjustable and stable.In the wave filter loop that the inductance capacitance resonant tank of the in parallel of a relative high quality factor (Q value) or series connection consists of, add resistance and (contain adjustable resistance, potentiometer, or method of equal value), so that quality factor are mainly determined by lumped parameters such as resistors, rather than be distributed the parameter decision, obtain desirable, stable Q value.The Q value has a lot of physical significances, such as the too high highest movement speed that also can affect under the accuracy requirement of Q value here.
The wave filter that consists of for the inductance capacitance resonant tank of above-mentioned parallel connection or series connection, and between the output terminal of its prime, and stability and the sufficient quality factor of employing weak coupling method to guarantee this resonant tank between the input end of rear class, the method of these weak couplings realizes by one of following method at least, 1) capacitive coupling, 2) inductive coupling, 3) resistively couple, 4) the winding mode is transformer coupled.
The present invention after wave filter that the inductance capacitance resonant tank of in parallel or series connection consists of and analog to digital conversion thereof respectively to the fft algorithm in the interpretation employing digital processing that is no less than 3 road signal phases, then after calculating displacement by the displacement calculating section, be weighted again and overlap-add procedure.FFT can accurately obtain phase differential, can also directly obtain the movement velocity of system under test (SUT) by the variable of frequency, and this is very important sometimes.FFT software and hardware mature and reliable, research and develop perfect, in addition the Broad Spectrum Analysis of Infinitesimal of FFT also be fit to the movement velocity of large testee, also can be used for the assessment of system self and diagnosis, can also and other system share, being fit to very much be applied in to have people directly maintenance or the occasion remote measuring and controlling intervention, that have very high reliability and easy-maintaining to require, medium such as the radiation environment such as radiation and space.This general structure can obtain accurate, stable technical indicator, and simple in structure, good reliability.
Final step in the inventive method is superposition, and whole system has kept the longest separately discrete channel part, does like this being convenient to detect these discrete channel parts.Such as with the input short of three paths and input identical signal, both can compare and detect the triple channel Output rusults and the evaluation work state, this is conducive to fast detecting and remote control detection etc.
Another technical scheme of the present invention is: a kind of laser heterodyne interferometry device that adopts above-mentioned laser heterodyne interferometry method comprises: the first light-dividing device obtains A1, A2...An road light signal, wherein n 〉=4 with the light signal light splitting of A road; The second light-dividing device, the B road light signal light splitting that will have with the A road light signal of output frequency difference obtains B1 road light signal and remaining light signal thereof, described all the other light signals are obtained B2...Bn road light signal, wherein n 〉=4 by the second light-dividing device light splitting after the reflection unit reflection; Interfere to form device, so that A1 road light signal and B1 road light signal are interfered the reference signal that forms, A2...An road light signal forms n-1 drive test amount signal with the respectively corresponding interference of B2...Bn road light signal; Signal detecting device is converted to respectively 1 the tunnel with reference to analog electrical signal, n-1 drive test amount analog electrical signal with above-mentioned 1 tunnel reference signal, n-1 drive test amount signal; The first filtering and modular converter carry out respectively the first filtering and analog to digital conversion to n-1 drive test amount analog electrical signal, and correspondence obtains n-1 drive test amount digital electric signal; The second filtering and modular converter carry out the second filtering and analog to digital conversion to 1 the tunnel with reference to analog electrical signal, and correspondence obtains 1 road reference number electric signal; FFT phase place reading module calculates n-1 drive test amount digital electric signal phasing degree and 1 road reference number electrical signal phase angle; The displacement computing module according to n-1 drive test amount digital electric signal phasing degree and 1 road reference number electrical signal phase angle, calculates n-1 road displacement measurement; The weighted stacking module is carried out real number ranking operation and additive operation with the n-1 road displacement measurement that obtains.
The present invention has omitted explanation and the statement of some prior aries, row as omitted to the FFT system, adopt theorem, power-supply system wiring board distribution filtering electric capacity, be the set discussion details such as amplifier, general foundation of system-gain and block diagram etc.
The invention has the beneficial effects as follows: the present invention is on common laser heterodyne interference system-based, creatively optical path is divided into multichannel, carry out respectively the process such as adjustment, signal processing, weighted stacking of electronics, length with the electronics minute adjustment, light filling is learned the short of minute adjustment, the optics accurate adjustment that has omitted complicated or other non-electronic adjustment, the substitute is the adjustment and the signal processing method that adopt electronics and eliminate nonlinearity erron, reduced the complexity that optics is adjusted, reduce cost, improved efficient.Simultaneously, effectively eliminate or reduced significantly the periodicity interference component such as nonlinearity erron and then improve measuring accuracy or reduce interference, cooperate simultaneously fast fourier transform algorithm accurately to try to achieve signal phase, and the analog filter of selecting by particular design, quality factor adjusting resistance etc. improve the measuring accuracy of whole system, antijamming capability is strong, stable, be conducive to large-scale production, production cost is low.
Description of drawings
Fig. 1 the present invention is based on the opticator principle schematic that fft algorithm is eliminated the laser heterodyne interferometry method of nonlinearity erron.
Fig. 2 is the filter circuit schematic diagram that the parallel inductance capacitance resonant tank of the one-level among the present invention consists of.
Fig. 3 the present invention is based on the laser heterodyne interferometry ratio juris schematic diagram that fft algorithm is eliminated nonlinearity erron.
Embodiment
Below in conjunction with accompanying drawing the present invention is described in further details.
The system that realization the present invention is based on the laser heterodyne interferometry method of fft algorithm elimination nonlinearity erron can be divided into opticator and electronics signal processing afterwards.Wherein the principle of opticator as shown in Figure 1, the present invention has increased the part in the dotted line frame among the figure on the basis of an original opticator.
At first, set forth the opticator principle of work of original difference interference measuring system: send laser by laser instrument 101, incide acousto-optical device 103 through first's catoptron 102, shone second portion catoptron 114 behind the shift frequency, transmitted light is reflected by measuring prism 115, incide third part catoptron 111, reflecting part and another bundle light are interfered through the first polaroid 131.The light (it provides reference ray for each road interference portion of back) that is reflected by first's catoptron 102 is through the first catoptron 125, again through after the 4th partially reflecting mirror 124, the 5th partially reflecting mirror 123, the 6th partially reflecting mirror 122, the second catoptron 121, together incide the first polaroid 131 with the reflected light of third part catoptron 111, the interference light of its outgoing partly converts the difference frequency of two light to electric signal by the first photodetector 141.This electric signal has wherein included the displacement information that obtains as measuring-signal above measuring prism 115, also contain the nonlinearity erron composition.
The light that the light that is reflected by second portion catoptron 114 and the 4th partially reflecting mirror 124 reflect converges, incide the second polaroid 134, the interference light of its outgoing partly converts the difference frequency of two light to electric signal by the second photodetector 144, and this electric signal is exactly reference signal.
Above-mentioned laser instrument 101, first's catoptron 102 and acousto-optical device 103 have consisted of the double-frequency laser generator that frequency has elementary errors, also can be replaced by other scheme.
The present invention has increased the part in the dotted line frame among Fig. 1, and it mainly comprises two new measurement light arm/light paths and corresponding circuit part.
With original the first smooth arm that is consisted of by the third part catoptron 111 among the figure, the first polaroid 131, the first photodetector 141 etc., have three light arms, or be called three optical paths, and obtaining thus measuring-signal output 1, measuring-signal output 2 and measuring-signal output 3, these two new measurement light arms are identical with the first smooth arm structurally.Add reference signal, altogether four road signals output, this four road signal has just consisted of the output of opticator, is transferred to the electronics signal processing of back, as described in Figure 3.
In the electronics signal processing, the wave filter (filtering part for first passage to the four-way is respectively 211 among Fig. 3,221,231,241) that its signal consists of through inductance capacitance resonant tank in parallel or that connect shown in Figure 2 respectively; Analog to digital conversion part (respectively be in figure 212,222,232,242 for first passage to the four-way); The part of calculating phase angle in the described system of Fig. 3 is called FFT part (be in figure 213,223,233,243 for first to fourth passage); Then three drive test amount data respectively the displacement calculating section (for first to third channel be respectively 214 among the figure, 224,234) carry out the cycle count of phase bit comparison and phase differential with reference signal, and be converted into displacement, finish corresponding displacement measurement, obtain the measurement result on each road; Certainly the nonlinearity erron that contains equally destruction system accuracy separately among the result.Again three tunnel measurement result is delivered to respectively weighted stacking arithmetic section 301 and carry out the real number ranking operation, then do additive operation and just can draw last measurement result, the fundamental frequency of its nonlinearity erron has been eliminated or has significantly suppressed.
Claims (10)
1. eliminate the laser heterodyne interferometry method of nonlinearity erron based on fft algorithm, it is characterized in that: the method comprises:
On the light path that exists the nonlinearity erron interference component, obtain at least 3 drive test amount signals and 1 tunnel reference signal by light splitting, and make at least 3 drive test amount signals wherein periodically nonlinearity erron is different in the angle of circumference scope of the phasing degree on the frequency content that will be eliminated a correspondence separately.
At least 3 drive test amount signals and 1 tunnel reference signal are separately converted to corresponding at least 3 drive test amount analog electrical signals and 1 tunnel with reference to analog electrical signal;
The first filtering and analog to digital conversion are carried out respectively in each road of described at least 3 drive test amount analog electrical signals, and correspondence obtains at least 3 drive test amount digital electric signals; Carry out the second filtering and analog to digital conversion with 1 the tunnel with reference to analog electrical signal, correspondence obtains 1 road reference number electric signal.
Described at least 3 drive test amount digital electric signals are inputted respectively corresponding FFT phase place reading module with 1 road reference number electric signal, calculate at least 3 drive test amount signal phase angles and 1 tunnel reference signal phasing degree;
The cycle count of phase bit comparison and phase differential is carried out respectively with 1 tunnel reference signal phasing degree in described at least 3 drive test amount signal phase angles, and is converted into displacement, obtains at least 3 tunnel displacement measurement, and contain nonlinearity erron in each road displacement measurement this moment;
At least 3 tunnel displacement measurement that obtain are carried out the real number ranking operation, carry out again additive operation and can obtain final measurement;
Described the first filtering adopts the single-stage resonance filter.
2. the laser heterodyne interferometry method of eliminating nonlinearity erron based on fft algorithm as claimed in claim 1, it is characterized in that: described single-stage resonance filter comprises the inductance capacitance resonant tank of parallel connection or series connection.
3. the laser heterodyne interferometry method of eliminating nonlinearity erron based on fft algorithm as claimed in claim 1 is characterized in that: adopt the weak coupling mode to be coupled between described single-stage resonance filter and its prime output terminal and the rear class input end.
4. the laser heterodyne interferometry method of eliminating nonlinearity erron based on fft algorithm as claimed in claim 1 is characterized in that: add resistance or equivalent resistance adjustment quality factor in the resonant tank of described single-stage resonance filter, so that quality factor are adjustable and stable.
5. the laser heterodyne interferometry method of eliminating nonlinearity erron based on fft algorithm as claimed in claim 3, it is characterized in that: described weak coupling method is capacitive couplings or inductive coupling method or resistively couple method or the transformer coupled method of winding type.
6. the laser heterodyne interferometry method of eliminating nonlinearity erron based on fft algorithm as claimed in claim 1 is characterized in that: in the described at least 3 drive test amount signals at least 3 periodically the phase differential of nonlinearity errons be not less than 60 °.
7. the laser heterodyne interferometry method of eliminating nonlinearity erron based on fft algorithm as claimed in claim 1, it is characterized in that: described the first filtering and the second filtering adopt different types of wave filter.
8. the laser heterodyne interferometry method of eliminating nonlinearity erron based on fft algorithm as claimed in claim 1 is characterized in that: the wave filter of described the first filtering and the second filtering employing identical type.
9. the laser heterodyne interferometry method of eliminating nonlinearity erron based on fft algorithm as claimed in claim 1, it is characterized in that: the step that obtains at least 3 drive test amount signals and 1 tunnel reference signal by light splitting comprises: the A road light signal of output obtains respectively A1, A2...An road light signal, wherein n 〉=4 by at least 4 light-dividing devices successively; The B road light signal that has frequency difference with the A road light signal of exporting obtains B1 road light signal by light-dividing device, and all the other light signals of B road obtain B2...Bn road light signal, wherein n 〉=4 by light-dividing device after reflecting by reflection unit successively; A1 road light signal and B1 road light signal are interfered the formation reference signal, and the respectively corresponding interference of A2...An road light signal and B2...Bn road light signal forms n-1 drive test amount signal.
10. the laser heterodyne interferometry device of an employing such as the described laser heterodyne interferometry method of claim 1-9 is characterized in that: comprising:
The first light-dividing device obtains A1, A2...An road light signal, wherein n 〉=4 with the light signal light splitting of A road;
The second light-dividing device, the B road light signal light splitting that will have with the A road light signal of output frequency difference obtains B1 road light signal and remaining light signal thereof, described all the other light signals are obtained B2...Bn road light signal, wherein n 〉=4 by the second light-dividing device light splitting after the reflection unit reflection;
Interfere to form device, so that A1 road light signal and B1 road light signal are interfered the reference signal that forms, A2...An road light signal forms n-1 drive test amount signal with the respectively corresponding interference of B2...Bn road light signal;
Signal detecting device is converted to respectively 1 the tunnel with reference to analog electrical signal, n-1 drive test amount analog electrical signal with above-mentioned 1 tunnel reference signal, n-1 drive test amount signal;
The first filtering and modular converter carry out respectively the first filtering and analog to digital conversion to n-1 drive test amount analog electrical signal, and correspondence obtains n-1 drive test amount digital electric signal;
The second filtering and modular converter carry out the second filtering and analog to digital conversion to 1 the tunnel with reference to analog electrical signal, and correspondence obtains 1 road reference number electric signal;
FFT phase place reading module calculates n-1 drive test amount digital electric signal phasing degree and 1 road reference number electrical signal phase angle;
The displacement computing module according to n-1 drive test amount digital electric signal phasing degree and 1 road reference number electrical signal phase angle, calculates n-1 road displacement measurement;
The weighted stacking module is carried out real number ranking operation and additive operation with the n-1 road displacement measurement that obtains.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310231388.1A CN103322922B (en) | 2013-06-09 | 2013-06-09 | The optical heterodyne interference method of nonlinearity erron is eliminated based on fft algorithm |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310231388.1A CN103322922B (en) | 2013-06-09 | 2013-06-09 | The optical heterodyne interference method of nonlinearity erron is eliminated based on fft algorithm |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103322922A true CN103322922A (en) | 2013-09-25 |
| CN103322922B CN103322922B (en) | 2016-01-13 |
Family
ID=49191828
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201310231388.1A Expired - Fee Related CN103322922B (en) | 2013-06-09 | 2013-06-09 | The optical heterodyne interference method of nonlinearity erron is eliminated based on fft algorithm |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN103322922B (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5539520A (en) * | 1992-10-19 | 1996-07-23 | Dr. Johannes Heidenhain Gmbh | Interferometer using frequency modulation of the carrier frequency |
| CN101067546A (en) * | 2006-06-20 | 2007-11-07 | 哈尔滨工业大学 | Method and apparatus for reducing heterodyne interference nonlinear error first harmonic component |
| CN101893448A (en) * | 2010-07-16 | 2010-11-24 | 中国科学院长春光学精密机械与物理研究所 | Method for eliminating or reducing nonlinearity errors in laser heterodyne interferometry |
-
2013
- 2013-06-09 CN CN201310231388.1A patent/CN103322922B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5539520A (en) * | 1992-10-19 | 1996-07-23 | Dr. Johannes Heidenhain Gmbh | Interferometer using frequency modulation of the carrier frequency |
| CN101067546A (en) * | 2006-06-20 | 2007-11-07 | 哈尔滨工业大学 | Method and apparatus for reducing heterodyne interference nonlinear error first harmonic component |
| CN101893448A (en) * | 2010-07-16 | 2010-11-24 | 中国科学院长春光学精密机械与物理研究所 | Method for eliminating or reducing nonlinearity errors in laser heterodyne interferometry |
Non-Patent Citations (3)
| Title |
|---|
| 陈洪芳 等: "激光外差干涉的非线性误差补偿", 《光学精密工程》 * |
| 高宏堂 等: "单频纳米激光干涉仪非线性误差及其修正方法", 《计量学报》 * |
| 黎永前 等: "外差干涉非线性误差修正方法研究", 《西北工业大学》 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN103322922B (en) | 2016-01-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101936747B (en) | Method for eliminating fundamental waves and odd harmonics of nonlinear errors in wave detection method | |
| CN103364775B (en) | Optical frequency comb calibration-based dual-color laser scanning absolute distance measuring device and method | |
| CN104729402A (en) | High-optical-subdivision grating interferometer based on plane mirrors | |
| CN107063479B (en) | Minimum phase measurement system and method based on quantum weak measurement | |
| CN111538027B (en) | Laser ranging device and method for high-resolution measurement | |
| Martynov et al. | Quantum correlation measurements in interferometric gravitational-wave detectors | |
| CN105043243A (en) | Orthogonal homodyne laser interferometer and measurement method thereof | |
| CN106338333A (en) | High-robustness homodyne laser vibration measurer based on wave plate yawing and four-step adjustment method thereof | |
| CN201464160U (en) | System for measuring phase delay devices with different wavelengths by single wavelength light source | |
| CN104048617B (en) | Sensing modulating method for high-precision fiber bragg grating insensitive to polarization state changes | |
| CN103322926B (en) | Periodicity nonlinearity erron in signals transmission or interference inversion | |
| CN101738167A (en) | Resonant cavity frequency stabilization-based absolute distance measurement system and implementing method thereof | |
| CN103322923B (en) | The optical heterodyne interference method of nonlinearity erron is eliminated based on square wave mean value | |
| CN101017082A (en) | Nanometer precision real-time interferometric measurement device of object surface shape and measurement method therefor | |
| CN100593686C (en) | Optical interference measuring device and its method | |
| CN103322905B (en) | The optical heterodyne interference method of nonlinearity erron is eliminated based on two-stage or multistage resonant filtering | |
| CN103322906A (en) | Optical heterodyne interference method for removing non-linear error based on capacitance charging timing method | |
| CN103322904B (en) | Optical heterodyne interference method for eliminating non-linear errors based on resonant filtering method and inner product method | |
| CN103322903B (en) | Based on during C meter and the optical heterodyne interference method of the nonlinearity erron that disappears of multiple-stage filtering | |
| CN101629804B (en) | Common-path laser interferometer | |
| CN103322925B (en) | The optical heterodyne interference method of nonlinearity erron is eliminated based on phaselocked loop filter method | |
| CN103322922B (en) | The optical heterodyne interference method of nonlinearity erron is eliminated based on fft algorithm | |
| CN104655029B (en) | A kind of position phase reinforced membranes method for measuring thickness and system | |
| CN103322924B (en) | The optical heterodyne interference method of nonlinearity erron is eliminated based on timing counter algorithm | |
| CN103322907B (en) | Optical heterodyne interference method for eliminating non-linear errors based on inner product method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20160113 Termination date: 20170609 |