CN103163529B - Distance measuring system based on pseudo thermal light second-order relevance - Google Patents

Abstract

The invention discloses a distance measuring system based on pseudo thermal light second-order relevance. The distance measuring system based on the pseudo thermal light second-order relevance comprises a pseudo thermal light source, a beam splitter, a detection module, a transmitting device, a receiving device and a distance measuring module, wherein the distance measuring module measures distance by using a distance measuring method in accordance with measurement and curve fitting. The distance measuring system based on the pseudo thermal light second-order relevance has the characteristics of high accuracy and high environmental interference resistance, remote and high-accuracy distance measurement can be realized, and measurement dead zones are eliminated.

Description

Based on the range measurement system of counterfeit thermo-optical double velocity correlation

Technical field

The present invention relates to a kind of continuous light association range measurement system, particularly relate to a kind of range measurement system based on counterfeit thermo-optical double velocity correlation.

Background technology

Continuous light association range finding is based on continuous light ranging technology and corresponding technology, has acted on the features such as laser ranging monochromaticity goes with coherence, high directivity, and has had the characteristic of corresponding technology environment resistant interference.Common continuous light association range finding comprises ranging phase method, pseudo-random code ranging, interfere type range finding and chaos laser range-measurement.

The phase place change that Laser Range Finding Based on Phase is produced by measurement continuous print modulation signal roundtrip propagation on testing distance carrys out the measured signal travel-time indirectly, thus tries to achieve tested distance.Laser Range Finding Based on Phase system is the frequency with radio wave band, carry out amplitude modulation(PAM) to laser beam and measure light modulated coming and going once the produced phase delay of survey line, again according to the wavelength of light modulated, the distance converted representated by this phase delay, namely determines laser by indirect method and comes and goes time needed for target.Ranging phase method has high-precision specific, generally can reach millimetre-sized precision, but has cyclophysis due to phase place, thus Laser Range Finding Based on Phase to be not suitable for detection remote.

Pseudo-random code laser ranging is modulated in the amplitude change of laser by pseudo-random code by amplitude modulator, then at receiving end, echoed signal and local reference signal directly carried out related operation, obtains the travel-time and convert obtaining distance.Its distance accuracy is determined by pseudo-random code spreading rate, and namely spreading rate is higher, and distance accuracy is higher.But randomizer at a high speed is generally difficult to the speed more than 1Gbps, so pseudo-random code precision of laser ranging is generally limited in more than 10cm.

Interfere type range finding is also a kind of ranging phase method in principle, but it is not the phase differential by measuring laser modulation signal, but the phase place superposition relation (interference) measuring the light wave of non-modulated itself is found range.Because the wavelength of light is extremely short. particularly the monochromaticity of laser is high, and its wavelength value is very accurate, so the resolution utilizing interferometric method to find range is at least half-wavelength, precision is micron order, and interferometric method range finding has the high characteristic of precision.But interferometric method range finding can only measure relative distance, and will carry out absolute interferometry in long distance, the discriminating of ambiguity is extremely important but very difficult, so interferometric method range finding is not suitable for the range finding of long distance.

Chaos laser range-measurement originates from the class impulse function characteristic utilizing chaotic signal correlation curve carefully sharp, first the people such as K.Myneni proposed to utilize chaotic laser light pulse train to carry out range finding research in calendar year 2001, the chaotic laser light pulse train that they utilize light feedback semiconductor laser to produce achieves the range observation of target, but the bandwidth of detectable signal limits its distance accuracy.Subsequently through the large quantity research of scholar, in chaotic distance-testing, obtain the distance accuracy of 6cm at present.

Therefore, those skilled in the art be devoted to exploitation one can realize remote, high-precision range measurement system.

Summary of the invention

Because the above-mentioned defect of prior art, technical matters to be solved by this invention is to provide one can realize remote, high-precision range measurement system.The present invention proposes a kind of range measurement system based on counterfeit thermo-optical double velocity correlation.Compare with existing continuous light ranging technology, the range measurement system based on counterfeit thermo-optical double velocity correlation that the present invention proposes has very large advantage, owing to can calculate the theoretical formula of the double velocity correlation curve of counterfeit thermo-optical field, the method that have employed curve can promote its precision greatly; Secondly because counterfeit thermo-optical field double velocity correlation curve has unimodal characteristic, there is not the dead band of any measurement in it; Finally owing to adopting the mode of single photon detection and correlation measurement, this system has good environment resistant interference characteristic for neighbourhood noise.

The object of the invention is to, for the blank using the range finding of counterfeit thermo-optical, propose a kind of range measurement system based on counterfeit thermo-optical double velocity correlation completely newly, the high precision that this system has, without blind area and environmental interference resistance.

For achieving the above object, the technical solution used in the present invention is as follows:

The invention provides a kind of range measurement system based on counterfeit thermo-optical double velocity correlation, comprise counterfeit thermal light source module, beam splitter, detecting module, emitter, receiving trap and range finder module, described detecting module comprises the first detector, the second detector, wherein, described counterfeit thermal light source module sends light beam, described light beam is divided into two-way through described beam splitter, and wherein a road is received by described first detector; Lead up to described emitter collimator and extender irradiate target object in addition, the reflection echo light beam of described target object is received by described receiving trap, and is input to described second detector; Described first detector exports the photoimpact of reference signal, described second detector exports the photoimpact of measuring-signal, the photoimpact of described reference signal and the photoimpact of measuring-signal are sent to described range finder module, and described range finder module exports the distance of the relatively described range measurement system of described target object.

Wherein, described range finder module adopts coincidence measurement algorithm and curve fitting algorithm, the output of described first detector and described second detector is carried out burst coincidence counting and obtains the sample point of counterfeit thermo-optical double velocity correlation curve by described coincidence measurement algorithm, the a series of sample point matchings obtained of described coincidence measurement algorithm to be become a smooth curve by the theoretical formula of counterfeit thermo-optical field by described curve fitting algorithm, and export the distance of the relatively described range measurement system of described target object, the precision of this range measurement system is significantly promoted by described curve fitting algorithm.Preferably, described sample point is 2000 sample points.

Further, the time that the photoimpact of described reference signal and the photoimpact of measuring-signal arrive described range finder module is respectively t ₁and t ₂, described distance is L, can be expressed as: c is the speed that light is propagated.

Further, described counterfeit thermal light source module comprises adjustable attenuator, lens, frosted glass, pin hole; The semiconductor laser being 780nm by wavelength sends continuous laser first through described adjustable attenuator, then through described lens, converge to the surface of described frosted glass, described frosted glass rotates, laser produces counterfeit thermo-optical by the frosted glass of described rotation, and described counterfeit thermo-optical is exported by described pin hole, described pin hole implementation space filtering, make described counterfeit thermo-optical by having identical spatial character after described pin hole, to reduce the impact of space correlation on time correlation.

Further, the frosted glass of described rotation, by motor driving, regulates described motor rotary speed can change the rotational angular velocity of described frosted glass, thus accelerates or reduce the linear velocity at hot spot place, frosted glass surface.

Further, described detecting module also comprises device light beam being carried out to filtering and coupling, the device of described filtering and coupling has two-way, described counterfeit thermal light source module sends light beam, described light beam is divided into two-way through described beam splitter, and wherein a road is received by described first detector through described filtering and coupling device Zhong mono-tunnel; Lead up to described emitter collimator and extender irradiate target object in addition, described target object reflection echo light beam is received by described receiving trap, and another road in described filtering and coupling device is input to described second detector; The output of described first detector is as reference signal, and the output of described second detector is as measuring-signal.

More one step ground, in order to reduce the impact of background radiation on result of detection, it is 780 ± 2nm that the device of described filtering and coupling have employed centre wavelength, and bandwidth is 10 ± 2nm, peak transmittance is minimum be 50% narrow-band interference filter plate carry out filtering.

Further, described detecting module also comprises high speed acquisition circuit, and the output of described first detector and the second detector arrives the time of described range finder module through the photoimpact of reference signal described in described high speed acquisition circuit record and the photoimpact of measuring-signal.

Further, described high speed acquisition circuit temporal resolution is 1ps.

Further, described coincidence measurement algorithm is for each label value to add time delay τ in measuring-signal time series label ₀+ i τ, choose the time tag sequence of reference signal as benchmark, in Reference Signal time tag sequence, each time tag is as the mid point of a time interval, and the length of time interval is and meets gate-width, and in the time interval of each reference signal, search has time delay τ ₀the time tag of the measuring-signal of+i τ, if there is the time tag of measuring-signal to fall in interval, then note meets number and adds one; After having searched for all time tags in signal road, namely obtain time delay τ ₀several n (τ) is met under+i τ, and according to equation calculate this time delay τ ₀normalized time second order coherence function g under+i τ ⁽²⁾(τ), complete an according calculation, namely obtain a sample point, the value of adjustment i, calculates all sample points.

Further, wherein τ ₀for measuring starting point, value-4us, i are sample point number, i:0 ~ 1999, τ value 4ns.

Further, the described counterfeit thermo-optical field theory formula that described curve fitting algorithm adopts is: $g^{\left(2\right)}\left(\mathrm{\τ}\right)=1+{\left(\frac{f}{1+f}\right)}^2{e}^{-{(\mathrm{\τ}-\mathrm{\Δ\τ})}^2/p^2}+\frac{2f}{{(1+f)}^2}{e}^{-{(\mathrm{\τ}-\mathrm{\Δ\τ})}^2/q^2}$ In formula, f is described counterfeit thermo-optical and coherent states field light intensity ratio, and p is the live width parameter of described counterfeit thermo-optical, and q is described coherent light live width parameter; Δ τ is the position of secondorder correlation function peak value, and τ is function variable, dependent variable g ⁽²⁾(τ) different values is had according to the different values of time delay τ.

Be described further below with reference to the technique effect of accompanying drawing to design of the present invention, concrete structure and generation, to understand object of the present invention, characteristic sum effect fully.

Accompanying drawing explanation

Fig. 1 is the structural representation of the range measurement system based on counterfeit thermo-optical double velocity correlation of a preferred embodiment of the present invention.

Fig. 2 is the structural representation of the range measurement system based on counterfeit thermo-optical double velocity correlation of another preferred embodiment of the present invention.

Embodiment

As shown in Figure 1, in a preferred embodiment of the present invention, range measurement system based on counterfeit thermo-optical double velocity correlation comprises counterfeit thermal light source module, beam splitter, detecting module, emitter, receiving trap and range finder module, described detecting module comprises the first detector, the second detector, wherein, described counterfeit thermal light source module sends light beam, and described light beam is divided into two-way through described beam splitter, and wherein a road is received by described first detector; Lead up to described emitter collimator and extender irradiate target object in addition, described target object reflection echo light beam is received by described receiving trap, and is input to described second detector; The output of described first detector is as reference signal photon, the output of described second detector is as measuring-signal photon, the output of described first detector and the output of described second detector are sent to described range finder module, and described range finder module exports the distance of the relatively described range measurement system of described target object.

In the present embodiment, the coincidence measurement algorithm thinking of range finder module is: in a road time series label, each label value adds certain time delay τ, choose the time tag sequence on an other road as benchmark, using wherein each time tag as the mid point of a time interval, and the length of time interval is and meets gate-width.In each time interval, search has the time tag on that road of time delay τ, if free label falls in interval, then note meets number and adds one.After having searched for all time tags in signal road, namely obtain meeting several n (τ) under certain time delay τ, and according to equation normalized time second order coherence function g under calculating this time delay τ ⁽²⁾(τ) according calculation, is completed.Adjustment time delay τ recalculates and meets number, re-starts according calculation, until meet the sample points needed for curve.

Adopt curve fitting algorithm calculate amount of delay Δ τ corresponding to peak value by, the counterfeit thermo-optical field that rotating ground glass is formed has following secondorder correlation function expression formula: $g^{\left(2\right)}\left(\mathrm{\τ}\right)=1+{\left(\frac{f}{1+f}\right)}^2{e}^{-{(\mathrm{\τ}-\mathrm{\Δ\τ})}^2/p^2}+\frac{2f}{{(1+f)}^2}{e}^{-{(\mathrm{\τ}-\mathrm{\Δ\τ})}^2/q^2}$ In formula, f is thermo-optical and coherent states field light intensity ratio, and p is thermo-optical live width parameter, and q is coherent light live width parameter; Δ τ is the position of secondorder correlation function peak value; Select above formula as treating fitting function, according to the discrete sample point meeting algorithm and obtain, pass through fitting algorithm, the value of amount of delay Δ τ can be simulated, adopt data fitting algorithms, the temporal resolution of system final resolution programmable single-chip system front end single-photon detector, significantly improves system performance.

As shown in Figure 2, wherein, described counterfeit thermal light source module comprises adjustable attenuator, lens, frosted glass, pin hole; The semiconductor laser being 780nm by wavelength sends continuous laser first through described adjustable attenuator, then through described lens, converge to the surface of described frosted glass, described frosted glass rotates, laser beam produces counterfeit thermo-optical by the frosted glass of described rotation, and described counterfeit thermo-optical is exported by described pin hole, described pin hole implementation space filtering, make described counterfeit thermo-optical by having identical spatial character after described pin hole, to reduce the impact of space correlation on time correlation.Laser instrument selects wavelength to be the continuous laser of 780nm, and the frosted glass through being converged to High Rotation Speed after overdamping accurately by one group of lens obtains required counterfeit thermo-optical.The radius wherein choosing frosted glass is 9cm, its rotating speed 10 revolution per second.Subsequently, the counterfeit thermo-optical produced is after being placed on the pin hole after frosted glass, by the beam splitter of a 50:50, light beam is divided into measuring-signal photon and reference signal photon two-way, and be coupled to respectively in Transmission Fibers, the single-photon detector of band optical fiber pigtail is utilized to collect two-way photon, and be the high speed acquisition circuit record two-way photon time of arrival of 1ps by temporal resolution, the time series of generation is transferred to range finder module, and calculates distance according to algorithm.In the present embodiment, in order to reduce the impact of background radiation on result of detection, have employed centre wavelength is 780 ± 2nm, bandwidth is 10 ± 2nm, peak transmittance is minimum be 50% narrow-band interference filter plate carry out filtering, should ensure that flashlight impinges perpendicularly on narrow band filter slice surface for obtaining best filter effect, if when incident light incides optical filter surface with the angle of deflection, the wavelength corresponding to filter plate transmittance peak can be caused to move to short wavelength direction, and the shape of transmission wave band can change, obviously, the distortion of significantly change and the passband shapes of peak wavelength can cause transmitance in the free transmission range of design originally obviously to decline.

More than describe preferred embodiment of the present invention in detail.Should be appreciated that the ordinary skill of this area just design according to the present invention can make many modifications and variations without the need to creative work.Therefore, all technician in the art, all should in claims of the present invention under this invention's idea on the basis of existing technology by the available technical scheme of logical analysis, reasoning, or a limited experiment.

Claims (1)

1. the range measurement system based on counterfeit thermo-optical double velocity correlation, comprise counterfeit thermal light source module, beam splitter, detecting module, emitter, receiving trap and range finder module, described detecting module comprises the first detector, the second detector, wherein, described counterfeit thermal light source module sends light beam, described light beam is divided into two-way through described beam splitter, and wherein a road is received by described first detector; Lead up to described emitter collimator and extender irradiate target object in addition, the reflection echo light beam of described target object is received by described receiving trap, and is input to described second detector; Described first detector exports the photoimpact of reference signal, described second detector exports the photoimpact of measuring-signal, the photoimpact of described reference signal and the photoimpact of measuring-signal are sent to described range finder module, and described range finder module exports the distance of the relatively described range measurement system of described target object;

Described detecting module also comprises device light beam being carried out to filtering and coupling, the device of described filtering and coupling has two-way, described counterfeit thermal light source module sends light beam, described light beam is divided into two-way through described beam splitter, and wherein a road is received by described first detector through described filtering and coupling device Zhong mono-tunnel; Lead up to described emitter collimator and extender irradiate target object in addition, described target object reflection echo light beam is received by described receiving trap, and another road in described filtering and coupling device is input to described second detector; The output of described first detector is as reference signal, and the output of described second detector is as measuring-signal;

It is 780 ± 2nm that the device of described filtering and coupling have employed centre wavelength, and bandwidth is 10 ± 2nm, peak transmittance is minimum be 50% narrow-band interference filter plate carry out filtering;

Described detecting module also comprises high speed acquisition circuit, and the output of described first detector and the second detector arrives the time of described range finder module through the photoimpact of reference signal described in described high speed acquisition circuit record and the photoimpact of measuring-signal;

Described range finder module adopts coincidence measurement algorithm and curve fitting algorithm, the output of described first detector and described second detector is carried out burst coincidence counting and obtains the sample point of counterfeit thermo-optical double velocity correlation curve by described coincidence measurement algorithm, the a series of sample point matchings obtained of described coincidence measurement algorithm to be become a smooth curve by the theoretical formula of counterfeit thermo-optical field by described curve fitting algorithm, and export the distance of the relatively described range measurement system of described target object;

The time that the photoimpact of described reference signal and the photoimpact of measuring-signal arrive described range finder module is respectively t ₁and t ₂, described distance is L, can be expressed as: c is the speed that light is propagated;

Described counterfeit thermal light source module comprises adjustable attenuator, lens, frosted glass, pin hole; The semiconductor laser being 780nm by wavelength sends continuous laser first through described adjustable attenuator, then through described lens, converge to the surface of described frosted glass, described frosted glass rotates, laser produces counterfeit thermo-optical by the frosted glass of described rotation, and described counterfeit thermo-optical is exported by described pin hole, described pin hole implementation space filtering, make described counterfeit thermo-optical by having identical spatial character after described pin hole, to reduce the impact of space correlation on time correlation;

The frosted glass of described rotation, by motor driving, regulates described motor rotary speed can change the rotational angular velocity of described frosted glass, thus accelerates or reduce the linear velocity at hot spot place, frosted glass surface;

Described coincidence measurement algorithm is for each label value to add time delay τ in measuring-signal time series label ₀+ i τ, choose the time tag sequence of reference signal as benchmark, in Reference Signal time tag sequence, each time tag is as the mid point of a time interval, and the length of time interval is and meets gate-width, and in the time interval of each reference signal, search has time delay τ ₀the time tag of the measuring-signal of+i τ, if there is the time tag of measuring-signal to fall in interval, then note meets number and adds one; After having searched for all time tags in signal road, namely obtain time delay τ ₀several n (τ) is met under+i τ, and according to equation calculate this time delay τ ₀normalized time second order coherence function g under+i τ ⁽²⁾(τ), complete an according calculation, namely obtain a sample point, the value of adjustment i, calculates all sample points; Wherein τ ₀for measuring starting point, i is sample point number;

The described counterfeit thermo-optical field theory formula that described curve fitting algorithm adopts is:

$g^{\left(2\right)}\left(\mathrm{\τ}\right)=1+{\left(\frac{f}{1+f}\right)}^2{e}^{-{(\mathrm{\τ}-\mathrm{\Δ\τ})}^2/p^2}+\frac{2f}{{(1+f)}^2}{e}^{-{(\mathrm{\τ}-\mathrm{\Δ\τ})}^2/q^2}$ In formula, f is described counterfeit thermo-optical and coherent states field light intensity ratio, and p is the live width parameter of described counterfeit thermo-optical, and q is described coherent light live width parameter; Δ τ is the position of secondorder correlation function peak value, and τ is function variable, dependent variable g ⁽²⁾(τ) different values is had according to the different values of time delay τ.