CN102692622A - Laser detection method based on dense pulses - Google Patents
Laser detection method based on dense pulses Download PDFInfo
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- CN102692622A CN102692622A CN2012101701692A CN201210170169A CN102692622A CN 102692622 A CN102692622 A CN 102692622A CN 2012101701692 A CN2012101701692 A CN 2012101701692A CN 201210170169 A CN201210170169 A CN 201210170169A CN 102692622 A CN102692622 A CN 102692622A
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Abstract
The invention relates to the field of laser detection, and discloses a laser detection method based on dense pulses. The laser detection method includes steps that a laser emits grouping detection laser pulses to detected targets, wherein the number of the grouping detection laser pulses is larger than or equal to one, and each group of detection laser pulses includes multiple dense pulses; a first photoelectric converter receives echo laser pulses of the detection laser pulses reflected by the detected targets and surrounding environment optical noises, converts the echo laser pulses and the optical noises into corresponding electric signals, wherein the echo laser pulses include information of the detected targets; a signal processor is used for processing the electric signals converted by a detection unit, highlighting the electric signals corresponding to the echo laser pulses according to the time interval among the dense pulses, suppressing electric noises generated by the electric signals corresponding to the optical noises and circuits, and finally acquiring information of the detected target according to the electric signals corresponding to the echo laser pulses. The laser detection method based on the dense pulses can suppress noises, highlight signals, increase signal to noise ratio and reduce the minimum detectable optical power.
Description
Technical field
The present invention relates to technical field of laser detection, relate in particular to a kind of laser acquisition method based on intensive pulse.
Background technology
The luminous power that the development of weak light detection device and corresponding weak signal treatment circuit thereof makes people to detect is more and more littler; The photomultiplier of some specification, avalanche photo diode (APD) can produce response to single photon; Thereby be applied to single photon detection (Wolfgang Becker.Advanced time-correlated single photon counting techniques [M] .2005; Berlin; Heidelberg:Springer Verlag Berlin Heidelberg), for the visible light of 500nm, corresponding single photon energy is 4 * 10
-19J, visible its detectable luminous energy is very little, thereby can be used for atomic weak photodetection.In practical application; When carrying out photodetection; Except flashlight got into photo-detector, the parasitic light of surrounding environment also can get under a lot of situation, and accurately record flashlight just needs that certain signal to noise ratio (S/N ratio) is arranged between flashlight and the parasitic light; Generally require its strength ratio to be greater than 5; This minimum optical power that just makes that detector can signals detected light depends on the luminous power of parasitic light to a great extent, and is in order to reduce the minimum detectable signal luminous power, to improve signal to noise ratio (S/N ratio), the simplest, directly way is exactly the power that improves the emissive power of flashlight or reduce parasitic light.Improve the emissive power of flashlight and can bring the increase of laser instrument volume and the increase of power consumption, thereby can not infinitely improve; Reducing noise light power can reduce to receive field angle or through design and the corresponding narrow band filter of laser instrument emission wavelength the light that gets into detector carried out Filtering Processing through the design to detector and corresponding optical antenna thereof, and the reception field angle of detector can not be very little, otherwise its survey will be very high to alignment request, and too small field angle can limit the flashlight that gets into detector; The bandwidth of wave filter can not be too narrow, and bandwidth is narrow more, and its transmitance is low more; In the time of the parasitic light decay, flashlight also can be decayed, and; Bandwidth is narrow more, makes more difficultly, and cost is also just high more; Very uneconomical, therefore, parasitic light power also can not infinitely reduce.
Adopt the time correlation Detection Techniques of multiple-pulse stack or the method for optical heterodyne detection can effectively improve signal to noise ratio (S/N ratio), reduce the minimum detectable signal luminous power, but these two kinds of methods all have limitation in practical application.
The method of multiple-pulse stack is to send out a pulse, launches next pulse again after receiving the echoed signal of direct impulse, and the needed time is longer; And be not suitable for the detection of very fast moving target, because when target travel, the degree of correlation of participating in each relevant signal pulse can descend; Relevant effect can reduce, and target speed is fast more, and relevant effect is poor more; When because mistiming between two signal pulses causing of target travel during greater than the time width of pulse itself; Can't carry out time correlation (Hu Guangshu. digital signal processing--theoretical, algorithm and realization (second edition) [M], 2003, Beijing: publishing house of Tsing-Hua University: 33-38).This is because the temporal correlation of return laser beam depends primarily on the interval of adjacent pulse, and the temporal correlation of adjacent pulse signal is from transmit the relatively mistiming Δ t of (main ripple) of adjacent two laser pulse echoed signals
0Confirm, satisfy:
In the formula, V is the line-of-sight distance pace of change of target relative measurement point, T
PBe the time interval of adjacent two laser pulses, c is the light velocity, Δ t
0Value mainly be subject to the width (being generally 15ns) of exploring laser light, can know by (1) formula, as Δ t
0When confirming, the line-of-sight distance pace of change V of target relative measurement point and the time interval T of adjacent two laser pulses
PBetween be inversely proportional to T
PBig more, the speed V of the target that the mode of available multiple-pulse stack is measured is more little, reduces to measure the time interval T between the pulse
P, adopt the train of impulses technology, V is increased, but because the distance L between measurement point and the target is satisfied:
L＝cT
P (2)
Thus it is clear that, reduce to measure the time interval T between the pulse
PCan reduce the operating distance of laser acquisition accordingly; This mainly is because utilize in the laser measuring technique of train of impulses; " police guard at as entrance " LDMS in the US missile defense system (Wang Rongrui. U.S.'s missile defence laser radar technique [J]. laser and infrared, 1999,29 (5): what 263-266) adopt is that 3 laser pulses are formed a train of impulses; The time interval between the pulse is 8ms, can realize 100～1000 kilometers range findings; Also adopt 3 pulses to form a train of impulses in the train of impulses laser ranging technique that China Huabei (North China) Institute of Electro-Optics proposes; The recurrent interval of adopting in the experiment is 300～550us; Range finding distance farthest is that (stroke is far away for 112km; Li Songshan. train of impulses laser ranging technique research [J]. laser and infrared, 2006,36 (supplementary issues): 797-799).
The method of optical heterodyne detection is had relatively high expectations to the coherence of light; When laser transmitted in atmosphere, atmospheric turbulence effect can have a strong impact on the coherence of laser, therefore; It is restricted (Guo Peiyuan that the method that optical heterodyne detects is used in atmosphere; Pay poplar. photoelectric detecting technology and application (second edition) [M], 2011, Beijing: publishing house of BJ University of Aeronautics & Astronautics).
In addition; In the satellite laser ranging technology, can adopt the laser pulse (a few KHz) of high repetition frequency, the time interval between the laser pulse equates and between recording geometry and tested artificial satellite, comes and goes the needed time less than laser; In this method; Detecting laser continues to launch the laser pulse of high repetition to measured target, writes down the x time of each exploring laser light pulse, and detector detects the echo-pulse that is returned by target; The time of reception of record echo-pulse; Orbit according to artificial satellite calculates light round used time between sniffer and measured target in advance, and according to confirming the exploring laser light pulse corresponding with each echo-pulse this computing time, the corresponding time of reception of basis and x time obtain the range information of tested artificial satellite again.Compare with traditional laser ranging that is lower than 10Hz; High Repetition Frequency Laser range finding has increased the echo data amount greatly; And then increased substantially measuring accuracy, but the computed range of satellite with respect to recording geometry known in the requirement of this detection method in advance, could judge corresponding (DEGNAN J J.Satelite laser ranging in the 1990 ' s:report of the 1994 belmont workshop [R] .Maryland:NASA with which transponder pulse of echo-pulse like this; Conference Publication; 1994:3283), in the satellite laser ranging, measured target is a cooperative target; The object run velocity survey is to the angular velocity of artificial satellite, and its influence to the echo laser pulse time interval is little.
To sum up, when utilizing the weak light detection device directly to carry out photodetection, because the influence of environment parasitic light, signal to noise ratio (S/N ratio) is lower; Though adopt the time correlation Detection Techniques of multiple-pulse stack or the method for optical heterodyne detection can improve signal to noise ratio (S/N ratio); Reduce the minimum detectable signal luminous power; But the time correlation Detection Techniques of multiple-pulse stack are unfavorable for the target of long-range detection rapid movement because the time interval between the adjacent exploring laser light pulse is too big, and that the method for optical heterodyne detection is influenced by atmospheric turbulence is bigger; The high Repetition Frequency Laser ranging technology that adopts in the satellite laser ranging need be known the computed range of measured target and measurement point in advance; If do not know that in advance distance or the computed range of measured target and time gap deviation are bigger, then can not utilize this method to obtain the range information of target, and high Repetition Frequency Laser direct impulse is to continue emission; The time interval between the adjacent direct impulse equates that measured target is a cooperative target.
Summary of the invention
The technical matters that (one) will solve
The technical matters that the present invention will solve is: the signal to noise ratio (S/N ratio) when how to improve Fast Moving Object to unknown distance and carrying out laser acquisition, reduce the minimum detectable luminous power, and detection method do not receive the influence of atmospheric turbulence, and adaptability is strong.
(2) technical scheme
In order to solve the problems of the technologies described above; The present invention provides a kind of laser acquisition method based on intensive pulse; Laser instrument is not to continue emission to the exploring laser light pulse of measured target emission, but the emission of dividing into groups, and can survey the noncooperative target of the rapid movement of unknown distance; And do not receive the influence of atmospheric turbulence, this method may further comprise the steps:
S1, detection signal generator control laser instrument are to the pulse of measured target emission grouping exploring laser light, and wherein, the group number of said exploring laser light pulse is more than or equal to 1;
S2, first photoelectric commutator receive the echo laser pulse of said exploring laser light pulse after said measured target reflection and reach the optical noise that is formed by surround lighting, and convert said echo laser pulse and said optical noise into corresponding electric signal;
S3, institute's electrical signal converted is handled, detected the corresponding echo electric pulse of said echo laser pulse, and confirm the said exploring laser light pulse corresponding with each said echo electric pulse, the said echo electric pulse of foundation obtains the letter of said measured target;
Comprise the time interval arrives the first photoelectric commutator required time through the measured target reflection from laser instrument less than light a plurality of laser pulses in each group exploring laser light pulse; The time interval between the adjacent said laser pulse is unfixing; Concrete numerical value confirms that according to actual needs said a plurality of laser pulses form one group of intensive pulse.
Preferably; Among the step S1, said laser instrument is once launched one group of said intensive pulse to said measured target, among the step S3; After said first photoelectric commutator received said echo laser pulse, next organized said intensive pulse to said laser instrument to said measured target emission again.
Preferably, among the step S1, said detection signal generator is when the said laser instrument of control is sending the exploring laser light pulse, and also the signal processor to execution in step S3 sends the reference signal that comprises each interpulse time interval information in the said intensive pulse; Perhaps
Among the step S1; Said laser instrument sends laser pulse, separates through spectroscope, a part of directive measured target; Form said exploring laser light pulse; A part is laser pulse as a reference, and said reference laser pulse forms said reference signal behind second photoelectric commutator, transfer to said signal processor processes.
Preferably; Step S3 is specially: in institute's electrical signal converted, the electric pulse that the difference that satisfies the time interval between the time interval and the corresponding adjacent exploring laser light pulse that said reference signal provides between the adjacent electric pulse is less than or equal to adjacent pulse time interval deviation tolerance limit is the echo electric pulse; Confirm the said exploring laser light pulse that each said echo electric pulse is corresponding according to time sequencing that transmits and receives or the time interval information between said echo electric pulse.
Preferably; Said adjacent pulse time interval deviation tolerance limit depends on the speed of related movement of said measured target with respect to said laser instrument and said first photelectric receiver; Said speed of related movement is big more, and said adjacent pulse time interval deviation tolerance limit is also big more.
Preferably, the characteristic information that comprises said measured target in the said echo laser pulse.
Preferably, the characteristic information of said measured target comprises that size, the distance apart from said laser instrument and said first photelectric receiver, movement velocity, acceleration, reflectivity, the reflectivity of measured target distribute and relative reflectance distributes.
Preferably; Among the step S2; Utilize first photoelectric commutator to convert said echo laser pulse and said optical noise into corresponding electric signal, and after said echo laser pulse handles through optical antenna and narrow band filter, converge to first photoelectric commutator again and change; Said reference laser pulse gets into second photoelectric commutator and converts corresponding reference signal into.
Preferably; Characterisitic parameter according to said first photoelectric commutator, said narrow band filter and said optical antenna; Calculate the peak power of individual pulse in the said echo laser pulse and arrive time of said first photoelectric commutator; According to said second photoelectric commutator and said spectroscopical characterisitic parameter calculate the exploring laser light pulse from said laser instrument through said measured target reflection arrive the required time of said first photoelectric commutator and each said echo laser pulse of receiving the ratio of the peak power of individual pulse in peak power and the corresponding said exploring laser light pulse of individual pulse, pass through the characteristic information that processing obtains measured target.
(3) beneficial effect
Technique scheme has following advantage: the laser acquisition method based on intensive pulse of the present invention; Compare with traditional time correlation optical detector technology, detection range only receives pulsegroup restriction at interval, does not receive the restriction of intensive pulse interval; Therefore; In the identical time, can realize the related operation of a plurality of intensive pulses, thereby save detection time significantly; In addition; Because the intensive burst length in the group is relevant not to be the mode that adopts simple pulse to superpose one by one, but each group is done as a whole being correlated with, and has improved the dirigibility of computing like this; Can make the echoed signal and the reference burst signal that detect carry out simple crosscorrelation; Also can advance processing such as horizontal lock, heterodyne amplification,, reduce the minimum detectable luminous power to improve signal to noise ratio (S/N ratio) to greatest extent to echoed signal.
Description of drawings
Fig. 1 is a method flow diagram of the present invention;
Fig. 2 is the sniffer synoptic diagram based on a kind of implementation of laser acquisition method of the present invention;
Fig. 3 is the distribution of pulses synoptic diagram based on a kind of implementation of laser acquisition method of the present invention;
Fig. 4 is the device synoptic diagram based on laser acquisition method measured target relative reflectance surface distributed of the present invention;
Fig. 5 is the distribution of pulses synoptic diagram based on laser acquisition method measured target relative reflectance surface distributed of the present invention.
Embodiment
Below in conjunction with accompanying drawing and embodiment, specific embodiments of the invention describes in further detail.Following examples are used to explain the present invention, but are not used for limiting scope of the present invention.
With reference to Fig. 1, Fig. 2 and Fig. 3 the laser acquisition method that the present invention is based on intensive pulse is described below; Laser instrument is not to continue emission to the exploring laser light pulse of target emission; But the emission of dividing into groups; The time interval between the exploring laser light pulse can equate also can be unequal, and measured target can also can be noncooperative target for cooperative target, and measured target can be unknown with respect to the distance of said laser instrument and said first photelectric receiver; Be applicable to the detection of fast-moving target, and do not receive the influence of atmospheric turbulence.
Fig. 1 is the process flow diagram of the laser acquisition method based on intensive pulse according to the invention, and the laser acquisition method that the present invention is based on intensive pulse comprises three steps:
S1, detection signal generator control laser instrument are to the pulse of measured target emission grouping exploring laser light, and wherein, the group number of exploring laser light pulse is more than or equal to 1.
S2, first photoelectric commutator receive the echo laser pulse of exploring laser light pulse after the measured target reflection and the optical noise of surrounding environment light formation; And convert echo laser pulse and optical noise into corresponding electric signal, comprise the information of measured target in the echo laser pulse;
S3, signal processor are handled the first photoelectric commutator electrical signal converted: the echo electric pulse that detects echo laser pulse correspondence according to the time interval between each pulse in the intensive pulse; And confirm the exploring laser light pulse corresponding with each echo electric pulse, obtain the information of measured target according to the echo electric pulse;
Wherein, comprise the time interval in each group exploring laser light pulse to arrive a plurality of laser pulses of first photoelectric commutator required time from laser instrument through the measured target reflection less than light, said a plurality of laser pulses form one group of intensive pulse.
The time interval between the intensive pulse of two adjacent groups is all identical, perhaps the time interval between the intensive pulse of part two adjacent groups identical, perhaps the time interval between the intensive pulse of all two adjacent groups is all inequality.
Each is organized in the intensive pulse, and the time interval between the adjacent laser pulse is all identical, perhaps the time interval between the adjacent laser pulse of part identical, perhaps the time interval between all adjacent laser pulses is all inequality.
Each number of organizing the laser pulse that comprises in the intensive pulse is all identical, and the number of the laser pulse that perhaps comprises in the intensive pulse of part group is identical, and it is inequality that perhaps each organizes the individual number average of the laser pulse that comprises in the intensive pulse.
Each energy of organizing each single laser pulse in the intensive pulse is all identical, and perhaps the energy of part single laser pulse is identical, and perhaps the energy of each single laser pulse is all inequality.
Sniffer synoptic diagram based on a kind of implementation of the laser acquisition method based on intensive pulse according to the invention is as shown in Figure 2, and corresponding distribution of pulses synoptic diagram is as shown in Figure 3.
According to the step that provides among Fig. 1; Detection signal generator 1 is according to the 2 emission grouping exploring laser light pulses 3 of the control of the direct impulse signal form shown in 12 laser instrument among Fig. 3 among Fig. 2; Send the reference signal that comprises exploring laser light pulse interval information to signal processor 9 simultaneously; Can comprise the transmitting optics antenna in the laser instrument 2, be used for reducing the angle of divergence of exploring laser light, each group direct impulse G in the direct impulse signal 12 among Fig. 3
iComprise a plurality of time intervals arrive first photoelectric commutator, 8 required times through measured target 4 reflections from laser instrument 2 less than light pulse C
j, form one group of intensive pulse 11, when once surveying; Exploring laser light pulse 3 can be one group of intensive pulse; Also can be the intensive pulses of many groups, direct impulse 3 be when organizing intensive pulse more, and each organizes the number of the laser pulse that comprises in the intensive pulse can be all identical; The number of the laser pulse that comprises in the intensive pulse that also can partly organize is identical, also can each to organize the individual number average of the laser pulse that comprises in the intensive pulse inequality; The time interval Δ G of the intensive pulse of two adjacent groups
iCan be all identical, time interval Δ G that also can the adjacent two groups of intensive pulses of part
iIdentical, time interval Δ G that also can the intensive pulse of all two adjacent groups
iAll inequality; Each organizes intensive pulse G
iIn, the time interval Δ C between adjacent two laser pulses
jCan be all identical, the time interval Δ C between also can adjacent two laser pulses of part
jIdentical, the time interval Δ C between also can all adjacent two laser pulses
jAll inequality; In addition, each is organized in the intensive pulse, and the energy of each single laser pulse can be all identical, and perhaps the part laser single-pulse energy is identical, and perhaps the energy of each single laser pulse is all inequality; For direct impulse 3 are situation of the intensive pulse of many groups, and laser instrument 2 is to one group of intensive pulse of measured target 4 emissions, and after first photoelectric commutator 8 received corresponding echo laser pulse, next organized intensive pulse to laser instrument 2 to measured target 4 emissions again.Exploring laser light pulse 3 after measured target 4 reflections, after echo laser pulse 5 passes through optical antenna 6 and narrow band filter 7, converges to photoelectric commutator 8 in Fig. 2; Simultaneously; The optical noise 51 that produces in the external environment also converges to photoelectric commutator 8, if the optical power density of echo laser pulse 5 is enough big, does not need 6 pairs of echo laser pulses 5 of optical antenna to assemble; Photoelectric commutator 8 also can normally be surveyed echo laser pulse 5, and then optical antenna 6 can remove; If in the response spectrum scope of photoelectric commutator 8; The luminous power of echo laser pulse 5 is much larger than the luminous power of ambient light noise 51; Or beyond the spectral range of echo laser pulse 5, the luminous power of ambient light noise 51 is very low, and then narrow band filter 7 can remove; It is thus clear that whether optical antenna 6 uses and will confirm according to actual conditions with narrow band filter 7.Photoelectric commutator 8 converts light signal (echo laser pulse and optical noise) into and transfers to signal processor 9 behind the electric signal and handle; The time interval between the exploring laser light pulse that signal processor 9 provides according to detection signal generator 1; And estimate the speed of related movement of measured target 4 with respect to said laser instrument and said first photelectric receiver; Size according to speed of related movement; Confirm adjacent pulse time interval deviation tolerance limit; And then the echo electric pulse in the electric signal after 8 conversions of judgement photoelectric commutator; And confirm the exploring laser light pulse corresponding with each echo electric pulse, concrete steps are: in institute's electrical signal converted, the electric pulse that the difference that satisfies the time interval between the time interval and the corresponding adjacent exploring laser light pulse that reference signal provides between the adjacent electric pulse is less than or equal to adjacent pulse time interval deviation tolerance limit is the echo electric pulse; If in the intensive pulse of exploring laser light of emission; The time interval of each laser pulse equates; Then can confirm and the pairing exploring laser light pulse of echo electric pulse according to the time sequencing that transmits and receives; Certainly; Also can confirm the exploring laser light pulse that each echo electric pulse is corresponding, for example can confirm the corresponding exploring laser light pulse of two echo electric pulses of head and the tail earlier, confirm the corresponding exploring laser light pulse of other echo electric pulses according to the time interval between two echo electric pulses of other echo electric pulses and this then according to the time interval information between the echo electric pulse; In intensive pulse; Unequal situation of the time interval between each pulse; Can certainly confirm and the pairing exploring laser light pulse of echo electric pulse according to the time sequencing that transmits and receives; Also can confirm the exploring laser light pulse that each echo electric pulse is corresponding according to the time interval information between the echo electric pulse; At this moment because the time interval between the adjacent echo electric pulse is different, therefore, directly just can confirm pairing exploring laser light pulse according to the time interval of adjacent echo electric pulse.
Obviously, can not be judged as the electric impulse signal that the electric pulse of echo electric pulse or the optical noise 51 that produces for external environment cause, or be the electrical noise that circuit itself produces, can ignore.Owing to contain the information of measured target 4 in the echo laser pulse 5, echo laser pulse 5 corresponding electric pulses are handled, obtain the information of measured target 4 among Fig. 2, show by display 10.
Be distributed as example to measure measured target surface relative reflectance below, set forth the laser acquisition method based on intensive pulse according to the invention.Present embodiment is not in order to limitation the present invention.All any modifications of within spirit of the present invention and principle, being made, be equal to replacement etc., all should be included within protection scope of the present invention.
Utilize device synoptic diagram that the relative reflectance of the laser acquisition method measured target based on intensive pulse according to the invention distributes with reference to figure 4; The corresponding distribution of pulses synoptic diagram that distributes based on the surperficial relative reflectance of the laser acquisition method measurement target based on intensive pulse according to the invention is with reference to figure 5, and measured target 4 is static with respect to sensing point.Among Fig. 4 in detection signal generator 1 control chart 4 laser instrument 2 launch one group of intensive pulse of laser according to the pulse signal form shown in 14 among Fig. 5.In the present embodiment, one group of intensive pulse of laser is adopted in the detection each time of every bit, wherein comprised six adjacent time intervals to arrive the laser pulses of 8 needed times of first photoelectric commutator from laser instrument 2 through measured target 4 reflection very much, be respectively C less than light
1, C
2, C
3, C
4, C
5And C
6, the time interval between the adjacent pulse equates, is Δ C; The single pulse energy of each laser pulse equates that 14 laser pulse sequence is divided into exploring laser light pulse 3 and reference laser pulse 12 among the laser instrument 2 emission shapes among Fig. 4 such as Fig. 5 behind spectroscope 11 '; Exploring laser light pulse 3 is in Fig. 4 after testee 4 reflection; Echo laser pulse 5 gets into photoelectric commutator 8 through optical antenna 6 and narrow band filter 7, and the distribution of pulses of said echo laser pulse 5 is shown among Fig. 5 15, and is corresponding with exploring laser light distribution of pulses 14; Each group echo laser pulse G ' comprises 6 laser pulses, is respectively C '
1, C '
2, C '
3, C '
4, C '
5And C '
6Interval between adjacent two laser pulses; Also be Δ C; When echo laser pulse 5 got into photoelectric commutator 8, the optical noise 51 that produces in the surrounding environment also got into photoelectric commutators 8 through optical antenna 6 and narrow band filter 7, and photoelectric commutator 8 converts light signal into and transfers to signal processor 9 behind the electric signal and handle; Reference laser pulse 12 gets into reference light electric transducer 13 '; Entering signal processor 9 is handled after converting electric signal into; Owing to know the splitting ratio of spectroscope 11 ' in advance, just can be known by inference the intensity of exploring laser light pulse 3 so by the intensity of reference laser pulse 12: in signal processor 9, the intensity of six electric pulses that reference laser pulse 12 is changed in reference light electric transducer 13 ' is judged; According to the characterisitic parameter of reference light electric transducer 13 ' obtain each reference laser pulse peak power (Jeff Hecht work. Jia Dongfang etc. translate. fiber optics [M]; Beijing: the People's Telecon Publishing House, 2004,333-338); The peak power of 6 reference laser pulses in the reference laser pulse 12 is calculated mean value; Obtain the average peak power of single light pulse, thus, obtain the average peak power of individual pulse in the exploring laser light pulse 3 again according to the splitting ratio of spectroscope 11 '.
Electric signal for photoelectric commutator 8 outputs; Signal processor 9 combines the time interval between the electric impulse signal that reference signal (also can replace with reference laser pulse 12) that detection signal generators 1 provide imports into photoelectric commutator 8 to calculate contrast; When time interval of the electric impulse signal that photoelectric commutator 8 imports into and the time interval between the reference signal pulse equate, when promptly equating with the pulse interval of exploring laser light pulse 3, then corresponding electric impulse signal is exactly the electric impulse signal of echo laser pulse 5 conversions; Correspondingly; Pulse interval and reference signal are unequal to be exactly the corresponding electric pulse of the optical noise that produces of surrounding environment 51 or the electrical noise of circuit itself, should be noted that in the present embodiment; Because in detection process; Relative distance between sniffer (all devices that comprise measured target 4 left sides among Fig. 4) and the measured target does not change, so the pulse interval of echo laser pulse 5 and the pulse interval of reference signal equate; If target is motion, then difference a little to some extent.After the electric impulse signals that echo laser pulse 5 is corresponding are confirmed out; Signal processor 9 is according to the intensity of the electric signal of photoelectric commutator 8 inputs, the light transfer characteristic parameter of photoelectric commutator 8; Calculate the light pulse of inciding photoelectric commutator 8 peak power (Jeff Hecht work. Jia Dongfang etc. translate. fiber optics [M]; Beijing: People's Telecon Publishing House; 2004; The size of the background noise that the certain transmitted spectrum scope that 333-338), has according to the transmitance of the peak power, the narrow band filter 7 that incide the light pulse of photoelectric commutator 8 and owing to narrow band filter 7 is then introduced calculates the peak power of the echo laser pulse 5 that incides narrow band filter 7.6 pairs of light of optical antenna have the effect of converging, and are used to strengthen the light signal that gets into photoelectric commutator 8, and its receiving aperture, transmitance and receiving angle scope are all influential to the effect of converging; According to these parameters, can by the laser pulse peaks power that gets into narrowband light filter 7 counter push away the laser pulse peaks power that obtains beam incident optical antenna 6 (Mao Dengsen, Zhang Jilong. the application [J] of weak laser radiation detection technology in laser warning equipment. the measuring technology journal; 2004; 18 (4): 373-376), the peak power to six all pulses averages again, obtains the average peak power of echo laser pulse individual pulse; Right with the average peak power ratio of the individual pulse of exploring laser light pulse; Can obtain the relative reflectance of the corresponding sensing point of measured target 4, because the purpose of present embodiment is the relative reflectance distribution of measurement target, therefore; As long as the position of adjustment incident light; Be in the vertical plane of paper measured target 4 to be scanned, just can obtain the surperficial relative reflectance distribution character of measured target 4, show by display 10.
Laser acquisition method based on intensive pulse of the present invention; Compare with traditional time correlation optical detector technology, detection range only receives pulsegroup restriction at interval, does not receive the restriction of intensive pulse interval; Therefore; In the identical time, can realize the related operation of a plurality of intensive pulses, thereby save detection time significantly; In addition; Because the intensive burst length in the group is relevant not to be the mode that adopts simple pulse to superpose one by one, but each group is done as a whole being correlated with, and has improved the dirigibility of computing like this; Can make the echoed signal and the reference burst signal that detect carry out simple crosscorrelation; Also can advance processing such as horizontal lock, heterodyne amplification,, reduce the minimum detectable luminous power to improve signal to noise ratio (S/N ratio) to greatest extent to echoed signal; Used 3 pulses as a train of impulses in the train of impulses laser ranging technique, can use laser pulse more than 4 and 4 in the method that the present invention proposes fully as one group of intensive pulse.
Laser acquisition method based on intensive pulse of the present invention, the optical heterodyne detection compared with techniques with traditional has workable; Can be in atmosphere advantages of application, traditional optical heterodyne detection technology relies on stronger to echo light frequency, phase place, polarization state; System's adjustment accuracy requirement is high, and poor operability is considered when laser transmits in atmosphere; Atmospheric turbulence effect can have a strong impact on the coherence of laser, and therefore, it is restricted that the method that optical heterodyne detects is used in atmosphere.Laser acquisition method based on intensive pulse of the present invention is carried out opto-electronic conversion earlier, and then electric signal is carried out heterodyne handle, and has the heterodyne amplification equally, but the coherence of light is no longer done requirement, therefore, can be used for the detection of atmosphere target.
Laser acquisition method based on intensive pulse of the present invention; Compare with high Repetition Frequency Laser range finding in the satellite laser ranging technology; Need not foresee the computed range between measured target and the measurement point (can think said laser instrument and said first photelectric receiver); Just need not estimate the distance of measured target; Can directly use method proposed by the invention that target is found range, widen the range finding range of application, particularly find range for the target of unknown distance; High Repetition Frequency Laser distance-finding method in the satellite laser ranging can't use, and the laser distance measurement method based on intensive pulse that the present invention proposes can normally use.
The above only is a preferred implementation of the present invention; Should be pointed out that for those skilled in the art, under the prerequisite that does not break away from know-why of the present invention; Can also make some improvement and replacement, these improvement and replacement also should be regarded as protection scope of the present invention.
Claims (9)
1. the laser acquisition method based on intensive pulse is characterized in that, may further comprise the steps:
S1, detection signal generator control laser instrument are to the pulse of measured target emission grouping exploring laser light, and wherein, the group number of said exploring laser light pulse is more than or equal to 1;
S2, first photoelectric commutator receive the echo laser pulse of said exploring laser light pulse after said measured target reflection and reach the optical noise that is formed by surround lighting, and convert said echo laser pulse and said optical noise into corresponding electric signal;
S3, institute's electrical signal converted is handled, detected the corresponding echo electric pulse of said echo laser pulse, and confirm the said exploring laser light pulse corresponding with each said echo electric pulse, the said echo electric pulse of foundation obtains the information of said measured target;
Wherein, Comprise the time interval arrives the first photoelectric commutator required time through the measured target reflection from laser instrument less than light a plurality of laser pulses in each group exploring laser light pulse; The time interval between the adjacent said laser pulse is unfixing, and said a plurality of laser pulses form one group of intensive pulse.
2. the method for claim 1; It is characterized in that; Among the step S1, said laser instrument is once launched one group of said intensive pulse to said measured target, among the step S3; After said first photoelectric commutator received said echo laser pulse, next organized said intensive pulse to said laser instrument to said measured target emission again.
3. the method for claim 1; It is characterized in that; Among the step S1; Said detection signal generator is when the said laser instrument of control is sending the exploring laser light pulse, and also the signal processor to execution in step S3 sends the reference signal that comprises each interpulse time interval information in the said intensive pulse; Perhaps
Among the step S1; Said laser instrument sends laser pulse, separates through spectroscope, a part of directive measured target; Form said exploring laser light pulse; A part is laser pulse as a reference, and said reference laser pulse forms said reference signal behind second photoelectric commutator, transfer to said signal processor processes.
4. method as claimed in claim 3; It is characterized in that; Step S3 is specially: in institute's electrical signal converted, the electric pulse that the difference that satisfies the time interval between the time interval and the corresponding adjacent exploring laser light pulse that said reference signal provides between the adjacent electric pulse is less than or equal to adjacent pulse time interval deviation tolerance limit is the echo electric pulse; Confirm the said exploring laser light pulse that each said echo electric pulse is corresponding according to time sequencing that transmits and receives or the time interval information between said echo electric pulse.
5. method as claimed in claim 4; It is characterized in that; Said adjacent pulse time interval deviation tolerance limit depends on the speed of related movement of said measured target with respect to said laser instrument and said first photelectric receiver; Said speed of related movement is big more, and said pulse interval deviation tolerance limit is also big more.
6. the method for claim 1 is characterized in that, comprises the characteristic information of said measured target in the said echo laser pulse.
7. method as claimed in claim 6; It is characterized in that the characteristic information of said measured target comprises that the size of measured target, the distance apart from said laser instrument and said first photelectric receiver, movement velocity, acceleration, reflectivity, reflectivity distribute and relative reflectance distributes.
8. the method for claim 1; It is characterized in that; Among the step S2; Utilize said first photoelectric commutator to convert said echo laser pulse and said optical noise into corresponding electric signal, and after said echo laser pulse handles through optical antenna and narrow band filter, converge to said first photoelectric commutator again and change; Said reference laser pulse gets into second photoelectric commutator and converts corresponding reference signal into.
9. method as claimed in claim 8; It is characterized in that; Characterisitic parameter according to said first photoelectric commutator, said narrow band filter and said optical antenna; Calculate the peak power of individual pulse in the said echo laser pulse and arrive time of said first photoelectric commutator; According to said second photoelectric commutator and said spectroscopical characterisitic parameter calculate the exploring laser light pulse from said laser instrument through said measured target reflection arrive the required time of said first photoelectric commutator and each said echo laser pulse of receiving the ratio of the peak power of individual pulse in peak power and the corresponding said exploring laser light pulse of individual pulse, pass through the characteristic information that processing obtains measured target.
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